PLUNGER-DRIVEN AUTO-INJECTORS

• US 20140330216A1
• Filed: 04/22/2014
• Published: 11/06/2014
• Est. Priority Date: 05/01/2013
• Status: Active Grant

• Current Assignee: UNL Holdings, LLC
• Original Assignee: Unitract Syringe Pty Limited (Unilife Corp.)
• Inventors: Weaver, Philip A., Lumme, Katlin M.
• Granted Patent: US 9,750,885 B2
• Time in Patent Office: Days
• US Class Current: 604/198
• CPC Class Codes: A61M 2005/206 With automatic needle insertion
• CPC Class Codes: A61M 2005/2073 preventing premature release, e.g. by making use of a safety lock
• CPC Class Codes: A61M 2207/00 Methods of manufacture, assembly or production
• CPC Class Codes: A61M 5/2033 Spring-loaded one-shot injectors with or without automatic needle insertion multishot dosing syringes A61M5/31525, needle insertion only A61M5/3287
• CPC Class Codes: A61M 5/31513 Piston constructions to improve sealing or sliding
• CPC Class Codes: A61M 5/3157 Means providing feedback signals when administration is completed A61M5/20 takes precedence
• CPC Class Codes: A61M 5/3232 Semi-automatic needle retraction, i.e. in which triggering of the needle retraction requires a deliberate action by the user, e.g. manual release of spring-biased retraction means
• CPC Class Codes: A61M 5/3234 Fully automatic needle retraction, i.e. in which triggering of the needle does not require a deliberate action by the user
• CPC Class Codes: Y10T 29/49904 Assembling a subassembly, then assembling with a second subassembly

Abstract

Plunger sub-assemblies for automatic injectors include a plunger outer having one or more engagement prongs, a plunger inner having one or more engagement slots which correspond with the engagement prongs of the plunger outer, and a retraction biasing member. The retraction biasing member is retained in a first energized state between the plunger outer and plunger inner when the engagement prongs of the plunger outer are releasably engaged with the engagement slots of the plunger inner. The one or more engagement prongs are capable of flexing substantially radially to release from engagement with the engagement slots of the plunger inner to permit the retraction biasing member to expand from the first energized state to a second expanded state. An automatic injector having a plunger sub-assembly includes a housing, an activation mechanism, and a plunger sub-assembly at least partially mounted within a syringe cartridge having a needle assembly.

Claims

12. An automatic injector comprising a housing;

a syringe cartridge;

a needle assembly comprising a retractable needle;

a plunger sub-assembly comprising a plunger outer having one or more engagement prongs, a plunger inner having one or more engagement slots and a retraction biasing member, whereby the one or more engagement prongs and the one or more engagement slots are capable of releasable engagement to retain the retraction biasing member in an initially energized state between the plunger outer and the plunger inner, wherein the plunger sub-assembly is at least partially mounted within the syringe cartridge; and

an activation mechanism operable to facilitate sequential depression of the plunger sub-assembly to deliver one or more fluids from the syringe cartridge through the needle assembly and subsequent retraction of the plunger inner when the plunger inner is engaged with the retractable needle.

1. A plunger sub-assembly for an automatic injector, the plunger sub-assembly comprising a plunger outer having one or more engagement prongs, a plunger inner having one or more engagement slots and a retraction biasing member, whereby the one or more engagement prongs and the one or more engagement slots are capable of releasable engagement to retain the retraction biasing member in an initially energized state between the plunger outer and the plunger inner.

2. The plunger sub-assembly of claim 1, wherein the plunger outer has two engagement prongs for releasable engagement with respective engagement slots of the plunger inner.

3. The plunger sub-assembly of claim 1, wherein the refraction biasing member is retained in an initially energized state between a base of the plunger outer and a ledge of the plunger inner.

4. The plunger sub-assembly of claim 1, wherein release of engagement between the engagement prongs and engagement slots allows release of the retraction biasing member from an initially energized state to facilitate retraction of the plunger inner when the plunger inner is engaged with a retractable needle.

5. The plunger sub-assembly of claim 4, wherein the one or more engagement prongs are capable of flexing substantially radially to release from engagement with the engagement slots of the plunger inner.

6. The plunger sub-assembly of claim 1, wherein the refraction biasing member is a spring.

7. The plunger sub-assembly of claim 6, wherein the spring is retained in an initially compressed state between the plunger outer and the plunger inner.

8. The plunger sub-assembly of claim 7, wherein release of engagement between the engagement prongs and engagement slots allows release of the spring from the initially compressed state to an expanded state to facilitate retraction of the plunger inner when the plunger inner is engaged with a retractable needle.

9. The plunger sub-assembly of claim 1, wherein the plunger inner has a seal-engaging member.

10. The plunger sub-assembly of claim 9, wherein the seal-engaging member engages a complementary recess of a plunger seal.

11. The plunger sub-assembly of claim 10, wherein the seal-engaging member and the complementary recess of the plunger seal each have complementary screw threads.

13. The automatic injector of claim 12, further comprising an injection biasing member residing in an initial energized state substantially within the plunger inner.

14. The automatic injector of claim 13, the injection biasing member held in an initially energized state between the housing and the plunger inner.

15. The automatic injector of claim 14, wherein the plunger inner comprises one or more locking hooks which initially directly engage a locking plateau of the housing.

16. The automatic injector of claim 15, wherein the activation mechanism is operable to directly trigger disengagement of the locking hooks from the locking plateau of the housing.

17. The automatic injector of claim 16, wherein the activation mechanism comprises a button which is operable to directly trigger disengagement of the locking hooks from the locking plateau of the housing.

18. The automatic injector of claim 17, wherein the button is rotatable and depressible to thereby directly trigger disengagement of the locking hooks from the locking plateau of the housing.

19. The automatic injector of claim 13, wherein the housing further comprises one or more recesses whereby substantially radial flexion of the engagement prongs into the recesses permits the engagement prongs to disengage from the engagement slots of the plunger inner to permit release of the refraction biasing member for retraction of the retractable needle.

20. The automatic injector of claim 19, arranged so that substantially no additional force is needed to disengage the plunger outer from the plunger inner beyond the force utilized to axially translate the plunger sub-assembly to a portion of the housing where the engagement prongs may radially flex into the recesses.

21. A method of assembly of an automatic actuator including the steps of:

(i) inserting an injection biasing member into a housing and compressing the injection biasing member between the housing and the plunger inner, substantially or at least partially within a chamber of the plunger inner, by releasably engaging the plunger inner with the housing;

(ii) assembling a plunger sub-assembly by engaging one or more engagement prongs of a plunger outer with one or more engagement slots of a plunger inner so that a retraction biasing member is retained in an initially energized state between said plunger outer and plunger inner; and

(iii) inserting the plunger sub-assembly into the housing such that at least a portion of the plunger inner resides within a barrel of a syringe cartridge is permitted to axially translate therein.

22. The method of claim 20, wherein the injection biasing member is initially maintained in an energized state substantially within an upper portion of the plunger inner.

23. The method of claim 20 which further includes the step of:

attaching an activation mechanism to the housing wherein the activation mechanism is configured to directly contact the one or more locking hooks of the plunger inner upon activation.

24. The method of claim 20, wherein the engagement prongs of the plunger outer are maintained in a releasably engaged configuration with the engagement slots of the plunger inner by a first inner diameter of the housing.

25. The method of claim 20 which further includes one or more steps including:

(iv) filling a drug chamber of a syringe cartridge with a drug fluid; and

(v) inserting the distal end of the plunger sub-assembly into the proximal end of the syringe cartridge.

26. The method of claim 25, wherein steps (iv) and (v) may occur before or after step (iii).

21-1. The method of claim 20, wherein at step (i) one or more locking hooks of the plunger inner directly engage with a locking plateau of the housing.