Multiple chamber automatic injector

Abstract

An automatic injector is provided having at least two chambers containing different ingredients of a medicament separated by an impermeable membrane. A lance is movable independently of a plunger to cut or pierce the membrane before a spring-loaded drive member for the plunger is released to drive a needle out of the body of the injector and discharge the medicament through the needle. A removable safety clip is provided for preventing movement of art actuating cap into an operative position for advancing the lance, and release of the drive member is preventable by a removable safety pin until the injector is to be used. a sealing structure. One of the chambers has a needle disposed therein. The sealing structure is conditionable to permit the ingredients to mix in the injector in response to a predetermined actuating procedure before the ingredients are injected.

Description

This is a continuation of application Ser. No. 08/109,643, filed on Aug. 20, 1993, which was abandoned upon the filing hereo, which is a Reissue Application of application Ser. No. 396,325 filed Aug. 21, 1989, now U.S. Pat. No. 5,041,088.movable elongated member or lance 34 having a cylindrical stem 35 which extends at one end through the plunger 33 and which carries on its other end a cutter 36 spaced a short distance away from the membrane 29.

The bore portion 24 of lesser internal diameter contains releasable drive means for the plunger 33 in the form of a tubular collet 37 surrounded by a helical spring 38. The collet 37 at one end has an enlarged head 39 which engages with the plunger 33 and at its other end has a latching means in the form of a frusto-conical portion divided by one or more slots into barbs 40 which extend through a central opening 41 in an annular collar or latch ring 42 at the end of the body 1 onto which the actuating cap 4 fits. If the collet 37 is formed from a plastics material one slot may be sufficient, but a metal collet preferably has four slots in its frusto-conical portion. The barbs 40 of the frusto-conical portion engage with the outer face of the collar 42 and the spring 38 is held in compression between the inner face of the collar 42 and the head 39 of the collet 37.

Within the tubular collet 37 there is a drive pin 43 which engages at one end with the lance 34 and at its opposite end with the shank 21 of the safety pin 5 which extends partly within the divided frusto-conical portion 40 of the collet 37. In a modified construction, not shown, the drive pin 43 and safety pin 5 may comprise a single component. With a separate drive pin 43 an interference fit may be provided between the drive pin 43 and the collet 37. This allows the drive pin 43 to slide within the collet bore with negligible friction, but will prevent the drive pin 43 from falling out of the collet 37 during assembly and also will stop the drive pin moving into a position where it may prevent firing by preventing the collet barbs from collapsing fully. FIG. 2 shows the interference fit provided at 47 between the collet 37 and the end of the drive pin 43 adjacent to the shank 21 of the safety pin 5. Preferably, however, two or more ribs are provided at the opposite end of the drive pin 43 with a slot or slots up the end of the drive pin to provide a spring-type cantilever interference fit.

In use the first and second chambers 27 and 28 of the injector are filled with different ingredients of a medicament to be injected. For instance, the second chamber 28 may contain a medicament in powdered form and the first chamber 27 a diluent for the powder, or vice versa. Alternatively, the chambers may contain different liquid ingredients of a medicament that are incompatible if stored together for any significant length of time. The pre-filled automatic injector may be carried by a user in the condition shown in the drawings and preferably contained within a close fitting flexible plastics sleeve (not shown) which has appropriate labelling, attachment means, e.g. a button hole, and is designed to act as a casualty marker tag after use. When the user needs to self-inject the medicament into his/her body he/she follows the procedure described below.

The user pulls the ring 18 of the safety clip 3 to remove the band 16 from the body of the injector breaking the tamper evident tag 45. Then, by pressing down on the head 19 of the safety pin 5 the flange 12 of the annular portion of the actuating cap 4 moves over the annular ridge 14 and the drive pin 43 moves within the collet 37 and advances the lance 34 which ruptures the membrane 29, allowing the ingredients in the chambers 27 and 28 to mix.

It will be appreciated that the membrane may be ruptured in a variety of ways. As shown in FIGS. 2 and 3 the cutter 36 on the lance 34 may be arranged to cut a plurality of radial slits (e.g. four) in the membrane 29 allowing the cut sectors to be pushed by the head of the lance 34 against the wall of the liner 26 allowing free passage of the plunger through the membrane region. A central recess 44 in the cutter 36 is designed to allow fluid to flow down the end of the needle tube. Alternatively, the cutter 36 on the lance may be arranged to cut the periphery of the membrane 29 which can then fold up into the central recess 44 in the lance so that it does not obstruct the flow of liquid ingredients from the second chamber 28 into the first chamber 27. The lance, however, may take different forms and the membrane 29 may be ruptured by a piercing action instead of a cutting action.

After the ingredients of the medicament within the injector have been thoroughly mixed together, the user removes safety pin 5, places the end cap 2 on an appropriate part of his/her body, his/her thigh for example, and self-injects the medicament into his/her body by pressing on the actuating cap 4.

Removal of the shank 21 of the safety pin 5 from within the divided frusto-conical portion of the collet 37 allows the barbs 40 to collapse inwardly when the part of the end wall 9 that defines the aperture 10 engages the barbs 40. When the barbs 40 of the collet 37 collapse inwardly through the collar 42, the compressed spring 38 is released and drives the collet 37, plunger 33 and lance 34 forwards in the body.

When the collet 37 starts moving the plunger 33 drives the lance 34 down onto the needle disc 32, the needle 30 then pierces the needle guide 31, sealing bush 6 and portion 8 of the end cap 2 and continues moving into the body of the user until the needle disc 32 is touching the needle guide 31. During the movement of the needle 30 the medicament will be pumped out of the chambers 27 and 28 through the needle 30 by the plunger 33. The medicament will normally enter the needle tube through a hole in the end of the needle opposite its pointed end. There may, however, also be provided a slot in the side of the needle tube, just below the needle disc so that if the end of the needle tube is blocked by a piece of the cut membrane there is a second path for the fluid to flow down the needle tube. When the needle stops moving the plunger 33 will continue moving and will slide over the top of the cylindrical stem 35 of the lance 34. This will continue until the plunger 33 is pushed to the bottom of the lance 34 which will be on top of the needle disc 32 therefore expelling the medicament from both chambers 27 and 28 of liner 26. At the end of the operation of the automatic injector the needle 30 will be fully projecting from the end cap 2, the cutter 36 of the lance 34 will be on top of the needle disc 32, the plunger 33 will be on top of the cutter 36, the collet 37 will be on top of the plunger 33, the spring 38 will be fully extended, the drive pin 43 should remain in the collet 37, the safety pin 5 and clip 3 will be removed with the tamper evident tag 45 broken indicating that the device has been used and the actuating cap 4 may be pushed fully down on top of the body 1 or returned to its original position by the spring 38.

It will be appreciated that the multi-chamber automatic injector of the present invention is simple to operate and effectively stores the different ingredients of the medicament in separate chambers with minimal risk of the ingredients being mixed together until the user is ready to self-inject the medicament into his/her body. This substantially prolongs the storage life of the injector and also greatly increases the number of different medicaments which can be injected using the automatic injector.

Claims

1. An automatic injector comprising:

a body incorporating at least two chambers containing different ingredients of a medicament, said at least two chambers being including a forward ingredient chamber containing a first ingredient of said medicament and rearward ingredient chamber containing a second ingredient of said medicament, said forward and rearward ingredient chambers being longitudinally disposed adjacent one another within said body and kept in a normally sealed relation from one another,

separated by a thin impermeable membrane,

a needle held normally contained in a sheathed position within said body, said forward ingredient chamber, said needle being movable to an unsheathed position projecting from said body and being capable of dispensing said medicament therethrough,nd .

a releasable drive means assembly within said body which when released drives said needle from said sheathed position into an said unsheathed position projecting from said body,

a sealing structure for maintaining said forward and rearward chambers in said normally sealed relation from one another, said sealing structure permitting said chambers to intercommunicate to allow the ingredients to mix within said body in response to a predetermined mixing procedure; and

an expulsion means member disposed within said body for discharging the medicament through said needle, and a cutting or piercing means which is movable within said body from a first position in which it is separated from said membrane to a second position where it is forcibly in contact with said membrane so as to cut or pierce said membrane before said drive means is released. 2. An automatic injector according to claim 1, wherein said chambers for the different ingredients of the medicament are arranged axially in said body of the

injector.3. An automatic injector according to claim 2 1, wherein a first one of said chambers is arranged to contain said needle in said sheathed position and a second one of said chambers said rearward ingredient chamber is arranged to contain said cutting or piercing means a movable elongated member being manually movable from a first position to a second position and being cooperable with said sealing structure so that said movement from said first position to said second position enables said ingredients to mix within said body before said releasable drive assembly is

released.4. An automatic injector according to claim 3, wherein the automatic injector has a substantially cylindrical bore within said body lined by, and further comprising a tubular cartridge which defines disposed within said bore said tubular cartridge defining said longitudinally disposed forward and rearward adjacent axially spaced chambers, and said

wherein said sealing structure is in the form of an impermeable membrane separating said forward and rearward chambers extends, said impermeable membrane extending transversely across said cartridge at an a longitudinally intermediate point along the length of said

cartridge. 5. An automatic injector according to claim 4, wherein said tubular cartridge is formed from a chemically inert, impermeable,

low-friction plastics material. 6. An automatic injector according to claim 1, wherein said cutting or piercing means comprises a lance further comprising a movable elongated member cooperable with said sealing structure so that movement of said elongated member from a first position to a second position breaks said sealing structure to permit said ingredients to mix, and wherein said expulsion member for discharging the medicament through the needle is in the form of a plunger having a bore extending therethrough, said elongated member being arranged to extend through asaid bore in said plunger and be slidable relative to said plunger which constitutes said

expulsion means for discharging the medicament through the needle. 7. An automatic injector according to claim 6, wherein said releasable drive means assembly comprises a spring-loaded drive member engageable with said plunger , a spring, and a latching means associated with said releasable drive means, said latching means portion serving for holding a said spring in compression, said drive means assembly being urged by said spring to advance said plunger

when said latching means portion is released. 8. An automatic injector according to claim 7, wherein said needle carries a disc and said lance movable elongated member is engageable with said disc after said lance has cut or pierced said membrane elongated member breaks said sealing structure to permit said ingredients to mix, said lance movable elongated member being subsequently movable with or by said plunger to force said needle out of said body of the injector into said unsheathed position, said plunger being arranged to continue its movement when said needle is in said unsheathed position to expel said medicament from said

chambers through said needle. 9. An automatic injector according to claim 8, further including means for a drive pin being manually movable for advancing said lance which is elongated member from said first position to said second position to break said sealing structure, said elongated member being movable independently of said drive member of said releasable drive means

assembly. 10. An automatic injector according to claim 9, wherein said drive member of said releasable drive means assembly comprises a tubular collet engageable with said plunger, and said means drive pin for advancing said lance elongated member is comprises a drive pin

movable within said collet. 11. An automatic injector according to claim 1 3, wherein a first removable safety element prevents movement of said cutting or piercing means elongated member and a second removable safety element prevents release of

said drive means assembly. 12. An automatic injector according to claim 11, wherein an end cap is provided on said body, said end cap being movable relative to said body with said second safety element when said first safety element is removed to advance said cutting or piercing means elongated member and said end cap being subsequently movable relative to said body to effect release of said releasable drive means assembly and advance

said expulsion means member. 13. An automatic injector according to claim 12, wherein a tamper evident means member is provided for indicating removal of said first

removable safety element. 14. An automatic injector comprising:

a body incorporating at least two chambers, each containing different ingredients of a medicament, such chambers being adjacent to one another and separated by a thin impermeable membrane,

a sealing structure for maintaining said chambers in a normally sealed relation from one another, said sealing structure permitting said chambers to intercommunicate to allow the ingredients to mix within said body in response to a predetermined mixing procedure,

a needle normally held in a sheathed position within said body,

a releasable drive means assembly within said, body which, when released, drives said needle from said sheathed position into an unsheathed position projecting from said body, said releasable drive assembly including a spring-loaded drive member movable within said body and a latching portion for releasably latching said drive member,

a plunger within said body constituting expulsion means for discharging the medicament through said needle,

cutting or piercing means comprising a lance an elongated member arranged to extend through, and be slidable relative to, said plunger, said releasable drive means comprising a spring-loaded drive member being engageable with said plunger and capable of moving said plunger forwardly within said body upon release of said latching means portion associated with said releasable drive means assembly,

a spring heldmaintained in compression by within said body when said latching means portion is in a latched condition, said drive member being urged by said spring to advance said plunger when said latching means portion is released from said latched condition, and

means a manually engageable portion for advancing said lance which is elongated member, said elongated member being

movable independently of said drive member. 15. An automatic injector according to claim 14, wherein said drive member of said releasable drive means assembly comprises a tubular collet engageable with said plunger, and wherein said means for advancing said lance comprises a manually engageable portion is in the form of a drive pin which is movable within said collet. 16. An automatic injector comprising:

a body;

a tubular cartridge disposed within said body and incorporating at least two ingredient chambers including a forward ingredient chamber and a rearward ingredient chamber, each of said forward and rearward ingredient chambers containing different ingredients of a medicament;

a sealing structure constructed and arranged to maintain said forward and rearward ingredient chambers in normally sealed relation from one another, said sealing structure permitting said forward and rearward chambers to intercommunicate and the ingredients to mix in response to a predetermined manual mixing procedure;

a manually movable structure constructed and arranged to be manually engaged and manually moved during said predetermined manual mixing procedure from a first position to a second position so as to eliminate said sealed relation between said forward and rearward chambers and thereby permit said ingredients to mix within said body;

a needle normally contained within said forward ingredient chamber and being movable to an extended position projecting outwardly from said body;

a plunger disposed within said cartridge and being slidably movable within said cartridge for discharging the medicament through said needle; and

a releasable spring assembly being releasable to move said needle from said forward ingredient chamber to said extended position and to move said plunger within said body to discharge the medicament through the needle.17. An automatic injector according to claim 16, wherein said body has a rearward end and a forward end, said manually movable structure comprising an elongated member extending through said plunger and a manually engageable portion extending outwardly from said rearward end of said body, and an elongated member extending through said plunger, said manually engageable portion being manually engageable and movable to move said elongated member in sliding relation through said plunger so that said elongated member breaks said sealing structure to permit said ingredients to mix.