Multi-cartridge medication injection device

• US 5,584,815 A
• Filed: 04/19/1995
• Issued: 12/17/1996
• Est. Priority Date: 04/02/1993
• Status: Expired due to Fees

• Current Assignee: Eli Lilly and Company
• Original Assignee: Eli Lilly and Company
• Inventors: Stringer, Christopher J., Schoenberg, Stephen J., Marsh, Matthew, Karshmer, David L., Lada, Christopher O., Pawelka, Gerhard E. F.
• Primary Examiner(s): Green, Randall L.
• Assistant Examiner(s): VANOVER, PERRY
• Application Number:
  US08/424,660
• Time in Patent Office: 608 Days
• Field of Search: 604/191, 604/90, 604/82-83, 604/211, 604/232, 604/237, 604/205, 604/186, 604/240, 604/207-209, 604/135-137
• US Class Current: 604/191
• CPC Class Codes: A61M 2005/2407 from the rear
• CPC Class Codes: A61M 2005/2488 via rotation, e.g. threads or bayonet
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 2205/582 by tactile feedback
• CPC Class Codes: A61M 2205/583 by visual feedback
• CPC Class Codes: A61M 2205/585 having magnification means, e.g. magnifying glasses
• CPC Class Codes: A61M 5/19 having more than one chamber , e.g. including a manifold coupling two parallelly aligned syringes through separate channels to a common discharge assembly surgical glue applicators A61B17/00491
• CPC Class Codes: A61M 5/24 Ampoule syringes, i.e. syringes with needle for use in combination with replaceable ampoules or carpules, e.g. automatic ampoules or carpules A61J1/06
• CPC Class Codes: A61M 5/2448 comprising means for injection of two or more media, e.g. by mixing
• CPC Class Codes: A61M 5/2466 by piercing without internal pressure increase A61M5/2429 takes precedence
• CPC Class Codes: A61M 5/31535 Means improving security or handling thereof, e.g. blocking means, means preventing insufficient dosing, means allowing correction of overset dose
• CPC Class Codes: A61M 5/31541 Means preventing setting of a dose beyond the amount remaining in the cartridge
• CPC Class Codes: A61M 5/31543 piston rod reset means, i.e. means for causing or facilitating retraction of piston rod to its starting position during cartridge change
• CPC Class Codes: A61M 5/31553 without axial movement of dose setting member
• CPC Class Codes: A61M 5/31561 using freely adjustable volume steps
• CPC Class Codes: A61M 5/31563 interacting with a displaceable stop member
• CPC Class Codes: A61M 5/3157 Means providing feedback signals when administration is completed A61M5/20 takes precedence
• CPC Class Codes: A61M 5/31581 performed by rotationally moving or pivoting actuator operated by user, e.g. an injection lever or handle

Abstract

A multi-cartridge dispenser for delivering two liquid medications through a single needle. The dispenser includes independent dual channel metering mechanism, dual channel drive mechanisms, and dual channel lock and pullback mechanisms. The wing must be in its "up" position for metering to take place. The wing reciprocatingly moves a driver between a pre-injection position and a post-injection position to reciprocatingly advance the leadscrews upon an injection stroke. The dosage indicator automatically rotates to its initial zero position upon the injection stroke. The lock and pullback mechanism automatically prevents rotation of the leadscrew upon metering and injection. It also locks out the cartridge retainers so that the retainers can be removed from the housing only while the wing is in its "down" position. The pullback sleeve unloads a pullback key during a cartridge change in order to enable the leadscrew to be spun freely back to its home position.

Claims

1. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container mounted to said housing and including a piston, an exit and an injectable product between said piston and said exit;

a drive stem disposed in said housing and engageable with said piston;

a tubular element threadably coupled to said drive stem such that said tubular element is rotatable with respect to said drive stem, wherein relative rotation between said tubular element and said drive stem controls the amount of telescopic extension of said drive stem from said tubular element to establish a set dosage of injectable product to be delivered, wherein a first coupling element is secured to said tubular element for rotation with said tubular element;

a drive assembly secured to said tubular element and movable with respect to said housing between a pre-injection position and a post-injection position for axially moving said drive stem with respect to said housing, to drive said piston within said container upon movement of said drive assembly from said pre-injection position to said post-injection position; and

a user-engageable dose setting assembly including a second coupling element engageable with said first coupling element for rotation with said first coupling element to enable a user to effect said relative rotation between said tubular element and said drive stem, wherein said first coupling element is in engagement with and rotatable with said second coupling element while said drive assembly is in said pre-injection position, and said first coupling element is axially spaced from said second coupling element while said drive assembly is in said post-injection position, thereby preventing a user from setting a dose while said drive assembly is in its post-injection position.

2. The apparatus of claim 1, wherein said piston is axially movable in said container toward said exit to define an axis of ejection of said injectable product, wherein said drive assembly includes an actuator movable in a direction transverse to said axis of ejection for moving said drive assembly between said pre-injection position and said post-injection position.

3. The apparatus of claim 1, wherein said dose setting assembly is rotatable between an initial radial position and a final radial position for establishing said set dosage of injectable product to be delivered while said drive assembly is in said pre-injection position, wherein a spring is secured to both said housing and said dose setting assembly for automatically biasing said dose setting assembly to said initial radial position upon movement of said drive assembly from said pre-injection position to said post-injection position.

4. The apparatus of claim 3, wherein said dose setting assembly comprises a sleeve-like indicator dial, wherein a first axial end of said dial is secured to a user-engageable knob and a second axial end of said dial comprises a set of ratchet teeth for engagement with said first ratchet element of said drive assembly.

5. The apparatus of claim 4, wherein said dose setting assembly includes a bearing element between said knob and a portion of said dial, said bearing element being secured to said housing and said knob and dial being rotatable with respect to said bearing element, wherein a first end of said spring is secured to said bearing element and a second end of said spring is secured to one of said knob and said dial.

6. The apparatus of claim 4, wherein said dial includes a plurality of numerals spaced thereabout, wherein said housing includes an opening therein and said dial is arranged in said housing such that a numeral appears in said opening, thereby indicating to the user the number of dosage units constituting said set dosage.

7. The apparatus of claim 6, wherein the numeral 0 appears in said opening while said dose setting assembly is in said initial radial position.

8. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container mounted to said housing and including a piston, an exit and an injectable product between said piston and said exit;

a tubular element disposed in said housing, said tubular element including an internally threaded surface;

a drive stem telescopingly extending through said inner diameter surface and including a first axial end engageable with said piston, a second and opposite axial end comprising an enlarged diameter portion, and an externally threaded surface between said first end and said second end, said externally threaded surface in engagement with said internally threaded surface of said tubular element;

a nut secured to said drive stem for restraining rotation of said drive stem upon rotation of said tubular element, said drive stem being axially movable with respect to said tubular element upon rotation of said tubular element, wherein relative rotation between said tubular element and said drive stem controls the amount of telescopic extension of said drive stem from said tubular element to establish a set dosage of injectable product to be delivered, wherein said amount of telescopic extension of said drive stem from said tubular element is at a maximum upon said enlarged diameter portion of said drive stem engaging said internally threaded surface of said tubular element; and

a drive assembly coupled to said drive stem for axially moving said drive stem to drive said piston.

9. The apparatus of claim 8, wherein said drive assembly is secured to said tubular element, said tubular element being axially stationary upon rotation of said tubular element.

10. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container mounted to an end of said housing and including a piston, an exit and an injectable product between said piston and said exit;

a drive stem disposed in said housing and drivingly coupled to said piston;

a drive assembly coupled to said drive stem for moving said drive stem to drive said piston within said container;

a rotatable piece secured to said drive stem for rotation with said drive stem;

a locking sleeve disposed about said drive stem and coupled to said rotatable piece to restrict rotation of said rotatable piece, said rotatable piece and said locking sleeve being in engagement with one another while said container is mounted to said housing to prevent rotation of said rotatable piece and said drive stem; and

a disengaging mechanism coupled to at least one of said rotatable piece and said locking sleeve for automatically disengaging said locking sleeve from said rotatable piece upon removal of said container from said housing, thereby permitting said rotatable piece and said drive stem to be rotated with respect to said housing.

11. The apparatus of claim 10, wherein said disengaging mechanism comprises a locking device keyed to said locking sleeve and movable between a locked position and an unlocked position, wherein in said locked position, said locking device is in tight engagement with said rotatable piece thereby forcing said rotatable piece into locking engagement with said locking sleeve for preventing rotation of said rotatable piece and drive stem, and wherein in said unlocked position, said locking device is spaced from said rotatable piece, thereby permitting said rotatable piece to be spaced from said locking sleeve, thereby enabling rotation of said rotatable piece and said drive stem with respect to said housing.

12. The apparatus of claim 11, including a holder for said container, said holder including means for rotating said locking device between said locked position and said unlocked position.

13. The apparatus of claim 12, including means for securing said holder to said locking device while said locking device is in said locked position.

14. The apparatus of claim 11, including means for locking said locking device in said locked position.

15. The apparatus of claim 10, wherein said rotatable piece includes a first set of ratchet teeth and said locking sleeve includes a second set of ratchet teeth, wherein said first set of ratchet teeth are in engagement with said second set of ratchet teeth upon engagement with one another.

16. An apparatus for effecting delivery of an injectable product, comprising:

a housing;

a cartridge received in said housing for containing and sealing an injectable product therein, said cartridge including an exit end and a piston axially movable in said cartridge to define an axis of ejection of the injectable product from said cartridge;

a manually adjustable dosage metering mechanism rotatably disposed in said housing for enabling a user to selectively set a dosage of the injectable product to be delivered without effecting delivery of the injectable product from said cartridge, said dosage metering mechanism including a dial having a first stop member, wherein said housing includes a second stop member, said first stop member engageable with said second stop member to limit rotation of said dial to less than 360°

to thereby establish a-maximum dosage setting; and

a delivery mechanism for engaging and axially advancing said piston a distance sufficient to cause said set dosage to be delivered out of said cartridge, said delivery mechanism including a hand operated actuator.

17. A medication dispensing device for effecting the simultaneous delivery of two injectable products, comprising:

a housing;

a first cartridge received in said housing and containing and sealing a first injectable product therein, said first cartridge having a first exit end and including a first piston therein;

a second cartridge received in said housing and containing and sealing a second injectable product therein, said second cartridge having a second exit end and including a second piston therein;

a first dosage metering mechanism disposed in said housing and including a first dosage adjuster coupled to a first plunger-engageable member such that adjustment of said first dosage adjuster establishes a first set dosage of injectable product to be delivered;

a second dosage metering mechanism disposed in said housing and including a second dosage adjuster coupled to a second plunger-engageable member such that upon adjustment of said second dosage adjuster such that adjustment of said second dosage adjuster establishes a second distance with respect to said housing to establish a second set dosage of injectable product to be delivered;

a manifold secured to said first and second exit of said first and second cartridges, respectively, for enabling the mixing of said first and second set dosages of said first and second injectable products within said manifold upon delivery from said respective cartridges into said manifold, said manifold being in fluid communication with said first and second cartridges and containing a common exit for enabling the mixed injectable product to be delivered to a user; and

a drive mechanism coupled to said first and second plunger-engageable members for simultaneously axially advancing said first and second members a distance sufficient to engage and axially advance said first and second pistons, respectively, to effect simultaneous delivery of said first and second set dosages into said manifold and out through said common exit, said drive mechanism moveable to axially retract said first and second plunger-engagement members away from said respective first and second pistons after said delivery of said mixed injectable product.

18. The dispensing device of claim 17, wherein said first dosage metering mechanism is coupled to said first plunger-engageable member such that upon adjustment of said first dosage adjuster, said first member is axially advanceable a first distance with respect to said housing to establish said first set dosage of injectable product to be delivered without effecting delivery of the first injectable product and said second dosage metering mechanism is coupled to said second plunger-engageable member such that upon adjustment of said second dosage adjuster, said second member is axially advanceable a second distance with respect to said housing to establish said second set dosage of injectable product to be delivered without effecting delivery of the second injectable product.

19. The dispensing device of claim 17, wherein said drive mechanism includes a carrier, wherein said first and second plunger-engageable members are secured to said carrier and axially movable therewith, said carrier being axially advanceable upon actuation of said injector mechanism to simultaneously advance said members to effect simultaneous delivery of said first and second set dosages.

20. The dispensing device of claim 17, wherein the axial advancement of said first and second pistons in said first and second cartridges, respectively, defines a first axis of delivery and a second axis of delivery, respectively, said first and second axes of delivery being generally parallel to one another, wherein said dispensing device includes a hand-operated actuator movable in a direction transverse to said axes of delivery to effect delivery of the mixed injectable product.

21. The dispensing device of claim 17, wherein said drive mechanism operates independently of said first and second metering mechanisms.

22. The dispensing device of claim 17, wherein said first and second dosage adjustors are rotatable to set said first and second dosages.

23. The dispensing device of claim 22, wherein said first and second dosage adjusters are rotatable in both a clockwise direction and a counterclockwise direction thereby enabling each of said respective first and second members to be translated axially forwardly and rearwardly to enable a user to selectively increase and decrease said first and second set dosages prior to actuating said injector mechanism.

24. The dispensing device of claim 17, wherein said first and second plunger-engageable members are leadscrews coupled to said respective first and second dosage metering mechanisms in such a manner that adjustment of each said respective dosage adjustor causes said respective leadscrew to translate axially in a non-rotary manner within said housing.

25. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container mounted within said housing and including a piston, an exit and an injectable product between said piston and said exit;

a drive stem disposed in said housing and drivingly coupled to said piston;

a drive assembly mounted to said housing and axially movable in said housing between a dose-setting position and an injection position for moving said drive stem to drive said piston within said container, said drive assembly including a first ratchet element; and

a dose setting assembly including a second ratchet element coupled to said first ratchet element to establish a set dosage of injectable product to be delivered, said dose setting assembly including an indicator element being movable from a zero dose reference position against a biasing force to a specific dose reference position upon the setting of a desired dose to be delivered, said first ratchet element being in engagement with said second ratchet element to maintain said indicator element in said specific dose position while said drive assembly is in said dose-setting position, said first ratchet element being movable out of engagement with said second ratchet element upon movement of said drive assembly from said dose-setting position to said injection position, thereby enabling said indicator element to be automatically biased by said biasing force back to its zero dose reference position.

26. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container mounted to said housing and including a piston, an exit and an injectable product between said piston and said exit;

an internally threaded nut disposed in said housing and rotatable with respect to said housing, and an externally threaded leadscrew disposed in said nut and drivingly coupled to said plunger;

means secured to said leadscrew for restraining said leadscrew against rotation upon rotation of said nut so that rotation of said nut causes translation of said leadscrew;

a drive assembly mounted to said housing and axially movable in said housing between a pre-injection position and a post-injection position for moving said leadscrew to drive said piston within said container, said drive assembly including a clutch element secured to said nut for rotation therewith, said clutch element including a first ratchet element, said clutch element, nut, and leadscrew being axially movable between said pre-injection position and said post-injection position; and

a dose setting assembly coupled to said drive assembly and comprising a rotatable element having a dose setting knob and a rotatable second ratchet element engageable with said first ratchet element while said drive assembly is in said pre-injection position so that rotation of said knob results in rotation of said nut, said rotatable element being rotatable against the force of a spring from an initial radial position to a selective final radial position for selectively advancing said leadscrew to set the dosage of injectable product to be delivered, said first ratchet element being spaced from said second ratchet element while said drive assembly is in said post-injection position, whereby said spring biases said rotatable element from said final radial position to said initial radial position upon movement of said drive assembly from said pre-injection position to said post-injection position.

27. The apparatus of claim 26, wherein said piston is axially movable in said container toward said exit to define an axis of ejection of said injectable product, wherein said drive assembly includes an actuator movable in a direction transverse to said axis of ejection for moving said drive assembly between said pre-injection position to said post-injection position.

28. The apparatus of claim 26, wherein said rotatable member includes a plurality of numerals spaced about said rotatable member, wherein said housing includes an opening therein and said rotatable member is arranged in said housing such that a numeral appears in said opening, thereby indicating to the user the number of dosage units constituting said set dosage.

29. The apparatus of claim 28, wherein the numeral 0 appears in said opening while said rotatable member is in its initial radial position.

30. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container mounted to said housing and including a piston, an exit and an injectable product between said piston and said exit;

piston-engagement means disposed in said housing for drivingly engaging said piston;

drive means mounted to said housing for moving said piston-engagement means between a pre-injection axial position and a post-injection axial position, with respect to said housing, to drive said piston within said container, said drive means including a first ratchet element, and a nut means coupled to said piston-engagement means for rotation with respect to said piston-engagement means, wherein relative rotation between said nut means and said piston-engagement means controls the amount of telescopic extension of said piston-engagement means from said nut means to establish a set dosage of injectable product to be delivered, said piston-engagement means being axially movable with said nut means between said pre-injection position and said post-injection position; and

dose setting means for setting a dosage of injectable product to be delivered, said dose setting means coupled to said drive means and comprising a rotatable element including a dose setting knob and a second ratchet element engageable with said first element while said drive means is in said pre-injection position, wherein said dose setting knob is coupled to said nut means while said piston-engagement means is in said pre-injection position so that rotation of said knob with respect to said housing results in rotation of said nut means, said rotatable element being rotatable against the force of a spring means from an initial radial position to a selective final radial position for selectively advancing said piston-engagement means to set the dosage of injectable product to be delivered, said first ratchet element being spaced from said second ratchet element while said piston-engagement means is in said post-injection position, whereby said spring means biases said rotatable element from said final radial position to said initial radial position upon movement of said piston-engagement means from said pre-injection position to said post-injection position.

31. The apparatus of claim 30, wherein said piston is axially movable in said container toward said exit to define an axis of ejection of said injectable product, wherein said drive means includes an actuator movable in a direction transverse to said axis of ejection for moving said piston-engagement means between said pre-injection position to said post-injection position.

32. The apparatus of claim 30, wherein said rotatable member includes a plurality of numerals spaced about said rotatable member, wherein said housing includes an opening therein and said rotatable member is arranged in said housing such that a numeral appears in said opening, thereby indicating to the user the number of dosage units constituting said set dosage.

33. The apparatus of claim 32, wherein the numeral 0 appears in said opening while said rotatable member is in its initial radial position.

34. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container received in said housing and including a piston, an exit and an injectable product between said piston and said exit;

a drive stem disposed in said housing and drivingly coupled to said piston; and

a drive assembly mounted to said housing and axially movable in said housing for moving said drive stem to drive said piston within said container;

wherein a locking mechanism is engageable with said drive stem and configured to restrict rotation of said drive stem with respect to said housing, said locking mechanism being in engagement with said drive stem while said container is securely mounted in said housing to prevent rotation of said drive stem with respect to said housing, said locking mechanism being automatically disengaged from said drive stem upon removal of said container from said housing, thereby permitting said drive stem to be rotated with respect to said housing.

35. An apparatus for the delivery of an injectable product, comprising:

a housing having a proximal end and a distal end;

a removable cartridge retainer received in said distal end of said housing;

a replaceable cartridge received in said cartridge retainer and including a piston, an exit and an injectable product between said piston and said exit, said cartridge retainer being removable to enable said cartridge to be replaced with another cartridge;

a drive stem disposed in said housing and drivingly coupled to said piston;

a dosage metering mechanism disposed in said housing to establish a first set dosage of the first injectable product to be delivered; and

a drive assembly mounted to said housing and axially movable in said housing for moving said drive stem to drive said piston within said cartridge;

wherein an automatic lockout mechanism is engageable with said drive stem and configured to prevent axial movement of said drive stem toward said proximal end of said housing independent of said dosage metering mechanism and said drive assembly, said lockout mechanism being in engagement with said drive stem while said cartridge retainer is securely mounted in said housing to prevent said independent axial movement of said drive stem with respect to said housing, said lockout mechanism being automatically disengaged from said drive stem upon removal of said cartridge retainer from said housing, thereby permitting said drive stem to be axially moved toward the proximal end of said housing independent of said dosage metering mechanism and drive assembly.

36. The apparatus of claim 35, wherein said automatic lockout mechanism comprises a pullback key having an opening that generally matches the shape of said drive stem and is rotatable with said drive stem, a pullback sleeve that is rotationally fixed with respect to said housing and engageable with said pullback key, and a lock key that is rotatable between an unlocked position and a locked position, wherein in said locked position, said pullback key is in engagement with said pullback sleeve to prevent rotation of said pullback key with respect to said housing, and wherein in said unlocked position, said pullback key is rotatable with respect to said pullback sleeve, thereby enabling said independent movement of said drive stem.

37. An apparatus for the delivery of an injectable product, comprising:

a housing;

a removable cartridge retainer received in said housing;

a replaceable cartridge received in said cartridge retainer and including a piston, an exit, and an injectable product between said piston and said exit, said cartridge retainer being removable to enable said cartridge to be replaced with another cartridge;

a drive stem disposed in said housing and drivingly coupled to said piston;

a drive assembly mounted to said housing and axially movable in said housing for moving said drive stem to drive said piston with said cartridge;

a hand-operated actuator for moving said drive assembly between a pre-injection position and a post-injection position; and

means for locking said cartridge retainer to said housing while said drive assembly is in one of said pre-injection and post-injection positions.

38. The apparatus of claim 37, wherein said cartridge retainer is locked to said housing while said drive assembly is in said pre-injection position.

39. The apparatus of claim 37, wherein said means for locking said container includes a lock key that is rotatable with respect to said housing while said drive assembly is in said post-injection position and said lock key is not rotatable with respect to said housing while said drive assembly is in said pre-injection position.

40. The apparatus of claim 39, wherein said cartridge retainer is keyed to said lock key such that said cartridge retainer is rotatable with said lock key.

41. An apparatus for the delivery of an injectable product, comprising:

a housing;

a cartridge retainer received in said housing;

a cartridge received in said cartridge retainer and including a piston, an exit and an injectable product between said piston and said exit;

a drive stem disposed in said housing and drivingly coupled to said piston; and

a drive assembly mounted to said housing and axially movable in said housing for moving said drive stem to drive said piston within said cartridge;

a hand-operated actuator for moving said drive assembly between a pre-injection position and a post-injection position;

wherein a rotatable piece is secured to said drive stem for rotation therewith, and a locking sleeve is disposed about said drive stem and configured to restrict rotation of said rotatable piece with respect to said housing, said rotatable piece and said locking sleeve being biased in unlocked relationship with one another, said rotatable piece and said locking sleeve being forced into locked engagement with one another while said retainer is mounted to said housing to prevent rotation of said rotatable piece and said drive stem with respect to said housing, said rotatable piece and said locking sleeve being automatically disengaged from one another upon removal of said retainer from said housing, thereby permitting said rotatable piece and said drive stem to be rotated with respect to said housing.

42. The apparatus of claim 41, wherein a spring is positioned in said housing with respect to said rotatable piece and said locking means to apply a biasing force sufficient to separate a first locking element of said rotatable piece from a second locking element of said locking means, said spring means being positioned in said housing such that upon said container being secured to said housing end, said spring means is compressed sufficiently to permit said rotatable piece to lockingly engage with said locking means.

43. The apparatus of claim 41, wherein said rotatable piece includes a first set of ratchet teeth and said locking means includes a second set of ratchet teeth, wherein said first set of ratchet teeth are in engagement with said second set of ratchet teeth while said container is mounted to said housing.

44. The apparatus of claim 41, wherein said plunger-engagement means is moveable axially from said housing end and toward a second and opposite housing end upon said container being removed from said housing.

45. An apparatus for the delivery of an injectable product, comprising:

a housing;

a container received in said housing and including a plunger, an exit and an injectable product between said plunger and said exit;

plunger-engagement means disposed in said housing for drivingly engaging said plunger; and

drive means mounted to said housing and axially movable in said housing for moving said plunger-engagement means to drive said plunger within said container,

wherein a rotatable piece is secured to said drive stem for rotation therewith, and a locking means is disposed about said drive stem and configured to restrict rotation of said rotatable piece with respect to said housing, said rotatable piece and said locking means biased in unlocked relationship with one another, said rotatable piece and said locking means being forced into locked engagement with one another while said container is mounted to said housing to prevent rotation of said rotatable piece and said plunger-engagement means with respect to said housing, said rotatable piece and said locking means being automatically disengaged from one another upon removal of said container from said housing, thereby permitting said rotatable piece and said plunger-engagement means to be rotated with respect to said housing.

46. A method of delivering a selected dosage of injectable product, the method comprising the steps of:

moving a hand-operated actuator to a pre-injection position;

rotating a knob extending from an injector housing to set a dosage of injectable product to be delivered out of a container mounted to an end of the housing, wherein the injectable product is in the container between a piston and an exit end of the container, wherein movement of the piston toward the exit end defines an axis of ejection of the injectable product from the container; and

continuously moving the actuator in a direction transverse to the axis of ejection from the pre-injection position to a post-injection position to move the piston and effect delivery of the injectable product.

47. The method of claim 46, wherein the step of continuously moving the actuator includes moving the actuator through a given angular range of motion, wherein incremental movement of the actuator results in a corresponding incremental axial advancement of a drive assembly which carries a piston-engaging stem.

48. The method of claim 46, wherein the step of rotating includes rotating the knob in a first rotational direction to increase the set dosage and then in a second and opposite rotational direction in order to decrease the set dosage.

49. The method of claim 46, wherein movement of the actuator causes the knob to be rotated back to an initial rotational position.

50. The method of claim 46, wherein the step of moving the actuator to the pre-injection position causes the piston-engaging stem to axially retract off of the piston.

51. A method of delivering a selected dosage of mixed injectable product, the method comprising the steps of:

moving a hand-operated actuator to a pre-injection position;

rotating a first knob of a first dosage metering mechanism disposed in an injector housing to set a first set dosage of first injectable product to be delivered out of a first container mounted in the housing, wherein the first injectable product is in the first container between a first piston and a first exit end of the first container, wherein the first piston is movable toward the first exit end along a first axis of ejection of the first injectable product from the first container;

rotating a second knob of a second dosage metering mechanism disposed in the injector housing to set a second set dosage of second injectable product to be delivered out of a second container mounted in the housing, wherein the second injectable product is in the second container between a second piston and a second exit end of the second container, wherein the second plunger is movable toward the second exit end along a second axis of ejection of the second injectable product from the second container, the second axis being generally parallel to the first axis; and

moving the actuator in a direction transverse to the first and second axes of ejection to a post-injection position to simultaneously axially advance first and second piston-engagement members in the housing to axially advance the first and second pistons, respectively, to effect simultaneous delivery of the first and second set dosages into a manifold attached to the first and second exit ends of the first and second containers and out through a needle extending from the manifold.

52. The method of claim 51, wherein the step of moving the actuator includes moving the actuator through a given angular range of motion, wherein incremental movement of the actuator results in a corresponding incremental axial advancement of a drive assembly which carries the first and second members.

53. The method of claim 51, wherein the step of rotating includes rotating at least one of the first and second knobs in a first rotational direction to increase the respective set dosage and then in a second and opposite rotational direction in order to decrease the respective set dosage.

54. The method of claim 51, wherein movement of the actuator causes at least one of the first and second knobs to be rotated back to an initial rotational position.

55. A method of delivering a selected dosage of injectable product, wherein the injectable product is in a cartridge between a piston and an exit end of the cartridge, the cartridge being replaceable and received in a removable cartridge retainer, the cartridge retainer being received in an injector housing and removable to enable the cartridge to be replaced with another cartridge, the method comprising the steps of:

moving a hand-operated mechanism to a pre-injection position, thereby automatically locking the cartridge retainer to the housing;

actuating a dosage metering mechanism disposed in the injector housing to set a dosage of injectable product to be delivered out of the cartridge; and

moving the hand-operated mechanism from the pre-injection position to a post-injection position to effect delivery of the injectable product, thereby automatically unlocking the cartridge retainer from the housing to permit the cartridge retainer to be removed from the housing.

56. The method of claim 55, wherein the step of moving the hand-operated mechanism to the pre-injection position automatically prevents the cartridge retainer from being rotatable with respect to the housing, and wherein the step of moving the hand-operated mechanism to the post-injection position automatically permits the cartridge retainer to be rotated with respect to the housing.

57. The method of claim 55, wherein movement of the hand-operated mechanism from the pre-injection position to the post-injection position causes the dosage metering mechanism to be automatically rotated back to an initial rotational position.

58. The method of claim 55, wherein movement of the hand-operated mechanism from the pre-injection position to the post-injection position causes the dosage metering mechanism to be decoupled from a drive mechanism which effects delivery of the injectable product.

59. The method of claim 55, including the step of removing the cartridge retainer and cartridge from the housing while the hand-operated mechanism is in the post-injection position.

60. The method of claim 59, including the step of inserting a second cartridge into the cartridge retainer.

61. The method of claim 60, including the step of attaching the cartridge retainer to the housing while the hand-operated mechanism is in the post-injection position.

62. The method of claim 61, wherein the step of attaching the cartridge retainer to the housing includes the steps of causing a second piston of the second cartridge to engage a piston-engagement member in the injector housing, forcing the piston-engagement member to translate axially within the housing toward the hand-operated member, and rotating the cartridge retainer within the housing to secure the cartridge retainer within the housing.

63. A method of delivering a selected dosage of injectable product, the method comprising the steps of:

rotating a cartridge retainer into a locked position with respect to an injector housing, thereby automatically causing a piston-engagement stem within the housing to become locked against rotation with respect to the housing;

setting a dosage of injectable product to be delivered out of a cartridge of liquid medication housed in the cartridge retainer and containing the liquid medication between a movable piston and an exit;

moving a hand-operated actuator to effect nonrotating axial advancement of the piston-engagement stem to effect delivery of the set dosage of injectable product out of the exit end;

removing the cartridge retainer and cartridge from the housing thereby automatically enabling the piston-engagement stem to be rotatable with respect to the housing; and

causing the piston-engagement stem to rotate with respect to the housing and simultaneously axially move toward an opposite end of the housing.

64. The method of claim 63, including the steps of inserting a second cartridge into the cartridge retainer and attaching the cartridge retainer to the housing, thereby automatically causing the piston-engaging stem to axially move toward the opposite end of the housing and then become locked against rotation with respect to the housing upon rotation of the cartridge retainer onto the housing.