Abstract:
A dispensing assembly has a glass tube assembly, a chamber housing, a needle, and a temperature control device. The glass tube assembly includes a glass tube with inner and outer surfaces and distal and proximal ends. A plunger is fluidly sealed to the inner surface of the glass tube at the proximal end, and a seal is located at the distal end of the glass tube. The chamber housing has an inner surface and an outer surface. The inner surface partially defines a chamber for receiving the glass tube assembly. The needle has sharp distal and proximal ends, traverses the chamber housing, and is fluidly coupled to the chamber. The temperature control device at least partially surrounds the chamber housing. The proximal end of the needle is arranged to puncture the seal when the glass tube assembly is pressed against the proximal end of the needle.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a single-use medical device and more particularly to a two-piece ophthalmic drug delivery device with a disposable tip end that uses a glass drug chamber. 
         [0002]    Several diseases and conditions of the posterior segment of the eye threaten vision. Age related macular degeneration (ARMD), choroidal neovascularization (CNV), retinopathies (e.g., diabetic retinopathy, vitreoretinopathy), retinitis (e.g., cytomegalovirus (CMV) retinitis), uveitis, macular edema, glaucoma, and neuropathies are several examples. 
         [0003]    These, and other diseases, can be treated by injecting a drug into the eye. Such injections are typically manually performed using a conventional syringe and needle.  FIG. 1  is a perspective view of a prior art syringe used to inject drugs into the eye. In  FIG. 1 , the syringe includes a needle  105 , a luer hub  110 , a chamber  115 , a plunger  120 , a plunger shaft  125 , and a thumb rest  130 . As is commonly known, the drug to be injected is located in chamber  115 . Pushing on the thumb rest  130  causes the plunger  120  to expel the drug through needle  105 . 
         [0004]    In using such a syringe, the surgeon is required to pierce the eye tissue with the needle, hold the syringe steady, and actuate the syringe plunger (with or without the help of a nurse) to inject the fluid into the eye. The volume injected is typically not controlled in an accurate manner because reading the vernier is subject to parallax error. Fluid flow rates are uncontrolled. and tissue damage may occur due to an “unsteady” injection. Reflux of the drug may also occur when the needle is removed from the eye. 
         [0005]    An effort has been made to control the delivery of small amounts of liquids. A commercially available fluid dispenser is the ULTRA™ positive displacement dispenser available from EFD Inc. of Providence, R.I. The ULTRA dispenser is typically used in the dispensing of small volumes of industrial adhesives. It utilizes a conventional syringe and a custom dispensing tip. The syringe plunger is actuated using an electrical stepper motor and an actuating fluid. With this type of dispenser, the volumes delivered are highly dependent on fluid viscosity, surface tension, and the specific dispensing tip. Parker Hannifin Corporation of Cleveland, Ohio distributes a small volume liquid dispenser for drug discovery applications made by Aurora Instruments LLC of San Diego, Calif. The Parker/Aurora dispenser utilizes a piezo-electric dispensing mechanism. While precise, this dispenser is expensive and requires an electrical signal to be delivered to the dispensing mechanism. 
         [0006]    U.S. Pat. No. 6,290,690 discloses an ophthalmic system for injecting a viscous fluid (e.g. silicone oil) into the eye while simultaneously aspirating a second viscous fluid (e.g. perflourocarbon liquid) from the eye in a fluid/fluid exchange during surgery to repair a retinal detachment or tear. The system includes a conventional syringe with a plunger. One end of the syringe is fluidly coupled to a source of pneumatic pressure that provides a constant pneumatic pressure to actuate the plunger. The other end of the syringe is fluidly coupled to an infusion cannula via tubing to deliver the viscous fluid to be injected. 
         [0007]    It would be desirable to have a portable hand piece for injecting a drug into the eye. Such a hand piece can include a limited reuse assembly attachable to and removable from a disposable tip segment. Properly dosing and delivering the drug can be challenging. A pre-set dosage of a drug suspended in a phase transition material must be heated before being delivered into the eye. This requires placing the material in a drug chamber that can be heated. Properly containing the material in a glass drug chamber would be advantageous. 
       SUMMARY OF THE INVENTION 
       [0008]    In one embodiment consistent with the principles of the present invention, the present invention is a dispensing assembly having a glass tube assembly, a chamber housing, a needle, and a temperature control device. The glass tube assembly includes a glass tube with inner and outer surfaces and distal and proximal ends. A plunger is fluidly sealed to the inner surface of the glass tube at the proximal end, and a seal is located at the distal end of the glass tube. The chamber housing has an inner surface and an outer surface. The inner surface partially defines a chamber for receiving the glass tube assembly. The needle has sharp distal and proximal ends, traverses the chamber housing, and is fluidly coupled to the chamber. The temperature control device at least partially surrounds the chamber housing. The proximal end of the needle is arranged to puncture the seal when the glass tube assembly is pressed against the proximal end of the needle. 
         [0009]    In another embodiment consistent with the principles of the present invention, the present invention is a dispensing assembly having a glass tube assembly, a chamber housing, a needle, and a heater. The glass tube assembly includes a glass tube with inner and outer surfaces and distal and proximal ends. A plunger is fluidly sealed to the inner surface of the glass tube at the proximal end, and a seal is located at the distal end of the glass tube. The glass tube contains a drug suspended in a phase transition compound. The chamber housing has an inner surface and an outer surface. The inner surface partially defines a chamber for receiving the glass tube assembly. The needle has sharp distal and proximal ends, traverses the chamber housing, and is fluidly coupled to the chamber. The heater at least partially surrounds the chamber housing and heats the drug and phase transition compound. The proximal end of the needle is arranged to puncture the seal when the glass tube assembly is pressed against the proximal end of the needle. 
         [0010]    In another embodiment consistent with the principles of the present invention, the present invention is a method of injecting a drug suspended in a phase transition compound into an eye. The method includes: providing a glass tube assembly comprising a glass tube having inner and outer surfaces and distal and proximal ends, a plunger fluidly sealed to the inner surface of the glass tube at the proximal end, and a seal located at the distal end of the glass tube, the glass tube containing a drug suspended in a phase transition compound; heating the glass tube assembly after it is located in a chamber housing having an inner surface and an outer surface, the inner surface partially defining a chamber for receiving the glass tube assembly; puncturing the seal with a needle having sharp distal and proximal ends, the needle located in the chamber housing and fluidly coupled to the chamber; and dispensing the drug suspended in the phase transition compound by moving the plunger toward the needle. 
         [0011]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed. The following description, as well as the practice of the invention, set forth and suggest additional advantages and purposes of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention. 
           [0013]      FIG. 1  is a perspective view of a prior art syringe. 
           [0014]      FIG. 2  is a view of an ophthalmic medical device including a disposable tip segment and a limited reuse assembly according to the principles of the present invention. 
           [0015]      FIG. 3  is an embodiment of a limited reuse assembly according to the principles of the present invention. 
           [0016]      FIG. 4  is a cross section view of a disposable tip segment and a limited reuse assembly according to the principles of the present invention. 
           [0017]      FIG. 5  is a cross section view of a disposable tip segment according to the principles of the present invention. 
           [0018]      FIG. 6  is a cross section view of a chamber housing assembly according to the principles of the present invention. 
           [0019]      FIG. 7  is a cross section view of a glass tube assembly according to the principles of the present invention. 
           [0020]      FIGS. 8A &amp; 8B  are cross section views of a glass tube assembly and a chamber housing assembly according to the principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    Reference is now made in detail to the exemplary embodiments of the invention, examples of which are illustrated in the accompanying figures. Wherever possible, the same reference numbers are used throughout the figures to refer to the same or like parts. 
         [0022]      FIG. 2  depicts one view of an ophthalmic medical device including a disposable tip segment and a limited reuse assembly according to an embodiment of the present invention. In  FIG. 2 , the medical device includes a tip segment  205  and a limited reuse assembly  250 . The tip segment  205  includes a needle  210 , a housing  215 , and an optional light  275 . The limited reuse assembly  250  includes a housing  255 , a switch  270 , a lock mechanism  265 , and a threaded portion  260 . 
         [0023]    Tip segment  205  is capable of being connected to and removed from limited reuse assembly  250 . In this embodiment, tip segment  205  has a threaded portion on an interior surface of housing  215  that screws onto the threaded portion  260  of limited reuse assembly  250 . In addition, lock mechanism  265  secures tip segment  215  to limited reuse assembly  250 . Lock mechanism  265  may be in the form of a button, a sliding switch, or a cantilevered mechanism. Other mechanisms for connecting tip segment  205  to limited reuse assembly  250 , such as those involving structural features that mate with each other, are commonly known in the art and are within the scope of the present invention. 
         [0024]    Needle  210  is adapted to deliver a substance, such as a drug, into an eye. Needle  210  may be of any commonly known configuration. Preferably, needle  210  is designed such that its thermal characteristics are conducive to the particular drug delivery application. For example, when a heated drug is to be delivered, needle  210  may be relatively short (several millimeters) in length to facilitate proper delivery of the drug based on thermal characteristics. 
         [0025]    Switch  270  is adapted to provide an input to the system. For example, switch  270  may be used to activate the system or to turn on a heater. Other switches, buttons, or user-directed control inputs are commonly known and may be employed with limited reuse assembly  250  and/or tip segment  205 . 
         [0026]    Optional light  275  is illuminated when tip segment  205  is ready to be used. Optional light  275  may protrude from housing  215 , or it may be contained within housing  215 , in which case, optional light  275  may be seen through a clear portion of housing  215 . In other embodiments, optional light  275  may be replaced by an indicator, such as a liquid crystal display, segmented display, or other device that indicates a status or condition of disposable tip segment  205 . For example, optional light  275  may also pulse on and off to indicate other states, such as, but not limited to a system error, fully charged battery, insufficiently charged battery or faulty connection between the tip segment  205  and limited use assembly  250 . While shown on tip segment  205 , optional light  275  or other indicator may be located on limited reuse assembly  250 . 
         [0027]      FIG. 3  is another embodiment of a limited reuse assembly according to the principles of the present invention. Limited reuse assembly  250  includes a button  310 , a display  320 , and a housing  330 . Disposable tip segment  205  attaches to end  340  of limited reuse assembly  250 . Button  310  is actuated to provide an input to the system. As with switch  270 , button  310  may activate a heater or other temperature control device or initiate actuation of a plunger. Display  320  is a liquid crystal display, segmented display, or other device that indicates a status or condition of disposable tip segment  205  or limited reuse assembly  250 . 
         [0028]      FIG. 4  is a cross section view of a disposable tip segment and a limited reuse assembly according to an embodiment of the present invention.  FIG. 4  shows how tip segment  205  interfaces with limited reuse assembly  250 . In the embodiment of  FIG. 4 , tip segment  205  includes plunger interface  420 , plunger  415 , chamber housing  425 , tip segment housing  215 , temperature control device  450 , thermal sensor  460 , needle  210 , chamber  405 , interface  530 , and tip interface connector  520 . Limited reuse assembly  250  includes mechanical linkage  545 , actuator shaft  510 , actuator  515 , power source  505 , controller  305 , limited reuse assembly housing  255 , interface  535 , and limited reuse assembly interface connector  525 . 
         [0029]    Needle  210  is fluidly coupled to chamber  405 . In such a case, a substance contained in a glass tube assembly  600  in chamber  405  can pass through needle  210  and into an eye. Temperature control device  450  at least partially surrounds chamber housing  425 . In this case, temperature control device  450  is adapted to heat and/or cool chamber housing  425  and any substance contained in chamber  405 . Interface  530  connects temperature control device  450  with tip interface connector  520 . 
         [0030]    In limited reuse assembly  250 , power source  505  provides power to actuator  515 . An interface (not shown) between power source  505  and actuator  515  serves as a conduit for providing power to actuator  515 . Actuator  515  is connected to actuator shaft  5   10 . When actuator  515  is a stepper motor, actuator shaft  510  is integral with actuator  515 . Mechanical linkage interface  545  is connected to actuator shaft  510 . In this configuration, as actuator  515  moves actuator shaft  510  upward toward needle  210  mechanical linkage interface  545  also moves upward toward needle  210 . 
         [0031]    Controller  305  is connected via interface  535  to limited reuse assembly interface connecter  525 . Limited reuse assembly interface connecter  525  is located on a top surface of limited reuse assembly housing  255  adjacent to mechanical linkage interface  545 . In this manner, both limited reuse assembly interface connector  525  and mechanical linkage interface  545  are adapted to be connected with tip interface connector  520  and plunger interface  420  respectively. 
         [0032]    Controller  305  and actuator  515  are connected by an interface (not shown). This interface (not shown) allows controller  305  to control the operation of actuator  515 . In addition, an interface (not shown) between power source  505  and controller  305  allows controller  305  to control operation of power source of  310 . In such a case, controller  305  may control the charging and the discharging of power source  505  when power source  505  is a rechargeable battery. 
         [0033]    Controller  305  is typically an integrated circuit with power, input, and output pins capable of performing logic functions. In various embodiments, controller  305  is a targeted device controller. In such a case, controller  305  performs specific control functions targeted to a specific device or component, such as a temperature control device or a power supply. For example, a temperature control device controller has the basic functionality to control a temperature control device. In other embodiments, controller  305  is a microprocessor. In such a case, controller  305  is programmable so that it can function to control more than one component of the device. In other cases, controller  305  is not a programmable microprocessor, but instead is a special purpose controller configured to control different components that perform different functions. While depicted as one component, controller  305  may be made of many different components or integrated circuits. 
         [0034]    Tip segment  205  is adapted to mate with or attach to limited reuse assembly  250  as previously described. In the embodiment of  FIG. 4 , plunger interface  420  located on a bottom surface of plunger  415  is adapted to mate with mechanical linkage interface  545  located near a top surface of limited reuse assembly housing  255 . In addition, tip interface connector  520  is adapted to connect with limited reuse assembly interface connector  525 . When tip segment  205  is connected to limited reuse assembly  250  in this manner, actuator  515  and actuator shaft  510  are adapted to drive plunger  415  upward toward needle  210 . In addition, an interface is formed between controller  305  and temperature control device  450 . A signal can pass from controller  305  to temperature control device  450  through interface  535 , limited reuse assembly interface connector  525 , tip interface connector  520 , and interface  530 . 
         [0035]    In operation, when tip segment  205  is connected to limited reuse assembly  250 , controller  305  controls the operation of actuator  515 . Actuator  515  is actuated and actuator shaft  510  is moved upward toward needle  210 . In turn, mechanical linkage interface  545 , which is mated with plunger interface  420 , moves plunger  415  upward toward needle  210 . A substance located in a glass tube assembly  600  in chamber  405  is then expelled through needle  210 . 
         [0036]    In addition, controller  305  controls the operation of temperature control device  450 . Temperature control device  450  is adapted to heat and/or cool chamber housing  425 . Since chamber housing  425  is at least partially thermally conductive, heating or cooling chamber housing  425  heats or cools a substance located in a glass tube assembly  600  in chamber  405 . Temperature information can be transferred from thermal sensor  460  to controller  305  via any of a number of different interface configurations. This temperature information can be used to control the operation of temperature control device  450 . When temperature control device  450  is a heater, controller  305  controls the amount of current that is sent to temperature control device  450 . The more current sent to temperature control device  450 , the hotter it gets. In such a manner, controller  305  can use a feed back loop utilizing information from thermal sensor  460  to control the operation of temperature control device  450 . Any suitable type of control algorithm, such as a proportional integral derivative (PID) algorithm, can be used to control the operation of temperature control device  450 . 
         [0037]      FIG. 5  is a cross section view of a disposable tip segment for an ophthalmic medical device according to an embodiment of the present invention. In  FIG. 5 , disposable tip segment  205  includes housing  215 , needle  210 , chamber  405 , chamber housing  425 , temperature control device  450 , thermal sensor  460 , interface  530 , and tip interface connector  520 . Disposable tip segment  205  operates as a disposable injection device. 
         [0038]    In the embodiment of  FIG. 5 , needle  210  is fluidly coupled to chamber  405 . Temperature control device  450  at least partially surrounds chamber housing  425  and chamber  405 . Housing  215  forms an outer skin on disposable tip segment  205 . 
         [0039]    In various embodiments of the present invention, temperature control device  450  is a heating and/or a cooling device. Temperature control device  450  is in thermal contact with chamber housing  425 . As such, temperature control device  450  is capable of changing the temperature of the substance (in a glass tube assembly) in chamber  405 . Interface  530  and tip interface connector  520  couple temperature control device  450  to a limited reuse assembly. In such a case, temperature control device  450  can be powered and controlled by the limited reuse assembly. 
         [0040]    A substance to be delivered into an eye, typically a drug, is located in a glass tube assembly in chamber  405 . Typically, chamber  405  is cylindrical in shape. Temperature control device  450  is in thermal contact with chamber housing  425 . In this manner, temperature control device  450  is adapted to control the temperature of the contents of chamber  405 . Thermal sensor  460  provides temperature information to assist in controlling the operation of temperature control device  450 . 
         [0041]    In one embodiment of the present invention, the substance located in chamber  405  is a drug that is preloaded into sealed glass tube assembly  600  as depicted in  FIG. 7 . When a drug is preloaded into chamber  405 , a set quantity of the drug can be preloaded. For example,  100  microliters of a drug can be loaded into chamber  405 , and any quantity up to  100  microliters can be dispensed. In such a case, the plunger  415  can be moved a precise distance to deliver a precise dosage of drug from the chamber  405 , through the needle  210 , and into an eye. This provides for flexibility of dosing and for ease of assembly. 
         [0042]      FIG. 6  is a cross section view of a chamber housing assembly according to the principles of the present invention. In  FIG. 6 , temperature control device  450  at least partially surrounds chamber housing  425 . Chamber  405  is bounded by an interior surface of chamber housing  425 . Needle  210  has two sharp ends—one for piercing the eye and the other in chamber  405 . The glass tube assembly  600  of  FIG. 7  fits in chamber  405 . 
         [0043]      FIG. 7  is a cross section view of a glass tube assembly  600  according to the principles of the present invention. Glass tube  630  has a seal  620  on one end and a plunger  415  on the other. In this manner, a sealed drug chamber  640  is bounded by these components. This sealed chamber provides a safe environment for storing and transporting a drug. 
         [0044]    Glass tube  630  is a tube made of glass. As is commonly known, glass is a suitable material for contact with pharmaceuticals. A drug suspended in a phase transition compound is contained in glass tube  630 . The drug/compound mixture can be heated, since glass conducts heat, and can be carried in the glass tube until it is injected into an eye. 
         [0045]    Seal  620  and plunger  415  are located on either end of glass tube  630  as shown. Both seal  620  and plunger  415  are sealed to an interior surface of glass tube  630 . Seal  620  is preferably a self sealing elastomer that can be in the shape of a plug or disc. The outer surface of plunger  415  forms a fluidic seal with the inner surface of glass tube  630 . In this manner, drug chamber  640  is a sealed chamber that contains a drug or other substance that can be injected into an eye. Drug chamber  640  is a sealed chamber that allows the proper distribution and handling of a drug dosage. For example, a number of different glass tube assemblies can be manufactured—each with different drug dosages. A doctor can select the proper dosage and insert the glass tube assembly  600  into chamber  405  for injection into the eye. 
         [0046]      FIGS. 8A and 8B  are cross section views of a glass tube assembly  600  and a chamber housing assembly according to the principles of the present invention.  FIGS. 8A and 8B  show how the glass tube assembly  600  is placed in chamber  405 . The glass tube assembly  600  is inserted into chamber  405  such that the exterior surface of glass tube  630  at least partially contacts the interior surface of chamber housing  425 . Mechanical linkage interface  545  (driven by actuator shaft  510 ) can be used to push the glass tube assembly into chamber  405  and to pierce seal  620  (as shown in  FIG. 8B ). The sharp end of needle  210  located in chamber  405  pierces seal  620 . 
         [0047]    In one embodiment, a user inserts a glass tube assembly  600  into chamber  405  by hand, much like loading a shotgun shell into a shotgun. The disposable tip segment  205  that includes the chamber  405  can then be placed on a limited reuse assembly  250 . The temperature control device  450  is activated to heat the substance contained in drug chamber  640  when the substance is a drug suspended in a phase transition compound. The plunger is then moved forward to dispense the substance into the eye. 
         [0048]    In one case, the glass tube assembly is heated before it is pushed forward against the needle to pierce seal  620 . In this manner, the drug is properly heated before the seal  620  is pierced to deliver the drug. The mechanical linkage interface  545  can operate in two phases. In the first phase, the mechanical linkage interface  545  pushes the glass tube assembly  600  forward so that it can be heated. In the second phase, the mechanical linkage interface pushes the glass tube assembly  600  forward so that the seal  620  is pierced, and the contents of drug chamber  640  are delivered into the eye. 
         [0049]    From the above, it may be appreciated that the present invention provides an improved system for delivering precise volumes of a substance into an eye. The present invention provides a single use, disposable delivery device tip segment that is capable of delivering a precise dosage. The tip segment interfaces with a limited reuse assembly. The disposable tip segment has a chamber that receives a glass tube assembly containing a drug. The glass tube assembly is loaded into the disposable tip segment and the injection process is activated. The present invention is illustrated herein by example, and various modifications may be made by a person of ordinary skill in the art. 
         [0050]    Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.