Patent Publication Number: US-11654086-B2

Title: Pressure-regulating vial adaptors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. Nonprovisional application Ser. No. 17/149,165, filed Jan. 14, 2021, titled PRESSURE-REGULATING VIAL ADAPTORS, which is a continuation of U.S. Nonprovisional application Ser. No. 16/418,008, filed May 21, 2019, and issued as U.S. Pat. No. 10,918,573 on Feb. 16, 2021, titled PRESSURE-REGULATING VIAL ADAPTORS, which is a continuation of U.S. Nonprovisional application Ser. No. 15/476,566, filed Mar. 31, 2017, and issued as U.S. Pat. No. 10,299,989 on May 28, 2019, titled PRESSURE-REGULATING VIAL ADAPTORS, which is a continuation of U.S. Nonprovisional application Ser. No. 14/488,856, filed Sep. 17, 2014, and issued as U.S. Pat. No. 9,610,217 on Apr. 4, 2017, titled PRESSURE-REGULATING VIAL ADAPTORS, which claims the benefit of under 35 U.S.C. § 120 and 35 U.S.C. § 365(c) as a continuation of International Application No. PCT/US2013/033183, designating the United States, with an international filing date of Mar. 20, 2013, titled PRESSURE-REGULATING VIAL ADAPTORS, which claims the benefit of U.S. Provisional Application No. 61/614,250, filed Mar. 22, 2012, titled PRESSURE-REGULATING VIAL ADAPTORS, U.S. Provisional Application No. 61/684,095, filed Aug. 16, 2012, titled PRESSURE-REGULATING VIAL ADAPTORS, U.S. Provisional Application No. 61/705,988, filed Sep. 26, 2012, titled PRESSURE-REGULATING VIAL ADAPTORS, U.S. Provisional Application No. 61/755,800, filed Jan. 23, 2013, titled PRESSURE-REGULATING VIAL ADAPTORS, and U.S. Provisional Application No. 61/785,874, filed Mar. 14, 2013, titled PRESSURE-REGULATING VIAL ADAPTORS. The entire contents of each of the above-identified patent applications are incorporated by reference herein and made a part of this specification for all that they disclose. Any and all priority claims identified in the Application Data Sheet, or any correction thereto, are hereby incorporated by reference under 37 CFR § 1.57. 
    
    
     BACKGROUND 
     Field 
     Certain embodiments disclosed herein relate to adaptors for coupling with medicinal vials, and components thereof, and methods to contain vapors and/or to aid in regulating pressures within medicinal vials. 
     Description of Related Art 
     It is a common practice to store medicines or other medically related fluids in vials or other containers. In some instances, the medicines or fluids so stored are therapeutic if injected into the bloodstream, but harmful if inhaled or if contacted by exposed skin. Certain known systems for extracting potentially harmful medicines from vials suffer from various drawbacks. 
     SUMMARY 
     In some embodiments, an adaptor is configured to couple with a sealed vial and includes a housing apparatus. In some instances, the housing apparatus includes a distal extractor aperture configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In certain cases, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. The adaptor can also include an enclosure, such as a regulator enclosure, in fluid communication with the regulator channel. In some configurations, the regulator enclosure is configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when a fluid is withdrawn from the sealed vial via the extractor channel. Further, the adaptor can include a volume component, such as a filler, disposed within the regulator enclosure. The filler need not fill the entire enclosure. In some embodiments, the volume occupied or encompassed by the filler can be less than the majority of the interior volume of the enclosure, or at least the majority of the interior volume of the enclosure, or substantially all of the interior volume of the enclosure. In some instances, the filler is configured to ensure an initial volume of regulator fluid within the regulator enclosure, thereby permitting the adaptor to supply regulator fluid to the sealed vial from the regulator enclosure when fluid is withdrawn from the sealed vial via the extractor aperture. 
     In certain configurations, the adaptor is configured such that the regulator enclosure is outside the sealed vial when the adaptor is coupled with the sealed vial. In some cases, at least a majority of the volume of the regulator enclosure is not within a rigid housing or at least a substantial portion of the regulator enclosure is not within a rigid housing. 
     In certain instances, the housing apparatus comprises a medical connector interface in fluid communication with the extractor channel and is configured to couple with a syringe configured to hold a defined volume of fluid within a barrel. In some such cases, the filler is configured to ensure that the initial volume of regulator fluid is greater than or equal to the defined volume of fluid. In certain of such cases, the initial volume of regulator fluid within the regulator enclosure is greater than or equal to about 60 mL. In some embodiments, the regulator enclosure is configured to hold a maximum volume of regulator fluid when the regulator enclosure is fully expanded or unfolded, wherein the maximum volume is greater than or equal to about 180 mL. 
     In some embodiments, the regulator enclosure is constructed from a material system including a film, such as a polyethylene terephthalate film. In some instances, the film includes a metalized coating or metal component. For example, in some cases, the metalized coating comprises aluminum. 
     In certain embodiments, the pressure regulating vial adaptor includes a piercing member connected to the housing apparatus, and the enclosure is at least partially disposed within the piercing member. In some configurations, the pressure within the sealed vial is regulated by permitting the regulator enclosure to contract or fold in order to substantially equilibrate pressure on opposite sides of the regulator enclosure as the medicinal fluid is withdrawn from the sealed vial. In some instances, the regulator enclosure comprises a layer that is substantially impermeable to a medicinal fluid disposed within the vial, thereby impeding the passage of the medicinal fluid between an outer surface and an inner surface of the regulator enclosure. 
     In various embodiments, the adaptor further includes a hydrophobic filter disposed between the regulator enclosure and a distal regulator aperture. The hydrophobic filter can be configured to permit regulator fluid to flow between the regulator enclosure and the vial when the adaptor is coupled with the vial. In some arrangements, the hydrophobic filter is disposed within the regulator channel, which is itself disposed between the distal regulator aperture and the regulator enclosure. The filter can, for example, be a foamed material. For instance, in some configurations, the filler is made of polyurethane-ether foam. 
     In some embodiments, a method of withdrawing fluid from a sealed vial includes connecting a pressure regulating vial adaptor to the sealed vial, and withdrawing fluid from the sealed vial through the pressure regulating vial adaptor. In certain aspects, the pressure regulating vial adaptor includes a housing apparatus including a distal extractor aperture. In some cases, the distal extractor aperture is configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In certain instances, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. 
     In certain configurations, the pressure regulating vial adaptor also includes a regulator enclosure in fluid communication with the regulator channel. In some instances, the regulator enclosure is configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when a fluid is withdrawn from the sealed vial via the extractor channel. 
     In some embodiments, the pressure regulating vial adaptor further includes a filler disposed within the regulator enclosure. The filler can be configured to provide an initial volume of regulator fluid within the regulator enclosure, thereby permitting the adaptor to supply regulator fluid to the sealed vial from the regulator enclosure when fluid is withdrawn from the sealed vial via the extractor aperture. 
     In various embodiments, a method of manufacturing an adaptor for coupling with a sealed vial includes providing a housing apparatus including a distal extractor aperture. In some cases, the distal extractor aperture is configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In certain instances, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. 
     The method can also include disposing a filler within a regulator enclosure. The filler can be configured to ensure an initial volume of regulator fluid within the regulator enclosure, thereby permitting the adaptor to supply regulator fluid to the sealed vial from the regulator enclosure when fluid is withdrawn from the sealed vial via the extractor aperture. 
     In certain configurations, the method further includes placing the regulator enclosure in fluid communication with the regulator channel, such that the regulator enclosure is configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is less expanded or substantially or entirely unexpanded, or folded, when a fluid is withdrawn from the sealed vial via the extractor channel. 
     In some embodiments of the method, disposing the filler within a regulator enclosure includes forming or providing a fill opening in the regulator enclosure configured to allow the filler to pass therethrough, filling the regulator enclosure with the filler through the fill opening, and closing the fill opening. In certain embodiments of the method, placing the regulator enclosure in fluid communication with the regulator channel comprises aligning an enclosure opening in the regulator enclosure with a proximal regulator aperture of the housing apparatus, and fastening the regulator enclosure to the housing apparatus. 
     In various embodiments, an adaptor configured to couple with a sealed vial includes a housing apparatus including a distal extractor aperture configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In some cases, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. Also, the adaptor can include a regulator enclosure in fluid communication with the regulator channel. In some cases, the regulator enclosure is configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when a fluid is withdrawn from the sealed vial via the extractor channel. In certain embodiments, a rigid housing does not contain a substantial volume of the regulator enclosure. 
     In some embodiments, the regulator enclosure comprises a first side and a second side opposite the first side. In some instances, each of the first and second sides is configured to expand, contract, fold, or unfold as regulator fluid flows between the regulator channel and the regulator enclosure. In certain cases, the second side is configured to move away from the housing apparatus or towards the housing apparatus when regulator fluid passes through the regulator channel. In some cases, the first side comprises an inner surface forming a portion of the regulator enclosure interior and an outer surface forming a portion of the regulator enclosure exterior. In certain of such cases, the outer surface of the first side is oriented towards the housing apparatus. 
     In some embodiments, pressure within the sealed vial is regulated by allowing the regulator enclosure to contract or fold in order to substantially equilibrate pressure on opposite sides of the regulator enclosure as the medicinal fluid is withdrawn from the sealed vial. In some embodiments, the regulator enclosure comprises a layer that is substantially impermeable to a medicinal fluid disposed within the vial, thereby impeding the passage of the medicinal fluid between an outer surface and an inner surface of the enclosure. 
     The adaptor can further include a hydrophobic filter disposed between the regulator enclosure and a distal regulator aperture. The hydrophobic filter can be configured to permit regulator fluid to flow between the regulator enclosure and the vial when the adaptor is coupled with the vial. 
     The adaptor can also include a filler disposed within the regulator enclosure. The filler can be configured to ensure an initial volume of regulator fluid within the regulator enclosure, thereby permitting the adaptor to supply regulator fluid to the sealed vial from the regulator enclosure when fluid is withdrawn from the sealed vial via the extractor aperture. 
     In some embodiments, a vial adaptor configured to couple with a sealed vial includes a housing apparatus including a distal extractor aperture configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In some instances, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. In certain embodiments, the vial adaptor further includes a regulator enclosure in fluid communication with the regulator channel. In some cases, the regulator enclosure is configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when a fluid is withdrawn from the sealed vial via the extractor channel. 
     In some embodiments of the vial adaptor, the regulator enclosure has a first side and a second side generally opposite the first side. The first side can comprise an inner surface forming a portion of the regulator enclosure interior and an outer surface forming a portion of the regulator enclosure exterior. The outer surface of the first side can be oriented towards the housing apparatus. In some instances, each of the first and second sides is configured to expand, contract, fold, or unfold when regulator fluid, such as air, gas, or vapors, passes through the regulator channel. In certain configurations, the second side is configured to move away from the housing apparatus or towards the housing apparatus when regulator fluid passes through the regulator channel. In various cases, the regulator enclosure is not entirely contained within a rigid housing. 
     In some embodiments, a vial adaptor configured to couple with a sealed vial includes a housing apparatus including a distal extractor aperture configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In various configurations, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. In certain embodiments, the vial adaptor includes a regulator enclosure in fluid communication with the regulator channel and configured to receive a volume of regulating fluid. The regulator enclosure can be configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when a fluid is withdrawn from the sealed vial via the extractor channel. 
     In some embodiments, the regulator enclosure has a first layer connected with a second layer opposite the first layer. The first and second layers can be configured to receive the volume of regulating fluid therebetween. In certain configurations, each of the first and second sides is configured to expand, contract, fold, or unfold when regulator fluid passes through the regulator channel. In some instances, the second side is configured to move away from the housing apparatus or towards the housing apparatus when regulator fluid passes through the regulator channel. In some cases, the regulator enclosure is not entirely contained within a rigid housing. 
     In certain configurations, the first layer is made of a first sheet of material, and the second layer is made of a second sheet of material. In some instances, the first and second layers are connected at a periphery of the first and second layers. In some cases, the first and second layers each comprise a central portion, and the first and second layers are not connected at the central portions. 
     In some embodiments, a modular vial adaptor configured to couple with a sealed vial includes a pressure regulating vial adaptor module and a regulator fluid module. In some instances, the pressure regulating vial adaptor module includes a housing apparatus including a distal extractor aperture configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In certain cases, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. 
     The pressure regulating vial adaptor module can include a proximal regulator aperture in fluid communication with the regulator channel. In some configurations, the proximal regulator aperture is configured to permit ingress or egress of regulator fluid therethrough when the vial adaptor module is coupled with the sealed vial and fluid is withdrawn from the vial. 
     In certain instances, the regulator fluid module is configured to couple with the proximal regulator aperture and includes a regulator enclosure configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when regulator fluid passes through an enclosure opening in the regulator enclosure. 
     The regulator fluid module can include a fastener configured to couple the regulator enclosure with the proximal regulator aperture. In some instances, the regulator enclosure is not entirely contained within a rigid housing. In certain cases, the fastener includes a bonding member having first and second surfaces coated with adhesive. In some such cases, the bonding member is constructed from a material system comprising resilient material. 
     In some embodiments, the method of manufacturing a vial adaptor configured to couple with a sealed vial includes providing a pressure regulating vial adaptor module, and providing a regulator fluid module. The pressure regulating vial adaptor module can include a housing apparatus. The housing apparatus can include a distal extractor aperture configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In certain instances, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. 
     The pressure regulating vial adaptor module can include a proximal regulator aperture in fluid communication with the regulator channel. The proximal regulator aperture can be configured to permit ingress or egress of regulator fluid therethrough when the vial adaptor module is coupled with the sealed vial and fluid is withdrawn from the vial. 
     In some embodiments, the regulator fluid module includes a regulator enclosure. The regulator enclosure can be configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when regulator fluid passes through an enclosure opening in the regulator enclosure. The regulator fluid module can include a fastener configured to couple the regulator enclosure with the proximal regulator aperture. In some cases, the regulator enclosure is not entirely contained within a rigid housing. 
     The method can further include aligning the enclosure opening of the regulator enclosure with the proximal regulator aperture of the pressure regulating vial adaptor module. In certain embodiments, the method also includes fastening the regulator fluid module to the pressure regulating vial adaptor module. 
     In certain instances, the fastener comprises a bonding member having first and second surfaces coated with adhesive. In some such cases, the bonding member is constructed from a material system comprising resilient material. In some cases, the bonding member has a thickness greater than or equal to about 0.01 inches and less than or equal to about 0.03 inches. 
     In some embodiments, a regulator fluid module is configured to fasten to a pressure regulating vial adaptor module to form a vial adaptor for coupling with a sealed vial. The pressure regulating vial adaptor module can include a housing apparatus including a distal extractor aperture configured to permit withdrawal of fluid from the sealed vial when the adaptor is coupled to the sealed vial. In some cases, at least a portion of an extractor channel and at least a portion of a regulator channel pass through the housing apparatus. In certain instances, the housing apparatus also includes a proximal regulator aperture in fluid communication with the regulator channel. The proximal regulator aperture can be configured to permit ingress or egress of regulator fluid therethrough when the vial adaptor module is coupled with a sealed vial and fluid is withdrawn from the vial. 
     The regulator fluid module can include a regulator enclosure configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when regulator fluid passes through an enclosure opening in the regulator enclosure. 
     The regulator fluid module can include a filler within the regulator enclosure. The filler can be configured to supply an initial volume of regulator fluid within the regulator enclosure, thereby permitting the adaptor to supply regulator fluid to the sealed vial from the regulator enclosure when fluid is withdrawn from the sealed vial via the extractor aperture. 
     In various embodiments, the regulator fluid module includes a fastener configured to couple the regulator enclosure with the proximal regulator aperture such that the regulator fluid module is permitted to move small distances with respect to the pressure regulating vial adaptor module without causing the fastener to become ripped, torn, or otherwise damaged during routine manipulation of the vial adaptor. In some cases, the regulator enclosure is not entirely contained within a rigid housing. In certain configurations, the fastener substantially airtightly couples the regulator enclosure and the proximal regulator aperture. 
     In some embodiments, a method of manufacturing a modular adaptor for coupling with and regulating the pressure in a sealed vial includes forming a housing apparatus including a distal access aperture. The distal access aperture can be configured to permit transfer of fluid between a medical device and the sealed vial when the adaptor is coupled to the sealed vial. In some instances, at least a portion of an access channel and at least a portion of a regulator channel pass through the housing apparatus. The regulator channel can be in fluid communication with the sealed vial when the adaptor is coupled to the sealed vial. 
     The method can include connecting a coupling assembly such that the coupling assembly is in fluid communication with the regulator channel. The coupling assembly can include a membrane and a cover, which in turn can include an aperture. The coupling assembly can be configured to allow a flow of regulating fluid between the aperture and the regulator channel. In some instances, the flow of regulating fluid passes through the membrane. 
     In some embodiments, the method includes providing a regulator enclosure configured to be positioned in fluid communication with the aperture, such that the regulator enclosure is configured to move between a first orientation, in which at least a portion of the regulator enclosure is at least partially expanded or unfolded, and a second orientation, in which at least a portion of the regulator enclosure is at least partially unexpanded or folded, when a regulator fluid passes through an opening in the regulator enclosure. 
     In various cases, the method further includes selecting the regulator enclosure from a variety of sizes of regulator enclosures. In some embodiments, the selection can be based on the volume of the medicinal fluid to be withdrawn from the sealed vial. In some instances, the flow of regulating fluid passes between the aperture and the sealed vial when the medicinal fluid is withdrawn from the sealed vial via the access channel. In certain cases, the aperture is in fluid communication with ambient air prior to the regulator enclosure being positioned in fluid communication with the aperture. 
     In certain embodiments, a vial adaptor comprises a housing configured to couple the adaptor with a vial, an access channel, a regulator channel, and a regulator assembly. The access channel is configured to facilitate withdrawal of fluid from the vial when the adaptor is coupled to the vial. The regulator channel is configured to facilitate a flow of a regulating fluid from the regulator assembly to compensate for changes in volume of a medical fluid in the vial. In some embodiments, the regulator assembly includes a flexible member configured to expand and contract in accordance with changes in the volume of the medical fluid in the vial. In some embodiments, the flexible member is substantially free to expand and contract. In some embodiments, the flexible member is not partly or completely located in a rigid enclosure. In some embodiments, at least a majority of the flexible member is located in a rigid enclosure. In some embodiments, the regulator assembly includes a filter within the regulator channel. In some embodiments, the regulator assembly includes a check valve which can prevent liquid communication between a filter within the regulator channel and the vial. In some embodiments, the check valve can prevent liquid communication between the vial and a flexible member on the end of the regulator channel. 
     In some embodiments, a vial adaptor has an axial centerline and is configured to be used in an area with a floor. The vial adaptor can be configured to couple with a sealed vial. The vial adaptor can have a piercing member and an extractor channel, the extractor channel extending between a proximal extractor aperture and a distal extractor aperture and configured to permit withdrawal of fluid from the sealed vial when the vial adaptor is coupled to the sealed vial. In some variants, at least a portion of the extractor channel passes through at least a portion of the piercing member. The vial adaptor can include a regulator channel that extends between a proximal regulator aperture and a distal regulator aperture. In some embodiments, at least a portion of the regulator channel passes through at least a portion of the piercing member. 
     An occluder valve can be housed in the regulator channel and can be configured to transition between a closed configuration and an opened configuration in response to rotation of the vial adaptor about an axis of rotation between an upright position and an upside down position. In some configurations, the proximal extractor aperture is further from the floor than the distal aperture when the vial adaptor is in the upright position and the proximal extractor aperture is closer to the floor than the distal extractor aperture when the vial adaptor is in the upside down position. Furthermore, the occluder valve can inhibit passage of fluid past the occluder valve toward the proximal regulator aperture when the occluder valve is in the closed configuration. The axis of rotation can be perpendicular to the axial centerline of the vial adaptor and the manner in which the occluder valve transitions between the closed configuration and the opened configuration can be substantially independent of the axis of rotation about which the vial adaptor is rotated. 
     In certain cases, the occluder valve transitions to the closed configuration when the vial adaptor is rotated to the upside down position. Furthermore, in some certain cases, the occluder valve transitions to the opened configuration when the vial adaptor is rotated to the upright position. The occluder valve can have a generally cylindrical shape and an axial centerline. In some embodiments, the occluder valve is rotatable about the axial centerline of the occluder valve with respect to the regulator channel. 
     The vial adaptor can include a valve chamber in fluid communication with the regulator channel, an occluding member within the valve chamber, and a valve seat. In some embodiments, the occluder valve is configured to transition to the closed configuration upon engagement between the occluding member and the valve seat and is configured to transition to the opened configuration upon disengagement of the occluding member from the valve seat. In some cases, the occluding member moves within the valve chamber under the influence of gravity. The occluding member can be a spherical ball, have a cylindrical body with a tapered end, have an ellipsoidal shape, can have a generally cylindrical shape with an axial centerline, or can have some other suitable shape or combination of shapes. 
     In certain embodiments, the vial adaptor includes a filter. The filter can be positioned in the regulator channel between the occluder valve and the proximal regulator aperture. In some embodiments, the filter is a hydrophobic filter. 
     In some certain embodiments, a vial adaptor has an axial centerline and is configured to couple with a sealed vial. The vial adaptor can include a piercing member and an extractor channel. At least a portion of the extractor channel can pass through at least a portion of the piercing member. In some embodiments, the vial adaptor includes a regulator channel that can extend between a proximal regulator aperture and a distal regulator aperture, wherein at least a portion of the regulator channel passes through at least a portion of the piercing member. 
     The vial adaptor can include an occluder valve configured to be installed in at least a portion of the regulator channel via an installation path. The occluder valve can be further configured to transition between a closed configuration and an opened configuration. In some embodiments, the occluder valve includes a valve chamber in fluid communication with the regulator channel. The valve chamber can have an occluding member, a movement path for the occluding member, and a valve seat. In some embodiments, the occluder valve includes a valve channel in fluid communication with the valve chamber and the regulator channel, the valve channel having a flow path. The occluder valve can be configured to transition to the closed configuration when the occluding member is engaged with the valve seat. In some embodiments, the occluder valve is configured to transition to the opened configuration when the occluding member is disengaged from the valve seat. The angle formed between the movement path of the occluding member and the installation path of the occluder valve can be greater than 0° and less than 180°. In some embodiments, the movement path for the occluding member is not substantially parallel to the installation path of the occluder valve. 
     In some embodiments, the occluding member can be a spherical ball, have a cylindrical shape with one tapered end, have an ellipsoidal shape, or can have any other appropriate shape or combination of shapes. In some embodiments, the angle formed between the movement path of the occluding member and the installation path of the occluder valve is greater than about 45° and less than about 135°. In some embodiments, the angle formed between the movement path and the installation path is about 90°. The angle formed between the movement path and the installation path can be substantially the same as the angle formed between the axial centerline of the vial adaptor and the installation path. In some embodiments, the vial adaptor includes a filter in the regulator channel between the occluder valve and the proximal regulator aperture. The filter can be a hydrophobic filter. 
     A method of manufacturing a modular vial adaptor configured to couple with a sealed vial can include selecting a connector interface having an axial centerline. The connector interface can have a piercing member and an extractor channel, wherein the extractor channel passes through at least a portion of the piercing member. In some embodiments, the connector interface has a regulator channel extending between a proximal regulator aperture and a distal regulator aperture, wherein at least a portion of the regulator channel passes through at least a portion of the piercing member. 
     In some embodiments, the method of manufacturing can include coupling a regulator assembly with the proximal regulator aperture of the connector interface. The regulator assembly can include a regulator path configured to be in fluid communication with the regulator channel when the regulator assembly is couple with the connector interface. In some embodiments, the regulator includes an occluder valve installed at least partially within one or more of the regulator channel and the regulator path via an installation path. The occluder valve can be configured to transition between a closed configuration and an opened configuration. In some embodiments, the occluder valve includes a valve chamber in fluid communication with one or more of the regulator channel and the regulator path. The valve chamber can have an occluding member, a movement path for the occluding member, and a valve seat. In some embodiments, the occluder valve can have a valve channel in fluid communication with the valve chamber and one or more of the regulator channel and the regulator path. Furthermore, the valve channel can have a flow path. 
     The occluder valve can be configured to transition to the closed configuration when the occluding member is engaged with the valve seat. In some embodiments, the occluder valve is configured to transition to the opened configuration when the occluding member is disengaged from the valve seat. An angle formed between the movement path for the occluding member and the installation path of the occluder valve can be greater than 0° and less than 180°. 
     The method of manufacturing the modular vial adaptor could include installing the occluder valve at least partially into one or more of the regulator channel and the regulator path via an installation path. In some embodiments, the method includes selecting an occluder valve wherein the angle between the movement path in the occluder valve and the installation path of the occluder valve is substantially the same as the angle between the installation path and the axial centerline of the coupling interface. The method can include matching a protrusion of the regulator assembly with the proximal regulator aperture of the connector interface, wherein the protrusion and proximal regulator aperture are keyed. In some embodiments, the method includes matching an alignment feature on the occluder valve with an alignment feature of the regulator channel. Matching the alignment feature of the occluder valve with the alignment feature of the regulator channel can orient the occluder valve such that the movement path is substantially parallel to the axial centerline of the connector interface when the regulator assembly is coupled to the connector interface and the occluder valve is at least partially installed in one or more of the regulator channel and the regulator path. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Various embodiments are depicted in the accompanying drawings for illustrative purposes, and should in no way be interpreted as limiting the scope of the embodiments. In addition, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. 
         FIG.  1    schematically illustrates a system for removing fluid from and/or injecting fluid into a vial. 
         FIG.  2    schematically illustrates another system for removing fluid from and/or injecting fluid into a vial. 
         FIG.  2 A  schematically illustrates another system for removing fluid from and/or injecting fluid into a vial. 
         FIG.  3    illustrates another system for removing fluid from and/or injecting fluid into a vial. 
         FIG.  4    illustrates a perspective view of a vial adaptor and a vial. 
         FIG.  5    illustrates a partial cross-sectional view of the vial adaptor of  FIG.  4   , coupled with a vial, in a high-volume stage. 
         FIG.  6    illustrates a partial cross-sectional view of the vial adaptor of  FIG.  4    coupled with a vial in an expanded stage. 
         FIG.  7    illustrates an exploded perspective view of a vial adaptor. 
         FIG.  7 A  illustrates an assembled perspective view of the vial adaptor of  FIG.  7   , including a partial cross-sectional view taken through line  7 A- 7 A in  FIG.  7   . 
         FIG.  7 B  illustrates an underside perspective view of a vial adaptor that comprises a recess. 
         FIG.  8    illustrates an exploded perspective view of a portion of the vial adaptor of  FIG.  7   . 
         FIG.  9    illustrates an assembled perspective view of the portion of the vial adaptor of  FIG.  8   . 
         FIG.  10    illustrates an exploded perspective view of a base and a cover of a coupling of the vial adaptor of  FIG.  7   . 
         FIG.  10 A  illustrates an exploded perspective view of another example of a base and a cover of a coupling of a vial adaptor that can be used with any embodiment. 
         FIG.  11    illustrates a top view of the coupling of  FIG.  10   . 
         FIG.  12    illustrates a cross-sectional view of the coupling of  FIG.  11   , taken through line  12 - 12  in  FIG.  11   . 
         FIG.  13    illustrates a partial cross-sectional view of a vial adaptor coupled with a vial, the adaptor including a counterweight. 
         FIGS.  14 A- 14 F  illustrate cross-sectional views of a keyed coupling of the vial adaptor of  FIG.  13   , taken through line  20 - 20  in  FIG.  13   . 
         FIG.  15 A  illustrates a cross-sectional view of a vial adaptor. 
         FIG.  15 B  illustrates a partial cross-sectional view of a vial adaptor coupled with a vial, the vial adaptor including a valve. 
         FIG.  15 C  illustrates an assembled perspective view of the vial adaptor of  FIG.  7   , the vial adaptor including a valve. 
         FIG.  16 A  illustrates a partial cross-sectional view of a portion of an inverted vial adaptor, the vial adaptor including a ball check valve. 
         FIG.  16 B  illustrates a close-up cross-sectional view of the ball check valve of  FIG.  16 A . 
         FIG.  16 C  illustrates a perspective cross-sectional view of the ball check valve of  FIG.  16 A . 
         FIG.  16 D  illustrates a partial cross-sectional view of another ball check valve that can be used with any embodiment. 
         FIG.  17    illustrates a partial cross-sectional view of another vial adaptor, the vial adaptor including a ball check valve. 
         FIG.  18    illustrates a close-up cross-sectional view of a domed valve. 
         FIG.  19 A  illustrates a close-up cross-sectional view of a showerhead domed valve. 
         FIG.  19 B  illustrates an elevated view of the showerhead domed valve taken through the line B-B in  FIG.  19 A . 
         FIG.  20 A  illustrates a close-up cross-sectional view of a flap check valve. 
         FIG.  20 B  illustrates a perspective cross-sectional view of the flap check valve of  FIG.  20 A . 
         FIG.  21    illustrates a close-up cross-sectional view of a ball check valve in the piercing member of an adaptor. 
     
    
    
     DETAILED DESCRIPTION 
     Although certain embodiments and examples are disclosed herein, inventive subject matter extends beyond the examples in the specifically disclosed embodiments to other alternative embodiments and/or uses, and to modifications and equivalents thereof. Thus, the scope of the claims appended hereto is not limited by any of the particular embodiments described below. For example, in any method or process disclosed herein, the acts or operations of the method or process may be performed in any suitable sequence and are not necessarily limited to any particular disclosed sequence. Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding certain embodiments; however, the order of description should not be construed to imply that these operations are order dependent. Additionally, the structures, systems, and/or devices described herein may be embodied as integrated components or as separate components. For purposes of comparing various embodiments, certain aspects and advantages of these embodiments are described. Not necessarily all such aspects or advantages are achieved by any particular embodiment. Thus, for example, various embodiments may be carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other aspects or advantages as may also be taught or suggested herein. 
     The drawing showing certain embodiments can be semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown greatly exaggerated in the drawings. 
     For expository purposes, the term “horizontal” as used herein is defined as a plane parallel to the plane or surface of the floor of the area in which the device being described is used or the method being described is performed, regardless of its orientation. The term “floor” floor can be interchanged with the term “ground.” The term “vertical” refers to a direction perpendicular to the horizontal as just defined. Terms such as “above,” “below,” “bottom,” “top,” “side,” “higher,” “lower,” “upper,” “over,” and “under,” are defined with respect to the horizontal plane. 
     Numerous medicines and other therapeutic fluids are stored and distributed in medicinal vials or other containers of various shapes and sizes. These vials are hermetically sealed to prevent contamination or leaking of the stored fluid. The pressure differences between the interior of the sealed vials and the particular atmospheric pressure in which the fluid is later removed often give rise to various problems, as well as the release of potentially harmful vapors. 
     For instance, introducing a piercing member of a vial adaptor through the septum of a vial can cause the pressure within the vial to rise. This pressure increase can cause fluid to leak from the vial at the interface of the septum and piercing member or at the attachment interface of the adaptor and a medical device, such as a syringe. Also, it can be difficult to withdraw an accurate amount of fluid from a sealed vial using an empty syringe, or other medical instrument, because the fluid may be naturally urged back into the vial once the syringe plunger is released. Furthermore, as the syringe is decoupled from the vial, pressure differences can often cause an amount of fluid to spurt from the syringe or the vial. 
     Moreover, in some instances, introducing a fluid into the vial can cause the pressure to rise in the vial. For example, in certain cases it can be desirable to introduce a solvent (such as sterile saline) into the vial, e.g., to reconstitute a lyophilized pharmaceutical in the vial. Such introduction of fluid into the vial can cause the pressure in the vial to rise above the pressure of the surrounding environment, which can result in fluid leaking from the vial at the interface of the septum and piercing member or at the attachment interface of the adaptor and a medical device, such as a syringe. Further, the increased pressure in the vial can make it difficult to introduce an accurate amount of the fluid into the vial with a syringe, or other medical instrument. Also, should the syringe be decoupled from the vial when the pressure inside the vial is greater than the surrounding pressure (e.g., atmospheric), the pressure gradient can cause a portion of the fluid to spurt from the vial. 
     Additionally, in many instances, air bubbles are drawn into the syringe as fluid is withdrawn from the vial. Such bubbles are generally undesirable as they could result in an embolus if injected into a patient. To rid a syringe of bubbles after removal from the vial, medical professionals often flick the syringe, gathering all bubbles near the opening of the syringe, and then forcing the bubbles out. In so doing, a small amount of liquid is usually expelled from the syringe as well. Medical personnel generally do not take the extra step to re-couple the syringe with the vial before expelling the bubbles and fluid. In some instances, this may even be prohibited by laws and regulations. Such laws and regulations may also necessitate expelling overdrawn fluid at some location outside of the vial in certain cases. Moreover, even if extra air or fluid were attempted to be reinserted in the vial, pressure differences can sometimes lead to inaccurate measurements of withdrawn fluid. 
     To address these problems caused by pressure differentials, medical professionals frequently pre-fill an empty syringe with a precise volume of ambient air corresponding to the volume of fluid that they intend to withdraw from the vial. The medical professionals then pierce the vial and expel this ambient air into the vial, temporarily increasing the pressure within the vial. When the desired volume of fluid is later withdrawn, the pressure differential between the interior of the syringe and the interior of the vial is generally near equilibrium. Small adjustments of the fluid volume within the syringe can then be made to remove air bubbles without resulting in a demonstrable pressure differential between the vial and the syringe. However, a significant disadvantage to this approach is that ambient air, especially in a hospital setting, may contain various airborne viruses, bacteria, dust, spores, molds, and other unsanitary and harmful contaminants. The pre-filled ambient air in the syringe may contain one or more of these harmful substances, which may then mix with the medicine or other therapeutic fluid in the vial. If this contaminated fluid is injected directly into a patient&#39;s bloodstream, it can be particularly dangerous because it circumvents many of the body&#39;s natural defenses to airborne pathogens. Moreover, patients who need the medicine and other therapeutic fluids are more likely to be suffering from a diminished infection-fighting capacity. 
     In the context of oncology and certain other drugs, all of the foregoing problems can be especially serious. Such drugs, although helpful when injected into the bloodstream of a patient, can be extremely harmful if inhaled or touched. Accordingly, such drugs can be dangerous if allowed to spurt unpredictably from a vial due to pressure differences. Furthermore, these drugs are often volatile and may instantly aerosolize when exposed to ambient air. Accordingly, expelling a small amount of such drugs in order to clear a syringe of bubbles or excess fluid, even in a controlled manner, is generally not a viable option, especially for medical personnel who may repeat such activities numerous times each day. 
     Some devices use rigid enclosures for enclosing all or a portion of a volume-changing component or region for assisting in regulating pressure within a container. Although such enclosures can provide rigidity, they generally make the devices bulky and unbalanced. Coupling such a device with a vial generally can create a top-heavy, unstable system that is prone to tipping-over and possibly spilling the contents of the device and/or the vial. 
     Indeed, certain of such coupling devices include relatively large and/or heavy, rigid components that are cantilevered or otherwise disposed a distance from of the axial center of the device, thereby exacerbating the tendency for the device to tip-over. 
     Additionally, such rigid enclosures can increase the size of the device, which can require an increase in material to form the device and otherwise increase costs associated manufacturing, transporting, and/or storing the device. Further, such rigid enclosures can hamper the ability of the device to expand or contract to deliver a regulating fluid to the vial. No feature, structure, or step disclosed herein is essential or indispensable. 
       FIG.  1    is a schematic illustration of a container  10 , such as a medicinal vial, that can be coupled with an accessor  20  and a regulator  30 . In certain arrangements, the regulator  30  allows the removal of some or all of the contents of the container  10  via the accessor  20  without a significant change of pressure within the container  10 . In some embodiments, the regulator  30  can include one or more portions of any of the example regulators shown and/or described in International Patent Publication Number WO 2013/025946, titled PRESSURE-REGULATING VIAL ADAPTORS, filed Aug. 16, 2012, the entire contents of which are incorporated by reference and made part of this specification. 
     In general, the container  10  is hermetically sealed to preserve the contents of the container  10  in a sterile environment. The container  10  can be evacuated or pressurized upon sealing. In some instances, the container  10  is partially or completely filled with a liquid, such as a drug or other medical fluid. In such instances, one or more gases can also be sealed in the container  10 . In some instances, a solid or powdered substance, such as a lyophilized pharmaceutical, is disposed in the container  10 . 
     The accessor  20  generally provides access to contents of the container  10  such that the contents may be removed or added to. In certain arrangements, the accessor  20  includes an opening between the interior and exterior of the container  10 . The accessor  20  can further comprise a passageway between the interior and exterior of the container  10 . In some configurations, the passageway of the accessor  20  can be selectively opened and closed. In some arrangements, the accessor  20  comprises a conduit extending through a surface of the container  10 . The accessor  20  can be integrally formed with the container  10  prior to the sealing thereof or introduced to the container  10  after the container  10  has been sealed. 
     In some configurations, the accessor  20  is in fluid communication with the container  10 , as indicated by an arrow  21 . In certain of these configurations, when the pressure inside the container  10  varies from that of the surrounding environment, the introduction of the accessor  20  to the container  10  causes a transfer through the accessor  20 . For example, in some arrangements, the pressure of the environment that surrounds the container  10  exceeds the pressure within the container  10 , which may cause ambient air from the environment to ingress through the accessor  20  upon insertion of the accessor  20  into the container  10 . In other arrangements, the pressure inside the container  10  exceeds that of the surrounding environment, causing the contents of the container  10  to egress through the accessor  20 . 
     In some configurations, the accessor  20  is coupled with an exchange device  40 . In certain instances, the accessor  20  and the exchange device  40  are separable. In some instances, the accessor  20  and the exchange device  40  are integrally formed. The exchange device  40  is configured to accept fluids and/or gases from the container  10  via the accessor  20 , to introduce fluids and/or gases to the container  10  via the accessor  20 , or to do some combination of the two. In some arrangements, the exchange device  40  is in fluid communication with the accessor  20 , as indicated by an arrow  24 . In certain configurations, the exchange device  40  comprises a medical instrument, such as a syringe. 
     In some instances, the exchange device  40  is configured to remove some or all of the contents of the container  10  via the accessor  20 . In certain arrangements, the exchange device  40  can remove the contents independent of pressure differences, or lack thereof, between the interior of the container  10  and the surrounding environment. For example, in instances where the pressure outside of the container  10  exceeds that within the container  10 , an exchange device  40  comprising a syringe can remove the contents of the container  10  if sufficient force is exerted to extract the plunger from the syringe. The exchange device  40  can similarly introduce fluids and/or gases to the container  10  independent of pressure differences between the interior of the container  10  and the surrounding environment. 
     In certain configurations, the regulator  30  is coupled with the container  10 . The regulator  30  generally regulates the pressure within the container  10 . As used herein, the term “regulate,” or any derivative thereof, is a broad term used in its ordinary sense and includes, unless otherwise noted, any active, affirmative, or positive activity, or any passive, reactive, respondent, accommodating, or compensating activity that tends to effect a change. In some instances, the regulator  30  substantially maintains a pressure difference, or equilibrium, between the interior of the container  10  and the surrounding environment. As used herein, the term “maintain,” or any derivative thereof, is a broad term used in its ordinary sense and includes the tendency to preserve an original condition for some period, with some small degree of variation permitted as may be appropriate in the circumstances. In some instances, the regulator  30  maintains a substantially constant pressure within the container  10 . In certain instances, the pressure within the container  10  varies by no more than about 1 psi, no more than about 2 psi, no more than about 3 psi, no more than about 4 psi, or no more than about 5 psi. In still further instances, the regulator  30  equalizes pressures exerted on the contents of the container  10 . As used herein, the term “equalize,” or any derivative thereof, is a broad term used in its ordinary sense and includes the tendency for causing quantities to be the same or close to the same, with some small degree of variation permitted as may be appropriate in the circumstances. In certain configurations, the regulator  30  is coupled with the container  10  to allow or encourage equalization of a pressure difference between the interior of the container  10  and some other environment, such as the environment surrounding the container  10  or an environment within the exchange device  40 . In some arrangements, a single device comprises the regulator  30  and the accessor  20 . In other arrangements, the regulator  30  and the accessor  20  are separate units. 
     The regulator  30  is generally in communication with the container  10 , as indicated by an arrow  31 , and a reservoir  50 , as indicated by another arrow  35 . In some configurations, the reservoir  50  comprises at least a portion of the environment surrounding the container  10 . In certain configurations, the reservoir  50  comprises a container, canister, bag, or other holder dedicated to the regulator  30 . As used herein, the term “bag,” or any derivative thereof, is a broad term used in its ordinary sense and includes, for example, any sack, balloon, bladder, receptacle, enclosure, diaphragm, or membrane capable of expanding and/or contracting, including structures comprising a flexible, supple, pliable, resilient, elastic, and/or expandable material. In some embodiments, the reservoir  50  includes a gas and/or a liquid. As used herein, the term “flexible,” or any derivative thereof, is a broad term used in its ordinary sense and describes, for example, the ability of a component to bend, expand, contract, fold, unfold, or otherwise substantially deform or change shape when fluid is flowing into or out of the container  10  (e.g., via the accessor  20 ). Also, as used herein, the term “rigid,” or any derivative thereof, is a broad term used in its ordinary sense and describes, for example, the ability of a component to generally avoid substantial deformation under normal usage when fluid is flowing into or out of the container  10  (e.g., via the accessor  20 ). In some embodiments, the reservoir  50  can include one or more portions of any of the example reservoirs shown and/or described in International Patent Publication Number WO 2013/025946, titled PRESSURE-REGULATING VIAL ADAPTORS, filed Aug. 16, 2012, the entire contents of which are incorporated by reference and made part of this specification. 
     In certain embodiments, the regulator  30  provides fluid communication between the container  10  and the reservoir  50 . In certain of such embodiments, the fluid in the reservoir  50  includes mainly gas so as not to appreciably dilute liquid contents of the container  10 . In some arrangements, the regulator  30  comprises a filter to purify or remove contaminants from the gas or liquid entering the container  10 , thereby reducing the risk of contaminating the contents of the container  10 . In certain arrangements, the filter is hydrophobic such that air can enter the container  10  but fluid cannot escape therefrom. In some configurations, the regulator  30  comprises an orientation-actuated or orientation-sensitive check valve which selectively inhibits fluid communication between the container  10  and the filter. In some configurations, the regulator  30  comprises a check valve which selectively inhibits fluid communication between the container  10  and the filter when the valve and/or the container  10  are oriented so that the regulator  30  is held above (e.g., further from the floor than) the regulator  30 . 
     In some embodiments, the regulator  30  prevents fluid communication between the container  10  and the reservoir  50 . In certain of such embodiments, the regulator  30  serves as an interface between the container  10  and the reservoir  50 . In some arrangements, the regulator  30  comprises a substantially impervious bag for accommodating ingress of gas and/or liquid to the container  10  or egress of gas and/or liquid from the container  10 . 
     As schematically illustrated in  FIG.  2   , in certain embodiments, the accessor  20 , or some portion thereof, is located within the container  10 . As detailed above, the accessor  20  can be integrally formed with the container  10  or separate therefrom. In some embodiments, the regulator  30 , or some portion thereof, is located outside the container  10 . In some arrangements, the regulator  30  is integrally formed with the container  10 . It is possible to have any combination of the accessor  20 , or some portion thereof, entirely within, partially within, or outside of the container  10  and/or the regulator  30 , or some portion thereof, entirely within, partially within, or outside of the container  10 . 
     In certain embodiments, the accessor  20  is in fluid communication with the container  10 . In further embodiments, the accessor  20  is in fluid communication with the exchange device  40 , as indicated by the arrow  24 . 
     The regulator  30  can be in fluid or non-fluid communication with the container  10 . In some embodiments, the regulator  30  is located entirely outside the container  10 . In certain of such embodiments, the regulator  30  comprises a closed bag configured to expand or contract external to the container  10  to maintain a substantially constant pressure within the container  10 . In some embodiments, the regulator  30  is in communication, either fluid or non-fluid, with the reservoir  50 , as indicated by the arrow  35 . 
     As schematically illustrated in  FIG.  2 A , in certain embodiments, the accessor  20 , or some portion thereof, can be located within the container  10 . In some embodiments, the accessor  20 , or some portion thereof, can be located outside the container  10 . In some embodiments, a valve  25 , or some portion thereof, can be located outside the container  10 . In some embodiments, the valve  25 , or some portion thereof, can be located within the container  10 . In some embodiments, the regulator  30  is located entirely outside the container  10 . In some embodiments, the regulator  30 , or some portion thereof, can be located within the container  10 . It is possible to have any combination of the accessor  20 , or some portion thereof, entirely within, partially within, or outside of the container  10  and/or the valve  25 , or some portion thereof, entirely within, partially within, or outside of the container  10 . It is also possible to have any combination of the accessor  20 , or some portion thereof, entirely within, partially within, or outside of the container  10  and/or the regulator  30 , or some portion thereof, entirely within, partially within, or outside of the container  10 . 
     The accessor  20  can be in fluid communication with the container  10 , as indicated by the arrow  21 . In some embodiments, the accessor  20  can be in fluid communication with the exchange device  40 , as indicated by the arrow  24 . 
     In certain embodiments, the regulator  30  can be in fluid or non-fluid communication with a valve  25 , as indicated by the arrow  32 . In some embodiments, the valve  25  can be integrally formed with the container  10  or separate therefrom. In some embodiments, the valve  25  can be integrally formed with the regulator  30  or separate therefrom. In certain embodiments, the valve  25  can be in fluid or non-fluid communication with the container  10 , as indicated by the arrow  33 . 
     In some embodiments the regulator  30  can be in fluid or non-fluid communication with the ambient surroundings, as indicated by the arrow  35 A. In some embodiments, the regulator  30  can be in fluid or non-fluid communication with a reservoir  50 , as indicated by the arrow  35 B. In some embodiments, the reservoir  50  can comprise a bag or other flexible enclosure. In some embodiments, the reservoir  50  comprises a rigid container surrounding a flexible enclosure. In some embodiments, the reservoir  50  comprises a partially-rigid enclosure. 
     According to some configurations, the regulator  30  can comprise a filter. In some embodiments, the filter can selectively inhibit passage of liquids and/or contaminants between the valve  25  and the reservoir  50  or the ambient surroundings. In some embodiments, the filter can selectively inhibit passage of liquids and/or contaminants between the reservoir  50  or ambient surroundings and the valve  25 . 
     In some embodiments, the valve  25  can be a one-way check valve. In some embodiments, the valve  25  can be a two-way valve. According to some configurations, the valve  25  can selectively inhibit liquid communication between the filter and/or reservoir  50  and the container  10 . In some embodiments, the valve  25  can selectively inhibit liquid communication between the container  10  and the filter and/or reservoir  50  when the container  10  is oriented above the exchange device  40 .  FIG.  3    illustrates an embodiment of a system  100  comprising a vial  110 , an accessor  120 , and a regulator  130 . The vial  110  comprises a body  112  and a cap  114 . In the illustrated embodiment, the vial  110  contains a medical fluid  116  and a relatively small amount of sterilized air  118 . In certain arrangements, the fluid  116  is removed from the vial  110  when the vial  110  is oriented with the cap  114  facing downward (e.g., the cap  114  is between the fluid and the floor). The accessor  120  comprises a conduit  122  fluidly connected at one end to an exchange device  140 , such as a standard syringe  142  with a plunger  144 . The conduit  122  extends through the cap  114  and into the fluid  116 . The regulator  130  comprises a bag  132  and a conduit  134 . The bag  132  and the conduit  134  are in fluid communication with a reservoir  150 , which comprises an amount of cleaned and/or sterilized air. The outside surface of the bag  132  is generally in contact with the ambient air surrounding both the system  100  and the exchange device  140 . The bag  132  comprises a substantially impervious material such that the fluid  116 , the air  118  inside the vial  110 , and the reservoir  150  do not contact the ambient air. 
     In the illustrated embodiment, areas outside of the vial  110  are at atmospheric pressure. Accordingly, the pressure on the syringe plunger  144  is equal to the pressure on the interior of the bag  132 , and the system  100  is in general equilibrium. The plunger  144  can be withdrawn to fill a portion of the syringe  142  with the fluid  116 . Withdrawing the plunger  144  increases the effective volume of the vial  110 , thereby decreasing the pressure within the vial  110 . Such a decrease of pressure within the vial  110  increases the difference in pressure between the vial  110  and the syringe  142 , which causes the fluid  116  to flow into the syringe  142  and the reservoir  150  to flow into the vial  110 . Additionally, the decrease of pressure within the vial  110  increases the difference in pressure between the interior and exterior of the bag  132 , which causes the bag  132  to decrease in internal volume or contract, which in turn encourages an amount of regulatory fluid through the conduit  134  and into the vial  110 . In effect, the bag  132  contracts outside the vial  110  to a new volume that compensates for the volume of the fluid  116  withdrawn from the vial  110 . Thus, once the plunger  144  ceases from being withdrawn from the vial  110 , the system is again in equilibrium. As the system  100  operates near equilibrium, withdrawal of the fluid  116  can be facilitated. Furthermore, due to the equilibrium of the system  100 , the plunger  144  remains at the position to which it has been withdrawn, thereby allowing removal of an accurate amount of the fluid  116  from the vial  110 . 
     In certain arrangements, the decreased volume of the bag  132  is approximately equal to the volume of liquid removed from the vial  110 . In some arrangements, the volume of the bag  132  decreases at a slower rate as greater amounts of fluid are withdrawn from the vial  110  such that the volume of fluid withdrawn from the vial  110  is greater than the decreased volume of the bag  132 . 
     In some arrangements, the bag  132  can be substantially and/or completely deflated, such that there is substantially no volume inside the bag  132 . In some instances, such deflation of the bag  132  effectively creates a difference in pressure between the inside of the bag  132  and the inside of the vial  110 . For example, a vacuum (relative to ambient) inside the vial  110  can be created when the bag  132  is deflated. In some instances, such deflation of the bag  132  creates substantially no restoring force that tends to create a pressure differential between the inside of the bag  132  and the inside of the vial  110 , such as when the bag  132  is generally non-resilient. 
     In certain embodiments, the syringe  142  comprises fluid contents  143 . A portion of the fluid contents  143  can be introduced into the vial  110  by depressing (e.g., toward the vial) the plunger  144 , which can be desirable in certain instances. For example, in some instances, it is desirable to introduce a solvent and/or compounding fluid into the vial  110 . In certain instances, more of the fluid  116  than desired initially might be withdrawn inadvertently. In some instances, some of the air  118  in the vial  110  initially might be withdrawn, creating unwanted bubbles within the syringe  142 . It may thus be desirable to inject some of the withdrawn fluid  116  and/or air  118  back into the vial  110 . 
     Depressing the plunger  144  encourages the fluid contents  143  of the syringe into the vial  110 , which decreases the effective volume of the vial  110 , thereby increasing the pressure within the vial  110 . An increase of pressure within the vial  110  increases the difference in pressure between the exterior and interior of the bag  132 , which causes the air  118  to flow into the bag  132 , which in turn causes the bag  132  to expand. In effect, the bag  132  expands or increases to a new volume that compensates for the volume of the contents  143  of the syringe  142  introduced into the vial  110 . Thus, once the plunger  144  ceases from being depressed, the system is again in equilibrium. As the system  100  operates near equilibrium, introduction of the contents  143  can be facilitated. Moreover, due to the equilibrium of the system  100 , the plunger  144  generally remains at the position to which it is depressed, thereby allowing introduction of an accurate amount of the contents  143  of the syringe  142  into the vial  110 . 
     In certain arrangements, the increased volume of the bag  132  is approximately equal to the volume of air  118  removed from the vial  110 . In some arrangements, the volume of the bag  132  increases at a slower rate as greater amounts of the contents  143  are introduced into the vial  110 , such that the volume of the contents  143  introduced into the vial  110  is greater than the increased volume of the bag  132 . 
     In some arrangements, the bag  132  can stretch to expand beyond a resting volume. In some instances, the stretching gives rise to a restorative force that effectively creates a difference in pressure between the inside of the bag  132  and the inside of the vial  110 . For example, a slight overpressure (relative to ambient) inside the vial  110  can be created when the bag  132  is stretched. 
       FIG.  4    illustrates an embodiment of a vial adaptor  200  for coupling with a vial  210 . The vial  210  can comprise any suitable container for storing medical fluids. In some instances, the vial  210  comprises any of a number of standard medical vials known in the art, such as those produced by Abbott Laboratories of Abbott Park, Ill. In some embodiments, the vial  210  is capable of being hermetically sealed. In some configurations, the vial  210  comprises a body  212  and a cap  214 . The body  212  preferably comprises a rigid, substantially impervious material, such as plastic or glass. In some embodiments, the cap  214  comprises a septum  216  and a casing  218 . The septum  216  can comprise an elastomeric material capable of deforming in such a way when punctured by an item that it forms a substantially airtight seal around that item. For example, in some instances, the septum  216  comprises silicone rubber or butyl rubber. The casing  218  can comprise any suitable material for sealing the vial  210 . In some instances, the casing  218  comprises metal that is crimped around the septum  216  and a portion of the body  212  in order to form a substantially airtight seal between the septum  216  and the vial  210 . In certain embodiments, the cap  214  defines a ridge  219  that extends outwardly from the top of the body  212 . 
     In certain embodiments, the adaptor  200  comprises an axial centerline A and a piercing member  220  having a proximal end  221  (see  FIG.  5   ) and a distal end  223 . As used herein the term, “proximal,” or any derivative thereof, refers to a direction along the axial length of the piercing member  220  that is toward the cap  214  when the piercing member  220  is inserted in the vial  210 ; the term “distal,” or any derivative thereof, indicates the opposite direction. In some configurations, the piercing member  220  comprises a sheath  222 . The sheath  222  can be substantially cylindrical, as shown, or it can assume other geometric configurations. In some instances, the sheath  222  tapers toward the distal end  223 . In some arrangements, the distal end  223  defines a point that can be centered with respect to the axial centerline A or offset therefrom. In certain embodiments, the distal end  223  is angled from one side of the sheath  222  to the opposite side. The sheath  222  can comprise a rigid material, such as metal or plastic, suitable for insertion through the septum  216 . In certain embodiments, the sheath  222  comprises polycarbonate plastic. 
     In some configurations, the piercing member  220  comprises a tip  224 . The tip  224  can have a variety of shapes and configurations. In some instances, the tip  224  is configured to facilitate insertion of the sheath  222  through the septum  216  via an insertion axis. In some embodiments, the insertion axis corresponds to the direction in which the force required to couple the adaptor  200  with the vial  210  is applied when coupling the adaptor  200  with the vial  210 . The insertion axis can be substantially perpendicular to a plane in which the cap  214  lies. In some embodiments, as illustrated in  FIG.  4   , the insertion axis is substantially parallel to the axial centerline A of the adaptor  200 . Furthermore, in some embodiments, the insertion axis is substantially parallel to the piercing member  220 . As illustrated, the tip  224 , or a portion thereof, can be substantially conical, coming to a point at or near the axial center of the piercing member  220 . In some configurations, the tip  224  angles from one side of the piercing member  220  to the other. In some instances, the tip  224  is separable from the sheath  222 . In other instances, the tip  224  and the sheath  222  are permanently joined, and can be unitarily formed. In various embodiments, the tip  224  comprises acrylic plastic, ABS plastic, or polycarbonate plastic. 
     In some embodiments, the adaptor  200  comprises a cap connector  230 . As illustrated, the cap connector  230  can substantially conform to the shape of the cap  214 . In certain configurations, the cap connector  230  comprises a rigid material, such as plastic or metal, that substantially maintains its shape after minor deformations. In some embodiments, the cap connector  230  comprises polycarbonate plastic. In some arrangements, the cap connector  230  comprises a sleeve  235  configured to snap over the ridge  219  and tightly engage the cap  214 . As more fully described below, in some instances, the cap connector  230  comprises a material around an interior surface of the sleeve  235  for forming a substantially airtight seal with the cap  214 . The cap connector  230  can be or can include adhesive tape, as known to those of skill in the art. In some embodiments, the cap connector  230  comprises an elastic material that is stretched over the ridge  219  to form a seal around the cap  214 . In some embodiments, the cap connector  230  resembles or is identical to the structures shown in  FIGS.  6  and  7    of and described in the specification of U.S. Pat. No. 5,685,866, the entire contents of which are hereby incorporated by reference herein and are made a part of this specification. 
     In certain embodiments, the adaptor  200  comprises a connector interface  240  for coupling the adaptor  200  with a medical connector  241 , another medical device (not shown), or any other instrument used in extracting fluid from or injecting fluid into the vial  210 . In certain embodiments, the connector interface  240  comprises a sidewall  248  that defines a proximal portion of an access channel  245  through which fluid may flow. In some instances, the access channel  245  extends through the cap connector  230  and through a portion of the piercing member  220  such that the connector interface  240  is in fluid communication with the piercing member  220 . The sidewall  248  can assume any suitable configuration for coupling with the medical connector  241 , a medical device, or another instrument. In the illustrated embodiment, the sidewall  248  is substantially cylindrical and extends generally proximally from the cap connector  230 . 
     In certain configurations, the connector interface  240  comprises a flange  247  to aid in coupling the adaptor  200  with the medical connector  241 , a medical device, or another instrument. The flange  247  can be configured to accept any suitable medical connector  241 , including connectors capable of sealing upon removal of a medical device therefrom. In some instances, the flange  247  is sized and configured to accept the Clave® connector, available from ICU Medical, Inc. of San Clemente, Calif. Certain features of the Clave® connector are disclosed in U.S. Pat. No. 5,685,866, the entire contents of which are incorporated by reference herein. Connectors of many other varieties, including other needle-less connectors, can also be used. The connector  241  can be permanently or separably attached to the connector interface  240 . In other arrangements, the flange  247  is threaded, configured to accept a Luer connector, or otherwise shaped to attach directly to a medical device, such as a syringe, or to other instruments. 
     In certain embodiments, the connector interface  240  is generally centered on the axial center of the adaptor  200 . Such a configuration provides vertical stability to a system comprising the adaptor  200  coupled with the vial  210 , thereby making the coupled system less likely to tip-over. Accordingly, the adaptor  200  is less likely to cause leaks, or spills, or disorganization of supplies occasioned by accidental bumping or tipping of the adaptor  200  or the vial  210 . 
     In some embodiments, the piercing member  220 , the cap connector  230 , and the connector interface  240  are integrally formed of a unitary piece of material, such as polycarbonate plastic. In other embodiments, one or more of the piercing member  220 , the cap connector  230 , and the connector interface  240  comprise a separate piece. The separate pieces can be joined in any suitable manner, such as by glue, epoxy, ultrasonic welding, etc. Connections between joined pieces can create substantially airtight bonds between the pieces. In some arrangements, any of the piercing member  220 , the cap connector  230 , or the connector interface  240  can comprise more than one piece. Details and examples of some embodiments of piercing members  220 , cap connectors  230 , and connector interfaces  240  are provided in U.S. Pat. No. 7,547,300 and U.S. Patent Application Publication No. 2010/0049157, the entirety of each of which is incorporated herein by reference. 
     In certain embodiments, the adaptor  200  comprises a regulator channel  225 , which extends through the connector interface  240  and/or the cap connector  230 , and through the piercing member  220  (see, e.g.,  FIG.  5   ). In the illustrated embodiment, the regulator channel  225  passes through a lumen  226  that extends radially outward from the connector interface  240 . In some embodiments, the channel  225  is formed as a part of the cap connector  230 . In certain embodiments, the regulator channel  225  terminates in a regulator aperture  228 . 
     In some embodiments, the adaptor  200  includes a regulator assembly  250 . In certain embodiments, the regulator assembly  250  comprises a coupling  252 . The coupling  252  can be configured to connect the regulator assembly  250  with the remainder of the adaptor  200 . For example, the coupling  252  can connect with the lumen  226  in substantially airtight engagement, thereby placing the coupling  252  in fluid communication with the regulator channel  225 . In some instances, the coupling  252  and the lumen  226  engage with a slip or interference fit. In certain embodiments, the coupling  252  and the lumen  226  comprise complimentary threads, such that the coupling  252  can be threadably connected with the lumen  226 . In some embodiments, the coupling  252  includes a passage  253  that extends through the coupling  252 . 
     In the illustrated embodiment, the regulator assembly comprises a bag  254  with an interior chamber  255 . The bag  254  is generally configured to stretch, flex, unfold, or otherwise expand and contract or cause a change in interior volume. In some cases, the bag  254  includes one or more folds, pleats, or the like. In certain arrangements, the interior chamber  255  of the bag  254  is in fluid communication with the regulator channel  225 , thereby allowing fluid to pass from the regulator channel  225  into the interior chamber  255  and/or from the interior chamber  255  into the regulator channel  225 . In some arrangements, the interior chamber  255  is in fluid communication with the passage  253  of the coupling  252 . 
     In certain embodiments, the regulator assembly  250  comprises a filler  256 , which can be located in the inner chamber  255  of the bag  254 . As used herein, the term “filler,” or any derivative thereof, is a broad term used in its ordinary sense and includes, for example, any support, stuffing, spacing, wadding, padding, lining, enclosure, reservoir, or other structure configured to inhibit or prevent the bag  254  from fully deflating at ambient pressure, or a combination of structures. In certain configurations, the filler  256  occupies substantially the entire volume of the entire inner chamber  255 . In other arrangements, the filler  256  occupies only a portion of the volume of the inner chamber  255 . In some configurations, the filler  256  comprises a network of woven or non-woven fibers. In some embodiments, the filler  256  is porous, such that regulating fluid (e.g., air) in the inner chamber  255  can enter a network or plurality of hollows within the filler  256 . For example, in some cases, the filler  256  is a sponge-like material. In certain configurations, the filler  256  is configured to be compressed by the bag  254 , without causing damage to the bag  254 . In some embodiments, the filler  256  has a lower durometer than the bag  254 . 
     As illustrated, the filler  256  can be positioned in the bag  254 . In certain embodiments, the filler  256  is positioned at about the radial center in the bag  254 . In other instances, the position of the filler  256  is offset with respect to the center of the bag  254 . In some embodiments, the position of the filler  256  changes relative to the bag  254 . For example, in some embodiments, the filler  256  moves (e.g., by force of gravity) relative to the bag  254  when the bag  254  changes volume, such as when the bag  254  expands. Such a configuration can, for example, enhance the ability of the bag  254  to expand and can decrease the likelihood of the bag  254  becoming snagged on or bound-up by the filler  256 . 
     In other embodiments, the position of the filler  256  is substantially constant with respect to the bag  254  and/or a coupling  252 . In some such embodiments, the filler  256  moves substantially in unison with the bag  254 . For example, the filler  256  can be configured to expand and contract at substantially the same rate as the bag  254 . In certain embodiments, the filler  256  is bonded with the bag  254 . In some such cases, the filler  256  is adhered or at least partially adhered to at least a portion of the bag  254 . In some cases, at least a portion of the filler  256  is formed as a part of the bag  254 . In certain embodiments, at least a portion of the filler  256  is maintained in position by one or more flexible legs that abut an inner surface of the bag  254 . In some configurations, at least a portion of the filler  256  is maintained in position by one or more beams that connect with the coupling  252 . In certain arrangements, at least a portion of the filler  256  is joined with the coupling  252 . 
       FIGS.  5  and  6    illustrate cross-sections of the vial adaptor  200  coupled with the vial  210 .  FIG.  5    illustrates a non-fully expanded condition and  FIG.  6    illustrates a fully-expanded condition. In the illustrated embodiment, the cap connector  230  firmly secures the adaptor  200  to the cap  214  and the piercing member  220  extends through the septum  216  into the interior of the vial  210 . Additionally, the regulator assembly  250  is engaged with the connector interface  240  such that the inner chamber  255  of the bag  254  is in fluid communication with the regulator channel  255  through the coupling  252 . In some embodiments, the piercing member  220  is oriented substantially perpendicularly with respect to the cap  214  when the adaptor  200  and the vial  210  are coupled. Other configurations are also contemplated. 
     In certain embodiments, the cap connector  230  comprises one or more projections  237  that aid in securing the adaptor  200  to the vial  210 . The one or more projections  237  extend toward an axial center of the cap connector  230 . In some configurations, the one or more projections  237  comprise a single circular flange extending around the interior of the cap connector  230 . The cap connector  230  can be sized and configured such that an upper surface of the one or more projections  237  abuts a lower surface of the ridge  219 , helping secure the adaptor  200  in place. 
     The one or more projections  237  can be rounded, chamfered, or otherwise shaped to facilitate the coupling of the adaptor  200  and the vial  210 . For example, as the adaptor  200  having rounded projections  237  is introduced to the vial  210 , a lower surface of the rounded projections  237  abuts a top surface of the cap  214 . As the adaptor  200  is advanced onto the vial  210 , the rounded surfaces cause the cap connector  230  to expand radially outward. As the adaptor  200  is advanced further onto the vial  210 , a resilient force of the deformed cap connector  220  seats the one or more projections  237  under the ridge  219 , securing the adaptor  200  in place. 
     In some embodiments, the cap connector  230  is sized and configured such that an inner surface  238  of the cap connector  230  contacts the cap  214 . In some embodiments, a portion of the cap connector  230  contacts the cap  214  in substantially airtight engagement. In certain embodiments, a portion of the inner surface  238  surrounding either the septum  216  or the casing  218  is lined with a material, such as rubber or plastic, to ensure the formation of a substantially airtight seal between the adaptor  200  and the vial  210 . 
     In the embodiment illustrated, the piercing member  220  comprises the sheath  222  and the tip  224 . The sheath  222  is generally sized and dimensioned to be inserted through the septum  216  without breaking and, in some instances, with relative ease. Accordingly, in various embodiments, the sheath  222  has a cross-sectional area of between about 0.025 and about 0.075 square inches, between about 0.040 and about 0.060 square inches, or between about 0.045 and about 0.055 square inches. In other embodiments, the cross-sectional area is less than about 0.075 square inches, less than about 0.060 square inches, or less than or equal to about 0.055 square inches. In still other embodiments, the cross-sectional area is greater than or equal to about 0.025 square inches, greater than or equal to about 0.035 square inches, or greater than or equal to about 0.045 square inches. In some embodiments, the cross-sectional area is about 0.050 square inches. 
     The sheath  222  can assume any of a number of cross-sectional geometries, such as, for example, oval, ellipsoidal, square, rectangular, hexagonal, or diamond-shaped. The cross-sectional geometry of the sheath  222  can vary along a length thereof in size and/or shape. In some embodiments, the sheath  222  has substantially circular cross-sections along a substantial portion of a length thereof. A circular geometry provides the sheath  222  with substantially equal strength in all radial directions, thereby preventing bending or breaking that might otherwise occur upon insertion of the sheath  222 . The symmetry of an opening created in the septum  216  by the circular sheath  222  prevents pinching that might occur with angled geometries, allowing the sheath  222  to more easily be inserted through the septum  216 . Advantageously, the matching circular symmetries of the piercing member  220  and the opening in the septum  216  ensure a tight fit between the piercing member  220  and the septum  216 , even if the adaptor  200  is inadvertently twisted. Accordingly, the risk of dangerous liquids or gases escaping the vial  210 , or of impure air entering the vial  210  and contaminating the contents thereof, can be reduced in some instances with a circularly symmetric configuration. 
     In some embodiments, the sheath  222  is hollow. In the illustrated embodiment, the inner and outer surfaces of the sheath  222  substantially conform to each other such that the sheath  222  has a substantially uniform thickness. In various embodiments, the thickness is between about 0.015 inches and about 0.040 inches, between about 0.020 inches and about 0.030 inches, or between about 0.024 inches and about 0.026 inches. In other embodiments, the thickness is greater than or equal to about 0.015 inches, greater than or equal to about 0.020 inches, or greater than or equal to about 0.025 inches. In still other embodiments, the thickness is less than or equal to about 0.040 inches, less than or equal to about 0.035 inches, or less than or equal to about 0.030 inches. In some embodiments, the thickness is about 0.025 inches. 
     In some embodiments, the inner surface of the sheath  222  varies in configuration from that of the outer surface of the sheath  222 . Accordingly, in some arrangements, the thickness varies along the length of the sheath  222 . In various embodiments, the thickness at one end, such as a proximal end, of the sheath is between about 0.015 inches and about 0.050 inches, between about 0.020 inches and about 0.040 inches, or between about 0.025 inches and about 0.035 inches, and the thickness at another end, such as the distal end  223 , is between about 0.015 inches and 0.040 inches, between about 0.020 inches and 0.030 inches, or between about 0.023 inches and about 0.027 inches. In some embodiments, the thickness at one end of the sheath  222  is greater than or equal to about 0.015 inches, greater than or equal to about 0.020 inches, or greater than or equal to about 0.025 inches, and the thickness at another end thereof is greater than or equal to about 0.015 inches, greater than or equal to about 0.020 inches, or greater than or equal to about 0.025 inches. In still other embodiments, the thickness at one end of the sheath  222  is less than or equal to about 0.050 inches, less than or equal to about 0.040 inches, or less than or equal to about 0.035 inches, and the thickness at another end thereof is less than or equal to about 0.045 inches, less than or equal to about 0.035 inches, or less than or equal to about 0.030 inches. In some embodiments, the thickness at a proximal end of the sheath  222  is about 0.030 inches and the thickness at the distal end  223  is about 0.025 inches. In some arrangements, the cross-section of the inner surface of the sheath  222  is shaped differently from that of the outer surface. The shape and thickness of the sheath  222  can be altered, e.g., to optimize the strength of the sheath  222 . 
     In some instances, the length of the sheath  222 , as measured from a distal surface of the cap connector  230  to the distal end  223 , is between about 0.8 inches to about 1.4 inches, between about 0.9 inches and about 1.3 inches, or between about 1.0 inches and 1.2 inches. In other instances, the length is greater than or equal to about 0.8 inches, greater than or equal to about 0.9 inches, or greater than or equal to about 1.0 inches. In still other instances, the length is less than or equal to about 1.4 inches, less than or equal to about 1.3 inches, or less than or equal to about 1.2 inches. In some embodiments, the length is about 1.1 inches. 
     In certain embodiments, the sheath  222  at least partially encloses one or more channels. For example, in the embodiment of  FIG.  5   , the sheath  22  partially encloses the regulator channel  225  and the access channel  245 . In some arrangements, the sheath  222  defines the outer boundary of a distal portion of the regulator channel  225  and the outer boundary of a distal portion of the access channel  245 . An inner wall  227  extending from an inner surface of the sheath  222  to a distal portion of the medical connector interface  240  defines an inner boundary between the regulator channel  225  and the access channel  245 . 
     In the embodiment shown, the access channel  245  extends from an access aperture  246  formed in the sheath  222 , through the cap connector  230 , and through the connector interface  240 . Thus, when a medical device, such as a syringe, is connected with the medical connector  241 , which in turn is coupled with the connector interface  240 , the medical device is in fluid communication with the inside of the vial  210 . In such arrangements, the contents of the vial  210  and the contents of the medical device can be exchanged between the vial  210  and the medical device. 
     In the illustrated embodiment, the regulator channel  225  extends from a distal end  223  of the sheath  222 , through the cap connector  230 , through a portion of the connector interface  240 , through the lumen  226 , and terminates at the regulator aperture  228 . In certain arrangements, such as in the arrangement shown, the regulator aperture  228  is in fluid communication with the passage  253  of the coupling  252 , which is in fluid communication with the inner chamber  255  of the bag  254 . Thus, in such arrangements, the inner chamber  255  is in fluid communication with the regulator channel  225 . Additionally, because in the illustrated embodiment the filler  256  is located in the inner chamber  255 , the filler  256  is also in fluid communication with the regulator channel  225 . 
     In certain configurations, the adaptor  200  comprises a filter  260 . In the embodiment illustrated, the filter  260  is located in the regulator channel  225  within the lumen  226 . In other embodiments, the filter  260  is located in the regulator channel  225  in the sheath  222 . In yet other embodiments, the filter  260  is located in the passage  253  in the coupling  252 . Still further embodiments have the filter  260  positioned in the inner chamber  255  of the bag  254 . Generally, the filter  260  is chemically or mechanically held in position, e.g., by adhesive or a snap ring. Certain embodiments include a plurality of filters  260 . For example, certain embodiments have a first filter located in the lumen  226  and a second filter located in the coupling  252 . 
     In some arrangements, the filter  260  is a hydrophobic membrane, which is generally configured to allow gases to pass therethrough, but to inhibit or prevent passage of liquids therethrough. In some configurations, gases (e.g., sterilized air) are able to pass through the filter  260  so as to move between the vial  210  and the bag  254 , but liquid from the vial  210  is blocked by the filter  260 . Embodiments of the adaptor  200  in which the filter  260  is located in the regulator channel  225  can therefore reduce the likelihood of liquid spilling from the vial  210  even if the regulator assembly  250  is detached. 
     In certain configurations, the filter  260  can remove particles and/or contaminants from the gas that passes through the filter. For example, in certain embodiments, the filter  260  is configured to remove nearly all or about 99.9% of airborne particles 0.3 micrometers in diameter. In some cases, the filter  260  is configured to remove microbes. In some embodiments, the filter  260  comprises nylon, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, or other plastics. In some embodiments, the filter  260  includes activated carbon, e.g., activated charcoal. In certain configurations, the filter  260  comprises a mat of regularly or randomly arranged fibers, e.g., fiberglass. In some arrangements, the filter  260  comprises Gore-Tex® material or Teflon® material. 
     In the illustrated embodiment, the lumen  226  is a hollow cylindrical member extending radially outward from the connector interface  240 . In other embodiments, the lumen  226  comprises other shapes, such as conical. The lumen  226  can have a variety of cross-sectional shapes, such as circular, square, rectangular, elliptical, diamond, star-shaped, polygonal, or irregular. As shown, in some embodiments, the lumen  226  extends radially outward less than the sleeve  235  of the cap connector  230 . However, in certain configurations, the lumen  226  extends radially outward beyond the sleeve  235  of the cap connector  230 . Such a configuration can, for example, facilitate a connection with the regulator assembly  250  such that the regulator assembly  250  is spaced-apart from the remainder of the adaptor  200  and from the vial  210 . 
     In some embodiments, the coupling  252  has a shape that is corresponding or complementary with the shape of the lumen  226 . For example, in some cases, the lumen  226  has a triangular shape and the coupling  252  has a triangular shape as well. The coupling  252  can have most any cross-sectional shape, such as circular, square, rectangular, elliptical, diamond, star-shaped, polygonal, or irregular. In certain configurations, the coupling  252  and the lumen  226  are correspondingly shaped to promote an orientation of the coupling  252  (and thus the regulator assembly  250 ) relative to the lumen  226  (and thus the remainder of the adaptor  200 ), as discussed below. 
     The coupling  252  can be configured to engage the lumen  226 . For example, in the embodiments illustrated, the coupling  252  is configured to be received by the lumen  226 . In other cases, the coupling  252  is configured to receive the lumen  226 . In some instances, the coupling  252  and the lumen  226  connect with a slip fit or a press fit. In some configurations, the coupling  252  and the lumen  226  connect with a hose-barb connection. In certain arrangements, the coupling  252  and the lumen  226  connect with a threaded connection. For example, in certain cases the coupling  252  and the lumen  226  have corresponding standard luer lock connections. In some embodiments, the connection between the coupling  252  and the lumen  226  is substantially airtight, so as to inhibit or prevent outside air from entering the regulator channel  225 . Such a configuration can reduce the likelihood that microbes or impurities will enter vial  210 , thereby enhancing patient safety by reducing the likelihood of contaminating the medical fluid. 
     In some arrangements, the connection between the coupling  252  and the lumen  226  includes a feedback device to alert the user that the connection has been made. For example, in certain arrangements, the connection between the coupling  252  and the lumen  226  includes a detent mechanism, e.g., a ball detent, which can provide a tactile indication that the connection has been made. Some embodiments include an audible signal, e.g., a click, snap, or the like, to indicate that coupling  252  has been connected with the lumen  226 . 
     In some embodiments, the connection between the coupling  252  and the lumen  226  is substantially permanent. For example, in certain configurations, the coupling  252  and lumen  226  are sonically welded. In some cases, the coupling  252  and lumen  226  are permanently attached with an adhesive, such as glue, epoxy, double-sided tape, solvent bond, or otherwise. In some embodiments, the coupling  252  and lumen  226  joined with a permanent snap fit mechanism (e.g., a generally 90° hook and a corresponding generally 90° valley), such that the coupling  252  and lumen  226  are substantially restrained from being separated after the snap mechanism has been engaged. Permanent connection of the coupling  252  and lumen  226  can encourage one-time-use of the adaptor  200 , including one-time-use of the regulator assembly  250 . Further, permanent connection of the regulator assembly  250  and with the remainder of the adaptor  200  reduces the total number of unique parts to be inventoried, maintained, and prepared prior to use. In some embodiments, the coupling  252  is formed substantially monolithically with (e.g., molded during the same operation as) the remainder of the adaptor  200 . 
     In some cases, the coupling  252  and lumen  226  are connected during the process of manufacturing the adaptor  200 , e.g., at the factory. In some configurations, the regulator assembly  250  is a separate item from the remainder of the adaptor  200  and is configured to be connected with the remainder of the adaptor  200  by a user. For example, the piercing member  220 , cap connector  230 , and connector interface  240  may be provided in a first package and the regulator assembly  250  may be provided in a second package. In some user-connected configurations, the connection is substantially permanent. For example, in some cases one of the coupling  252  and the lumen  226  includes an adhesive (e.g., double-sided tape) which substantially permanently bonds the coupling  252  and the lumen  226  when the user connects the coupling  252  and the lumen  226 . On the other hand, in certain user-connected embodiments, the coupling  252  is configured to be detachable from the lumen  226 , even after the coupling  252  has been connected with the lumen  226 . For example, in certain embodiments the coupling  252  and the lumen  226  are releasably joined with threads or a release mechanism, such as a detent or a set-screw. Such a configuration can facilitate operations (e.g., voluminous pharmaceutical compounding operations) in which the transfer of a volume of regulating fluid from the regulator assembly  250  into the vial  210  is desired that is greater that the volume of regulating fluid contained in the regulator assembly  250 , as discussed below. In some embodiments, when the regulator assembly  250  is detached, the contents therein are sealed off from the environment, such as by way of a one-way valve. 
     In the illustrated embodiment, the coupling  252  is joined with the bag  254 . In some cases, the bag  254  and coupling  252  are welded or joined with adhesive. As shown, the connection of the bag  254  and the coupling  252  generally fluidly connects the passage  253  with the inner chamber  255  of the bag  254 . To facilitate fluid communication, the bag  254  can include a bag aperture  257 , such as a slit or hole. In some cases, the bag aperture  257  is produced with a hot implement, such as a soldering iron. 
     The bag  254  is generally configured to unfold, unroll, expand, contract, inflate, deflate, compress, and/or decompress. The bag  254  can comprise any of a wide variety of flexible and/or expandable materials. For example, in certain embodiments, the bag  254  comprises polyester, polyethylene, polypropylene, saran, latex rubber, polyisoprene, silicone rubber, vinyl, polyurethane, or other materials. In certain embodiments, the bag  254  comprises a material having a metal component to further inhibit fluid (including gas or air) leakage through the material of the bag, e.g., metalized biaxially-oriented polyethylene terephthalate (also known as PET and available under the trade name Mylar®). In some embodiments, the bag  254  comprises a laminate. For example, the bag  254  can be constructed of a layer of 0.36 Mil (7.8 #) metalized (e.g., aluminum) PET film and a layer of 0.65 Mil (9.4 #) linear low-density polyethylene. In some embodiments, the bag  254  comprises a material capable of forming a substantially airtight seal with the coupling  252 . In certain embodiments, the bag  254  is transparent or substantially transparent. In other embodiments, the bag  254  is opaque. In many instances, the bag  254  comprises a material that is generally impervious to liquid and air. In certain embodiments, the bag  254  comprises a material that is inert with respect to the intended contents of the vial  210 . For example, in certain cases, the bag  254  comprises a material that does not react with certain drugs used in chemotherapy. In some embodiments, the bag  254  comprises latex-free silicone having a durometer between about 10 and about 40. 
     In certain configurations, the bag  254  includes a coating. For example, in some embodiments, the bag  254  includes a coating that reduces the porosity of the bag  254 . In some cases, the coating is evaporated aluminum or gold. In some cases, the coating includes a water soluble plastic configured to form a barrier to inhibit passage of gases thereacross. In certain instances, the coating is applied to the outside of the bag  254 . In other instances, the coating is applied to the inside of the bag  254 . In some cases, the coating is applied to the inside and the outside of the bag  254 . In some embodiments, the coating is a polyolefin. 
     In certain embodiments, the bag  254  is located entirely outside of the vial  210 . In certain arrangements, the bag  254  is positioned entirely outside of the remainder of the adaptor (e.g., the piercing member  220 , cap connector  230 , and connector interface  240 ). In some embodiments, the bag  254  is substantially free to expand in generally any direction. For example, in the embodiment illustrated, there is no rigid enclosure surrounding or partially surrounding a portion of the bag  254 . In some instances, a rigid housing does not contain a substantial portion of the bag  254 . In some embodiments, in the fully deflated state, the bag  254  is not within a rigid enclosure. In certain configurations, the bag  254  is substantially free to expand in generally any direction, e.g., proximally, distally, radially away from the vial  210 , radially toward the vial  210 , etc. 
     In some embodiments, the bag  254  is configured to freely expand without being constrained by, for example, a rigid enclosure. Such unconstrained expansion of the bag  254  can reduce the force needed to expand the bag  254 . For instance, as the bag  254  does not contact a rigid enclosure, there is no frictional force between the bag  254  and such an enclosure, which could otherwise increase the force needed to expand the bag  254 . In certain aspects, unconstrained expansion of the bag  254  reduces the likelihood of the bag  254  being damaged during expansion. For example, because the bag  254  does not contact a rigid enclosure, there is less risk of the bag  254  being damaged (e.g., pierced, torn, or snagged on a burr or other defect of such an enclosure) during expansion or deflation. Further, unconstrained movement of the bag  254  lessens the chance of a coating on the bag  254  being smeared or rubbed-off. In some embodiments, the bag  254  does not bump, rub, slide against, or otherwise statically or dynamically contact a rigid surface of the adaptor  200  during expansion. In certain configurations, the bag  254  contacts only the coupling  252 , regulating fluid, and ambient air. 
     In certain embodiments, the bag  254  includes a first side  258  and a second side  259 . In some instances, the first side  258  is closer to the connector interface  240  than the second side  259 . In some cases, the first side  258  is bonded with the coupling  252 , but the second side  259  is not. In certain configurations, the first side  258  connects with the second side  259 . In some such cases, the first side  258  connects with the second side  259  at a peripheral edge of each of the sides  258 ,  259 . In certain instances, the second side  259  does not touch a rigid surface during expansion of the bag  254 . In some configurations, substantially all or a majority of the surface area of the bag  254  that is exposed to the ambient environment is flexible. In certain embodiments, generally the entire bag  254  is flexible. 
     In some embodiments, each of the sides  258 ,  259  includes an inner surface and an outer surface. As illustrated in  FIG.  6   , the inner surface of each of the sides  258 ,  259  can be in contact with the inner chamber  255 , and the outer surface of each of the sides  258 ,  259  can be in contact with the ambient environment. 
     In certain instances, the inner surface of each of the sides  258 ,  259  is oriented towards the inside of the bag  254 . As used herein, the phrase “oriented towards,” or any derivative thereof, is a broad term used in its ordinary sense and describes, for example, generally aligning or positioning something in the direction of the member indicated. For example, if a first member is oriented towards a second member, then the first member is generally aligned or positioned in the direction of the second member. In the case of a side or a surface being oriented toward a member, the side or surface is aligned or positioned such that a normal from the side or surface intersects the member. In certain configurations, the first side  258  is oriented towards the connector interface  240 . 
     In certain instances, the outer surface of each of the sides  258 ,  259  is oriented outwardly from the bag  254 . In some cases, the second side  259  is oriented away from the connector interface  240 . In some such cases, a normal extending from the outer surface of the second side  259  does not intersect the connector interface  240 . 
     In certain embodiments, the second side  259  is oriented opposite from the first side  258 . As used herein, the term “opposite,” or any derivative thereof, is a broad term used in its ordinary sense and describes, for example, something at the other end, side, or region from a member. For example, each side in a rectangle is opposite one other side and non-opposite two other sides. In some instances, the second side  259  is oriented away from the connector interface  240 . In such instances, a normal extending from the outer surface of the second side  259  does not intersect the connector interface  240 . 
     In some embodiments, the bag  254  includes a first layer and a second layer. As used herein, the term “layer,” or any derivative thereof, is a broad term used in its ordinary sense and describes, for example, a thickness, ply, or stratum of material. In some embodiments, a layer can include multiple components, plies, or strata of material. In some instances, the first layer is the first side  258  and the second layer is the second side  259 . In certain configurations, the first and second layers are connected. For example, a periphery of the first layer can be connected to or formed unitarily or monolithically with a periphery of the second layer. Such configurations can, for example, aid in forming the bag  254 , e.g., by rendering the bag  254  substantially airtight at the periphery. In some instances, the first layer is a first sheet of metalized PET and the second layer is a second sheet of metalized PET, and the first and second layers are bonded (e.g., heat sealed) together at the peripheries. In certain embodiments, the first and second layers each have a central portion. For example, in a configuration in which the first and second layers are each substantially circular in peripheral shape, the central portions can be at about the radial center of each of the first and second layers. In certain instances, the central portion of the first layer is unattached or not connected with the central portion of the second layer. Thus, in some such instances, the first and second portions can move relative to each other. 
     In some embodiments, one or both of the first and second layers include one or more sub-layers. For example, the first and/or second layers can each include a plastic sub-layer and a metal sub-layer. In certain embodiments, the first and second sub-layers have interfacing surfaces that are bonded together. In some cases, substantially the entire area of the interfacing are bonded. Generally, the sub-layers are not configured to receive a substantial volume or any appreciable volume (e.g., of regulating fluid) therebetween. On the other hand, in some embodiments, the first and second layers are configured to receive the regulating fluid therebetween. For example, in a configuration in which the first layer is the first side  258  and the second layer is the second side  259 , the regulating fluid can be received between the first and second layers (see  FIG.  6   ). 
     In various embodiments, the adaptor  200  does not include a rigid enclosure that wholly or partially contains the bag  254 . For example, any volume of the bag inside a rigid enclosure may encompass (if at all) less than half of the bag  254  or a very small portion of the volume of the bag (e.g., smaller than or equal to the volume inside the piercing member on the adapter or smaller than or equal to the volume inside the cap of the connector). In some embodiments, any volume of the bag inside a rigid enclosure (if at all) is less than or equal to half of the volume inside a vial or vials to which the adapter is configured to be connected. A rigid enclosure can increase the weight and total material of the adaptor  200 , thereby increasing material and manufacturing costs. Moreover, since rigid enclosures may be positioned a distance apart from the axial center of the adaptor, omitting a rigid enclosure can eliminate the moment of force that is imposed by the weight of such an enclosure. Thus, the adaptor  200  can promote stability and reduce the chance of tipping-over. Stability of the adaptor and vial can be particularly important in dealing with cytotoxic drugs, as tipping could increase the likelihood of spills or other unintended exposure and/or release. 
     Certain embodiments of the adaptor  200  have a center of mass that is not substantially disposed from the axial center of the adaptor  200 , when the regulator assembly  250  is connected with the remainder of the adaptor  200  and the adaptor  200  is mated with the vial  210 . For instance, some embodiments of the adaptor  200  have center of mass that is less than or equal to about 0.50 inches, less than or equal to about 0.25 inches, less than or equal to about 0.125 inches, or less than or equal to about 0.063 inches apart from the axial center of the adaptor  200 . 
     In some instances, the bag  254  is expandable to substantially fill a range of volumes such that a single adaptor  200  can be configured to operate with vials  210  of various sizes. In some embodiments, the bag  254  is configured to hold a volume equal to at least about 30, at least about 70, or at least about 90 percent of the volume of fluid contained within the vial  210  prior to the coupling of the adaptor  200  and the vial  210 . In some embodiments, the bag  254  is configured to hold a volume equal to about 70 percent of the volume of fluid contained within the vial  210  prior to the coupling of the adaptor  200  and the vial  210 . In various embodiments, the fluid in the bag  254  is a gas. For example, air, sterilized air, cleaned air, nitrogen, oxygen, inert gas (e.g., argon) or otherwise. In some embodiments, the sterilized air can be supplied by providing ambient air within the bag and then sterilizing the bag and air together. 
     The bag  254  has a fully expanded configuration ( FIG.  6   ) and at least one non-fully expanded configuration ( FIG.  5   ). In certain instances, in the fully expanded configuration, the volume of the inner chamber  255  of the bag  254  is at its maximum recommended volume. In certain instances, in the fully expanded configuration, the bag  254  contains at least about 100 mL, at least about 200 mL, or at least about 300 mL of fluid. In certain instances, in the fully expanded configuration, the bag  254  holds at least about 250 mL of fluid. In certain embodiments, in the fully expanded configuration, the bag  254  contains at least 180 mL of fluid. 
     In certain instances, in a non-fully expanded configuration, the bag  254  contains less than or equal to about 5 mL, less than or equal to about 40 mL, less than or equal to about 100 mL, or less than or equal to about 250 mL of fluid. In some instances, a non-fully expanded configuration of the bag  254  is a fully deflated configuration, in which the volume of the inner chamber  255  of the bag  254  is about zero. In some such instances, in the fully deflated configuration, the bag  254  contains substantially no fluid. 
     The bag  254  further has an initial configuration (e.g., the configuration prior to any regulating fluid being transferred between the vial  210  and the bag  254 ). Generally, the bag  254  contains a volume of fluid in the initial configuration to facilitate rapid and accurate withdrawal of fluid from the vial  210  upon connection of the adaptor  200  with the vial  210 . In certain embodiments, in the initial configuration, the bag  254  contains at least about 10 mL, at least about 50 mL, or at least about 90 mL of fluid. In certain embodiments, in the initial configuration, the bag  254  contains at least about 60 mL of fluid. In some embodiments, in the initial configuration, the bag  254  contains a volume of fluid that generally corresponds to the volume of a standard medical device or devices to which the adapter is configured to attach. For example, in certain instances, in the initial configuration, the bag  254  holds at least about 30 mL of fluid, which corresponds to the volume of a 30 mL syringe. In such instances, upon connection of the adaptor  200  with the vial  210 , about 30 mL of fluid are immediately available to be transferred between the bag  254  to the vial  210 , thereby allowing 30 mL of fluid to be immediately transferred between the vial  210  and the syringe. In some embodiments, the bag  254  has an initial volume of at least about the volume inside the cap plus inside of the piercing member, or at least about twice as large as the volume insider the cap plus inside of the piercing member. 
     In various arrangements, the bag  254  has an outer dimension (e.g., diameter or cross-sectional width or height) D of between about 1.0 inches and about 6.0 inches, between about 2.0 inches and about 5.0 inches, or between about 3.0 inches and about 4.0 inches. In some arrangements, the outer dimension is greater than or equal to about 3.0 inches, greater than or equal to about 4.0 inches, or greater than or equal to about 6.0 inches. In other arrangements, the outer diameter is less than or equal to about 8.0 inches, less than or equal to about 7.5 inches, or less than or equal to about 7.0 inches. In some embodiments, an outer dimension of the bag is greater than or equal to about the height or cross-sectional width of the vial or vials to which the adapter is configured to attach. In various arrangements, the bag  254  has a maximum total thickness T of between about 0.50 inches and about 2.00 inches, between about 0.60 inches and about 0.90 inches, and between about 0.70 inches and about 0.80 inches. In other arrangements, the maximum total thickness is less than about 1.00 inches, less than about 0.90 inches, or less than about 0.80 inches. In some arrangements, the maximum total thickness is about 0.75 inches. In certain instances, the diameter of the bag  254  is greater than the maximum total thickness of the bag  254 . In certain instances, the diameter of the bag  254  is greater than twice the maximum total thickness of the bag  254 . In some instances, it is desirable to prevent the bag  254  from bearing against the vial  210 . Accordingly, in some instances, the bag  254  is configured (e.g., dimensioned) such that even in the fully expanded state, the bag  254  is spaced apart from the vial  210 . 
     In some configurations, the bag  254  has a wall thickness W between about 0.001 and about 0.025 inches, between about 0.001 and about 0.010 inches, or between about 0.010 and about 0.025 inches. In other configurations, the wall thickness is greater than about 0.001 inches, greater than about 0.005 inches, greater than about 0.010 inches, greater than about 0.015 inches, or greater than about 0.020 inches. In still other configurations, the wall thickness is less than about 0.025 inches, less than about 0.020 inches, less than about 0.015 inches, less than about 0.010 inches, or less than about 0.005 inches. In some configurations, the wall thickness is about 0.015 inches. In some embodiments, the wall thickness is substantially constant. In some embodiments, the wall thickness can vary. For example, in some configurations, the wall thickness increases in an area of the bag  254  around the coupling  252 . 
     In some configurations, such as in the non-fully expanded configuration, the bag  254  is substantially irregularly shaped, as shown in  FIG.  5   . In other configurations, the bag  254  has shape that is generally spherical, generally conical, generally cylindrical, generally toroidal, or otherwise. For example, in some embodiments, in the fully expanded configuration, the bag  254  is shaped as a generally oblate spheroid. In certain instances, the bag  254  is substantially bulbous. In some arrangements, the bag  254  has a convex shape. In some configurations, the bag  254  has a concave shape. In some configurations, the shape of the bag  254  generally conforms to the shape of the filler  256 . In some arrangements, the bag  254  generally conforms to the shape of the filler  256  in a non-fully expanded configuration and deviates from the shape of the filler  256  in the fully expanded configuration. 
     The filler  256  can be configured to occupy various volumes within the bag  254 . For example, in some arrangements, the filler  256  occupies a volume greater than or equal to about 30, about 75, or about 90 percent of the volume of the bag  254 . In certain arrangements, the filler  256  is configured to maintain a space between the first and second sides  258 ,  259  of the bag  254 . In certain arrangements, the filler  256  is configured to ensure that the volume of the inner chamber  255  is not zero. 
     In general, the filler  256  is configured to provide a ready supply of regulating fluid, e.g., sterilized air, to the vial  210 . As discussed above, when the adaptor  200  is engaged with the vial  210  and a medical device (such as a syringe), and a portion of the fluid in the vial  210  is transferred from the vial  210  through the adaptor  200  into the medical device, the reduction in fluid volume in the vial  210  causes a pressure decrease in the vial  210 , thereby creating a pressure gradient between the interior and exterior of the vial  210 . This pressure gradient can cause surrounding air—which can contain microbes, impurities, and other contaminants—to leak into the vial  210  at the interface of the septum  216  and piercing member  220  or at the attachment interface of the adaptor  200  and a medical device. Further, such a pressure gradient can produce a restoring force that hinders the ability to withdraw an accurate amount of fluid from the vial  210 . However, the filler  256  can provide a ready supply of regulating fluid to the adaptor  200  to replace some or all of the fluid volume that has been transferred out to generally maintain equilibrium in the vial  210 , thereby lessening or preventing the aforementioned problems. 
     In certain arrangements, as fluid is removed from the vial  210  though the extraction channel  245 , a corresponding amount of regulating fluid from the filler  256  can substantially concurrently be introduced through the bag aperture  257 , the passage  253  in the coupling  252 , the regulator channel  225 , and into the vial  210 , thereby maintaining equilibrium. In some arrangements, the filler  256  includes a ready supply of regulating fluid prior to the regulator assembly  250  being connected with the remainder of the adaptor  200 . In some aspects, the filler  256  provides a reservoir of regulating fluid to the adaptor  200 . In certain arrangements, the filler  256  is configured such that a substantial portion of the first and second sides  258 ,  259  of the bag  254  do not contact each other. 
     In some configurations, the filler  256  has a similar shape as the bag  254 . For example, in some cases, in the fully expanded configuration, the bag  254  and the filler  256  are each generally shaped as an oblate spheroid. In other configurations, the filler  256  has a shape that is different than the bag  254 . For example, in certain instances, in the fully expanded configuration, the bag  254  has a substantially spheroidal shape and the filler  256  has a substantially cylindrical shape. In some such instances, the longitudinal axis of the cylindrically shaped filler  256  is generally parallel with the axial centerline of the adaptor  200 . In other such instances, the longitudinal axis of the cylindrically shaped filler  256  is orthogonal to the axial centerline of the adaptor  200 . 
     In certain embodiments, the filler  256  is configured to be deformed by the bag  254  when the bag  254  deflates. For example, in some instances, when the bag  254  deflates, the filler  256  decreases in volume by at least about 30, at least about 50, or at least about 90 percent. In certain instances, when the bag  254  is in the fully expanded configuration, the filler  256  has a first shape (e.g., spheroidal) and when the bag  254  is in the fully deflated configuration, the filler  256  has a second shape (e.g., disk-like). 
     In some such embodiments, the filler  256  is configured to be crushable or compressible and then return substantially to its original shape. For example, when the bag  254  deflates from the fully deflated configuration, the bag  254  substantially collapses the filler  256 , but during subsequent expansion of the bag  254 , the filler  256  returns to about its original shape. In other embodiments, the filler  256  is configured to be permanently deformed when it is crushed. For example, in some cases, the filler  256  comprises a thin-walled hollow member (e.g., an aluminum foil ball), which is configured to be permanently or irreversibly deformed, crushed, or otherwise decreased in volume during deflation of the bag  254 . This can provide an indicator that the adaptor  200  has already been used. In some embodiments, the filler  256  substantially maintains its shape when the bag  254  deflates. 
     In certain arrangements, the filler  256  is configured to contain a volume of gas, such as sterilized air. In certain cases, the filler  256  is porous. In some instances, the filler  256  is a sponge or sponge-like material. In certain arrangements, the filler  256  comprises cotton wadding. In certain configurations, the filler  256  comprises a mat of regularly or randomly arranged fibers configured to provide a network of chambers or spaces therein. In some embodiments, the filler  256  is made of low density foam. For example, in certain embodiments, the filler  256  is made of polyurethane-ether foam, and has a weight of, for example, about 1.05 pounds per cubic foot and an indentation load deflection (ILD) of, for example, about 38. In some embodiments, the filler  256  is made of polyether, polyester, polyethylene, or ether-like-ester (ELE). In some cases, the filler  256  is made of nylon, polypropylene, polyvinylidene fluoride, polytetrafluoroethylene, or other plastics. In certain embodiments, the filler  256  is a metal, e.g., aluminum or stainless steel. In certain embodiments, the filler  256  is treated with an anti-microbial or other compound to enhance sterility. In certain cases, the filler  256  comprises a sealed chamber, e.g., containing sterilized air, which is configured to open when a fluid is withdrawn from the vial  210 . In some embodiments, the filler  256  can be configured to bind with, absorb, generally neutralize, or otherwise chemically and/or mechanically interact with the fluid (such as vapors) entering the bag. 
     In various arrangements, at ambient pressure, the filler  256  has an outer dimension (e.g., a diameter or cross-sectional width or height) of between about 1.0 inches and about 6.0 inches, between about 2.0 inches and about 5.0 inches, or between about 3.0 inches and about 4.0 inches. In some arrangements, at ambient pressure the outer diameter of the filler  256  is greater than or equal to about 3.0 inches, greater than or equal to about 4.0 inches, or greater than or equal to about 6.0 inches. In certain embodiments, the diameter of the filler  256  at ambient pressure is about 4.00 inches. In other arrangements, at ambient pressure the outer diameter is less than or equal to about 8.0 inches, less than or equal to about 7.5 inches, or less than or equal to about 7.0 inches. In various arrangements, at ambient pressure the filler  256  has a maximum total thickness of between about 0.05 inches and about 0.99 inches, between about 0.20 inches and about 0.60 inches, and between about 0.25 inches and about 0.35 inches. In certain embodiments, the thickness of the filler  256  at ambient pressure is about 0.30 inches. In some arrangements, the maximum total thickness of the filler  256  at ambient pressure is about 1.00 inches. In some embodiments, at ambient pressure the diameter and thickness of the filler  256  are about the same as the diameter D and thickness T of the bag  254 . 
     With continued reference to  FIGS.  5  and  6   , certain processes for using the adaptor  200  comprise inserting the piercing member  220  through the septum  216  until the cap connector  230  is firmly in place. Accordingly, the coupling of the adaptor  200  and the vial  210  can be accomplished in one simple step. In certain instances, the medical connector  241  is coupled with the medical connector interface  240 . A medical device or other instrument (not shown), such as a syringe, can be coupled with the interface  240  or, if present, with the medical connector  241  (see  FIG.  4   ). For convenience, reference will be made hereafter only to a syringe as an example of a medical device suitable for attachment to the medical connector interface  240 , although numerous medical devices or other instruments can be used in connection with the adaptor  200  or the medical connector  241 . In some instances, the syringe is placed in fluid communication with the vial  210 . In some instances, the vial  210 , the adaptor  200 , the syringe, and, if present, the medical connector  241  are inverted such that the cap  214  is pointing downward (e.g., toward the floor). Any of the above procedures, or any combination thereof, can be performed in any possible order. 
     In some instances, a volume of fluid is withdrawn from the vial  210  into the syringe. As described above, the pressure within the vial  210  decreases as the fluid is withdrawn. Accordingly, in some instances, the regulating fluid in the filler  256  in the bag  254  flows through the regulator channel  225  and into the vial  210 . In some instances, the regulating fluid passes through the filter  260 . In some instances, the transfer of the regulating fluid from the filler  256  causes the bag  254  to deflate. In some arrangements, the transfer of the regulating fluid from the filler  256  and/or elsewhere in the bag  254  into the vial  210  generally maintains equilibrium in the vial  210 . In some cases, the volume of regulating fluid transferred from the filler  256  into the vial  210  is about equal to the volume of fluid withdrawn from the vial  210  into the syringe. 
     In certain instances, a volume of fluid is introduced into the vial  210  from the syringe. For example, in certain cases, a volume of fluid is introduced into the vial  210  to reconstitute a freeze-dried drug or for drug compounding purposes. As another example, in some instances, more fluid than is desired may inadvertently be withdrawn from the vial  210  by the syringe. As discussed above, as the fluid is introduced into the vial  210 , the pressure in the vial  210  increases. Thus, in some instances, regulating fluid in the vial  210  flows through the regulator channel  225  and into the bag  254 , as shown by the arrows in  FIG.  6   . In some instances, the regulating fluid passes through the filter  260 . In some instances, the transfer of the regulating fluid from the vial  210  causes the bag  254  to inflate. In certain of such instances, as the bag  254  inflates, it stretches, unfolds, or unrolls outward. In certain embodiments, the bag  254  is sufficiently flexible so as to substantially avoid producing a restoring force (e.g., a force in opposition to expansion or contraction of the bag  254 ). In some embodiments, the bag  254  does exert a restoring force. In some arrangements, the transfer of the regulating fluid from the vial  210  into the bag  254  maintains equilibrium in the vial  210 . In some cases, the volume of regulating fluid transferred from the vial  210  into the bag  254  is about equal to the volume of fluid introduced into the vial  210  from the syringe. 
     Thus, in certain embodiments, the adaptor  200  accommodates the withdrawal of fluid from, or the addition of fluid to, the vial  210  in order to maintain the pressure within the vial  210 . In various instances, the pressure within the vial  210  changes no more than about 1 psi, no more than about 2 psi, no more than about 3 psi, no more than about 4 psi, or no more than about 5 psi. 
     In some embodiments, a process for containing gases and/or vapors includes providing the piercing member  220 , cap connector  230 , and connector interface  240 . Generally, the process also includes piercing the septum of the vial  210  with the piercing member  220 . The piercing member  220  can provide access to medical fluid in the vial  210 . In certain embodiments, the process includes joining the regulator assembly  250  with the cap connector  230  or connector interface  240 , thereby fluidly connecting the regulator assembly  250  and the vial  210 . In some embodiments, the process also includes storing gases and/or or vapors displaced by a fluid that is introduced into the vial  210 . In certain configurations, all or a portion of the gases and/or vapors are stored in the regulator assembly  250 . Thus, the gases and/or vapors—which may pose substantial health hazards—can be sequestered and generally maintained apart from the ambient environment. In some embodiments, the process can include detaching the regulator assembly  250 . 
     As is evident from the embodiments and processes described above, the adaptor  200  allows a user to introduce liquid into (including returning unwanted liquid and/or air) and withdrawn liquid from the vial  210  without significantly changing the pressure within the vial  210 . As previously discussed, the capability to inject liquid into the vial can be particularly desirable in the reconstitution of lyophilized drugs. Also, as detailed earlier, the ability to inject air bubbles and excess fluid into the vial  210  can be particularly desirable in the context of oncology drugs. 
     Furthermore, the above discussion demonstrates that certain embodiments of the adaptor  200  can be configured to regulate the pressure within the vial  210  without introducing outside or ambient air into the vial  210 . For example, in some embodiments, the bag  254  comprises a substantially impervious material that serves as a barrier, rather than a passageway, between interior of the vial  210  and the ambient environment. Some embodiments of the adaptor  200  substantially reduce the risk of introducing airborne contaminants into the bloodstream of a patient. 
     As noted above, in some instances, the vial  210  is oriented with the cap  214  pointing downward when liquid is removed from the vial  210 . In certain embodiments, the access aperture  246  is located adjacent a bottom surface of the cap  214 , thereby allowing removal of most or substantially all of the liquid in the vial  210 . In other embodiments, access aperture  246  is located near the distal end  223  of the piercing member  220 . In some arrangements, the adaptor  200  comprises more than one access aperture  246  to aid in the removal of substantially all of the liquid in the vial  210 . 
       FIGS.  7 - 12    illustrate another embodiment of an adaptor  300 . The adaptor  300  resembles or is identical to the adaptor  200  discussed above in many respects. Accordingly, numerals used to identify features of the adaptor  200  are incremented by a factor of 100 to identify like features of the adaptor  300 . This numbering convention generally applies to the remainder of the figures. Any component or step disclosed in any embodiment in this specification can be used in other embodiments. 
     In certain embodiments, the adaptor  300  comprises a piercing member  320 , a cap connector  330 , a connector interface  340 , and a regulator assembly  350 . Further details and examples regarding some embodiments of piercing members  320 , cap connectors  330 , and connector interfaces  340  are provided in U.S. Patent Application Publication No. 2009/0216212, the entirety of each of which is incorporated herein by reference and is made a part of this specification. For clarity, the vial  210  is not illustrated. The adaptor  300  can mate with the vial  210  in a similar manner as the adaptor  200 . For example, when the adaptor  300  is mated with the vial  210 , the piercing member  320  extends through the septum  216  into the interior of the vial  210 . 
     In some embodiments, such as in the illustrated embodiment, the cap connector  330  comprises a body portion  380 , which in turn comprises a central portion  381  (that can be curved) and one or more tabs  382  (which can be opposing) attached to the central portion  381 . Each of the tabs  382  can be supported at a proximal end of the tab  382  by the central portion  381  of the body portion  380 . As shown, the distal end of the tabs  382  can each be unrestrained so as to allow the tab to deflect outward. 
     The body portion  380 , including the central portion  381  and tabs  382 , can help removably secure the vial adaptor  300  to the outside surface of the vial  210  and can help facilitate the removal of the vial adaptor  300  from the vial  210 . In some embodiments, the body portion  380  defines only one tab  382 , as opposed to a pair of opposing tabs  382 , the single tab being configured to removably secure the vial adaptor  300  to the outside surface of the vial  210  and to facilitate the removal of the vial adaptor  300  from the vial  210 . The single tab  382  can be of any suitable configuration, including those set forth herein. 
     In certain configurations, such as in the configuration illustrated in  FIG.  7 A , the piercing member  320  is supported by the body portion  380 . As illustrated, the piercing member  320  can project distally from the central portion  381  of the body portion  380 . The piercing member  320  can comprise an access channel  345  and a regulator channel  325 . In some embodiments, the regulator channel  325  begins at a distal regulator aperture  328   a , passes generally through the piercing member  320 , passes through a lumen  326  that extends radially outward from the connector interface  340 , and terminates at a proximal regulator aperture  328  ( FIG.  8   ). In certain instances, the lumen  326  extends radially outward from the connector interface  340  in only one direction. In some instances, the lumen  326  extends radially outward from the connector interface  340  in more than one direction, e.g., in two opposite directions. 
     In certain embodiments, the lumen  326  includes a barrier  383 , such as a wall, cap, plug, dam, cork, partition, or otherwise. In other configurations, the barrier  383  is configured to permit fluid to flow thereacross. For example, in some cases the barrier  383  is a filter, such as a hydrophobic or activated charcoal filter. In certain configurations, the barrier is configured to inhibit or prevent fluid flow thereacross. For example, in some cases the barrier is a continuous wall. In some such configurations, the barrier  383  blocks regulating fluid from exiting the adaptor  300 . 
     As illustrated in  FIG.  7 B , the cap connector  330  can include one or more recesses  397  at or near an interface between the piercing member  320  and the body portion  380 . In some embodiments, the one or more recesses  397  can comprise a generally annular region  399 . In some embodiments, the one or more recesses  397  are formed directly in the body portion  380 . The recesses  397  can help to create generally thin walls throughout the cap connector, avoiding one or more large or overly thick molded regions, and can diminish or limit the wall thickness of the cap connector  330 . In some embodiments, the recess can comprise one or more structural reinforcing members, such as struts, that extend across a portion of the recess to provide structural support. In some embodiments, one or more structural reinforcing members can be manufactured separately from the structure into which they are inserted. In some embodiments, providing generally thin walls in the cap connector  330  can assist in the molding process by avoiding excessive molding cycle time for the cap connector  330  and can conserve resources and manufacturing expense. In some embodiments, providing generally thin walls in the cap connector  330  can inhibit the formation of sinks and/or voids within the cap connector  330  during molding and manufacturing of the cap connector  330 . 
     The regulator assembly  350  can include a coupling  352 , a bonding member  384 , and a bag  354 . In some instances, the bag includes a filler (not shown), such as the filler  254  discussed above. The bag  354  can include a bag aperture  357 , which is illustrated as a linear slit but can take the form of most any opening in the bag. In certain configurations, the bag  354  is constructed of multiple sheets of material that have been joined (e.g., heat sealed) around the periphery. In some such configurations, such as shown in  FIG.  8   , the sealing operation produces a peripheral ridge  354   a  on the bag  354 . In cases, the bag  354  is produced from a balloon having a narrowing neck portion (such as the “4 Inch Round” balloon produced by Pioneer Balloon Company of Wichita, Kans.), wherein the neck portion is removed and the bag  354  is heat sealed around the periphery to enclose (aside from the bag aperture  357 ) a volume therein. In some instances, removal of the neck portion produces a flattened, truncated, or otherwise asymmetrical portion of the bag  359 , as shown in  FIG.  7   . 
     In certain embodiments, the bonding member  384  joins the coupling  352  with the bag  354 . For example, in certain instances, the bonding member  384  includes a double-sided adhesive, e.g., a member with an adhesive surface facing the coupling  352  and an adhesive surface facing the bag  354 . In the illustrated embodiment, the bonding member  384  comprises an adhesive first surface  834   a  and an adhesive second surface  834   b . As shown, the bonding member  384  can include an aperture  384   c . In some embodiments, the bonding member  384  is about 0.015 inches thick. In some embodiments, the bonding member  384  has a thickness of at least 0.01 inches and/or equal to or less than 0.03 inches. 
     In certain embodiments, the bonding member  384  is made of a flexible material, which can, for example, provide resiliency in the connection between the bonding member  384  and the coupling  352  and the bonding member  384  and the bag  354 . Such resiliency can allow the coupling  352  to slightly move relative to the bag  350 . Likewise, such resiliency can reduce the likelihood of the bag  354  being ripped, torn, or otherwise damaged during manipulation of the regulator assembly  350 , such as in the process of connecting the regulator assembly  350  with the remainder of the adaptor  300 . In certain configurations, the bonding member  384  is a foam (e.g., urethane, polyethylene, or otherwise), non-rigid plastic, rubber, paper, or cloth (e.g., cotton) material. In certain aspects, the bonding member  384  is made of doubled-sided foam tape. 
     In certain instances, the coupling  352  includes a base  385  and a cover  386 , which in turn can include an outer face  386   a  ( FIG.  8   ). In some embodiments, the bonding member  384  is configured to adhere to or otherwise join with the outer face  386   a . In some embodiments, the bonding member  384  is configured to adhere to or otherwise join with the bag  354 . The connections between the bonding member  384  and the outer face  386   a , as well as the connection between the bonding member  384  and the bag  354 , is substantially fluid tight (e.g., airtight) so that fluid passing between the coupling  352  and the bag  354  is inhibited from escaping. In some embodiments, the connection between the bonding member  384  and the coupling  352 , and the bonding member  384  and the bag  354 , is substantially permanent, such that once these components are joined they are not intended to be separated. In some embodiments, the connection between the bonding member  384  and the coupling  352 , and the bonding member  384  and the bag  354 , is configured to be temporary or detachable. 
     As shown in  FIG.  8   , a filter  360  can be housed between the base  385  and the cover  386 . The cover  386  can be substantially sealingly received by the base  385  so that substantially all of the fluid that is permitted to flow through the filter  360  flows through an opening  387  formed in the cover  386 . The base  385  and the cover  386  can be formed from any suitable material, such as plastic or metal. In some embodiments, the perimeter of the coupling  352  defines a non-circular shape, such as a square, triangular, polygonal, or other suitable or desired shape. 
     The cover  386  can be press-fit with or otherwise attached to the base  385  using adhesive, sonic welds, or by any other similar or suitable means. For example, as illustrated in  FIG.  12   , the cover  386  can be attached to the base  385  with one or more sonic welds  388 . The cover  385  and the base  386  can be joined together so that an annular protrusion  389  of the cover  385  is adjacent to an annular protrusion  390  on the base  385 . The protrusion  390  can have a stepped or extended lip portion  390   a  that can overlap the protrusion  389  formed on the cover  386  in the assembled configuration. The base  385  and the cover  386  can be made of various materials, such as metal or plastic. In some cases, the base  385  and the cover  386  are made of polycarbonate plastic. 
     In some embodiments, the cross-sectional area of the filter  360  is substantially larger than the cross-sectional area of the proximal regulator aperture  328 . Such a configuration can increase the rate that regulating fluid flows through the filter  360 , thereby providing sufficient regulating fluid to compensate for the introduction or withdrawal of fluid from the vial  210 . As discussed above, providing sufficient regulating fluid can inhibit or avoid a pressure gradient (e.g., a vacuum) between the inside and outside of the vial and can reduce or eliminate a restoring force on the plunger of the syringe. In some embodiments, the cross-sectional area of the filter  360  is at least about 5 times greater than the cross-sectional area of the proximal regulator aperture  328 . In some embodiments, the cross-sectional area of the filter  360  is between approximately 2 times greater and approximately 9 times greater than the cross-sectional area of the proximal regulator aperture  328 , or to or from any values within these ranges. Similarly, in some embodiments, the cross-sectional area of the filter  360  can be approximately 400 times greater than the cross-sectional area of the distal regulator aperture  328   a . In some embodiments, the cross-sectional area of the filter  360  can be between approximately 100 times greater and approximately 250 times greater, or between approximately 250 times greater and approximately 400 times greater, or between approximately 400 times greater and approximately 550 times greater than the cross-sectional area of the distal regulator aperture  328   a , or to or from any values within these ranges. 
     The filter  360  can be configured to remove or diminish particulate matter such as dirt or other debris, germs, viruses, bacteria, and/or other forms of contamination from fluid flowing into the vial adaptor  300 . The filter  360  can be formed from any suitable filter material. In some embodiments, the filter  360  can be hydrophobic and can have a mean pore size of approximately 0.1 micron, or between approximately 0.1 micron and approximately 0.5 micron. 
     As illustrated in  FIG.  9   , in certain configurations, the coupling  352  can be received in the proximal regulator aperture  328 . In some embodiments, a protrusion  385   a  (e.g., a boss) extending from the base  385  is configured to be substantially sealingly received within or around the outer perimeter of the proximal regulator aperture  328 . The protrusion  385   a  can generally define a regulator path. In some embodiments, the protrusion  385   a  is press-fit into the proximal regulator aperture  328  so as to create a generally sealed connection between the protrusion  385   a  and the proximal regulator aperture  328 . In some embodiments, adhesive, welds, or other materials or features can be used to provide the connection between the protrusion  385   a  and the proximal regulator aperture  328 . In some instances, the protrusion  385   a  and the proximal regulator aperture  328  are bonded with a solvent. The protrusion  385   a  can be sized and configured to have a sufficient wall thickness and diameter to ensure that the protrusion  385   a  is not inadvertently broken during use by an inadvertent contact with coupling  352 . In some embodiments, the regulator path can be in fluid communication with the regulator channel  425  when the protrusion  385   a  is connected to the proximal regulator aperture  328 . 
     An opening  387   a  can be formed through the protrusion  385   a  so that fluid flowing between the base  385  and the cover  386  will be filtered by the filter  360  before flowing through the opening  387  or  387   a . The size of the opening  387   a  formed through the protrusion  385   a , as well as the opening  387  formed in the cover  386 , can be designed to ensure a sufficient amount of fluid flow through the filter  360 . The diameter of the proximal regulator aperture  328  can be adjusted to accommodate any desired or suitable outside diameter of the protrusion  385   a.    
     With reference to  FIGS.  10 ,  11 , and  12   , the cover  386  can have a first inner annular protrusion  391  having one or more openings  391   a  therethrough, a second inner annular protrusion  392  having one or more openings  392   a  therethrough, and an outer annular protrusion  389 . In some embodiments, when the cover  386  is assembled with the base  385  and the filter  360 , the annular protrusions  389 ,  391 ,  392  and the openings  391   a ,  392   a  form a volume of space  393  between the inner surface of the cover  386  and the surface of the filter  360  into which regulating fluid can flow and circulate before or after passing through the filter  360 . Similarly, the base  385  can have a first inner annular protrusion  394  having one or more openings  394   a  therethrough, a second inner annular protrusion  395  having one or more openings  395   a  therethrough, and an outer annular protrusion  390 . In some embodiments, when the base  385  is assembled with the cover  386  and the filter  360 , the annular protrusions  390 ,  394 ,  395  and the openings  394   a ,  395   a  form a volume of space  396  between the inner surface of the base  386  and the surface of the filter  360  into which the regulating fluid can flow and circulate before or after passing through the filter  360 . In some configurations, the regulating fluid can access substantially the entire surface area of the filter  360 . 
     In some embodiments, regulating fluid can flow through the opening  387  formed in the cover  386  into the space  393  defined between the cover  386  and the filter  360 , through the filter  360 , into the space  377  defined between the filter  360  and the base  385 , through the opening  385   b  formed in the base  385 , through the proximal regulator aperture  382 , and into the regulator channel  325  formed in the vial adaptor  300 . Likewise, in certain embodiments, regulating fluid can flow through the regulator channel  325  formed in the vial adaptor  300 , through the proximal regulator aperture  382 , through the opening  385   b  formed in the base  385 , into the space  395  defined between the filter  360  and the base  385 , through the filter  360 , into the space  393  defined between the cover  386  and the filter  360 , and through the opening  387  formed in the cover  386 . In some instances, the opening  387  is in fluid communication with ambient air. 
     In some instances, the annular protrusions  390 ,  394 ,  395  are configured to maintain the shape and position of the filter  360  relative to the base  385  and the cover  386 . For example, the annular protrusion  390  can be configured to maintain the filter  360  about radially centered in the base  385  and the cover  386 , which can reduce the chance of fluid passing around (rather than through) the filter  360 . In some configurations, the annular protrusions  394 ,  395  are configured to substantially inhibit the filter  360  from becoming concave shaped as regulating fluid passes through the filter  360 , which can reduce the likelihood of the filter  360  being torn or otherwise damaged. 
       FIG.  10 A  illustrates an embodiment of a base  385 ′ and a cover  386 ′. Numerical reference to components is the same as previously described, except that a prime symbol (′) has been added to the reference. Where such references occur, it is to be understood that the components are the same or substantially similar to previously-described components unless otherwise indicated. For example, in some embodiments, the base  385 ′ has an opening  385   b ′. The opening  385   b ′ can be wider than an opening  387 ′ in the cover  386 ′. In some embodiments, wide openings  385   b ′ can allow for increased flow rates into the space  377  between the filter  360  and the base  385 ′ from the regulator channel  382 . In some embodiments, the opening  385   b ′ is smaller than the opening  387 ′ in the cover  386 ′. 
     In some embodiments, the base  385 ′ includes a plurality of inner annular protrusions. For example, the base  385 ′ can include a first inner annular protrusion  394 ′. The first inner annular protrusion  394 ′ can have one or more openings  394   a ′ circumferentially distributed about the first annular protrusion  394 ′ at generally the same distance from the opening  391   a ′. The base  385 ′ can include a second inner annular protrusion  395 ′. In some embodiments, the second inner annular protrusion  395 ′ includes one or more openings  395   a ′ distributed circumferentially about the second inner annular protrusion  395 ′ at generally the same distance from the opening  391   a ′. The base  385 ′ can include one or more additional inner annular protrusions. In some embodiments, the base  385 ′ includes 6 inner annular protrusions. In some embodiments, the base  385 ′ includes more than or less than 6 inner annular protrusions. One or more of the additional inner annular protrusions can have one or more openings. 
     In some embodiments, the cover  386 ′ includes a plurality of inner annular protrusions. For example, the cover  386 ′ can include a first inner annular protrusion  391 ′. The first inner annular protrusion  391 ′ can have one or more openings  391   a ′ circumferentially distributed about the first annular protrusion  391 ′ at generally the same distance from the opening  391   a ′. The cover  386 ′ can include a second inner annular protrusion  392 ′. In some embodiments, the second inner annular protrusion  392 ′ includes one or more openings  392   a ′ distributed circumferentially about the second inner annular protrusion  392 ′ at generally the same distance from the opening  391   a ′. The cover  386 ′ can include one or more additional inner annular protrusions. In some embodiments, cover  386 ′ includes 6 inner annular protrusions. In some embodiments, the cover  386 ′ includes more than or less than 6 inner annular protrusions. One or more of the additional inner annular protrusions can have one or more openings. 
     The protrusions  391 ′,  392 ′,  394 ′,  395 ′ and any additional inner annular protrusions on the cover  286 ′ and the base  385 ′ can have openings (e.g.,  391   a ′,  392   a ′,  394   a ′,  395   a ′) that are arranged in circumferential patterns such that openings on adjacent inner annular protrusions are circumferentially offset from one another to produce a non-direct or tortuous flow path. For example, the openings  392   a ′ can be circumferentially offset from the openings  391   a ′. In some arrangements, folding of the filter  360  into the openings  391   a ′,  392   a ′ can be inhibited, and/or the flow path can be encouraged to pass through a substantial portion of the filter in a circumferential or lateral direction by avoiding direct radial flow. In this description of the positioning, orientation, and/or shape of the protrusions, as with all other descriptions in this application, terms that apply to circular structures such as “circumferential” or “radial” or similar terms should be interpreted to apply to non-circular structures in a corresponding manner. 
     In some embodiments, the protrusions  391 ′,  392 ′,  394 ′,  395 ′ and/or any additional inner annular protrusions on the cover  386 ′ and the base  385 ′ can have generally rounded, chamfered, and/or filleted edges. In some such embodiments, one or more or all of the protrusions  391 ′,  392 ′,  394 ′,  395 ′ and/or any additional inner annular protrusions do not have sharp corners in order to reduce the possibility of damage to the filter  360  and to assist in the molding process. 
     In certain embodiments, the adaptor  300  is modularly configured. Such a configuration can, for example, facilitate manufacturability and promote user convenience by standardizing one or more parts of the adaptor  300 . For example, in some instances, the configuration of the piercing member  320 , cap connector  330 , the connector interface  340 , and the coupling  352  is substantially unchanged regardless of the volume of fluid to be transferred between the medical device and the vial  210 . Such standardization can, for example, reduce the number of unique components to be purchased, stored, and inventoried, while maintaining the functionality of the adaptor  300 . 
     In some modular embodiments, the adaptor  300  includes a first portion (e.g., the piercing member  320 , cap connector  330 , connector interface  340 , and coupling  352 —such as is shown in  FIG.  9   ) and a second portion (e.g., the bag  354 ). In certain embodiments, the first portion is separate and spaced-apart from the second portion in a first arrangement, and the first portion is connected with the second portion in a second arrangement. Some embodiments can allow for variety of configurations (e.g., sizes) of the bag  354  to be mated with a common configuration of the remainder of the adaptor  300 . For example, in some embodiments, 20 mL, 40 mL, and 60 mL configurations of the bag  354  are each connectable with a common configuration of the remainder of the adaptor  300 . In certain embodiments, the bag  354  configuration is selectable while the remainder of the adaptor  300  is unchanged. In some cases, the configuration of the bag  354  is selected based on the volume of fluid to be transferred between the medical device (e.g., syringe) and the vial  210 . For example, if about 25 mL of fluid is to be transferred from the medical device into the vial  210 , then a configuration of the bag  354  that is able to contain greater than or equal to about 25 mL of fluid can be selected and connected to the remainder of the adaptor  300 ; if, however, it is determined that a different volume of fluid is to be transferred from the medical device into the vial  210 , then the selection of the bag  354  can be changed without the need to change the remainder of the adaptor  300 . 
     Certain modular embodiments can provide a ready supply of filtered or otherwise cleaned regulating fluid without being connected with the bag  354 . For example, in some embodiments, the opening  387  of the cover  386  of the coupling  352  is in fluid communication with ambient air, thereby providing a supply of filtered air through the coupling  352 , the regulator channel  325 , and into the vial  210 , when the piercing member  320  is disposed in the vial  210  and fluid is withdrawn through the access channel  345 . In certain instances, the adaptor  300  does not include the bag  354  and/or the bonding member  384 . In some embodiments, the lumen  326  is configured to connect with a filtered or otherwise cleaned regulating fluid source. For example, the lumen  326  can be configured to connect with a tube in fluid communication with a tank of sterilized air. 
     In some embodiments, a process of manufacturing the vial adaptor  300  includes forming the piercing member  320 , cap connector  330 , and connector interface  340  in a first assembly. For example, in certain embodiments, the piercing member  320 , a cap connector  330 , a connector interface  340  are produced by the same operation (e.g., molding, machining, or otherwise). The process can also include forming the coupling  352 . For example, in some configurations, the base  385  and cover  386  are assembled with the filter  360  therebetween, as discussed above. In certain embodiments, the process also includes mating the coupling  352  with the lumen  326 , such as is shown in  FIG.  9   . Further, the process can include joining the bonding member  384  with the outer face  386   a  of the cover  386 . In some instances, the bonding member  384  is joined with the bag  354 . As shown in  FIG.  7   , the lumen  326 , the opening  387   a  in the base, the opening  387  in the cover  386 , and the bag aperture  357  can be aligned, thereby allowing regulating fluid to flow between the vial  210  and the bag  354 . 
     In some instances, the process of manufacturing the vial adaptor  300  can, for example, enable production of the adaptor  300  in discrete sub-assemblies, which can facilitate manufacturability. For example, a first sub-assembly can include the piercing member  320 , cap connector  330 , and connector interface  340 ; a second sub-assembly can include the coupling  352  (including the base  385 , the cover  386 , and the filter  360 ); and a third sub-assembly can include the bag  354  and bonding member  384 . Of course, other sub-assemblies are contemplated; for example, the second sub-assembly can include the coupling  352  and the bonding member  384 . In some cases, one or more of the sub-assemblies are supplied separately to the user (e.g., a healthcare worker). 
       FIG.  13    illustrates an embodiment of an adaptor  800  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. The adaptor comprises a regulator assembly  850  with a seal  864 , a counterweight  831 , and a keyed coupling  852 . As used herein, a “keyed coupling” is used in its broad and ordinary sense and includes couplings having a shape configured to match another coupling in one or more orientations. Furthermore, the illustrated embodiment of the adaptor  800  does not include a filler. In some such embodiments, the adaptor  800  includes a bag  854  that is sufficiently rigid to substantially inhibit the bag  854  from fully deflating (e.g., enclosing about zero volume). 
     In some embodiments, the seal  864  is configured to inhibit or prevent unintended transfer of regulating fluid out of the regulator assembly  850  and/or unintended transfer of ambient air into the regulator assembly  850 . For example, in the embodiment shown, prior to the regulator assembly  850  being connected with the remainder of the adaptor  800 , the seal  864  generally blocks the initial volume of regulating fluid (which may be at a pressure above ambient pressure) contained in the regulator assembly  850  from escaping into the ambient environment. Additionally, the seal  864  can generally block ambient air, which may contain microbes or impurities, from entering the regulator assembly  850 . 
     In the illustrated embodiment, the seal  864  comprises a membrane with a slit  865 . In certain instances, such as when the regulator assembly  850  is connected with the adaptor  800  and fluid is introduced or withdrawn through an access channel  845 , the pressure difference between the vial  210  and the bag  854  causes the slit  865  to open, thereby allowing regulating fluid to flow between the regulator assembly  850  and the vial  210 . Various other kinds and configurations of the seal  864  are contemplated. For example, in some embodiments, the seal  864  is a duck-bill valve. As another example, in some embodiments, the seal  864  comprises a substantially continuous (e.g., without a slit) membrane that is configured to rupture at a certain pressure differential (e.g., at least about 1 psi, at least about 2 psi, at least about 5 psi). 
     In the embodiment shown, the seal  864  is located in the coupling  852 . In some other embodiments, the seal  864  is disposed in alternate locations. For example, the seal  864  can be located in a passage  826 . In some arrangements, the seal  864  is configured to dislodge or detach from the adaptor  800  when fluid is introduced or withdrawn through the access channel  845 . For example, in certain instances, when fluid is withdrawn from the vial  210  through the access channel  845 , the seal  864  is dislodged from the regulator channel  825 , thereby allowing regulating fluid to flow into the vial  210 . In some such cases, the seal  864  is a tab or a sticker. In some such cases, the seal  864  separates from the adaptor  800  and falls into the vial  210 . 
     As shown, certain configurations of the adaptor  800  include a cap connector  830 , which in turn includes the counterweight  831 . The counterweight  831  can, for example, enhance the stability of the mated vial  210  and adaptor  800  and reduce the chances of the combination tipping. In certain arrangements, the counterweight  831  is configured to locate the center of mass of the adaptor  800  substantially on the axial centerline of the adaptor  800  when the regulator assembly  850  is connected to the adaptor  800 . In certain arrangements, the counterweight  831  has a mass that is about equal to the sum of the mass of an outwardly extending connection member  829  plus the mass of the regulator assembly  850  in the initial configuration. In some instances, the counterweight  831  comprises a mass of material generally located on the opposite side of the axial centerline as the regulator assembly  850 . In some instances, the counterweight  831  comprises an area of reduced mass (e.g., grooves, notches, or thinner walls) on the same side of the axial centerline as the regulator assembly  850 . 
     As shown in  FIGS.  14 A- 14 F , which illustrate cross-sectional views of various examples of the coupling  852 , the coupling  852  can be keyed or otherwise specially shaped. The connection member  829  typically is correspondingly keyed or otherwise specially shaped. Such a configuration can be useful to signal, control, or restrict the regulator assemblies  850  that can be connected with a given adaptor  800 . For example, a relatively large regulator assembly  850  (e.g., initially containing at least about 100 mL of regulating fluid) may be keyed so as not to mate with a relatively small adaptor  800  (e.g., sized and configured for to mate with vials  210  containing less than about 3 mL of fluid). In certain cases, the combination of a large regulator assembly and a small vial could be unstable and could exhibit an increased tendency to tip-over, and thus would be undesirable. However, by keying sizes of the regulator assembly  850  so as to mate only with appropriate sizes of the adaptor  800 , such concerns can be reduced or avoided. In various embodiments, the coupling  852  can be male or female and the connection member  829  can be correspondingly female or male. 
     Various types of keyed couplings  852  are contemplated. In some embodiments, the shape of the coupling  852  inhibits or prevents rotation of the regulator assembly in relation to the remainder of the adaptor  800 . For example, as shown in  FIG.  14 A , the coupling  852  can be substantially rectangular. The connection member  829  can be correspondingly rectangular to matingly engage with the coupling  852 . Similarly, as shown in  FIG.  14 B , the coupling  852  can be substantially diamond-shaped. The connection member  829  can be correspondingly diamond-shaped to matingly engage with the coupling  852 . Likewise, as shown in  FIG.  14 C , the coupling  852  can include notches, grooves, bumps or the like. The connection member  829  can be correspondingly shaped to matingly engage with the notches, grooves, bumps or the like of the coupling  852 . 
     In certain embodiments, the shape of the coupling  852  establishes the orientation of the regulator assembly  850  with regard to the remainder of the adaptor  800 . For example, in the embodiment illustrated in  FIG.  14 C , the coupling  852  (and thus the regulator assembly  850 ) are configured to mate with the connection member  829  in only two possible orientations. In some embodiments, such as the embodiments illustrated in  FIGS.  14 D,  14 E, and  14 F , the coupling  852  (and thus the regulator assembly  850 ) is configured to mate with the connection member  829  in only a single possible orientation. 
     Some embodiments provide feedback to alert the user that mating engagement of the coupling  852  and the connection member  829  has been achieved. For example, in certain instances, the connection between the coupling  852  and the connection member  829  includes a detent mechanism, e.g., a ball detent, which can provide tactile indication of engagement. Some embodiments include an audible signal, e.g., a click, snap, or the like, to indicate engagement. 
     Certain embodiments link the coupling  852  and the connection member  829  so as to inhibit or prevent subsequent separation. For example, some arrangements include an adhesive in one or both of the coupling  852  and connection member  829 , such that mating engagement adheres the coupling  852  and the connection member  829  together. In certain other arrangements, mating engagement of the coupling  852  and connection member  829  engages one-way snap-fit features. 
       FIG.  15 A  illustrates an embodiment of an adaptor  1700  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein, and also includes a valve  1770 . The adaptor  1700  is configured to engage with a vial  10 . In some embodiments, the adaptor  1700  includes a regulator assembly  1750 . In some configurations, the regulator assembly  1750  includes a protrusion  1785   a  which can be substantially sealingly attached to (e.g., received within or around the outer perimeter of) a lumen  1726  of the regulator assembly  1750 . The protrusion  2085   a  can facilitate fluid communication between two or more features (e.g., a filter, enclosure, bag and/or valve) of the regulator assembly. In some embodiments, the protrusion  2085   a  can generally define a regulator path. The regulator path can be in fluid communication with the regulator channel a regulator channel  1725  of the regulator assembly  1750 . The longitudinal axis of the protrusion  1785   a  and/or the lumen  1726  can be at least partially, substantially, or wholly perpendicular to the axial centerline of the adaptor  1700 . In some embodiments, the longitudinal axis of the protrusion  1785   a  and/or the lumen  1726  is at least partially, substantially, or wholly parallel to the axial centerline of the adaptor  1700 . In some embodiments, the angle between the longitudinal axis of the protrusion  1785  and the axial centerline of the adaptor  1700  is greater than or equal to about 5° and/or less than or equal to about 85°. In some embodiments, the angle is about 60°. In certain embodiments, the angle between the longitudinal axis of the protrusion  1785  and the axial centerline of the adaptor  1700  can be any angle between 0° and 90° or a variable angle that is selected by the user. Many variations are possible. 
     In some embodiments, the regulatory assembly includes a filter  1760 . The filter  1760  can include a hydrophobic filter. In some embodiments, the valve  1770  or a portion thereof is located within a lumen  1726  of the adaptor  1700 . In some embodiments, the valve  1770  or a portion thereof is located outside the lumen  1726  of the adaptor  1700  within the protrusion  1785   a  of the regulator assembly  1750 . 
     According to some embodiments, the valve  1770  is configured to permit air or other fluid that has passed through the filter  1760  to pass into the container  10 . In some embodiments, the valve  1770  is configured to selectively inhibit fluid from passing through the valve  1770  from the container  10  to the filter  1760 . 
     In some configurations, the valve  1770  is selectively opened and/or closed depending on the orientation of the adaptor  1700 . For example, the valve  1770  can be configured to allow fluid flow between the container  10  and the filter  1760  without restriction when the adaptor  1700  is positioned above (e.g., further from the floor than) a vial  10  to which the adaptor is attached. In some embodiments, the valve  1770  can be configured to prevent fluid flow from the container  10  to the filter  1760  when the vial  10  is positioned above the adaptor  1700 . 
     In some embodiments, the valve  1770  can open and/or close in response to the effect of gravity upon the valve  1770 . For example, the valve  1770  can include components that move in response to gravity to open and/or close channels within the valve  1770 . In some embodiments, channels within the valve  1770  can be constructed such that the effect of gravity upon fluid within the adaptor  1700  can prevent or allow the fluid to pass through the channels within the valve  1770 . 
     For example, the valve  1770  can comprise an orientation-sensitive or orientation-dependent roll-over valve. In some embodiments, a roll-over valve  1770  can comprise a weighted sealing member. In some embodiments, the weighted sealing member can be biased to seal and/or close the valve  1770  when the vial  10  is positioned above the adaptor  1700 . In some embodiments, the sealing member can be biased to seal the valve  1770  by the force of gravity. In some embodiments, the sealing member can be biased to seal the valve  1770  through the use of a compression spring. The sealing member can be constructed such that it can transition to open the valve  1770  when the adaptor  1700  is positioned above the vial  10 . For example, the weight of the sealing member can be high enough that it overcomes the force of the compression spring and moves to an open position when the adaptor  1700  is positioned above the vial  10 . 
     In some embodiments, the valve  1770  can comprise a swing check valve. In some embodiments, the valve  1770  can comprise a weighted panel rotatably connected to the wall of the regulator channel  1925 . The weighted panel can be oriented such that, when the adaptor  1700  is positioned above the vial  10 , the weighted panel is rotated to an open position wherein the weighted panel does not inhibit the flow of fluid through the regulator channel  1925 . In some embodiments, the weighted panel can be configured to rotate to a closed position wherein the weighted panel inhibits the flow of fluid through the regulator channel  1925  when the vial  10  is positioned above the adaptor  1700 . 
     According to some configurations, the valve  1770  can be a check valve which can transition between two or more configurations (e.g., an open and closed configuration). In some embodiments, the valve  1770  can change configurations based on user input. For example, the valve  1770  and/or regulator assembly  1750  can include a user interface (e.g., a button, slider, knob, capacitive surface, switch, toggle, keypad, etc.) which the user can manipulate. The user interface can communicate (e.g., mechanically, electronically, and/or electromechanically) with the valve  1770  to move the valve  1770  between an opened configuration and a closed configuration. In some embodiments, the adaptor  1700  and/or regulator assembly  1750  can include a visual indicator to show whether the valve  1770  is in an open or closed configuration. 
     According to some embodiments, the valve  1770  is configured to act as a two-way valve. In such configurations, the valve  1770  can allow for the passage of fluid through the valve  1770  in a first direction  1770 A at one pressure differential while allowing for the passage of fluid in a second direction  1770 B at a different pressure differential. For example, the pressure differential required for fluid to pass in a first direction  1770 A through the filter  1770  can be substantially higher than the pressure differential required for fluid to pass through the filter  1770  in a second direction  1770 B. 
       FIG.  15 B  illustrates an embodiment of an adaptor  1800  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. The adaptor  1800  includes a regulator assembly  1850  which, in some embodiments, can include a valve  1870 . The valve  1870  can be located in a regulator channel  1825  within a lumen  1826  of the adaptor  1800  between a container  10  and a bag or other enclosure  254 . In some embodiments, the valve  1879 , or a portion thereof, is located outside of the lumen  1826  and within a coupling  1852  of the regulator assembly  1850 . In some embodiments, the valve  1870  is configured to permit regulator fluid and/or other fluid to pass from the enclosure  1854  to the container  10 . In some embodiments, the valve  1870  is configured to inhibit or prevent the passage of fluid from the container  10  to the enclosure  1854 . 
     In some configurations, the valve  1870  is selectively opened and/or closed depending on the orientation of the adaptor  1800 . For example, the valve  1870  can be configured to allow fluid flow between the container  10  and the enclosure  1854  without restriction when the adaptor  1800  is oriented above a vial  10  to which the adaptor is attached. In some embodiments, the valve  1870  is configured to prevent fluid flow from the container  10  to the enclosure  1854  when the vial  10  is positioned above the adaptor  1800 . Furthermore, in some embodiments, the valve  1870  is configured to act as a two-way valve in substantially the same manner as described above with regard to the valve  1770 . 
       FIG.  15 C  illustrates an embodiment of an adaptor  1900  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. The adaptor  1900  can include a valve  1970  situated in a regulator channel  1925  within a protrusion  1985   a  of a regulator assembly  1950  between a container  10  and a filter  1960 . In some embodiments, the valve  1970 , or some portion thereof, is located in the regulator channel  1925  outside the protrusion  1985   a . The regulator assembly  1950  can include an enclosure  1954 . In some embodiments, the valve  1970  restricts the flow of fluid through the regulator channel  1925  in substantially the same way as other valves (e.g.,  1770 ,  1870 ) described herein. 
       FIGS.  16 A- 16 C  illustrate an embodiment of a vial adaptor  2000  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. In some embodiments, the vial adaptor  2000  includes a connector interface  2040  and a piercing member  2020  in partial communication with the connector interface  2040 . In some embodiments, the vial adaptor  2000  includes a regulator assembly  2050 . 
     The regulator assembly  2050  can include an orientation-actuated or orientation-dependent or orientation-sensitive occluder valve, such as a ball check valve  2070 . In some embodiments, the occluder valve can be removably inserted into one or more lumens of the regulator assembly  2050  via an installation path. The installation path can be defined by the axial centerline of the lumen or portion thereof into which the occluder valve is inserted. In some embodiments, the occluder valve is configured to transition between an open configuration and a closed configuration based upon the orientation of the vial adaptor  2000  (e.g., the orientation of the vial adaptor  2000  with respect to the floor). In some such embodiments, the occluder valve is configured to transition from a first configuration corresponding with a first orientation of the vial adaptor  2000  to a second configuration corresponding with a second orientation of the vial adaptor  2000 . The occluder valve can be configured to transition from the first orientation to the second orientation independent of the path of rotation of the vial adaptor  2000 . In some embodiments, the occluder valve can include an occluding member configured to move about within a valve chamber. For example, the occluding member could be configured to engage with and disengage from a valve seat within the valve chamber depending on the configuration of the occluder valve and the orientation of the vial adaptor  2000 . The occluding member can have an ellipsoidal shape, a spherical shape, a generally cylindrical shape with a tapered end, or any other appropriate shape. 
     In some configurations, the ball check valve  2070  is located in a lumen of the regulator assembly and/or in a lumen of the connector interface  2040 . For example, the ball check valve  2070  can be located in a regulator channel  2025  within a lumen  2026  of the regulator assembly  2050 . In some embodiments, the ball check valve  2070  is removable from the regulator channel  2025 . In certain variants, the ball check valve  2070  includes a retaining member that prevents or impedes the ball  2073  from falling out of the ball check valve  2070  when it is removed from the regulator channel  2025 . The ball check valve  2070  can be rotatable about its axial centerline within the regulator channel  2025 . In some embodiments, the ball check valve  2070  can be installed in other lumens of the vial adaptor  2000 . In some configurations, the regulator assembly  2050  includes a lumen or appendage or protrusion  2085   a  which can be substantially sealingly attached to (e.g., received within or around the outer perimeter of) the lumen  2026  of the regulator assembly  2050 . The protrusion  2085   a  can facilitate fluid communication between two or more features (e.g., a filter, enclosure, bag and/or valve) of the regulator assembly. According to some configurations, the ball check valve  2070 , or some portion thereof, can be located in the regulator channel  2025  within the protrusion  2085   a . In some embodiments, the ball check valve  2070  and protrusion  2085   a  form a unitary part. In some embodiments, the ball check valve  2070  and lumen  2026  form a unitary part. 
     In some embodiments, the ball check valve  2070  includes a first chamber  2074  in fluid communication with the vial  10  via the regulator channel  2025 . The ball check  2070  can include a second chamber  2072  in selective fluid communication with the first chamber  2074 . According to some configurations, the first chamber  2074  has a substantially circular cross section with a diameter or cross-sectional distance DV 1  and height H 2 . In some embodiments, the longitudinal axis of the first chamber  2074  is parallel to the axial centerline of the vial adaptor  2000 . In some embodiments, the longitudinal axis of the first chamber  2074  is positioned at an angle away from the axial centerline of the vial adaptor  2000 . The angle between the longitudinal axis of the first chamber  2074  and the axial centerline of the vial adaptor  2000  can be greater than or equal to about 15° and/or less than or equal to about 60°. In some embodiments, the angle between the longitudinal axis of the first chamber  2074  and the axial centerline of the vial adaptor  2000  is approximately 45°. Many variations are possible. In some embodiments, the second chamber  2072  also has a substantially circular cross section with a diameter or cross-sectional distance DV 2 . Many other variations in the structure of the first and second chambers are possible. For example, other cross-sectional shapes may be suitable. 
     In some embodiments, the ball check valve  2070  can include a shoulder  2078  between the first chamber  2074  and second chamber  2072 . The shoulder  2078  can comprise a sloped or tapering surface configured to urge a ball  2073  to move toward an occluding position under the influence of gravity when the vial adaptor is oriented such that the vial is above the vial adaptor. In some embodiments, the angle θ between the shoulder  2078  and the wall of the first chamber  2074  is less than or equal to about 90°. In some embodiments, the angle θ is less than or equal to about 75° and/or greater than or equal to about 30°. In some embodiments, the second chamber  2072  is in fluid communication with the first chamber  2074  when the ball check valve  2070  is in an open configuration. In some embodiments, the inner wall of the first chamber  2074  can gradually taper into the inside wall of the second chamber  2072  such that the first and second chambers  2074 ,  2072  constitute a single generally frustoconical chamber. 
     In some embodiments, the ball  2073  can rest on a circular seat when in the occluding position. In some embodiments, the circular seat is formed by the shoulder  2078 . In some embodiments, the longitudinal axis of the circular seat is generally parallel to the longitudinal axis of the first chamber  2074 . In some embodiments, the longitudinal axis of the first chamber  2074  can define a general movement path for the ball  2073  or other occluding member (e.g., the ball  2073  can generally move to and/or from the occluding position in a direction generally parallel to the longitudinal axis of the first chamber  2074 ). In some embodiments, the movement path of the occluding member is not substantially parallel to the installation path of the ball check valve  2070 . For example, the movement path of the occluding member can be substantially perpendicular to the installation path of the ball check valve  2070 . In certain variations, the longitudinal axis of the circular seat forms an angle with the respect to the longitudinal axis of the first chamber  2074 . The angle formed between the longitudinal axis of the circular seat and the longitudinal axis of the first chamber  2074  can be greater than or equal to about 5° and/or less than or equal to about 30°. In some embodiments, the angle is approximately 10°. Many variations can be used. In some embodiments, the longitudinal axes of the first chamber  2074  and the circular seat are generally parallel to the axial centerline of the adaptor  2000 . In some embodiments, some configurations can reduce the likelihood that the ball  2073  will “stick to” the circular seat or to the inner walls of the first chamber  2074  when the ball check valve  2070  is transitioned between the opened and closed configurations, as will be explained below. 
     In certain configurations, the longitudinal axis of the first chamber  2074  can be substantially parallel to the axial centerline of the ball check valve  2070 . In some embodiments, the longitudinal axis of the first chamber  2074  can define the movement path of the ball  2073 . As illustrated in  FIG.  16 C , the longitudinal axis of the first chamber  2074  can be perpendicular to the axial centerline of the ball check valve  2070 . In some embodiments, the angle between the longitudinal axis of the first chamber  2074  and the axial centerline of the ball check valve  2070  is greater than or equal to about 5° and/or less than or equal to about 90°. In some embodiments, the angle is about 60°. Many variations are possible. In some embodiments, the angle between the longitudinal axis of the first chamber  2074  and axial centerline of the ball check valve  2070  is the same as the angle between the axial centerline of the ball check valve  2070  and the axial centerline of the vial adaptor  2000 . In some such embodiments, the longitudinal axis of the first chamber  2074  can be aligned with the axial centerline of the vial adaptor  2000 . 
     The ball check valve  2070  can also include a valve channel  2071 . According to some embodiments, the valve channel  2071  is in fluid communication with the second chamber  2072 . In some embodiments, the valve channel  2071  generally defines a flow path between the second chamber  2072  and a portion of the regulator channel  2025  opposite the second chamber  2072  from the first chamber  2074 . The valve channel  2071  can have an interface  2071   a  with the second chamber  2072 . The interface  2071   a  can be non-parallel and non-perpendicular to longitudinal axis of the first chamber  2074 .  FIG.  16 D  illustrates an embodiment of a ball check valve  2070 ′. Numerical reference to components is the same as previously described, except that a prime symbol (′) has been added to the reference. Where such references occur, it is to be understood that the components are the same or substantially similar to previously-described components unless otherwise indicated. For example, in some embodiments, the interface  2071   a ′ can be generally parallel to the longitudinal axis of the first chamber  2074 . In some embodiments, the interface between the valve channel  2071  and the second chamber  2072  can be generally perpendicular to the longitudinal axis of the first chamber  2074 . As illustrated in  FIGS.  16 A- 16 C , the ball check valve  2070  can include one or more sealing portions  2079 . The one or more sealing portions  2079  can resist movement of the ball check valve  2070  within the regulator channel  2025 . In some embodiments, the one or more sealing portions  2079  inhibit fluid from flowing around and bypassing the ball check valve  2070 . In some embodiments, the one or more sealing portions  2079  include one or more annular protrusions that extend from the valve channel  2071 . Many variations are possible. 
     As illustrated in  FIG.  16 A , the ball check valve  2070  has a distal opening  2075   a . In some embodiments, the ball check valve  2070  has a plurality of distal openings. The distal opening  2075   a  defines the fluid boundary (e.g., the interface) between the first chamber  2074  and the regulator channel  2025 . In some embodiments, the ball check valve  2070  includes a first valve channel in fluid communication with both the regulator channel  205  and the first chamber  2074 . In such embodiments, the distal opening  2075   a  defines the fluid boundary (e.g., the interface) between the first valve channel and the regulator channel  2025 . The ball check valve  2070  further includes a proximal opening  2075   b  that defines the fluid boundary (e.g., the interface) between the valve channel  2071  and the regulator channel  2025 . 
     The ball check valve  2070  can be configured such that fluids that enter and exit the ball check valve  2070  through the distal opening  2075   a  and the proximal opening  2075   b  flow through the interfaces defined by each opening in a direction generally perpendicular to the interfaces. For example, as illustrated in  FIG.  16 B , regulator fluid FR that enters and/or exits the ball check valve  2070  through the proximal opening  2075   b  has a flow direction (horizontal with respect to  FIG.  16 B ) that is generally perpendicular to the interface (vertical with respect to  FIG.  16 B ) defined by the proximal opening  2075   b . Similarly, the flow of liquid into and out of the ball check valve  2070  through the distal opening  2075   a  is in a direction generally perpendicular to the interface defined by the proximal opening  2075   a . In some embodiments, the direction of flow through one or more of the distal opening  2075   a  and the proximal opening  2075   b  is oblique or perpendicular to the movement path of the ball  2073  or other occluding member. The angle formed between either interface and the movement path of the ball  2073  can be the same as the angle formed between the same interface and the insertion axis of the adaptor  2000 . 
     According to some embodiments, the occluder valve  2070  includes a moveable occluder, such as a ball  2073 . All references herein to a ball can apply to an occluder of any other shape, such as a generally cubic occluder, a generally cylindrical occluder, a generally conical occluder, combinations of these shapes, etc. In some embodiments, the ball  2073  is generally spherical or has another suitable shape. The ball  2073  can be constructed of a material with a higher density than the liquid L or other fluid within the vial  10 . The ball  2073  can have a diameter DB. In some configurations, the diameter DB of the ball  2073  is less than the diameter DV 1  and height H 2  of the first chamber  2074 . For example, in some embodiments the ratio of the diameter DB of the ball  2073  to the diameter DV 1  of the first chamber  2074  is less than or equal to about 9:10 and/or greater than or equal to about 7:10. In some configurations, the diameter DB of the ball  2073  is greater than the diameter DV 2  of the second chamber  2072 . For example, in some embodiments the ratio of the diameter DV 2  of the second chamber  2072  to the diameter DB of the ball  2073  is less than or equal to about 9:10 and/or greater than or equal to about 7:10. In some embodiments, the ball  2073  is can move between at least two positions within the first chamber  2074 . For example, movement of the ball  2073  can be governed by gravity, external forces on the vial adapter, fluids within the regulator channel, other forces, or a combination of forces. The wall  2077 ,  2077 ′ of the first chamber  2074 ,  2074 ′ nearest the access channel  2045  can have varying wall thickness. In some embodiments, increasing the thickness of the wall  2077 ,  2077 ′ can increase the durability of the ball check valve  2070 ,  2070 ′. In some embodiments, increasing the thickness of the wall  2077 ,  2077 ′ can reduce the possibility of damage to the ball check valve  2070 ,  2070 ′ during installation. 
     As illustrated in  FIGS.  16 A- 16 C , the ball  2073  in the ball check valve  2070  can be configured to rest upon the shoulder  2078  at the opening of the second chamber  2072  when the adaptor  2000  and vial  10  are oriented such that the force of gravity is influencing the fluid contained within the vial to be urged toward the vial adaptor (e.g., when at least some portion of the vial  10  is above the connector interface  2040 ). The ball check valve  2070  can be oriented such that the longitudinal axis of the first chamber  2074  and the longitudinal axis of the circular seat are substantially parallel to the axial centerline of the vial adaptor  2000 . In such embodiments, the ball  2073  can be configured to transition to the occluding position (e.g., resting on the circular seat) in a substantially consistent manner independent of the direction of rotation of the vial  10  and the connector interface  2040 . For example, in such embodiments, the manner in which the ball  2073  moves toward the shoulder  2078  or circular seat when the vial  10  is rotated from below connector interface  2040  to above the connector interface  2040  would be substantially consistent and independent of whether the vial  10  and connector interface  2040  were rotated about the longitudinal axis of the lumen  2026 , about an axis perpendicular to the longitudinal axis of the lumen  2026  and to the axial centerline of the vial adaptor  2000 , or about any other axis of rotation therebetween. Furthermore, in such embodiments, parallel alignment between the longitudinal axis of the first chamber  2074  and the axial centerline of the adaptor  2000  can assist the user of the adaptor  2000  in visualizing the alignment of the ball check valve  2070 . In some configurations, the contact between the ball  2073  and the shoulder  2078  can form a seal  2076 . The seal  2076  can put the ball check valve  2070  in a closed configuration and inhibit passage of liquid L and/or other fluid from the vial  10  through the ball check valve  2070  when the vial  10  is oriented above the connector interface  2040 . 
     In some embodiments, the ball  2073  can be configured to move away from the shoulder  2078  when the adaptor  2000  and vial  10  are oriented such that fluid within the vial is urged away from the vial adaptor under the force of gravity (e.g., when at least a portion of the connector interface  2040  is positioned above the vial  10 ). In some embodiments (such as, for example, embodiments in which the longitudinal axes of the first chamber  2074  and the circular seat are parallel to the axial centerline of the vial adaptor  2000 ), the ball  2073  can be configured to move away from the shoulder  2078  in a substantially consistent manner independent of the direction of rotation of the vial  10  and the connector interface  2040 . For example, in such embodiments, the manner in which the ball  2073  moves away from the shoulder  2078  when the vial  10  is rotated from above connector interface  2040  to below the connector interface  2040  would be substantially consistent and independent of whether the vial  10  and connector interface  2040  were rotated about the longitudinal axis of the lumen  2026 , about an axis perpendicular to the longitudinal axis of the lumen  2026  and to the axial centerline of the vial adaptor  2000 , or about any other axis of rotation therebetween. Movement of the ball  2073  away from the shoulder  2078  can open or break the seal  2076  and put the ball check valve  2070  in an open configuration such that the first chamber  2074  and second chamber  2072  are in fluid communication. In some embodiments, the ball check valve  2070  includes a resilient biasing member which can bias the ball  2073  toward the shoulder  2078  and thus bias the ball check valve  2070  to a closed configuration. In some configurations, the biasing member can be a spring. In some configurations, the biasing member can be a flexible member. In some embodiments, the biasing force provided by the resilient biasing member can be less than the weight of the ball  2073 . 
     In some embodiments, the ball  2073  can move about the first chamber  2074  under the influence of gravity. In some configurations, gravity can cause the ball  2073  to move toward the second chamber  2072  and rest upon the shoulder  2078  at the opening of the second chamber  2072 . As explained above, the resting of the ball  2073  upon the shoulder  2078  can create a seal  2076  which can put the ball check valve  2070  in a closed configuration and inhibit passage of liquid L and/or other fluid from the vial  10  through the ball check valve  2070 . In some configurations, gravity can cause the ball  2073  to move away from the shoulder  2078 . Movement of the ball  2073  away from the shoulder  2078  under the influence of gravity can open or break the seal  2076  and put the ball check valve  2070  in an open configuration such that the first chamber  2074  and second chamber  2072  are in fluid communication. Since the diameter or cross-section of the first chamber DV 1  is greater than the diameter or cross-section DB of the ball  2073 , fluid can flow through the first chamber, around the outside surface of the ball  2073 . 
     Certain aspects of the operation of the ball check valve  2070  while the ball check valve  2070  is in a closed configuration will now be described. For example, in some embodiments when no fluid is being introduced to or withdrawn from the vial  10  via the access channel  2045 , the pressure within the vial  10  is substantially the same as the pressure in the valve channel  2071 . In such a situation, the pressure in the first chamber  2074  can be substantially the same as the pressure in the second chamber  2072 . In some embodiments, positioning of the vial  10  above the connector interface  2040  can cause liquid L or other fluid to move from the vial  10  to the first chamber  2074 . In some embodiments, the ball  2073  will remain at rest on the shoulder  1078  and create a seal  2076  when there is equilibrium in the pressure between the first chamber  2074  and the second chamber  2072 . The seal  2076  can inhibit passage of liquid L and/or other fluid from the vial  10  through the ball check valve  2070 . 
     In some embodiments, withdrawal of fluid from the vial  10  through the access channel  2045  can create lower pressure in the vial  10  and first chamber  2074  than the pressure within the second chamber  2072 . The pressure differential can cause the ball  2073  to move away from the shoulder  2078  into the first chamber  2074 . The movement of the ball  2073  away from the shoulder  2078  can break the seal  2076  and permit regulator fluid FR to pass from through the second chamber  2072  and around the ball  2073 . The regulator fluid FR can then pass through the first chamber  2074  and through the regulator channel  2025  into the vial  10 . In some embodiments, the regulator fluid FR is fluid which has passed through a filter in the regulator assembly  2050 . In some embodiments, the regulator fluid FR is a fluid contained in the inner volume of an enclosure of the regulator assembly  2050 . Passage of regulator fluid FR into the vial  10  can offset, reduce, substantially eliminate, or eliminate the pressure differential between the first chamber  2074  and the second chamber  2072  and allow the ball  2073  to return to a resting position on the shoulder  2078 . In some embodiments, the passage of regulator fluid FR into the vial  10  helps to maintain equilibrium between the interior of the vial  10  and the interior of the regulator assembly  2050 . The return of the ball  2073  to a resting position on the shoulder  2078  can recreate or produce the seal  2076  and prevent passage of liquid L or other fluid from the vial  10  through the ball check valve  2070 . 
     In some embodiments, introduction of fluid to the vial  10  through the access channel  2045  (e.g., when diluents, mixing fluids, or overdrawn fluids are injected into the vial  10  via an exchange device  40 ) can create higher pressure in the vial  10  and first chamber  2074  than the pressure within the second chamber  2072 . This difference in pressure can cause the ball  2073  to be pushed onto the shoulder  2078  and thus tighten the seal  2076 . Tightening of the seal  2076  can inhibit the passage through the ball check valve  2070  of fluid L from the vial  10 . In some embodiments, the tightening of the seal  2076  can cause the internal pressure within the vial  10  and first chamber  2074  to continue to increase as more fluid is introduced into the vial  10  via the access channel  2045 . In some embodiments, a continual increase in pressure within the vial  10  and first chamber  2074  can dramatically increase the force required to introduce more fluid to a prohibitive level, and eventually increase the likelihood of fluid leaks from the vial  10  and adaptor  2000  or between these components. It can therefore be desirable for the ball check valve  2070  to be in an open position when fluids are injected into the vial  10 . 
     Movement of the ball  2073  away from the shoulder  2078  can open or break the seal  2076  and put the ball check valve  2070  in an open configuration. Certain aspects of the operation of the ball check valve  2070  while the ball check valve  2070  is in an open configuration will now be described. For example, in some embodiments when no fluid is being introduced to or withdrawn from the vial  10  via the access channel  2045 , the pressure within the vial  10  remains substantially constant. In some embodiments, the vial  10  is in fluid communication with and has the same substantially constant internal pressure as the first and second chambers  2074 ,  2072  and valve channel  2071  of the ball check valve  2070 . 
     In some embodiments, withdrawal of fluid from the vial  10  through the access channel  2045  can lower the pressure in the vial  10  and subsequently lower the pressure in the first chamber  2074 . This lowering of pressure in the vial  10  and first chamber  2074  can create a pressure differential between the first chamber  2074  and second chamber  2072  of the ball check valve  2070 . The pressure differential can cause regulator fluid FR to pass through the first chamber  2074  and through the regulator channel  2025  into the vial  10 . In some embodiments, the regulator fluid FR is fluid which has passed through a filter in the regulator assembly  2050 . In some embodiments, the regulator fluid FR is a fluid contained in the inner volume of an enclosure of the regulator assembly  2050 . Passage of regulator fluid FR into the vial  10  can offset, reduce, substantially eliminate, or eliminate the pressure differential between the first chamber  2074  and the second chamber  2072 . In some embodiments, the passage of regulator fluid FR into the vial  10  helps to maintain equilibrium between the interior of the vial  10  and the interior of the regulator assembly  2050 . 
     In some embodiments, introduction of fluid to the vial  10  through the access channel  2045  (e.g., when diluents, mixing fluids, or overdrawn fluids are injected into the vial  10  via an exchange device  40 ) can create higher pressure in the vial  10  and first chamber  2074  than the pressure within the second chamber  2072 . This differential in pressure can cause fluid from the vial  10  to pass from the vial  10 , through the ball check valve  2070  and into the regulator assembly  2050 . In some embodiments, the fluid from the vial  10  can pass through the check valve  2070  and through a filter. In some embodiments, the fluid from the vial  10  passes through the check valve  2070  and into a bag or other enclosure. Passage of fluid from the vial  10  through the ball check valve  2070  can lower the pressure within the vial  10  and maintain equilibrium between the interior of the vial  10  and the interior of the regulator assembly  2050 . In some embodiments, regulator fluid FR is ambient air or sterilized gas, or filtered air or gas. 
     In some embodiments, especially those in which portions of the vial adaptor are modular or interchangeable, the internal and/or external cross section of the lumen  2026  can include one or more alignment features. For example, the internal and/or external cross section of the lumen can be keyed or otherwise specially shaped. Some examples of potential shapes and their benefits are illustrated in  FIGS.  14 A- 14 F  and discussed above. The protrusion  2085   a  and/or ball check valve  2070  can include a corresponding alignment feature (e.g. corresponding keying or other special shaping). Such a configuration can be useful to signal, control, or restrict the regulatory assembly  2050  that can be connected with, or made integral with, the adaptor  2000 . For example, keying of or shaping of the ball check valve  2070  and/or the channel in which it is placed could provide a user of the adaptor  2000  with confirmation that the ball check valve  2070  is properly aligned (e.g., aligning the first chamber  2074  on the side of the vial  10 ) within the regulator assembly  2050 . This alignment of ball check valve  2070  can allow for proper and/or predictable functioning of the regulatory assembly  2050 . 
     In some embodiments, the exterior of the regulator assembly  2050  can include one or more visual indicators to show the alignment of the ball check valve  2070 . In some embodiments, the visual indicators include notches, words (e.g., top and/or bottom), arrows or other indicators of alignment. In some embodiments, the protrusion  2085   a , lumen  2026 , and/or body of the valve  2070  are constructed of a substantially transparent material to provide the user of the adaptor  2000  with visual confirmation of the configuration of the valve (e.g., to permit viewing the position of the ball to indicate whether the valve is in an open or closed configuration). 
     In some embodiments, the regulator assembly  2050  can include one or more indicators (e.g., visual or audible) to indicate when the ball  2073  is in the occluding position. For example, the regulator assembly  2050  could include one or more light sources (e.g., LED lights, chemiluminescent lights, etc.) that can be configured to emit light when the ball  2073  is in the occluding position. In some embodiments, the adaptor  2000  can include a power source (e.g., one or more batteries, AC input, DC input, photovoltaic cells, etc.) configured to supply power to at least one of the one or more indicators. In some embodiments, the ball  2073  is constructed of an electrically conductive material. In such embodiments, the ball check valve  2070  can be configured such that the ball  2073  completes a circuit between the power source and the light source when the ball  2073  is in the occluding position. In some embodiments, the adaptor  2000  can include a gyroscopic sensor configured to sense when the ball  2073  is in the occluding position. In certain such embodiments, a controller to which the sensor is connected can direct power to activate the one or more indicators when the vial  10  is held above the adaptor  2000 . 
       FIG.  17    illustrates an embodiment of an adaptor  2100  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. In some embodiments, a ball check valve  2170  includes a first valve channel  2171 A in fluid communication with both a regulator channel  2125  and a first chamber  2174  of the ball check valve  2170 . The ball check valve  2100  can include a second valve channel  2171 B in fluid communication with a second chamber  2172  of the ball check valve  2170 . In some embodiments, the ball check valve  2170 , or some portion thereof, is positioned in the regulator channel  2125  within a protrusion  2185   a . In some embodiments, the ball check valve  2170 , or some portion thereof, is positioned in the regulator channel  2125  within a lumen  2126  of the adaptor  2100 . In some embodiments, the ball check valve  2170 , or some portion thereof, is positioned in the regulator channel  2125  outside a protrusion  2185   a . In some embodiments, the ball check valve  2170 , or some portion thereof, is positioned in the regulator channel  2125  outside a lumen  2126  of the adaptor  2100 . In some embodiments, the ball check valve  2170  and protrusion  2185   a  form a unitary part. In some embodiments, the ball check valve  2170  and lumen  2126  form a unitary part. 
       FIG.  18    illustrates an embodiment of an adaptor  2200  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. In some embodiments, a regulator assembly  2250  includes a flexible valve, such as a domed valve  2270 . The domed valve  2270  can include a domed portion  2273 . The domed portion  2273  can include a concave side  2275 B and a convex side  2275 A. In some embodiments, the domed valve  2270  can include an annular flange  2278  attached to the domed portion  2273 . In some embodiments, the annular flange  2278  and domed portion  2273  constitute a unitary part. The domed portion  2273  can have a wall thickness T 3 . The wall thickness T 3  can be substantially constant throughout the domed portion  2273 . In some embodiments, the thickness T 3  of the domed portion  2273  can vary across the domed valve  2270 . 
     In some embodiments, the domed valve  2270 , or some portion thereof, is positioned in a regulator channel  2225  within a lumen  2226  of the adaptor  2200 . In some embodiments, the domed valve  2270 , or some portion thereof, is positioned in the regulator channel  2225  outside a protrusion  2285   a . In some embodiments, the domed valve  2270 , or some portion thereof, is positioned in the regulator channel  2225  outside a lumen  2226  of the adaptor  2200 . In some embodiments, the domed valve  2270  is fixed within the regulator channel  2225 . The domed valve  2270  can be fixed within the regulator channel  2225  via, for example, adhesives, welding, fitted channels within the regulator channel  2225  or otherwise. 
     In some embodiments, the domed portion  2273  includes one or more slits  2274  or some other opening. In some embodiments, the one or more slits  2274  are biased to a closed position by the domed portion  2273  and/or annular flange  2278 . The domed valve  2270  can inhibit and/or prevent the passage of fluid through the regulator channel  2225  when the one or more slits  2274  are in a closed position. In some embodiments, the one or more slits  2274  are configured to open in response to one or more cracking pressures and allow fluid to flow through the one or more slits  2274 . In some embodiments, the geometry and/or material of the domed valve  2270  can cause the cracking pressure required to allow fluid to flow through the one or more slits  2274  in a first direction F 1  to be substantially higher than the cracking pressure required to allow fluid to flow through the one or more slits  2274  in a second direction F 2 . 
     Certain aspects of the operation of the domed valve  2270  will now be described. For example, in some embodiments when no fluid is being introduced to or withdrawn from a vial  10  via an access channel  2245  of the adaptor  2200 , the pressure within the vial  10  remains substantially constant. In some embodiments, the vial  10  is in fluid communication with and has the same substantially constant internal pressure as the pressure P 1  in the regulator channel  2225  in the region of the convex side  2275 A of the domed valve  2270 . In some embodiments, the pressure P 2  in the region of the concave side  2275 B of the domed valve  2270  is substantially the same as the pressure P 1  when no fluid is being introduced to or withdrawn from the vial  10 . In such a configuration, the one or more slits  2274  of the domed valve  2270  can be biased closed by the domed portion  2273  of the domed valve  2270 . 
     In some embodiments, withdrawal of fluid from the vial  10  through the access channel  2045  can lower the pressure in the vial  10  and subsequently lower the pressure P 1  in the region of the convex side  2275 A. This lowering of the pressure P 1  can create a pressure differential between the convex side  2275 A and concave side of  2275 B of the domed valve  2270 . In some embodiments, withdrawal of fluid from the vial  10  can create a pressure differential across the domed valve  2270  high enough to overcome the cracking pressure of the domed valve  2270  and open the one or more slits  2274  to allow fluid to flow in a second direction F 2  through the domed valve  2270 . In some configurations, regulator fluid FR flows in a second direction F 2  through the domed valve  2270  when the one or more slits  2274  are opened and the pressure P 2  on the concave side  2275 B of the valve  2270  is higher than the pressure P 1  on the convex side  2275 A of the valve  2270 . Passage of regulator fluid FR through the domed valve  2270  and/or into the vial  10  can raise the pressure within the vial  10 . Raising of the pressure within the vial  10  can raise the pressure P 1  in the region of the convex surface  2275 A of the domed valve  2270 . Raising of the pressure P 1  in the region of the convex surface  2275 A can lower the pressure differential across the valve  2270  below the cracking pressure and cause the one or more slits  2274  to shut. In some embodiments, the passage of regulator fluid FR in a second direction F 2  through domed valve  2270  helps maintain equilibrium between the interior of the vial  10  and interior of the regulator assembly  2050  when fluid is withdrawn from the vial  10  via the access channel  2245 . In some embodiments, the regulator fluid FR is fluid which has passed through a filter in the regulator assembly  2250 . In some embodiments, the regulator fluid FR is a fluid contained in the inner volume of an enclosure of the regulator assembly  2250 . 
     In some embodiments, introduction of fluid to the vial  10  through the access channel  2245  (e.g., when diluents, mixing fluids, or overdrawn fluids are injected into the vial  10  via an exchange device  40 ) can raise the pressure in the vial  10 . Raising the pressure within the vial  10  can raise the pressure P 1  in the region of the convex surface  2275 A of the domed valve  2273 . Raising of the pressure P 1  in the region of the convex surface  2275 A can create a pressure differential across the domed valve  2273 . In some embodiments, introduction of fluid into the vial  10  can create a pressure differential across the domed valve  2270  high enough to overcome the cracking pressure of the domed valve  2270  and open the one or more slits  2274  to allow fluid to flow in a first direction F 1  through the domed valve  2270 . In some configurations, as explained above, the cracking pressure required to permit fluid to flow in the first direction F 1  is substantially higher than the cracking pressure required to permit fluid to flow in a second direction F 2  through the domed valve  2270 . In some embodiments, flow of fluid from the vial  10  through the domed valve  2270  in a first direction F 1  can lower the pressure in the vial  10 . Lowering of the pressure within the vial  10  can lower the pressure P 1  in the region of the convex surface  2275 A and can lower the pressure differential across the valve  2270  below the cracking pressure and cause the one or more slits  2274  to shut. In some embodiments, passage of fluid through the domed valve  2270  in a first direction F 1  helps maintain equilibrium between the interior of the vial  10  and the interior of the regulator assembly  2250 . 
       FIGS.  19 A- 19 B  illustrate an embodiment of an adaptor  2300  and a valve with multiple openings, such as a showerhead domed valve  2370 . The adaptor  2300  can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. The showerhead domed valve  2370  can include a domed portion  2373 . The domed portion  2373  can include a concave side  2375 B and a convex side  2375 A. In some embodiments, the showerhead domed valve  2370  can include an annular flange  2378  attached to the domed portion  2373 . In some embodiments, the annular flange  2378  and domed portion  2373  constitute a unitary part. The domed portion  2373  can have a wall thickness T 4 . The wall thickness T 4  can be substantially constant throughout the domed portion  2373 . In some embodiments, the thickness T 4  of the domed portion  2373  can vary across the showerhead domed valve  2370 . 
     In some embodiments, the showerhead domed valve  2370 , or some portion thereof, is positioned in a regulator channel  2325  within a lumen  2326  of the adaptor  2300 . In some embodiments, the showerhead domed valve  2370 , or some portion thereof, is positioned in the regulator channel  2325  outside a protrusion  2385   a . In some embodiments, the showerhead domed valve  2370 , or some portion thereof, is positioned in the regulator channel  2325  outside a lumen  2326  of the adaptor  2300 . In some embodiments, the showerhead domed valve  2370  is fixed within the regulator channel  2325 . The showerhead domed valve  2370  can be fixed within the regulator channel  2325  via, for example, adhesives, welding, fitted channels within the regulator channel  2325  or otherwise. 
     In some embodiments, the domed portion  2373  includes one or more openings or central slits  2374 . In some embodiments, the one or more central slits  2374  are arranged in a generally crisscross configuration. In some embodiments, the one or more central slits  2374  are generally parallel to each other. In some embodiments, the domed portion  2373  includes one or more outer slits  2374 A. In some embodiments, the number of outer slits  2374 A is less than or equal to about 30 and/or greater than or equal to about 4. 
     In some embodiments, the one or more central slits  2374  and/or outer slits  2374 A are biased to a closed position by the domed portion  2373  and/or annular flange  2378 . The showerhead domed valve  2370  can inhibit and/or prevent the passage of fluid through the regulator channel  2325  when the slits  2374 ,  2374 A are in a closed position. In some embodiments, the slits  2374 ,  2374 A are configured to open in response to one or more cracking pressures and allow fluid to flow through the slits  2374 ,  2374 A. In some embodiments, the geometry and/or material of the showerhead domed valve  2370  can cause the cracking pressure required to allow fluid to flow through the slits  2374 ,  2374 A in a first direction F 1  to be substantially higher than the cracking pressure required to allow fluid to flow through the slits  2374 ,  2374 A in a second direction F 2 . In some embodiments, the cracking pressures required to allow fluid to flow through the showerhead domed valve  2370  in a first direction F 1  and second direction F 2  are less than the cracking pressures required to allow fluid to flow through the domed valve  2270  in a first direction F 1  and second direction F 2 , respectively. In some embodiments, the showerhead domed valve  2370  functions in substantially the same way as the domed valve  2270  when fluid is introduced to or removed from the vial  10  via the access channel  2345 . 
       FIGS.  20 A- 20 B  illustrate an embodiment of an adaptor  2400  that can have components or portions that are the same as or similar to the components or portions of other vial adaptors disclosed herein. In some embodiments, a regulator assembly  1450  includes an opening and closing occluder valve  2470 , such as a flap check valve  2470 , with a portion of the occluding component remaining affixed to structure within the vial adaptor  2400  as the occluder valve  2470  transitions between the open and closed states. The flap check valve  2470  can include a sealing portion  2479 . The sealing portion  2479  can comprise, for example, a hollow stopper shaped to fit snugly in a regulator channel  2425  of a regulator assembly  2450 , one or more annular protrusion or some other feature suitable for fixing the flap check valve  2470  in place within the regulator channel  2425 . In some embodiments, flap check valve  2470 , or some portion thereof, is positioned in a regulator channel  2425  within a lumen  2426  of the adaptor  2400 . In some embodiments, the flap check valve  2470 , or some portion thereof, is positioned in the regulator channel  2425  outside a protrusion  2485   a . In some embodiments, the flap check valve  2470 , or some portion thereof, is positioned in the regulator channel  2425  outside a lumen  2426  of the adaptor  2400 . In some embodiments, the flap check valve  2470  is fixed within the regulator channel  2425 . 
     According to some configurations, the flap check valve  2470  can include a seat portion  2477  attached to the sealing portion  2479 . In some embodiments, the seat portion  2477  and sealing portion  2479  form a unitary part. In some embodiments, the seat portion  2477  and sealing potion  2479  are separate parts. The flap check valve  2470  can include a flap  2473 . The flap  2473  can have a first end  2473 A and a second end  2473 B. The first end  2473 A of the flap  2473  can be rotatably attached to the sealing portion  2479  and/or seat portion  2477 . 
     In some embodiments, the flap  2473  can be configured to rest upon the seat portion  2477  when the adaptor  2400  and vial  10  are oriented such that the vial  10  is above the connector interface of the adaptor  2400 . In some configurations, contact between the flap  2437  and the seat portion  2477  can form a seal  2476  between the interior  2472  and the exterior  2474  of the flap check valve  2470 . The seal  2476  can put the flap check valve  2470  in a closed configuration and inhibit passage of liquid L and/or other fluid from the vial  10  through the flap check valve  2470 . In some embodiments, the flap  2473  can be configured to rotate away from the seat portion  2477  when the adaptor  2400  and vial  10  are oriented such that the connector interface of the adaptor  2400  is above the vial  10 . Movement of the flap  2473  away from the seat member  2477  can eliminate the seal  2476  and put the flap check valve  2470  in an open configuration such that the interior  2472  and exterior  2474  of the flap check valve  2470  are in fluid communication. 
     In some embodiments, the flap  2473  can move toward and away from the seat portion  2477  under the influence of gravity. As explained above, contact between the flap  2473  and the seat portion  2477  can form a seal  2476  between the interior  2472  and exterior  2474  of the flap check valve  2470 , putting the flap check valve  2470  in a closed configuration and inhibiting passage of liquid L and/or other fluid from the vial  10  through the flap check valve  2470 . In some configurations, gravity can cause the flap  2473  to move away from the seat portion  2477  and break the seal  2476 . Movement of the flap  2473  away from the seat portion  2477  under the influence of gravity can eliminate the seal  2476  and put the flap check valve  2470  in an open configuration such that the exterior  2474  and interior  2472  are in fluid communication. In some embodiments, the flap  2473  is biased to the closed position. The biasing force can be provided by, for example, one or more torsion springs, or another feature suitable for biasing the flap  2473  toward the seat portion  2477  (e.g., tensile force, memory materials, magnets, etc.). In some embodiments, the biasing torque upon the flap  2473  at the first end  2473 A is less than the torque created at the first end  2437 A when the weight of flap  2473  is pulled away from the seat portion  2477  due to the force of gravity (e.g., when the seat portion  2477  is positioned above the flap  2473 ). 
     Certain aspects of the operation of the flap check valve  2470  while the flap check valve  2470  is in a closed configuration will now be described. For example, in some embodiments when no fluid is being introduced to or withdrawn from the vial  10  via an access channel  2445 , the pressure within the vial  10  is substantially the same as the pressure in the interior  2472  of the flap check valve  2470 . In such a situation, the pressure P 2  in the interior  2472  of the flap check valve  2470  can be substantially the same as the pressure P 1  in the exterior  2474  of the flap check valve  2470 . In some embodiments, positioning of the vial  10  above the flap check valve  2470  can cause liquid L or other fluid to move from the vial  10  to the exterior  2474  of the flap check valve  2470 . In some embodiments, the flap  2473  will remain at rest on the seat portion  2477  and create a seal  2476  when there is equilibrium in the pressure between the exterior  2474  and interior  2472  of the flap check valve. The seal  2476  can inhibit passage of liquid L and/or other fluid from the vial  10  through the flap check valve  2470 . 
     In some embodiments, withdrawal of fluid from the vial  10  through the access channel  2445  can create lower pressure in the vial  10  and exterior  2474  of the flap check valve  2470  than the pressure in the interior  2472  of the flap check valve  2470 . The pressure differential can cause the flap  2473  to move away from the seat portion  2477 . The movement of the flap  2473  away from the seat portion  2477  can break the seal  2476  and permit regulator fluid FR to pass from through the interior  2472  of the flap check valve  2470  to the exterior  2474  of the flap check valve  2470 . The regulator fluid FR can then pass through the regulator channel  2425  into the vial  10 . In some embodiments, the regulator fluid FR is fluid which has passed through a filter in the regulator assembly  2450 . In some embodiments, the regulator fluid FR is a fluid contained in the inner volume of an enclosure of the regulator assembly  2450 . Passage of regulator fluid FR into the vial  10  can offset, reduce, substantially eliminate, or eliminate the pressure differential between the first exterior  2474  and interior  2472  of the flap check valve  2470  and allow the flap  2473  to return to a resting position on the seat portion  2477 . In some embodiments, the passage of regulator fluid FR into the vial  10  helps to maintain equilibrium between the interior of the vial  10  and the interior of the regulator assembly  2450 . The return of the flap  2473  to a resting position on the seat portion  2477  can recreate the seal  2476  and prevent passage of liquid L or other fluid from the vial  10  through the flap check valve  2470 . 
     In some embodiments, introduction of fluid to the vial  10  through the access channel  2445  (e.g., when diluents, mixing fluids, or overdrawn fluids are injected into the vial  10  via an exchange device  40 ) can create higher pressure in the vial  10  and exterior  2474  of the flap check valve  2470  than the pressure within the interior  2472  of the flap check valve  2470 . This difference in pressure can cause the flap  2473  to be pushed onto the seat portion  2477  and thus tighten the seal  2476 . Tightening of the seal  2476  can inhibit the passage through the flap check valve  2470  of fluid L from the vial  10 . In some embodiments, the tightening of the seal  2476  can cause the internal pressure within the vial  10  and the pressure P 1  in the region of the exterior  2474  of the flap check valve  2470  to continue to increase as more fluid is introduced into the vial  10  via the access channel  2445 . In some embodiments, a continual increase in pressure within the vial  10  can dramatically increase the force required to introduce more fluid to a prohibitive level, and eventually increase the likelihood of fluid leaks from the vial  10  and adaptor  2400  or between these components. It can therefore be desirable for the flap check valve  2470  to be in an open position when fluids are injected into the vial  10 . 
     Movement of the flap  2473  away from the seat portion  2477  can eliminate the seal  2476  and put the flap check valve  2470  in an open configuration. In some embodiments, the opened flap check valve  2470  functions in much the same way as the opened ball check valve  2070  described above with regard to the passage of fluids through the flap check valve  2470  upon the introduction of fluid to or withdrawal of fluid from the vial  10  via the access channel  2445 . In some embodiments, the regulator assembly  2450  can have many of the same keying, shaping, and/or alignment features described above with respect to the ball check valve  2070  (e.g., transparent materials, visual alignment indicators, shaped channels and/or a shaped valve). 
       FIG.  21    illustrates an embodiment of an adaptor  2500 . The adaptor  2500  can include a piercing member  2520 . In some embodiments, the piercing member  2520  is disposed within a vial  10 . The piercing member  2520  can include an access channel  2545  in communication with an exchange device  40 . In some embodiments, the piercing member  2530  includes a regulator channel  2525  which includes a gravity or orientation occluder valve, such as a ball check valve  2520 . The ball check valve  2570  can include a first channel  2574  with a substantially circular cross section and a diameter D 1  in fluid communication with the vial  10 . In some embodiments, the ball check valve  2570  includes a second channel  2572  with a substantially circular cross section and diameter D 2  in selective fluid communication with the first channel  2574 . Many other variations in the structure of the first and second chambers are possible. For example, other cross-sectional shapes may be suitable. 
     The ball check valve  2570  can include a shoulder  2578  between the first channel  2574  and second channel  2572 . In some embodiments, the angle θ 2  between the shoulder  2578  and the wall of the first channel  2574  can be about 90°. In some embodiments, the angle θ 2  can be less than or greater than 90°. For example, in some embodiments the angle θ 2  is less than or equal to about 75° and/or greater than or equal to about 30°. In some embodiments, the second channel  2572  is in fluid communication with the first channel  2574  when the ball check valve  2570  is in an open configuration. In some embodiments, the inner wall of the first channel  2574  can gradually taper into the inside wall of the second channel  2572  such that the first and second channels  2574 ,  2572  constitute a single frustoconical channel. 
     The occluder valve can include an occluder, such as a ball  2573 . In some embodiments, the ball  2573  is constructed of a material which has a higher density than the liquid L and/or other fluids within the vial  10 . The ball  2573  can be spherical or some other suitable shape. In some embodiments, the ball  2573  has a diameter DB2. The diameter DB2 could be less than the diameter D 1  of the first channel  2574  and more than the diameter D 2  of the second channel  2572 . For example, in some embodiments the ratio of the diameter DB2 of the ball  2573  to the diameter D 1  of the first channel  2574  is less than or equal to about 9:10 and/or greater than or equal to about 7:10. In some embodiments the ratio of the diameter D 2  of the second channel  2572  to the diameter DB2 of the ball  2573  is less than or equal to about 9:10 and/or greater than or equal to about 7:10. In some embodiments, the ball check valve  2570  can include a capture member  2577 . The capture member  2577  can inhibit the ball  2570  from moving out of the first channel  2574 . 
     In some configurations, the ball  2573  can behave in much the same way as the ball  2073  of the ball check valve  2070 . For example, the ball  2573  can move within the first channel  2574  under the influence of forces in much the same way the ball  2073  can move around the first chamber  2074  of the ball check valve  2070 . Resting of the ball  2573  against the shoulder  2578  of the ball check valve  2570  can create a seal  2560  which can inhibit the passage of liquid L and/or other fluids within the vial into the regulator channel  2525 . In many respects, the ball check valve  2570  behaves in the same or substantially the same manner as the ball check valve  2070  under the influence of gravity, alignment of the adaptor  2570  and/or other forces. 
     Although the vial adaptor has been disclosed in the context of certain embodiments and examples, it will be understood by those skilled in the art that the vial adaptor extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the embodiments and certain modifications and equivalents thereof. For example, some embodiments are configured to use a regulating fluid that is a liquid (such as water or saline), rather than a gas. As another example, in certain embodiments the bag comprises a bellows. It should be understood that various features and aspects of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the vial adaptor. For example, the ball check valve  2070  can be incorporated into the embodiments of  FIGS.  15 A- 15 C . Accordingly, it is intended that the scope of the vial adaptor herein-disclosed should not be limited by the particular disclosed embodiments described above, but should be determined only by a fair reading of the claims that follow.