BACKGROUND OF THE INVENTION Safe and effective drug therapy by injection depends not only upon accurate diagnosis, but also on efficient and reliable introduction of the medical substance into the subcutaneous cellular tissue without introducing contaminants or ambient air. The applicable drug or pharmaceutical must first be drawn from the resident container or vial into a syringe before injection. The integrity and features of the vial, therefore, are influential over the overall safety of the injection.

Typically, great care must be taken when a needle cannula of a syringe is used in conjunction with a vial containing a pharmaceutical to be administered to the patient. As the pharmaceutical is drawn out of the container via the needle cannula, precautions must be taken to avoid air being drawn into the syringe. In rigid vials, air must be introduced into the container to fill the void created as the liquid pharmaceutical is withdrawn. This volume of air then becomes susceptible to being mixed with the pharmaceutical or being drawn in through the needle cannula and creating 'air pockets in the syringe barrel. Catastrophic consequences could result if these air pockets are subseqμently injected into the patient along with the liquid pharmaceutical. Also, drawing ambient air into the vial can introduce airborne contaminants to the pharmaceutical.

Some patients, or their parents or guardians, must administer pharmaceuticals on a regular basis. Some medications are very expensive and are also very critical as to dose. Therefore, it is important that the amount of the medication aspirated into the syringe for each dose be precise. Since the person administering the pharmaceutical may not be

medically trained, obtaining accurate, consistent injections is often difficul -

SUMMARY OF THE INVENTION The present invention is directed to a device which permits even an untrained person to easily and accurately fill a syringe with the correct dose of a liquid pharmaceutical. The invention is particularly suitable for users who have impaired vision or reduced manual dexterity because clear visual and audible indications are provided as to the dose being drawn into the syringe. Further, the invention permits the withdrawal of a liquid pharmaceutical from a container without the need to introduce air into the container, thus reducing possibility of contamination of the pharmaceutical. The syringe filling and metering device for pharmaceutical containers is used with containers of the type including a variable volume region housing the liquid pharmaceutical and a needle access portion pierceable by the needle cannula of the syringe. The needle access portion is typically a septum or a pierceable piston. The device includes structure which couples the syringe to the container so that the needle cannula pierces the needle access portion of the container. This is typically accomplished by mounting the syringe in a syringe carrier. An elongate piston stop is held in place by a piston driver to which the syringe carrier is threadably connected. The syringe can be driven toward the septum end of the cartridge by rotating the syringe carrier relative to the piston driver. The elongate piston stop holds the piston in place so that the barrel of the cartridge is driven over the piston, thus forcing the contents of the cartridge through the needle cannula and into the syringe. Therefore, the amount of pharmaceutical aspirated into the syringe can be easily and precisely controlled by controlling the number of full and partial revolutions of the syringe carrier relative to the piston driver. The invention can also be practiced with the needle cannula piercing the piston so that the movement of the needle end of the syringe into the barrel of the container forces the piston down the barrel to

force the liquid pharmaceutical through the needle cannula and into the syringe.

One of the primary advantages of the invention, in addition to the ease of use and accuracy, is that one embodiment can be practiced with conventional pharmaceutical cartridges of the type having a septum at one end, a cylindrical barrel and a piston at the other.

Other features and advantages of the invention will appear from the following description in which the preferred embodiments have been set forth in detail in conjunction with the accompanying drawings .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 s an overall isometric view showing a syringe filling and metering device for pharmaceutical containers made according to the invention;

FIG. 2 is an exploded isometric view of the device of FIG. l shown with a pharmaceutical cartridge and a syringe; FIGS. 2A-2E are large cross-sectional views taken along lines 2A-2A through 2E-2E of FIG. 2;

FIG. 3 shows the components of FIG. 2 in an assembled condition with portions broken away to show internal structure;

FIG. 4 is a cross-sectional view of the assembly of FIG. 3 shown in the preactuation, post-piercing position; FIG. 5 shows the assembly of FIG. 4 in the post- actuation, pre-removal condition with a substantial portion of the contents of ^' the cartridge having been forced into the syringe according to the number of turns of the syringe carrier relative to the piston driver; FIG. 6 is a cross-sectional view of an alternative embodiment of the invention shown in the preactuation, post- piercing condition; and

FIG. 7 shows the assembly of FIG. 6 in a post- actuation, pre-removal condition with a portion of the contents of the vial forced into the syringe.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a syringe-filling and metering device 2 specially adapted for use with a conventional pharmaceutical cartridge 4, ^' shown in FIG. 2, and a conventional syringe 6. Device 2 includes a generally tubular syringe carrier 8 having a central bore 10 including a proximal portion 12 and a distal portion 14, seen best in FIGS. 4 and 5, partially separated by an annular ring 16. Proximal portion 12 of central bore 10 is sized so that the barrel 18 of syringe 6 fits snugly within portion 12. The maximum axial movement of syringe 6 into bore 10 is limited by the engagement of a shoulder 20 at one end of barrel 18 with a complementarily positioned shoulder 22 within portion 12 as shown in FIG. 4. Distal portion 14 of bore 10 is sized to accept cartridge 4. Annular ring 16 is sized and configured to engage a similarly configured ring 24 at the proximal end 26 of cartridge 4. Thus, when cartridge 4 is in the position of FIG. 4, cartridge 4 is snugly retained within distal portion 14 of central bore 10. Syringe carrier 8 also includes a number of axially positioned gripping ridges 28 at the proximal end 30 of syringe carrier 8, threads 32 along the central portion 34 of syringe carrier 8, a detent lock 36 at the distal end 38 of central portion 34 and unit markings 40 along central portion 34. The use of these various elements will be discussed below. Device 2 also includes a piston driver 42 having internal threads 44 sized to engage external threads 32 as syringe carrier 8 is threaded into the interior 46 of piston driver 42. Piston driver 42 also includes an axially extending detent ridge 48 sized and positioned to engage detent lock 36 each time syringe carrier 8 is rotated once with respect to piston driver 42. Note that detent lock 36 has a central depressed region 50 so that detent ridge 48 can fit within region 50 to temporarily secure syringe carrier 8 and piston driver 42 against ^' relative rotary motion in either direction. Piston driver 42 has gripping ridges 52 at its proximal end 54. The distal end 56 is a closed end with an internally extending, generally cylindrical piston stop 58. Piston stop 58, as shown in FIGS. 3 and 4, is positioned to

engage a movable piston 60 of cartridge 4 so to keep piston 60 from moving in the direction of arrow 62, that is, towards distal end 56 of piston driver 42. Piston stop 58 has a hollow interior 64 used to house a spare needle assembly 66. A cap 68 is mounted over distal end 56 to cover interior 64 of piston stop 58 and thus keep needle assembly 66 within interior 64. If desired, distal end 56 could be covered with a peel-off sterility film to keep interior 64 clean. Cap 68 has a number of internally extending ridges 70, which help secure cap 68 securely to distal end 56 of piston driver 42.

FIG. 3 illustrates device 2, cartridge 4, and syringe 6 in a preactuation, partially piercing condition with the needle cannula 72 of syringe 6 partially piercing a septum .74 of cartridge 4. Full insertion of syringe 6 into bore 10, with threads 32, 44 engaged to the extent shown in FIG. 4, causes needle cannula 72 to fully pierce septum 74 as shown FIG. 4. The user then grasps syringe carrier 8 and piston driver 42 at gripping ridges 28, 52 and rotates syringe carrier 8 so that it moves into interior 46 of piston driver 42 as shown in FIG. 5. This causes the barrel 76 of cartridge 4 to move over piston stop 58, driving piston 60 along the barrel and thus forcing the liquid pharmaceutical 78 into barrel 18 of syringe 6.

The amount of pharmaceutical delivered into syringe 6 is indicated in several ways. The user can count the number of rotations of syringe carrier 8 within piston driver 42 through the engagement of detent lock 36 with detent ridge 48. This provides both a tactile and audible indication of the amount of pharmaceutical 78 being delivered into syringe 6. The distance syringe carrier 8 moves into piston driver 42 is indicated by unit markings 40 as they pass into interior 46 of piston driver 42. Further, since syringe carrier 8 and piston driver 42 are preferably made from clear materials, such as polycarbonate or acrylic, this permits the movement of piston 60 within cartridge 4 and the movement of piston 80 at the end of stem 82 to be viewed. After the appropriate dose has been provided to syringe 6, the syringe is removed from central bore 10 of syringe carrier 8 using finger grips 84 and the injection is give .

FIGS. 6 and 7 illustrate an alternate embodiment of the invention. These figures illustrate a syringe filling and metering device 90 in combination with syringe 6 and a vial 92. Vial 92 typically includes a- glass, cup-shaped container 94 having a closed distal end 96 and an open proximal end 98. Container 94 houses a pierceable, elastomeric piston 100 and contains a liquid pharmaceutical 102 between piston 100 and end 96. Device 90 includes an adaptor ring 104 having an internal bead 106 which engages a like groove 108 at proximal end 98 of container 94. Ring 104 has internal threads 110 which engage the external threads 112 of syringe carrier 114. Syringe carrier 114, like syringe carrier 8, has a central bore 116 sized to snugly hold syringe 6 therein. With syringe carrier 114 threadably engaged to ring 104, syringe 6 is fully inserted into bore 116 to permit needle cannula 72 to pierce piston 100 as shown in FIG. 6. To provide syringe 6 with the appropriate dose of pharmaceutical 102, user grasps ring 104 with one hand and the enlarged proximal end 118 of syringe carrier 114 with the other hand and rotates the syringe carrier to drive the syringe carrier into the interior of container 94. Doing so causes liquid pharmaceutical 102 to be driven up through needle cannula 72 and into barrel 18 of syringe 6. Appropriate dose markings and detent features can be used with device 90 if desired. Other modifications and variations can be made to disclose embodiments without departing from the subject invention as defined in the following claims. For example, vial 92 could include a pierceable septum at distal end 96.