NEEDLELESS HYPODERMIC JET INJECTOR DEVICE

Abstract: A needleless, three-shot, variable dose jet injector (1) comprises a body portion (2) having a passageway (5) and a trigger (7), a cylinder portion (11) onto which a medicament vial (17) can be screwed in order to vary the dose to be applied and a piston head (16) movable within the cylinder portion (11) to move a plunger (15) into the vial (17). The vial (17) has a bore (20) containg the medicament which exits through an orifice (19) under pressure from a plug (21) moving under actuation from the plunger (15). The piston head (16) is caused to move by the release of gas from one (28) of three chambers in a gas capsule (27) through an exit port (43) into the passageway (5) due to the trigger (7) opening a valve (31). The passageway (5) is arranged so as to only align with the exit port and valve of one of the three chambers at a time, so that, by rotating the capsule (27), three shots of gas can be provided in a single capsule.

Description: N__ nτ_T_ -SS HΪPQDERMEC JET INJECTOR DEVICE Background of the Invention This invention relates to a needleless hypodermic jet injector device and, more particularly, to such a device which includes a disposable gas powered plunger and a disposable medicament vial. For many years it has been the practice to deposit medicaments into the hypoderma by the use of a device including a tubular needle connected to a reservoir of medicament incorporating a piston. The needle was inserted through the epidermis into the hypoderma and the medicament was discharged by moving the piston along the reservoir. Such devices have several problems. Firstly, the penetration of the needle is a possible cause for infection and there is patient resistance to the discomfort associated with the insertion of the needle. It has been known to provide disposable injector devices, which are used once and then thrown away. Such devices have use in administration of, for example, local anaesthetic, insulin and the like. In particular, the diabetes sufferer has to endure the pain and inconvenience of frequent hypodermic needle injections to administer the insulin used in the control of diabetes. In the case of the diabetes sufferer, it is desirable to have a presterilised, disposable device for single and multiple (insulin ) injection use, that has its own power source while being small and light enough for the user to carry during the day. The device should be such that the user can vary the selected dose conveniently and accurately and it should be conveniently and safely operated. The diabetes sufferer needs to inject on at least one and up to three occasions daily, insulin at a dosage varying from less than 0.1 illilitres up to a maximum of 0.3 millilitres. Gas and spring operated jet injection devices have been invented as alternatives to the needle devices. In the gas operated device, liquid medicament is discharged from a reservoir through a port as a spray by a piston moved along the reservoir by subjecting it to a force created by the sudden release of gas. These devices have the obvious advantages that there is no skin penetration hence no discomfort and no possibility of infection. In addition, they are more easily used by persons of limited skill. The common forms of gas device comprise a holder to which is coupled a container of medicament in a manner aligning it with the piston to be gas operated and which provides means to hold a gas filled capsule in the holder. By puncturing the capsule the gas is released into a cylinder and the piston therein is driven into the container to discharge the medicament through a port in the container. Such an arrangement has several disadvantages. For example, the holder, as provided, is a relatively large member and is complex having to provide securement means for the medicament container and the gas capsule. It has to provide a piston mounting arrangement and means to releasably hold the gas capsule in a gas tight manner and puncture the gas capsule. In short, the device is large and complex and correspondingly expensive. One existing needleless injection device is described in US Patent No. 4,680,027 to Parsons et al . It employs a disposable syringe that is filled by the user with a selected amount of medication. Then a separate power supply mechanism is attached to the instrument and triggered to drive a plunger against the medication. This produces a high pressure jet for injection purposes. Although effective in many respects, the separate power supply mechanism reduces the portability and convenience of the Parsons device. Consequently it is desirable to have a needleless injection system that overcomes this concern. US Patent No. 4,596,556 describes a hypodermic injection apparatus having a spring-loaded firing mechanism that operates to release carbon dioxide from a capsule. This propels the capsule and a plunger toward a discharge aperture to discharge medication through the aperture. However, in being self-cocking, reloadable, and reusable the device is somewhat complicated. US Patent No. 3,688,765 describes another device that is intended for portable use. However, it uses a syringe in the form of a prefilled, sealed, ampoule that precludes dosage selection at the time of use. In addition, the detachable syringe, disposable carbon dioxide unit and re-usable pressurising unit represent three separate components with which the user must contend. Summary of the Invention The present invention, therefore, seeks to provide a simple and easy to use disposable, needleless, syringe, which reduces at least some of the above disadvantages and which can be easily used to cater for the needs of the diabetes sufferer. Accordingly, in one aspect the invention provides a disposable, needleless hypodermic jet injector device for introducing a liquid into a patient, the liquid being contained in a vial which includes a hollow body having an orifice end through which the liquid exits from within the vial, and a vial plug movably mounted within the hollow body and operable to push the liquid out through said orifice end, said device comprising a body portion having a first end including means for adjustably receiving said vial and a second end including means for receiving a gas capsule, the gas capsule having a plurality of independent, pressurised gas-containing chambers, each chamber having an openable exit port in an end of the capsule receivable within the device, the body portion further comprising a first part, adjacent said first end, including a cylinder containing a piston movable within said cylinder, said piston being provided with a piston rod extending towards said first end for engaging with the vial plug to cause movement thereof when the piston is moved in the cylinder, and a second part, adjacent said second end, including a passage extending from the first part to a part of said second end, the remainder of the second end being closed, for cooperating with each of the openable exit ports, in turn, and trigger means arranged for opening the one of the openable exit ports which cooperates with the passage for causing gas to exit from the respective chamber, flow through the passage and cause the piston to move thereby causing the piston rod and vial plug to be moved. Preferably, the means for receiving the vial comprises a mounting means for receiving and mounting the vial in an adjustable fashion so that the dose delivered therefrom can be adjusted according to volume of liquid to be delivered. In a preferred embodiment, the mounting means comprises a threaded recess with which an external thread on the vial can cooperate so that the vial can be threaded longitudinally along the recess to adjust the volume of liquid providing the dose. Preferably, the mounting means includes one or more detent means for engaging the vial at one or more positions corresponding to particular predetermined doses. In one preferred embodiment, the means for receiving the gas capsule comprises a thread for cooperating with a matching thread on the gas capsule. Preferably, the passage is open at a restricted part of the second end for cooperating with only one of the openable exit ports of the capsule. In a preferred embodiment, the means for receiving the gas capsule allows the gas capsule and the passage opening at the second end to be relatively moved, for example rotated, so as to bring each of the openable exit ports, in turn, into cooperation with the passage opening. Preferably, the passage opening takes up a third of the area of the second end, the gas capsule having three gas chambers, each having an openable exit port in one respective third of the end of the capsule, the capsule being rotatable to bring each exit port into cooperation with the passage opening, in turn. Preferably, the means for receiving the gas capsule includes detent means at each of the positions at which an exit port is in cooperation with the passage opening. The trigger means preferably comprises a finger portion on the outside of the body portion, a longitudinal trigger portion within the passage and a connecting portion connecting the finger portion and the trigger portion and extending through a longitudinal aperture in the wall of the body portion. The trigger means is preferably longitudinally movable within the aperture such that the trigger portion moves within the passage, an end of trigger portion reaching the second end of the body portion so as to engage and open the openable exit port of the gas capsule when the trigger means has been moved towards the second end. A biasing means preferably biases the trigger means towards the first end of the device. In a second aspect of the present invention, there is provided a gas capsule having a plurality of independent, pressurised gas-containing chambers, each chamber having an openable exit port in an end of the capsule for cooperation, in turn, with an opening in an injector device. Preferably, the end of the capsule is circular and the exit ports are equally circumferentially spaced therein. Preferably, the chambers are longitudinally extending in the capsule. In one preferred embodiment, three chambers are provided; although any number could be used. The end of the capsule is preferably provided with a thread for cooperating with a matching thread on the injector device. The openable exit ports are preferably provided with valve means which can be opened by a trigger means on the injector device. It will be apparent, therefore, that the trigger means directly releases compressed gas, stored in the capsule, from each capsule chamber, one at a time. By rotating the capsule, each of the three gas charges can be released. The gas pressure acts upon the piston to drive the piston rod which in turn acts upon the plug in the vial to eject the selected dosage of medication through an orifice in the discharge end of the vial section. Brief Description Of The Drawings One embodiment of the invention will now be more fully described, by way of example, with reference to the drawings, of which: Figure 1 is a cross-sectional view of an injector device according to the invention with a vial and gas capsule attached thereto; Figure 2 is a cross-sectional view of a trigger used in the injector device along line A-A of Figure 1; Figure 3 is a cross-sectional view of the body portion of the device along line B-B of Figure 1; and Figure 4 is a cross-sectional view of the gas capsule along line C-C of Figure 1. Detailed Description of A Preferred Embodiment As illustrated in the drawings, the an injector device 1 according to one embodiment of the invention comprises a cylindrical body portion 2 having an external thread section 3 at one end, an internal thread section 4 at the other end, and a passage 5 extending longitudinally through the body portion 2 between the two ends. The passageway 5 at the other end is of substantially the same width as the internal diameter of the internal threaded section 4, but, at the first end, is of reduced cross-sectional area, as shown in Figure 3, so as to cover only a third sector of the internal diameter of the body portion 2. Body portion 4 is also provided with a slot 6 in which trigger 7 is assembled into and moves slidably within body portion 2. Trigger 7, as shown in Figure 2, includes finger portion 8 arranged outside body portion 4, trigger plunger 9 arranged within passageway 5 and trigger stem 10 connecting the finger portion 8 and the trigger plunger 9 through slot 6. The slot 6 is longitudinal so as to allow longitudinal movement of the finger portion 8 to cause longitudinal movement of the trigger plunger 9 within passageway 5. Threaded onto the internal thread section 4 of body portion 2 is cylinder portion 11 having a longitudinal bore 12 therein extending from passageway 5 to an internally threaded end section 13. A shoulder 14 is provided in the bore 12 adjacent the internally threaded end section 13. Cylinder portion 11 is attached to body portion 2 by screwing the cylinder portion into the body internal thread section 4 until a shoulder 25 on outside of cylinder portion 11 engages body end face 26. The shoulder 14 serves as a piston stop, as will be described later, and a guide for a plunger 15 having a piston head 16 sealingly slidably mounted in the cylinder bore 12. There is a gas exhaust port 46 in the wall of the cylinder portion 11 in communication with the bore 12. A liquid medicament vial 17 is provided as a fitment for the device. The vial 17 has a vial thread section 18 enabling it to be screwed into the cylinder thread section 13. The vial has an orifice 19 at its fore end and the orifice 19 is sealed by a seal that will yield when pressure is applied to liquid medicament housed in a bore 20 of vial 12. Pressure is applied to the medicament by a plug 21 slidably housed in the vial bore 20. The exterior of the vial 17 is marked in any suitable manner to indicate fractions of the capacity of the vial bore 20. For example there may be external markings on the vial to divide the bore length into five sections each of Y mis. By threading the vial 17 into the cylinder portion 11, the markings on the vial 17 will pass by a datum mark on the cylinder portion 11, for example an end face 22 of the cylinder portion 11 could be such a mark. Detent means is preferably provided whereby the detent is releasably engaged each time a graduation on the vial 17 is aligned with the datum mark. In this way the vial 17 can be releasably locked in a desired position. By axially moving the vial 17 (as a result of rotating it) the position of the vial 17 relative to the end 24 of the plunger 15 changes. When the vial 17 is fully "in" the maximum amount of the medicament will be ejected. By threading the vial 17 "out", the amount of medicament ejected will be reduced. • It will be noted that, as illustrated, the plunger 15 is in its zero position when aligned with the end face 22 of the cylinder portion 11. The stroke of the piston head 16 is limited to the distance "X" and therefore when the vial 17 is threaded fully into the cylinder portion 11 so that the end face 23 of vial 17 engages the end of the threaded section of the cylinder portion 11, the plug 21 will be adjacent the end 24 of the plunger 15. The maximum stroke of the plug 21 is slightly greater than "X". I follows that when the piston head 16 moves the distance "X", the plug 21 will move the same distance and substantially the whole of the medicamen in the vial 17 will be ejected. If the vial 17 is moved "out" of the cylinder portion 11, the plunger end 24 will be spaced from the plug 21 and although the plunger 15 will move "X", the plug 21 will move less than "X". A gas capsule 27 comprising three longitudinal chambers 28, 29, 30 and three valves 31, 32, 33 arranged at exit ports 43, 44, 45 of the respective longitudinal chambers 28, 29, 30, is attached to body portion 24 by screwing an internal thread section 34 onto the body external thread section 3 until an end face 35 of the capsule 27 approaches an en face 36 of the body external thread section 34 and capsule pins 37, 38, 39 provided on the capsule end face 35 engage detents 40, 41, 42 provided on the body end face 36. As shown in Figure 4, the three longitudinal chambers each take up a third sector of the capsule 27 and the detents are arranesd so that only one of the valves 31, 31, 33 is aligned with the end of the passageway 5 in body portion 2. As trigger 7 is moved slidably along slot 6 in body portion 2 towards capsule 27, the trigger plunger 9 moves through passageway 5 to operate on the one of the valves 31, 32, 33 which is aligned with the passageway 5 to release the gas pressure from the corresponding one of the chambers 28, 29, 30 and allow gas to travel through passageway 5 in body portion 2 and into cylinder portion 11, driving piston head 16 and plunger 15 into vial 17 and displacing plug 21 and the contents of vial 17 in the form of a high pressure jet through the orifice 19. The gas in the chambers 28, 29, 30 is released by the trigger plunger 9 entering through exit ports 43, 44, 45 and opening valves 31, 32, 33. The three detents 40, 41, 42 on body end face 36 and the three corresponding capsule pins 37, 38, 39 on capsule end face 35 ensure that alignment of trigg. plunger 9 and exit ports 43, 44, 45 is maintained in only three possible positions. It is presently intended that the device will be made substantially completely from thermosetting plastic materials, using the injection moulding process. Operational Sequence In an operational sequence, a vial 17 would be fitted to the device 1 and the amount of medicament to be ejected would be chosen by the degree to which the vial 17 is threaded into the cylinder portion 11. The device would be positioned with the orifice 19 over the part of the user where the "injection" is to take place. As the trigger 7 is slidably moved along the body portion 2, the trigger plunger 9 would enter one of the exit ports 43, 44, 45, opening the corresponding one of valves 31, 32, 33, and thereby releasing gas from the corresponding one of chambers 28, 29, 30. The gas travels through body portion 2, driving piston head 16 and plunger 15 the distance "X" until piston head 16 engages the cylinder shoulder 14. At this time the exhaust port 46 will be uncovered and the gas behind the piston head 16 escapes to atmosphere. Whilst the piston head 16 is advancing the plunger end face 24 would be driving the plug 21 along the vial bore 20 causing the medicament therein to eject through orifice 19. Depending on the amount the vial 17 is threaded into the cylinder portion 11, the plug 21 will move the distance "X" or a fraction of that distance and the amount of medicament ejected will vary accordingly. Whilst a presently preferred embodiment of the invention has been described hereinbefore it is to be understood that variations can be made to the specific embodiment described without departing from the inventive concept. By way of example only: The manner in which the piston 9 is regulated in its travel can be other than as disclosed. The manner in which the cartridge chamber valves are opened can be other than as described. The manner in which the gas under pressure in the cartridge chambers is sealed can be other than as described.

Claims: CLAIMS 1. A disposable, needleless hypodermic jet injector device for use with a gas capsule having a plurality of independent, pressurised gas-containing chambers, each chamber having an openable exit port in an end of the capsule receivable within the device, for introducing a liquid into a patient, the liquid being contained in a vial which includes a hollow body having an orifice end through which the liquid exits from within the vial, and a vial plug movably mounted within the hollow body and operable-to push the liquid out through said orifice end, said device comprising a body portion having a first end including means for receiving said vial and a second end including means for receiving the gas capsule, the body portion further comprising a first part, adjacent said first end, including a cylinder containing a piston movable within said cylinder, said piston being provided with a piston rod extending towards said first end for engaging with the vial plug to cause movement thereof when the piston is moved in the cylinder, and a second part, adjacent said second end, including a passage extending from the first part to a part of said second end, the remainder of the second end being closed, for cooperating with each of the openable exit ports, in turn, and trigger means arranged for opening the one of the openable exit ports which cooperates with the passage for causing gas to exit from the respective chamber, flow through the passage and cause the piston to move thereby causing the piston rod and vial plug to be moved. 2. A jet injector device according to claim 1, wherein the means for receiving the vial comprises a mounting means for receiving and mounting the vial in an adjustable fashion so that the dose delivered therefrom can be adjusted according to volume of liquid to be delivered. 3. A jet Injector device according to claim 2, wherein the mounting means comprises a threaded recess with which an external thread on the vial can cooperate so that the vial can be threaded longitudinally along the recess to adjust the volume of liquid providing the dose. 4. A jet injector device according to claim 3, wherein the mounting means Includes one or more detent meaαs for engaging the vial at one or more positions corresponding to particular predetermined doses. 5. A jet injector device according to any preceding claim, wherein the means for receiving the gas capsule comprises a thread for cooperating with a matching thread on the gas capsule. _ _ 6. A jet injector device according to any preceding claim, wherein the passage is open at a restricted part of the second end for cooperating with only one of the openable exit ports of the capsule. 7. A jet injector device according to claim 6, wherein the means for receiving the gas capsule allows the gas capsule and the passage opening at the second end to be relatively moved so as to bring each of the openable exit ports, in turn, into cooperation with the passage opening. 8. A jet injector device according to claim 6,.wherein the gas capsule and the passage opening at the second end can be relatively rotated so as to bring each of the openable exit ports, in turn, into cooperation with the passage opening. 9. A jet injector device according to any one of claims 6 to 8, wherein the passage opening takes up a third of the area of the second end, the gas capsule having three gas chambers, each having an openable exit port in one respective third of the end of the capsule, the capsule being rotatable to bring each exit port into cooperation with the passage opening, in turn. 10. A jet injector device according to any one of claims 6 to 9, wherein the means for receiving the gas capsule includes detent means at each of the positions at which an exit port is in cooperation with the passage opening. 11. A jet injector device according to any preceding claim, wherein the trigger means comprises a finger portion on the outside of the body portion, a longitudinal trigger portion within the passage and a connecting portion connecting the finger portion and the trigger portion and extending through a longitudinal aperture in the wall of the body portion. 12. A jet injector device according to claim 11, wherein the trigger means is longitudinally movable-within the aperture such that the trigger portion moves within the passage, an end of trigger portion reaching the second end of the body portion so as to engage and open the openable exit port of the gas capsule when the trigger means has been moved towards the second end. 13. A jet injector device according to claim 12, further comprising a biasing means for biasing the trigger means towards the first end of the device. 08508 _ „ _ PCI7AU91/00514 14. A gas capsule having a plurality of independent, pressurised gas-containing chambers, each chamber having an openable exit port in an end of the capsule for cooperation, in turn, with an opening in an injector device. 15. A gas capsule according to claim 14, wherein the end of the capsule is circular and the exit ports are equally circumferentially spaced therein. 16. A gas capsule according to either claim 14 or claim 15, wherein the chambers are longitudinally extending in the capsule. 17. A gas capsule according to any one of claims 14 to 16, wherein three chambers are provided. 18. A gas capsule according to any one of claims 14 to 17, wherein the end of the capsule is provided with a thread for cooperating with a matching thread on the injector device. 19. A gas capsule according to any one of claims 14 to 18, wherein the openable exit ports are provided with valve means which can be opened by a trigger means on the injector device.

Inventors: ROSENZWEIG PETER ELLIOTT, ROSENZWEIG, PETER, ELLIOTT
Applicants: SY QUEST INT LTD, SY-QUEST INTERNATIONAL LIMITED
Application year: 1991
Main classification: B65D1
IPC codes: A61M5