Patent Publication Number: US-2013245492-A1

Title: Dispensing Device for Prefilled Syringe

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to the field of prefilled syringes. The present invention relates specifically to a dispensing device or driver for dispensing fluid from a prefilled syringe. 
     Prefilled syringes are used in a variety of areas, including for medical tests, therapeutic uses, and scientific uses. Prefilled syringes typically have a syringe body or syringe barrel and a plunger. The plunger head seals to the inner surface of the barrel forming a sealed cavity or chamber that holds a fluid, such as a medical test or therapeutic substances. The plunger includes a shaft coupled at one end to the plunger head, and at the other end, the shaft is coupled to a plunger top or disc, sized to facilitate engagement by a user&#39;s fingers or thumb. Pushing the plunger disc forces the plunger head toward a dispensing opening located through the syringe body resulting in the dispensing or ejection of fluid from the syringe body. 
     Such prefilled syringes are used in many areas. For example, prefilled syringes may be used to hold allergen test substances. Typically, each prefilled syringe holds a volume of a single allergen test substance that may be used for multiple allergy tests for multiple patients. For example, such allergen test prefilled syringes may originally hold  5  milliliters of test substance. During an allergy test, a health care worker typically will dispense a small volume (e.g., less than 100 microliters) of test substance from the prefilled syringe into a receiving chamber that has been attached to the skin of a patient receiving an allergy test. The receiving chamber holds the allergen test substance in contact with the patient&#39;s skin, and the test area of skin is monitored for allergic reaction. Because only a small amount of the test substance is used for a single test, the prefilled syringe is used for multiple allergy tests for multiple patients. A typical health care facility will have a number of different prefilled syringes, each one holding a different allergen test substance. 
     BRIEF SUMMARY OF THE INVENTION 
     One embodiment of the invention relates to a dispensing device or driver configured to engage a prefilled syringe to improve the precision of the volume of fluid dispensed from the prefilled syringe. The driver is removably engageable with the prefilled syringe such that the dispensing device may be used with multiple prefilled syringes. Further, the various structures of the driver are also configured to only engage with exterior or dry portions of the prefilled syringe (i.e., portions not in contact with the substance of the prefilled syringe) allowing the driver to be used with prefilled syringes holding different allergen test substances. The driver is configured to impart both axial and rotational movement to the plunger of the prefilled syringe allowing for more precise dispensing of the substance from the prefilled syringe as compared to direct operation of the plunger that the prefilled syringe was originally equipped with. 
     Another embodiment of the invention relates to a driver for engaging a sealed, prefilled syringe. The prefilled syringe includes a syringe body, a flange extending from an upper end of the syringe body, and a plunger received within the syringe body. The driver includes a handle body and a shaft. The handle body includes a first end, a second end opposite the first end, a central passage extending through the body from the first end to the second end, and an attachment structure located at the second end. The attachment structure is configured to rigidly attach to the flange of the prefilled syringe such that the syringe body is held in a fixed position relative to the handle body. The driver includes a threaded inner surface located within the central passage of the handle body. The shaft of the driver is configured to extend through the central passage of the handle body. The shaft includes a first end, a second end opposite the first end, an engagement section adjacent the second end and a threaded outer surface portion configured to engage the threaded inner surface. The engagement section includes a first slot formed in the shaft configured to receive a portion of the syringe plunger. The driver is configured such that rotation of the shaft relative to the handle body causes advancement of the shaft through the central passage imparting both rotational movement and axial movement to the plunger of the prefilled syringe. 
     Another embodiment of the invention relates to a system for dispensing fluid from a prefilled syringe. The system includes a prefilled syringe and a driver. The prefilled syringe includes a syringe body having an upper end, a lower end opposite the upper end, and a central cavity extending from the upper end to the lower end. The prefilled syringe includes a plunger including a plunger head received within the central cavity of the syringe body and a plunger shaft coupled to the plunger head. The plunger shaft extends from the plunger head toward the upper end. The plunger head forms a seal within the central cavity defining a contents chamber. The prefilled syringe includes a fluid located within the contents chamber. The driver includes a driver body rigidly attached to the upper end of the prefilled syringe such that the syringe body is held in a fixed position relative to the driver body. The driver includes a rotating actuator engaging the plunger of the prefilled syringe configured to impart both rotational and axial movement to the plunger to dispense the fluid from the prefilled syringe. 
     Another embodiment of the invention relates to a method of modifying a prefilled syringe. The method includes the step of providing a prefilled syringe. The prefilled syringe includes a syringe body including a first end, a second end opposite the first end, and a central cavity extending from the first end to the second end. The prefilled syringe includes a plunger including a plunger seal, plunger top and a plunger shaft extending between the plunger seal and the plunger top. The prefilled syringe includes a fluid located within the central cavity. The method includes the step of providing a driver including a rotating actuator, and the driver is configured to impart both rotational and axial movement to the plunger to dispense the fluid from the prefilled syringe. The method includes the step of cutting the plunger shaft at a position between the plunger seal and the plunger top and removing the portion of the plunger shaft above the cut including the plunger top. The method includes coupling the rotating actuator of the driver to the plunger. 
     Other aspects, objectives and advantages of embodiments of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       This application will become more fully understood from the following detailed description, taken in conjunction with the accompanying figures, wherein like reference numerals refer to like elements in which: 
         FIG. 1  is a perspective view of a dispenser according to an exemplary embodiment; 
         FIG. 2A  is an exploded view of the dispenser of  FIG. 1  according to an exemplary embodiment; 
         FIG. 2B  is a perspective view of a prefilled syringe according to an exemplary embodiment; 
         FIG. 2C  is a perspective view of a prefilled syringe according to an exemplary embodiment; 
         FIG. 2D  is a detailed perspective view of a handle body of the dispenser of  FIG. 1  according to an exemplary embodiment; 
         FIG. 2E  is a detailed perspective view of a shaft and indicator of the dispenser of  FIG. 1  according to an exemplary embodiment; 
         FIG. 3  is a detailed view showing the connection between a driver and prefilled syringe according to an exemplary embodiment; 
         FIG. 4  is a sectional view showing a handle body of a driver according to an exemplary embodiment; 
         FIG. 5A  is a perspective view of a sleeve assembly according to an exemplary embodiment; 
         FIG. 5B  is an exploded view of the sleeve assembly of  FIG. 5A  according to an exemplary embodiment; 
         FIG. 5C  is a perspective view of a sleeve assembly according to another exemplary embodiment; 
         FIG. 6A  is a perspective view of a dispenser in a first position according to an exemplary embodiment; 
         FIG. 6B  is a perspective view of the dispenser of  FIG. 6A  in a second position according to an exemplary embodiment; and 
         FIG. 7  is flow-diagram showing modification of a prefilled syringe is shown according to an exemplary embodiment. 
     
    
    
     While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring generally to the figures, a dispensing device or driver configured to engage a prefilled syringe is shown according to exemplary embodiments. Generally, the driver discussed herein is a device separate from the prefilled syringe that is configured to engage the preexisting plunger of a prefilled syringe and functions to impart both axial and rotational motion to the plunger of the prefilled syringe in a manner that provides for a precise amount of fluid to be dispensed from the prefilled syringe. In particular, the rotational movement of the plunger acts to overcome static friction between the plunger and the inner surface of the syringe in a manner that limits or prevents sudden axial motion, and thereby, acts to provide for increased dispensing accuracy from a prefilled syringe as compared to manual operation of the standard push-actuated plunger of the prefilled syringe. 
     The movement of the prefilled syringe plunger provided by the driver is precisely controllable by the user of the driver such that the user can accurately dispense very small volumes (e.g., less than 30 microliters) of substance from the prefilled syringe as needed from a particular application. The driver is configured to be non-permanently attached to the prefilled syringe so that the driver may be used with multiple prefilled syringes. In addition, the driver is configured to engage only dry (i.e., non-content contacting) surfaces of the prefilled syringe, and thus, preventing contamination between different prefilled syringes as the driver is used between different prefilled syringes with different contents. The driver is also configured to provide one or more indication (e.g., audible, tactile, and/or visual, etc.) that the desired amount of fluid has been dispensed from the prefilled syringe. In the specific embodiments shown in the figures, the driver is configured to be easily attached to the prefilled syringe and is configured to be easily operated manually by the user to dispense fluid. 
     Referring to  FIG. 1 , a dispensing system, shown as dispenser  10 , configured to precisely dispense a volume of liquid material is shown according to an exemplary embodiment. Dispenser  10  includes a driver, shown as plunger driver  12 , and a prefilled syringe  14 . Plunger driver  12  includes a body, shown as handle body  16 , a rotating actuator, shown as driver shaft  18 , and a knob, shown as end knob  20 . Generally, handle body  16  includes a lower or front end  22  coupled to prefilled syringe  14 , and as will be discussed in more detail below, driver shaft  18  passes through an upper or rear end  24  of handle body  16  to engage the plunger of prefilled syringe  14 . 
     Referring to  FIG. 2A , an exploded view of dispenser  10  is shown according to an exemplary embodiment. As generally shown in  FIG. 2A , to assemble dispenser  10 , shaft  18  extends through handle body  16  to engage the plunger of prefilled syringe  14 . Handle  16  rigidly engages the upper end of the outer body of prefilled syringe  14 , and knob  20  mounts to the upper end of shaft  18 . Rotation of shaft  18  may be applied by the user via knob  20  which in turn causes rotation and axial advancement of the plunger of prefilled syringe  14  causing the ejection of fluid from syringe  14 . Each of the components of dispenser  10  will be discussed in more detail below. 
     Referring to  FIG. 2B  a detailed view of prefilled syringe  14  is shown. Prefilled syringe  14  is shown having a syringe body  26  having a lower, dispensing end  28  and an upper end  30 . Syringe body  26  includes a central cavity or channel  32  formed within the syringe body that extends from upper end  30  to dispensing end  28 . Syringe  14  includes a plunger  34  having a plunger head  36  and a plunger shaft  38 . Plunger shaft  38  includes a lower end coupled to plunger head  36  and an upper end  40 . Plunger head  36  forms a seal with the inner surface of syringe body  26  defining a contents chamber  42  of prefilled syringe  14  located within central cavity  32  between dispensing end  28  and plunger head  36 . A fluid or substance  44  is contained within chamber  42 . In one embodiment, substance  44  is an allergen test substance that may be applied to a patient&#39;s skin as part of an allergy test. In one such embodiment, prefilled syringe  14  is a  5  milliliter prefilled syringe. In other embodiments, other medical or therapeutic substances may be contained within chamber  42 . 
     Prefilled syringe  14  includes a flange, shown as syringe head  46 , located at upper end  30  and that extends radially outward from and is substantially perpendicular to syringe body  26 . In the embodiment shown, syringe head  46  is shaped as an elongated polygon having a major axis and a minor axis such that the syringe head  46  extends further from syringe body  26  along the major axis than along the minor axis. As explained in more detail below, syringe head  46  provides mounting surfaces that allows driver  12  to be coupled to prefilled syringe  14 . 
     In the embodiment shown in  FIG. 2B , the length of plunger shaft  38  is relatively short compared to the length of cavity  32  or to the length of syringe body  26 . In various embodiments the length of plunger shaft  38  is less than half the length of cavity  32 , preferably is less than a third of the length of cavity  32  and more preferably is less than a quarter of the length of cavity  32 . In the embodiment shown, plunger shaft  38  is formed of two substantially planar pieces of material positioned perpendicular to each other such that plunger shaft  38  has a substantially cross-shaped cross-section. Further, upper end  40  of plunger shaft  38  is not coupled to a radially extending planar plunger top (like the one shown in  FIG. 2C ), and the cross-sectional shape and area of upper end  40  of plunger shaft  38  is substantially the same as the cross-shaped cross-section of lower portions of plunger shaft  38 . Further,  FIG. 2B  shows prefilled syringe  14  holding the maximum amount of substance  44  (i.e., that is before any substance  44  has been dispensed), and in this embodiment, plunger shaft  38  is sized such that upper end  40  of plunger shaft  38  is substantially coplanar with the upper most surface of syringe head  46  when the prefilled syringe is full. As the plunger is advanced during dispensing of fluid from prefilled syringe  14 , upper end  40  of plunger shaft  38  moves axially downward within cavity  32 . 
     In one embodiment, prefilled syringe  14  is a standard prefilled syringe that is modified for engagement with driver  12 . Referring to  FIG. 2C , a typical, prefilled syringe  50  is shown. Prefilled syringe  50  is the type which a user&#39;s fingers or thumbs are used to directly actuate the syringe plunger  52  via application of force to a plunger top or thumb disc  54 . In one embodiment, the shaft of syringe plunger  52  is cut or severed after syringe  50  has been filled, resulting in prefilled syringe  14  having the shorter plunger shaft  38  shown in  FIG. 2B . In such embodiments, prefilled syringe  50  is purchased by a user (e.g., doctor&#39;s office, hospital, clinician, etc.). The user then cuts the shaft of plunger  52  at a position, shown by line  56 , along its length between the plunger&#39;s upper and lower ends to produce plunger shaft  38 . In one such embodiment, the shaft of plunger  52  is cut so that the cut or severed end of shaft  38  is substantially coplanar with the upper most surface of syringe head  46 . In one embodiment, driver  12  and prefilled syringe  14  may be included in a kit along with a cutter configured to cut the material of plunger  52 . In another embodiment, plunger  52  of syringe  50  may include a weakness, a score, or other frangible section that facilitates removal of the upper portion of plunger  52 . In another embodiment, plunger  52  may include an indicia, for example a guide line, that traverses the width of the shaft of plunger  52  that provides an indication of where plunger  52  is to be cut. In other embodiments, driver  12  is used with a syringe, such as syringe  14 , that is constructed with a shortened plunger shaft  38  as shown in  FIG. 2B  (e.g., prefilled syringe  14  may be purchased with a shortened plunger shaft  38 ). 
     Referring back to  FIG. 2A , dispenser  10  includes driver  12 , and driver  12  includes handle body  16 , threaded shaft  18  and knob  20 . Referring to  FIG. 2D  a detailed view of handle body  16  is shown. Handle body  16  includes a lower end  60 , an upper end  62  and a central channel or passage  64  extending through handle body  16  from the first end to the second end. As will be discussed in more detail below, threaded shaft  18  extends through central passage  64  of handle body  16  to engage with plunger  34  of prefilled syringe  14 . 
     In the embodiment shown, handle body  16  is shaped and sized to provide for an easy and comfortable grip within a hand of a user. Specifically, handle body  16  is elongated in the direction of passage  64  such that the length of handle body  16  is greater than both the width and thickness of the handle. Further, the opposing lateral surfaces  66  and  68  are curved surfaces extending first radially outward as the distance from upper end  62  increases and then curve radially inward from a maximum width as the distance from upper end  62  increases further. Handle body  16  includes a front face  70  extending between lateral surfaces  66  and  68  on one side of handle body  16  and a rear face  72  (opposite front face  70  in the orientation of  FIG. 2D ) extending between lateral surfaces  66  and  68  on the other side of handle body  16 . It should be understood that  FIG. 2D  shows front face  70  and that rear face  72  is substantially a mirror image of front face  70 . Front face  70  and rear face  72  includes one or more label area  74 . 
     Handle body  16  includes an attachment structure  76  located at lower end  60 . As explained in more detail below, attachment structure  76  is configured to rigidly engage syringe body  26  (i.e., engagement such that handle body  16  and syringe body  26  remain substantially fixed relative to each other during movement of syringe plunger  34  by driver  12 ). Generally, attachment structure  76  includes a flared collar  78  surrounding the lower opening to passage  64 . As shown in  FIG. 1  and  FIG. 3 , when coupled to prefilled syringe  14 , flared collar  78  partially surrounds an upper portion of syringe body  26 . As explained in more detail below, attachment structure  76  includes a first slot  80  formed through front surface  70  and a second slot  82  (also shown in  FIG. 4 ) formed through rear surface  72 . Slots  80  and  82  allow entry of the syringe head  46  into attachment structure  76  during attachment of driver  12  to syringe  14 . 
     Referring to  FIG. 2E , a detailed view of threaded shaft  18  is shown. Threaded shaft  18  includes a upper end  90  and a lower end  92 . Upper end  90  is configured to be coupled to knob  20 . In one embodiment, upper end  90  includes a post that is press-fit inside knob  20 . In another embodiment, upper end  90  includes a thread bore for receiving a screw coupling knob  20  to shaft  18 . 
     Shaft  18  includes an engagement structure or section, shown as pronged end  94  located adjacent lower end  92 . The engagement structure includes a least one slot configured to receive at least a portion of plunger shaft  38  of prefilled syringe  14 . In the embodiment of  FIG. 2E , the engagement structure includes four slots  96  evenly positioned at 90 degree intervals from each other and defining a void  102  that has a cross-sectional shape substantially matching the cross-sectional shape of plunger shaft  34 . Slots  96  and void  102  define four fingers or prongs  98  located adjacent lower end  92 . Each prong  98  includes an axial facing end surface  100 . As discussed below regarding  FIG. 3 , prongs  98  are shaped to surround plunger shaft  38  and axial facing end surfaces  100  are configured to engage an upward facing surface of plunger head  36 . The engagement between pronged end  94  and plunger head  36  allows movement of threaded shaft  18  to cause movement of plunger  34  resulting in dispensing of an amount of fluid proportional to the axial movement of plunger  34 . 
     A portion of the outer surface of shaft  18  includes threads  103 . Coupled to shaft  18  is an indicator, shown as sleeve assembly  104 . Sleeve assembly includes a cylindrical sleeve  106 , a pair of biasing elements, shown as bands  108 , and a plurality of rigid bodies, shown as pins  110 . Each band  108  circumscribes a portion of cylindrical sleeve  106  engaging four of the eight pins  110 . Bands  108  are made from an elastic material that is configured to urge or bias pins radially inward toward shaft  18 . 
     Threaded shaft  18  extends through and is coupled to cooperative threading located on the inner surface of a bore extending through the center of sleeve  106 . Shaft  18  includes a depression, shown as axial groove  112 , that cooperates with sleeve assembly  104  to provide an indication of the amount of rotation of shaft  18  that occurs during dispensing of fluid from prefilled syringe  14 . 
     Specifically, when assembled, sleeve assembly  104  is received within channel  64  of handle body  16  such that shaft  18  passes through both sleeve assembly  104  and handle body  16 . Cylindrical sleeve  106  is rigidly coupled to handle body  106  such that shaft  18  is allowed to rotate relative to both sleeve assembly  104  and handle body  16  to advance the head of the plunger of prefilled syringe  14 . As shaft  18  is rotated relative to sleeve assembly  104 , each pin  110  becomes sequentially aligned with axial groove  112 . When one of pins  110  becomes aligned with groove  112 , the elasticity of band  108  snaps the aligned pin  110  forward into groove  112  bringing a radially inwardly facing surface of pin  110  into sharp contact with the radially outward facing surface of groove  112 . The sharp contact between pin  110  and groove  112  generates noise and/or vibration that is detected by the user. Because pins  110  are evenly spaced around sleeve  106 , each time a pin  110  aligns with groove  112  the noise and/or vibration indicates that a predetermined amount of rotation of shaft  18  has been reached. In the embodiment shown, sleeve assembly  104  includes eight evenly space pins resulting in an indication of rotation after every ⅛ revolution (45 degree) of shaft  18 . 
     Referring back to  FIG. 2A , driver  12  includes knob  20 . Knob  20  is configured to be coupled to upper end  90  of shaft  18  and provides a handle or grip that the user holds while manually rotating shaft  18 . Knob  20  includes an outer, circumferential surface  120  that includes knurls that facilitate gripping by the user. The lower surface of knob  20  includes a mounting bore  122  that is sized to receive upper end  90  of shaft  18 . In the embodiment shown, knob  20  is rigidly coupled to shaft  18  by a press-fit engagement between shaft  18  and bore  122  such that rotation of knob  20  imparts the same rotation to shaft  18 . In other embodiments, other attachment structures or mechanisms may be used. For example, knob  20  may be coupled to shaft  18  via a fastener such as a screw or bolt. As discussed in more detail below, the outer axial or upper end surface  124  may be configured to display or hold label information that may be used to identify the contents of prefilled syringe  14 . 
     Referring to  FIG. 3 , a detailed view of the attachment between driver  12  and prefilled syringe  14  is shown. Generally, driver  12  engages prefilled syringe  14  in two areas. Shaft  18  engages plunger  34  of prefilled syringe  14  such that rotation of shaft  18  translates into both axial and rotational movement of plunger  34 . Handle body  16  rigidly engages outer syringe body  26  such that handle body  16  and outer syringe body  26  are fixed together allowing shaft  18  and plunger  34  to rotate relative to both handle body  16  and outer syringe body  26 . 
     Referring first to the engagement between shaft  18  and plunger  34  shown in  FIG. 3 , plunger shaft  38  is received within slots  96  and void  102  (both shown in  FIG. 2E ) such that prongs  98  surround each right angle segment of plunger shaft  38 . As noted above, each prong  98  includes an engagement surface, shown as axial facing surface  100 , that engages the upper surface or face of plunger head  36 . The engagement between surfaces  100  of prongs  98  and plunger head  36  is tight enough that rotation of shaft  18  translates into rotation of plunger head  36  (and plunger shaft  34 ). 
     In the embodiment shown, the only contact between shaft  18  and plunger  34  is the contact between surfaces  100  of prongs  98  and the upper surface of plunger head  36 . In such an embodiment, the circumferential dimension of each slot  96  between prongs  98  is large enough that there is a gap between each segment of plunger shaft  38  and the circumferential facing surfaces of prongs  98 . Thus, the circumferential surfaces of prongs  98  do not contact the outer surface of shaft  38 . By providing for only axial contact between shaft  18  and plunger head  36 , precise movement of plunger head  36  is provided which in turn provides precise control of the volume of substances dispensed from prefilled syringe  14 . Further as shown in  FIG. 3 , the outer diameter (i.e., the radial dimension) of prongs  98  is less than inner diameter of syringe body  26  such that there is a gap between the outer surface of prongs  98  and the inner surface of syringe body  26 . This gap eliminates potential contact that may otherwise impede the transmission of motion from shaft  18  to plunger head  36 . 
     Referring to both  FIG. 3  and  FIG. 4 , the structures providing the rigid engagement between handle body  16  and syringe body  26  are shown. As noted above, handle body  16  includes a first slot  80  and second slot  82  on opposing surfaces of handle body  16  that allow entry of syringe head  46  into attachment structure  76  of handle body  16 . As shown best in  FIG. 4 , attachment structure  76  includes a first engagement surface  130  and a second engagement surface  132  formed within handle body  16 . First engagement surface  130  faces upper end  62  of handle body  16 . Second engagement surface  132  opposes first engagement surface  130  and faces lower end  60  of handle body  16 . As shown, second engagement surface  132  is shown positioned between first engagement surface  130  and upper end  62  such that second engagement surface  132  is above surface  130  in the orientation of  FIG. 4 . 
     First engagement surface  130  and second engagement surface  132  define a gap  134  positioned between the two engagement surfaces. The height of gap  134  is such that a friction fit is provided between engagement surfaces  130  and  132  and the upper and lower surfaces of syringe head  46  following coupling of prefilled syringe  14  to driver  12 . In one embodiment, surfaces  130  and  132  may be slightly tapered such that the axial dimension of gap  134  decreases toward the center of handle body  16 . In this embodiment, the tapered engagement surfaces  130  and  132  provide a friction fit engagement with the surfaces of syringe head  46 . The friction fit is rigid such that handle body  16  is fixed relative to syringe body  26  during rotation of shaft  18 , and the friction fit is reversible such that when prefilled syringe  14  is empty, driver  12  may be detached (e.g., by application of manual force in a direction opposite from the force used to couple syringe  14  to drive  12 ) from prefilled syringe  14  allowing driver  12  to be reused attached to a second prefilled syringe  14 . 
     In various embodiments, handle body  16  is configured to provide a twist-lock between prefilled syringe  14  and handle body  16 . In the particular embodiment shown, prefilled syringe  14  is attached by inserting the center of syringe body  26  in the gap  136  provided between opposing sections of flared collar  78  in a rotational orientation such that the long axis of syringe head  46  is angled relative to an axis defined by slots  80  and  82  (e.g., a horizontal axis in the orientation of  FIG. 4 ). Prefilled syringe  14  is moved axially (e.g., upward in the orientation of  FIG. 4 ) toward engagement surface  132  such that the axial position of syringe head  46  aligns with the axial position of slots  80  and  82 . With syringe head  46  in place adjacent slots  80  and  82 , prefilled syringe  14  is rotated clockwise such that one wing of syringe head  46  passes through slot  80  into gap  134  and the other wing of syringe head  46  passes through slot  82  into gap  134 . Prefilled syringe  14  is rotated until the long axis of syringe head  46  is substantially parallel to the axis defined by slots  80  and  82  (e.g., a horizontal axis in the orientation of  FIG. 4 ). In this embodiment, engagement surfaces  130  and  132  are shaped such that when the long axis of syringe head  46  is substantially parallel to the axis defined by slots  80  and  82 , syringe head  46  is rigidly engaged between engagement surfaces  130  and  132 . 
     Each engagement surface  130  and  132  is divided in to two portions located on opposite sides of central passage  64  of handle body  16 . This radial symmetry provides that central passage  64  is aligned with the central bore and the plunger of prefilled syringe  14  following attachment. Axial alignment between central passage  64  and the central bore and the plunger of prefilled syringe  14  allows shaft  18  to properly engage syringe head  36  following coupling of driver  12  to syringe  14 . 
     Referring to  FIG. 5A  and  FIG. 5B , assembled and exploded views, respectively, of sleeve assembly  104  is shown according to an exemplary embodiment. Cylindrical sleeve  106  includes a generally cylindrical sidewall  140 , an upper end  142 , a lower end  144  and a bore  146  extending through sleeve  106  between upper end  142  and lower end  144 . The inner surface  148  of sleeve  106  is threaded to mate with the threading of shaft  18 . As noted above, shaft  18  is threaded through sleeve  106 , and sleeve  106  is rigidly fixed relative to the handle body  16 , allowing shaft  18  to be advanced through both sleeve  106  and handle body  16 . In other embodiments, sleeve assembly  104  is not a separate component attached shaft  18  but is an indicator integrally formed with the inner structure of handle body  16 . 
     In the embodiment shown in  FIG. 5A  and  FIG. 5B , sleeve assembly  104  is configured to provide an indication of rotation every ⅛ of a rotation. Thus, sleeve assembly  104  includes eight pins  110 , and cylindrical sleeve  106  includes eight openings  150  evenly spaced around the circumference of sleeve  106  for receiving pins  110 . Openings  150  are radial openings extending through cylindrical sidewall  140 . Pins  110  are located within the openings such that the radial inner most surfaces of pins  110  are permitted to contact the outer surface of shaft  18 . Elastic bands  108  are in contact with each pin  110  such that when axial groove  112  of shaft  18  is located beneath a given pin  110 , the band  108  pushes the pin inward creating an audible and/or tactile indication that shaft  18  has been rotated  45  degrees. 
     In the embodiment shown, cylindrical sleeve  106  includes a lower row  152  of four openings and an upper row  154  of openings  150 . The openings of lower row  152  are rotated 45 degrees relative to the openings of upper row  154 , resulting in one opening  150  every 45 degrees around the circumference of sleeve  106 . Using two staggered rows of openings allows for the use of larger pins  110  which provides for a louder audible indication of rotation and a stronger tactile indication of rotation than if all eight pins were positioned around sleeve  106  in a single row. 
     In the embodiment shown with two rows of openings and pins, sleeve assembly  170  includes two biasing elements, shown as two elastic bands  108 . In this embodiment, sleeve  106  includes two circumferential channels, shown as lower channel  156  and upper channel  158 . Lower channel  156  is positioned to axially bisect the openings of lower row  152  and upper channel  158  is positioned to axially bisect the openings of upper row  154 . Lower channel  156  receives one of the elastic bands  108 , and upper channel  158  receives the other elastic bands  108 . Lower and upper channels  156  and  158  act to retain elastic bands  108  in the proper position in engagement with pins  110 . 
     In the various embodiments, the materials of pins  110  and shaft  18  are selected to provide audible and/or tactile indications of rotation. In one embodiment, both pins  110  and shaft  18  are made from metal to provide an easily detected sound and vibration upon impact of shaft  18  by pin  110 . In particular, pins  110  and shaft  18  may be a nonreactive metallic metal such as stainless steel or brass. In other embodiments, other materials may be used as needed for a particular application. 
     Referring to  FIG. 5C , in other embodiments, the indicating element is configured to provide indications of rotation at other amounts of rotation to provide for the appropriate dispensed amount of fluid needed for a desired application. For example in  FIG. 5C , a sleeve assembly  170  is shown having four pins  110  and four openings  150  located every ninety degrees around the circumference of the sleeve assembly. In this embodiment, sleeve assembly  170  provides an indication of the amount of rotation every ¼ rotation (i.e., 90 degrees). Sleeve assembly  170  may be used for a driver intended for use with a prefilled syringe  14  that requires twice as much fluid to be delivered per application as compared to sleeve assembly  104 . Further, sleeve assembly  170  may be used for a driver in which shaft  18  has a lower thread pitch which requires a greater rotation of shaft  18  to obtain the desired amount of delivered fluid. 
     Referring to  FIG. 6A  and  FIG. 6B , operation of dispenser  10  to dispense fluid is shown according to an exemplary embodiment. Both  FIG. 6A  and  FIG. 6B  show rear perspective views of driver  12 .  FIG. 6A  shows driver  12  in a first position relative to syringe  14  in which handle body  16  is rigidly fixed to syringe body  26 , and shaft  18  is rigidly fixed to syringe plunger  34 . 
     To dispense a predetermined amount of fluid, shaft  18  is rotated clockwise in the direction shown by arrow  180  to a second position as shown in  FIG. 6B . As shaft  18  rotates through the threaded channel of sleeve  106 , shaft  18  causes both rotational and axial movement of plunger  34  of prefilled syringe  14 , shown by arrow  182 . Axial movement of plunger  34  decreases the volume of the contents chamber  44  resulting in the dispensing of the predetermined amount of fluid from prefilled syringe  14 . Because the volumes being dispensed are small, the rotational movement of plunger  34  allows for more precise dispensing of fluid by overcoming the static friction via rotational movement of plunger  34 . Thus, rotation of plunger  34  decreases the likelihood of inadvertent over-dispensing of fluid and abrupt movement of plunger  34  that could otherwise decrease the accuracy of the dispensed volume. 
     In various embodiments, dispenser  10  is configured to accurately dispense fluid as needed for a particular application. In particular, driver  12  and prefilled syringe  14  are configured such that a predetermined amount of fluid is dispensed from syringe  14  when shaft  18  is rotated a predetermined distance. In various embodiments, the predetermined rotational amount or distance is between 0 degrees and 180 degrees of rotation, and in some such embodiments, the predetermined amount of fluid dispensed during rotation is between 5 microliters and 50 microliters. 
     In other embodiments, the predetermined rotational amount is greater than or equal to ⅛ of a rotation and is less than or equal to a ½ of a rotation, and in some such embodiments, the predetermined amount of fluid to be dispensed is between 10 microliters and 40 microliters. In other embodiments, the predetermined rotational amount is greater than or equal to an ⅛ of a rotation and is less than or equal to a ¼ of a rotation, and the predetermined amount of fluid to be dispensed is between 10 microliters and 30 microliters. In one specific embodiment, the rotational amount is equal to an ⅛ of a rotation, and the predetermined amount of fluid to be dispensed is about 12 microliters (e.g., 12 microliters plus or minus one microliter). In another specific embodiment, the rotational amount is equal to a ¼ of a rotation, and the predetermined amount of fluid to be dispensed is about 24 microliters (e.g., 12 microliters plus or minus one microliter). In other embodiments, driver  12  is configured to dispense between 0.2 and 0.4 microliters per degree of rotation, specifically to dispense between 0.2 and 0.3 microliters per degree of rotation, and more specifically to dispense between 0.25 and 0.27 microliters per degree of rotation. In one specific embodiment, driver  12  is configured to dispense between 0.26 and 0.27 microliters per degree of rotation. It should be understood that given a particular desired delivery amount, the predetermined amount of rotation needed is a function of the thread pitch of shaft  18  (which correlates to the distance of axial movement of the shaft per degree of rotation) and a function of the area of the surface of the plunger head that is in contact with the fluid in prefilled syringe  14 . 
     Referring further to  FIG. 6A  and  FIG. 6B , in one embodiment, driver  12  includes a second indicating structure, shown as visual indicator  184 . Visual indicator  184  includes a series of evenly spaced marks  186  surrounding shaft  18 . Marks  186  are positioned on the outer surface of the upper end of handle body  16 . Marks  186  may be applied to the outer surface, for example, via paint or applied label. In other embodiments, marks  186  may be permanent marks molded into the material of body  16 . The number of marks  186  spaced around shaft  18  is determined by the predetermined rotational amount for a particular driver  18 , and in this embodiment, there are eight marks  186  such that the predetermined rotational amount is an ⅛ of rotation. However, visual indicator  184  may provide indication of any of the predetermined rotational amounts discussed herein. In this embodiment, groove  112  of shaft  18  acts as an alignment mark providing a visual indication that shaft  18  has been rotated the predetermined rotational amount when groove  112  aligns with the next clockwise mark  186 . Driver  12  may include only visual indicator  184 , only an audible/tactile indicator, such as sleeve assembly  104 , or both a visual indicator and an audible/tactile indicator. 
     Referring further to  FIG. 6A  and  FIG. 6B , knob  20  includes a label area  190  located on the axial surface away from shaft  18 . Because driver  12  is able to be used with multiple prefilled syringe  14 , label area  190  may include a label or indicia  196  that indicates the contents of the prefilled syringe currently attached to driver  12 . Knob  20  may include a cover  192  that snap fits onto knob  20  covering label  190  to protect the label information contained in label  190 . In this embodiment, the label held by label area  190  is coupled to the upper end of shaft  18  via label area  190  of knob  20  such that the label is substantially perpendicular to the longitudinal axis of the shaft. After attachment to prefilled syringe  14 , driver  12  may be stored upright in a rack, and the positioning of label area  190  substantially perpendicular to the longitudinal axis of shaft  18  is such that the label in label area  190  is facing generally upward when the driver is stored upright. This positioning may help ensure that label area  190  is readable when dispenser  10  is in storage. 
     Referring to  FIG. 7 , a flow-diagram of a method  200  of modifying a prefilled syringe is shown according to an exemplary embodiment. At step  202 , a prefilled syringe is provided. In one embodiment, the prefilled syringe provided is prefilled syringe  14  discussed herein. At step  204 , a driver is provided that includes a rotating actuator (e.g., shaft  18 ) that imparts both rotational and axial movement to the syringe plunger to dispense fluid from the prefilled syringe. In one embodiment, the driver is driver  12  discussed herein. At step  206 , the plunger shaft of the prefilled syringe is cut at a position between the plunger seal and the plunger top. At step  208 , the portion of the shaft of the prefilled syringe above the cut is removed. After this step the cut surface of the plunger shaft is the upper most surface of the plunger shaft. At step  210 , the rotating actuator of the driver is coupled to the plunger such that upon operation the rotating actuator imparts both rotational and axial movement to the plunger seal to dispense the predetermined amount of fluid from the prefilled syringe. In one embodiment of the method shown in  FIG. 7 , step  210  further includes rigidly coupling the driver to the syringe body such that the rotating actuator can rotate the plunger within the syringe body without also rotating the syringe body. In various embodiments, method  200  further includes the steps of assembling the driver by rigidly coupling sleeve assembly  104  to the inner surface of handle body  16  and coupling shaft  18  to the threaded inner surface of sleeve assembly  104 . 
     In various embodiments, a kit for dispensing liquid from a prefilled syringe is provided. In one embodiment, the kit may include one or more driver  12  and one or more prefilled syringe  14 . In one such embodiment, the kit includes the same number of drivers  12  as prefilled syringes  14 . In such embodiments, each prefilled syringe  14  contains a different substance. In various embodiments, the kit includes a cutting device. In various embodiments, the kit includes instructions setting forth the steps of method  200  discussed below. In one such embodiment, the instructions are coupled to the shaft of the prefilled syringe in a manner that is visible during cutting of the plunger shaft and during attachment of driver  12  to the prefilled syringe. For example, the instructions are attached to the portion of the syringe plunger between the cut and the plunger top. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.