AU660472B2 - A syringe - Google Patents

Description

OPI DATE 17/11/92 APPLN. ID 19839/92 llll ll 1lilllll AOJP DATE 1J/11/92 PCT NUMBER PCT/AU92/00178 111 111111 11 AU9219839 IN I KNAI IUNAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 5 International Publication Number: WO 92/18186 A61M 5/50, 5/315 Al (43) International Publication Date: 29 October 1992 (29.10.92) (21) International Application Number: PCT/AU9z/00178 Published With international search report.

(22) International Filing Date: 21 April 1992 (21.04.92) Priority data- PK 5665 17 April 1991 (17,04.91) AU 6 6 4 7 2 (71)(72) Applicant and Inventor: RYLES, Louis [AU/AU]; 8 Annoula Avenue, Biggera Waters, QLD 4216 (AU).

(74) Agent: MAXWELL, Peter, Francis; Peter Maxwell Associates, 255 Adelaide Street, Brisbane, QLD 4000 (AU).

(81) Designated States: AT, AT (European patent), AU, BB, BE (European patent), BF (OAPI patent), BG, BJ (OAPI patent), BR, CA, CF (OAPI patent), CG (OAPI patent), CH, CH (European patent), CI (OAPI patent), CM (OA- PI patent), CS, DE, DE (European patent), DK, DK (European patent), ES, ES (European patent), F r FR (European patent), GA (OAPI patent), GB, GB (European patent), GN (OAPI patent), GR (European patent), HU, IT (European patent), JP, KP, KR, LK, LU, LU (European patent), MC (European patent), MG, ML (OAPI patent), MN, MR (OAPI patent), MW, NL, NL (European patent), NO, PL, RO, RU, SD, SE, SE (European patent), SN (OAPI patent), TD (OAPI patent), TG (OAPI patent), US.

(54) Title: A SYRINGE (57) Abstract A single use syringe (10) for administering medicament which includes a needle attachment member gripping means constituting a closure of the distal end of the plunger (I1) of the syringe (10) and being adapted to engage a needle attachment member (26) so that the needle attachment member (26) can be retracted into the interior of the plunger (11) by vacuum within the plunger The syringe is intended to minimise the possibility of injury following use of the syringe, WO 92/18186 PCIT/AU9)2/001 78 -1- A SYRINGE FIELD OF THE INVENTION This invention relates to a safety syringe and in particular to a single use syringe having provision for retraction of a hypodermic needle into the body of the syringe.

BACKGROUND ART With the advent of contagious diseases such as AIDS and Hepatitis B, the possibility of so called "needle stick" injuries In the medical environment has proliferated along with many and varied arrangements for preventing accidental infection of medical workers as a result of this type of Injury. In addition, the proliferation of intravenous drug use has resulted In discarded syringes and needles on beaches and other areas where a passer-by can Inadvertently step on a needle and also be infected.

As a result of this, there has been a proliferation of proposals for single use disposable syringes whereby a needle is retrac'ted into the body of the syringe after a single use.

However, most of these arrangements involve complete reworking of the conventional disposable syringe construction in such a way that the conventional luer lock disposable needle fitments are done away with such that the arrangements proposed are too complex and too expensive. Many also require additional manual steps to retract the needle.

A typical example of the prior art is United States Patent No. 4,995,870 which describes a safety syringe where WO 92/18186 PC/AU92/00178 -2the needle has a barb on the end inside the syringe for.

engaging the syringe plunger when the plunger is depressed to inject its contents into a patient. Once the barb engages the plunger the operator unlocks the needle and then withdraws the plunger to retract the needle into the syringe.

The needle used is not a conventional luer lock fitment as it must have a barb on the end and the retraction,process requires two manual steps which erpose the operator of the syringe to the risk of "needle stick" injuries and are timeconsuming and inconvenient.

A number of automatically retracting syringes have therefore been proposed. These include spring-loaded devices such as that described in United States Patent No. 4,929,237 where a pushing force applied to the proximal end of the syringe moves the syringe within a housing against a spring to an operative position and releasing the pushing force allows the syringe to retract proximally drawing the needle back into the housing. The syringe is complex and likely to be expensive.

Australian Application No. 66,363/90 discloses a syringe where the plunger captures the needle and the plunger is withdrawn by a return spring when the downward pressure on it is released, thereby retracting the ne i..J The specification at iage 6, line 22 refers to withdrawing the entire plunger and the attached needle back into the barrel of the syringe using a vacuum, but proposes no f-ssible way to do this. The only embodiments described use a return WO 92/18186 PCr/U92/00178 -3spring and the snap lock engagement means used to secure the needle to the plunger leaves a very large space (best seen in Fig 3) in which medicament will remain when the plunger is withdrawn. The medicament is then likely to leak, creating a contamination hazard.

A vacuum-retractable syringe is proposed in Australian Application No. 70,672/91 where the needle id withdrawn into the interior of a hollow plunger under force of a vacuum within the plunger, however, in that invention the thrust exerted by the operator of the syringe must be sufficient to cause a washer at the end of travel of the plunger to rupture and to push a plug down through the washer to engage the needle. The needle mount (which is not a conventional luer lock) must also rupture so that the plug can withdraw the needle under vacuum into the plunger, where it is held in place by magnets. The syringe is complicated and unlikely to be feasible due to its complex operation.

These proposals have not found ready acceptance in the medical profession because of cost and inconvenience.

DISCLOSURE OF THE INVENTION According to the present invention there is provided a syringe for administering medicaments comprising:an elongate barrel for holding the medicament having a proximal and distal end; a hollow plunger having a closed proximal end protruding from the proximal end of the barrel and a distal end located within the barrel, said plunger being slidably mounted in said barrel and having vacuum means in its interior; a retractable needle attachment member for supporting a luer lock hypodermic needle, said needle attachment member being releasably retained at said distal end of said barrel; and gripping means for gripping and withdrawing said needle attachment member into said plunger, said gripping means constituting a releasable closure of said distal end of said plunger; and wherein a predetermined movement of said plunger into said barrel towards said needle attachment member causes said gripping means to engage portion of said barrel and thereby be released from said distal end of said plunger, engagement of said gripping means with said portion of said barrel further causing said gripping means to engage -aid needle attachment member to effect release of said needle attachment member from said distal end of said plunger and permit said gripping means to withdraw said needle attachment member into said interior of said plunger under the influence of said vacuum means therein.

The needle attachment member may be releasably retained by releasable catch means, the releasable catch means being adapted to be released by the gripping means.

The gripping means may include gripping members for engaging portion of the releasable catch means for releasing of same.

The needle attachment member includes a portion adapted for releasable attachment of a luer lock hypodermic needle and medicament can be expelled through the retractable needle attachment member and through the needle as the plunger is forced towards the distal end of the barrel.

oo e,i The plunger suitably includes a distal end face and portions of the gripping members may be co-operable o -C 14; with the end face to releasably retain the gripping means at the distal end of the plunger.

The gripping members are adapted to engage the portion of the barrel upon the predetermined movement of the plunger to release the cooperable portions of the gripping means from the distal end face of the plunger.

The portion of the barrel may comprise an abutment defining a camming surf;ce for contact by the gripping mcembers. The gripping members may include a leading camming surface and a trailing shoulder, the trailing shoulder comprising the portion of the gripping members co-operable with the distal end face of the plunger. The gripping members may comprise a plurality of circumferentially spaced claw members and the abutment of the barrel may comprise an annular abutment.

The catch means may include an annular shoulder or recess on or in an internal wall of the barrel and the needle attachment member may include at least one outwardly biased finger adapted to co-operate with the shoulder or recess. The at least one finger may be adapted to be engaged by the gripping means to release the catch means and also be gripped by the gripping means to withdraw the needle attachment member. The at least one finger may include a protrusion adapted to engage the annular shoulder or recess. The at least one finger may include a portion distally adjacent the protrusion constituting a pivot point for the biased finger such that :the biased finger bends outwardly maintaining the ,0o. engagement of the protrusion with the annular shoulder or S 30 recess when the needle attachment means is subject to force in the proximal direction. The needle attachment member may include a plurality of circumferentially spaced fingers.

The distal end of the barrel may include a reduced diameter portion, the needle attachment members being normally retained within the reduced diameter portion. A shoulder may be formed between the reduced 1T fr;t- !CJ/ diameter portion and remainder of the barrel, the shoulder comprising the portion of the plunger engaged by the gripping means.

The gripping means may include a first annular beading adjacent its proximal end and the plunger may include a second annular beading on its inside surface adjacent -he distal end of the plunger, wherein on manual withdrawal of the plunger in the proximal direction, the second annular beading on the plunger engages the first annular beading on the gripping means allowing the gripping means and operatively engaged needle attachment means to be ",3 WO 92/18186 P~/AtJ92/00178 -7withdrawn into the barrel in the event that the vacuum retraction fails.

A further safety feature of thi 'sent invention is that the syringe cover may be adapted to close the opening left by retraction of the needle attachment member.

BRIEF DESCRIPTION OF THE DRAWINGS In order that t&,e present invention can be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings and wherein: Fig. 1 is a perspective view of a syringe in accordance with one embodiment of the invention, Pig. 2 a view similar to Fig. 1 showing the needle in the retracted position after use, Fig. 3 to 8 are partial longitudinal cross-sectional views through the distal end of the barrel of the syringe shown in Figs. 1 and 2 (without a needle) illustrating the steps in the retraction process, Fig. 9 is a longitudinal cross-sectional view of the syringe shown in Figs. 1 and 2 illustrating the use of the protective cap to close the opening in a used syringe, and, Fig. 10 is a view similar to Fig. 3 showing the action of the locking projections in WO 92/18186 PC/AU92/00178 -8response to a resistive force of the skin of the user at the start of the injection process.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in Fig. 1, the syringe 10 comprises a hollow evacuated plunger 11 slidably mounted within an elongated barrel 12 which as a proximal end 13 and a distal end 14.

The hollow plunger 11 has a proximal end 15 protruding from the proxi-ml and 13 of the barrel 12 and a distal end 16 axially slidable within the barrel 12. The plunger 11 (or at least at a portion of It towards its distal end) is hollow and a chamber 23 inside plunger 11 is evacuated so that there is a vacuum inside the plunger. The barrel 12 has a flange 17 at its proxim3L end 13 that is gripped by the operator when using the syringe 10. At its distal end 14, the barrel 12 has a retaining shoulder 18 which retains the needle attachment member 26. The hypodermic needle 20 has a lock 19 by means of which the needle is attached to the member 26 and the arrangement is preferably a conventional luer lock hypodermic needle. The needle 20 is covered by protective cover 21 until just prior to use so that accidental puncture injuries cannot occur.

The syringe 10 in Fig. 1 is shown with cover 21 partially removed. When the cover 21 is removed, plunger 11 is pulled back in the direction of arrow A to draw a medicament (not shown) through needle 20 into the space 24 in the barrel 12. The barrel 12 (which may have a graduated WO 92/18186 WO 9218186PCT'/AU92/OO1 78 -9volume scale marked thereon) Is about half full In Fig. 1.

Further movement of the plunger 11 In the direction of arrow A will continue the filling of the t~rrel 12 and, once the desired vrolume of medicament has beeni drawn into the barrel 12 and needle 20 has been inserted Into a patient, the medicament can be expelled by depressing the plunger in the direction opposite to arrow A.

Fig. 2 shows syringe 10 after the medicament has been Injected into a patient. The needle 20 and locking element 19 are withdrawn Into evacuated chamber 23 in the p~lnger 11 by the action of the vacuum within the plunger (the process by which this occurs will be described below in relation to Figs. 3 to Protective cover 21 Is then Inserted into the opening 22 through which locking element 19 previously protruded to close of f the opening. This extra security feature is better illustrated in Fig. 9. The protective cover 21 is shaped and proportioned so that It will sit tightly ever locking element 19 and remrAin in place over the needle 20 prior to use but will also fit tightly Into opening 22 when that is creat~ed after use of the syringe to seal that opening.

Fig. 3 shows the final stage of the Injection process where the distal end 16 of the plunger 11 approaches the distal end 14 of the barrel 12. The space 24 (containing the medicament) within the barrel 12 is very small as most of the medicament 1.as been Injected Into the patient through the needle 20. Retratctable needle attachment member 26 has a coupling potlob 2%1- to which the locking element 19 (here a WO 92/18186 PCT/AU92/00178 conventional luer lock) is attached in the conventional manner is also shown. Gripping means 25 which are adapted to engage needle attachment member 26 are located at the distal end 16 of the plunger 11 and constitute the closure of evacuated chamber 23 therein. rings 39 are fitted around the distal end 16 of the plunger 11.

As shown in Fig. 4, as gripping means 25 approaches needle attachment member 26, claw member 27 (which is one of a plurality of circumferentially spaced claw members on gripping means 25) abuts finger 28 (which is one of a plurality of c'rcumferentially spaced fingers on needle attachment member 26). Each claw member 27 has a leading camming surface 32 and a trailing shoulder 33. The trailing shoulder 33 engages the distal face 35 of the plunger 11 so that as the plunger is pushed in the distal direction to expel the medicament, the gripping means 25 travels with it in the distal direction until the camming surface 32 abuts the surface 34 on the inside of the retaining shoulder 18.

The action of claw member 27 on finger 28 pushes it inwardly against the main portion of needle attachment member 26. As force in the distal direction is maintained on the plunger 11, claw member 27 starts to move past finger 28.

This is best seen in Fig. Each of the circumferential fingers 28 is outwardly biased and has a locking projection 29 thereon which engages with an annular shoulder 30 on retaining shoulder 18.

Retaining shoulder 18 is simply a moulded extension of barrel 12 therefore this effectively holds the needle attachment WO 92/18186 PCT/AU92/00178 -11member 26 at the distal end 14 of barrel 12 so that medicament may be delivered from the space 24 in the barrel 12 through a bore in needle attachment member 20 into the needle 20 and thence Anto the patient. An 0-ring 31 provides a seal around the needle attachment member 26 to prevent leakage of the medicament from the barrel 12.

Referring to Figs. S nd 6, it can be seen that with further movement of the plunger 11 in the distal direction (to fully discharge the contents of the syringe) the camming surface 32 of claw member 27 abuts surface 34 which causes the claw member 27 to bend inwardly. This results in the end of the claw member 27 engaging finger 28 on the needle attachment member 26 and in projection 29 fully disengaging shoulder 30 on the retaining shoulder 18. The needle attachment As, therefore, no longer anchored to the barrel 12 but is attached to the gripping mans 26 which form the distal closure of evacuated chamber 23. Since the inward bending of claw member 27 also disengages trailing shoulder 33 from the distal face 35 of the plunger 11, the gripping means 25 is drawn by the vacuum in the direction of arrow B into the evacuated chamber 23 in the plunger 11. As the needle attachment means 26 now engages the gripping means it and the needle 20 attached thereto by locking element 19 are also drawn into the evacuated chamber 23 ii, the plunger 11. Fig. 8 illustrates the needle 20 as it is retracting and reference once again to Fig. 2 shows the final position of the needle WO 92/18186 PTA9/07 PCT/AU92/00178 -12- In order to maintain a suitable vacuum In the chamber 23, it is preferred that the plunger 11 be made of a polymeric material capable of holding a vacuum fow a long period, such as polyethylene terephthalate (PET).

Alternatively, the plang~ar may be made of a material such as polypropylene or other conventional ma' rials which will hold a vacuum for 3 to 5 days. If the latter materials are used it is preferred to patk '-he syringe in a barrier bag whic)' will maintain a vacuim for a long period In and around the syringe. Suitable bags ar* well known to those skilled in the art.

The walls of chamber 23 (the interior walls of plunger 11) may be equipped with annular beading (not shown) to engage the annular beading 36 on the gripping means 25 to hold the retracted gripping means and the needle attached thereto in position within the plunger 11. Alternatively, the arrangement illustrated in iVig. 9 where the protective cap 21 is jammed into opening 22 covering the needle within the chamber Z3 and preventing it from moving in such a way thhz It could protrude from the openin~g 22 may be used.

The mechanism illustrated in Figs. 3 to 8 may also be uised In larger or smaller syringes than the syringe Illustrated atd in syringes where the retaining shoulder is off centre using the a&ame sizes, needle attachment means (but varying the size and/or shape of the gripping means) so that a standard needle can always be used.

The plunger 11 may optionally be equipped with annular beading 37 so that should the vacu=~ fail the beading 37 and WO 92/18186 PCT/AU92/00178 -13the beading 36 on the gripping means 2& will engage on manual retraction of the plunger so that the needle 20 can be retracted manually into the barrel 12. This is a useful back-up system and provides an additional security feature.

Fig. 10 shows the action of the locking projections 29 in response to the resistive force of the skin in the direction of arrow C. The pivot point 42 is close to the locking projections 29 so that the longitudinal load in the direction of arrow C forces the locking projections 29 outwards rather than inwards. The needle 20 has been omitted for the sake of clarity.

It will be appreciated from the foregoing that the present invention provides a safety syringe which is simple and cheap to manufacture and which can be equipped with a needle attachment member having the normal luer lock fitment and hence, can be used in place of a conventional hypodermic syringe. There are no manual steps necessary to retract the needle so operation of the syringe is no more difficult or time-consuming than a conventional syringe. Furthermore, sAnce retraction of the needle is automatic once the contents of the syringe have been expelled the operator is not exposed to the risk of puncture injuries by the used needle and the needle cannot be used again. This greatly reduces the risk of accidentally contracting diseases from the infected blood of a patient.

It will also be appreciated that while a specific form of the invention has been discussed above by way of WO 92/18186 PCT/AU92/00178 -14illustrative example of the present invention, many other variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as defined in the appended claims.

Claims (17)

1. A syringe for administering medicaments comprising:- an elongated barrel for holding a said medicament, said barrel having a proximal end and distal end; a hollow plunger having a closed proximal end protruding from the proximal end of said barrel and a distal end located within said barrel, said plunger being slidably mounted in said barrel and having vacuum means in its interior; a retractable needle attachment member for supporting a luer lock hypodermic needle, said needle attachment member being releasably retained at said distal end of said barrel; and gripping means for gripping and withdrawing said needle attachment member into said plunger, said gripping means constituting a releasable closure of said distal end of said plunger; and wherein a predetermined movement of said plunger into said barrel towards said needle attachment member causes said gripping means to engage portion of said barrel and thereby be released from said distal end of said plunger, engagement of said gripping means with said portion of said barrel further causing said gripping means to engage said needle attachment member to effect release of said needle attachment member from said distal end of said plunger and permit said gripping means to withdraw said needl> attachment member into said interior of said plunger under the influence of said vacuum means therein.

2. A syringe according to Claim 1 wherein said needle attachment member is releasably retained by releasable catch means, said releasable catch means being adapted to be released by said gripping means.

3. A syringe according to Claim 2 wherein said gripping means includes gripping members for engaging and releasing portion of said releasable catch means.

4. A syringe according to Claim 3 wherein said plunger includes a distal end face and wherein said portions of said gripping members are co-operable with said end face to releasably retain said gripping means at said distal end of said plunger. A syringe according to Claim 4 wherein said gripping members are adapted to engage said portion of said barrel upon said predetermined movement of said plunger to release said cooperable portions of said gripping means from said distal end face of said plunger.

6. A syriage according to Claim 5 wherein said portion of said barrel comprises an abutment defining a camming surface for contact by said gripping members.

7. A syringe according to Claim 6 wherein said gripping members include a leading camming surface and a trailing shoulder, said trailing shoulder comprising said portion of said gripping members co-operable with said distal end face of said plunger.

8. A syringe according to Claim 7 wherein said gripping members comprises a plurality of circumferentially spaced claw members and wherein said 30 abutment of said barrel comprises an annular abutment.

9. A syringe according to any one of Claims 2 to 8 wherein said catch means comprises an annular shoulder or recess on or in an internal wall of said barrel and wherein said needle attachment member includes at least one outwardly biased finger adapted to co-operate with said shoulder or recess. l r I. A syringe according to Claim 9 wherein said at least one finger is adapted to be engaged by said gripping means to release said catch means and gripped by said gripping means for withdrawing said needle attachment member.

11. A syringe according to Claim 9 or Claim wherein said at least one finger includes a protrusion adapted to engage said annular shoulder or recess.

12. A syringe according to Claim 11 wherein said at least one finger includes a portion distally adjacent said protrusion constituting a pivot point for said biased finger such that said biased finger bends outwardly maintaining the engagement of said protrusion with said annular shoulder or recess when the needle attachment means is subject to force in the proximal direction.

13. A syringe according to any one of Claims 9 to 12 wherein said needle attachment member includes a plurality of circumferentially spaced said fingers.

14. A syringe according to any one of the preceding claims wherein said gripping means includes a first annular beading adjacent its proximal end and wherein said plunger includes a second annular beading on its inside surface adjacent said distal end of said plunger, wherein ,on manual withdrawal of said plunger in the proximal direction, said second annular beading on said plunger S 30 engages said first annular beading on said gripping means allowing said gripping means and operatively engaged needle attachment means to be withdrawn into said barrel in the event that retraction by said vacuum means fails.

15. A syringe according to any one of the previous claims further including a syringe cover adapted to close the opening at said distal end of said barrel left by 4' retraction of said needle attachment member.

16. A syringe according to any one of the preceding claims wherein said needle attachment member includes a portion adapted for releasable attachment of said luer lock hypodermic needle.

17. A syringe according to any one of the preceding claims wherein said distal end of said barrel includes a reduced diameter portion, said needle attachment members being normally retained within said reduced diaieter portion.

18. A syringe according to claim 17 wherein a shoulder is formed between said reduced diameter portion and remainder of said barrel, said shoulder comprising said portion of said plunger engaged by said gripping means.

19. A syringe substantially as hereinbefore described with reference to the accompanying drawings. Dated this twentieth day of April 1995 LOUIS RYLES By My Patent Attorney JOHN Rj G. GARDNER t