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Last Updated: April 24, 2024

Claims for Patent: 5,891,086

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Summary for Patent: 5,891,086

Title:	Needle-less injector
Abstract:	In a needle-less injector combining an actuator and a medicament cartridge, the actuator includes a housing with a forward portion to which the cartridge is connected. An impact member is mounted within the housing inward of the forward portion so as to be movable toward the forward portion, where it may strike components of the cartridge to effect expulsion of a dose of medicament. A chamber is provided within the housing and is pre-filled with a pressurized gas which is in communication with and exerts a constant force on the impact member, tending to urge it towards the forward portion. Movement of the impact member is prevented by a latch which normally engages the impact member and prevents its forward movement, but is actuable to be moved out of such engagement, permitting movement of the impact member, the cartridge includes a piston which is mounted in the body of the cartridge with an interference fit and is made of a material which is substantially non-resilient when subjected to a slowly applied force, but is highly resilient when subjected to a rapidly applied force.
Inventor(s):	Weston; Terence Edward (Suffolk, GB)
Assignee:	Weston Medical Limited (Suffolk, GB)
Application Number:	08/591,585
Patent Claims:	1. An actuator for use in conjunction with a cartridge to form a needle-less injector, the cartridge being prefilled with a liquid to be injected in a subject, the cartridge having a liquid outlet and a free piston inward of the liquid outlet in contact with the liquid, said actuator comprising: (a) a housing having a forward portion adapted to be connected with the cartridge; (b) impact member mounted within said housing inward of the forward portion so as to be movable from a first position toward the forward portion to strike the free piston when a cartridge is connected and to continue to move the free piston toward the liquid outlet whereby a dose of the liquid is expelled through the liquid outlet in the cartridge; (c) a chamber within said housing prefilled with pressurized gas and connected with said impact member such that said pressurized gas is constantly in communication with and constantly exerts a force on said impact member to normally urge said impact member toward the liquid outlet; and (d) a latch within said housing which engages said impact member to prevent movement of the impact member toward the forward portion in response to said force exerted by said pressurized gas, and being mounted to be movable out of engagement with said impact member to a firing position, in which said latch permits such movement. 2. The actuator as claimed in claim 1, further comprising a gas outlet defined in said chamber for allowing residual gas to escape from said chamber after said dose of liquid has been expelled. 3. The actuator as claimed in claim 2, further comprising a cam engageable with said camming surface to move said latch to said firing position. 4. An actuator as claimed in claim 1, wherein said pressurized gas is air. 5. An actuator as claimed in claim 1, further comprising trigger means for operating said latch to thus initiate the injection in response to a predetermined contact force between the liquid outlet of the cartridge and the subject. 6. An actuator as claimed in claim 5, wherein said actuator has a user-holdable portion and means for mounting the cartridge so that the user-holdable portion is movable relative to the cartridge by the liquid outlet of the cartridge being urged into contact with the subject, and said latch comprises a latch member which is movable to said firing position by the relative movement between the user-holdable portion and the cartridge. 7. An actuator as claimed in claim 6, wherein said latch member is resilient. 8. An actuator as claimed in claim 1, wherein the energy stored by said pressurized gas is sufficient to expel a single dose of the liquid. 9. An actuator as claimed in claim 1, wherein the energy stored by said pressurized gas is sufficient to expel a plurality of successive doses of the liquid. 10. An actuator as claimed in claim 1, in combination with a connected cartridge that includes a separately held plurality of components which are to be mixed with one another prior to injection and a mixing member for mixing the plurality of components with one another, said impact member further comprising a mixing means being movable toward the liquid outlet for striking the mixing member, whereby the plurality of components are mixed with one another. 11. The actuator as claimed in claim 2, wherein said chamber is sealed. 12. An actuator as claimed in claim 1, wherein the movement of said impact member expels a fixed dose. 13. An actuator as claimed in claim 1, wherein the distance of travel of said impact member after striking the free piston determines the dose of the liquid expelled through the liquid outlet in the cartridge. 14. An actuator as claimed in claim 1 in combination with a cartridge, comprising means for retaining said cartridge for engagement with said actuator, said retaining means being constructed to permit the fixed mounting of said cartridge. 15. An actuator as claimed in claim 1, having means for removably receiving the said cartridge. 16. An actuator as claimed in claim 15 in combination with a cartridge, comprising means for retaining said cartridge for engagement with said actuator, said retaining means being constructed to permit removal of said cartridge. 17. The combination as claimed in claim 16, wherein said cartridge has a body comprising glass. 18. The combination as claimed in claim 17, wherein said glass is transparent. 19. The combination as claimed in claim 16, wherein said free piston of said cartridge comprises a plastics material. 20. The combination as claimed in claim 19, wherein said plastic material is a polymer or copolymer comprising a fluorinated hydrocarbon. 21. The combination as claimed in claim 19, wherein said plastic material is a polytetrafluoroethylene. 22. The combination as claimed in claim 19, wherein said plastic material is selected from the group consisting of tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, polychlorotrifluoroethylene, poly (vinylidene fluoride), tetrafluoroethylene-perfluoro(propyl vinyl ether) copolymer, and hexafluoroisobutylene-vinylidene fluoride copolymer. 23. An actuator in combination with a cartridge to form a needle-less injector, comprising: (a) said cartridge being prefilled with a liquid to be injected in a subject, said cartridge comprising, (i) a liquid outlet and a free piston inward of the liquid outlet in contact with the liquid; (ii) a separately held plurality of components which are to be mixed with one another prior to injection; and (iii) a mixing member for mixing the plurality of components with one another, wherein the plurality of compartments are separated by at least one partition and said cartridge further has a penetrating member so mounted therein as to be movable to a mixing position in which it penetrates the partition; and (b) said actuator comprising: (i) a housing adapted to be connected with the cartridge; (ii) impact member mounted within said housing inward of the free piston so as to be movable from a first position toward the liquid outlet to strike the free piston and to continue to move the free piston toward the liquid outlet whereby a dose of the liquid is expelled through the liquid outlet in the cartridge, said impact member further comprising a mixing means being movable toward the liquid outlet for striking the mixing member, said mixing means in striking said mixing member being further operable to move the penetrating member to the mixing position whereby the plurality of components are mixed with one another; (iii) a sealed chamber within said housing prefilled with pressurized gas and connected with said impact member such that said pressurized gas constantly exerts a force on said impact member when said impact member is in said first position to normally urge said impact member toward the liquid outlet; and (iv) a latch within said housing for engaging said impact member to prevent movement of the impact member toward the liquid outlet in response to said force exerted by said pressurized gas, and being movable to a firing position for permitting such movement. 24. A method of injecting a dose of liquid in a subject using an injector including a cartridge prefilled with the liquid and having a liquid outlet and a free piston in contact with the liquid, an impact member movable from a first position behind the free piston to first strike said free piston and then to continue to move the piston toward said liquid outlet to expel a dose of liquid through said liquid outlet; a chamber prefilled with pressurized gas which constantly contacts and exerts a force on said impact member in said first position to urge said impact member towards said piston a latch movable from a restraining position, in which said latch engages and prevents movement of the said impact member in response to the force exerted by the gas, to a firing position, in which said latch does not engage said impact member and permits such movement; (ii) causing said latch to move from said restraining position said method comprising the steps of to said firing position, whereby said impact member moves toward the liquid outlet, strikes said free piston, and continues to move said piston toward the liquid outlet to expel a single dose of said liquid. 25. The method of injecting a dose of liquid in a subject as claimed in claim 24, further comprising the step of disposing of said injector after the single dose has been expelled.

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