HK1143770B - Prefilled retractable syringe, plunger and needle assembly therefor - Google Patents

Abstract

A retractable syringe, plunger and releasable needle retaining assembly are provided. The retractable syringe typically has a glass barrel and is prefilled with fluid contents before use. The releasable needle retaining system comprises a retractable needle, a needle seal, a retaining member and an ejector member that is operable to release the retractable needle from the retaining member. The retaining member has a mating surface for mounting to a complementary mating surface of an interior wall of a syringe barrel. The plunger comprises a plunger outer, a plunger rod frangibly connected to a controlling member, a spring and a unitary plunger seal capable of engaging the retractable needle, wherein the plunger rod, plunger outer and the controlling member co-operate to releasably maintain the spring in an initially compressed state. After delivery of fluid contents of the syringe, the plunger forces the ejector member to release the retractable needle from the retaining member. Decompression of the spring at the end of depression of the plunger facilitates retraction of the retractable needle when engaged with the unitary plunger seal. Dual locking systems prevent re-use of the syringe after needle retraction.

Description

Prefilled retractable syringe, plunger and needle assembly thereof

Technical Field

The present invention relates to syringes. More particularly, the present invention relates to a retractable syringe including a needle retraction mechanism to prevent reuse of the syringe and/or needle stick injuries, wherein the needle retraction mechanism operates in a controlled manner.

Background

The practice of sharing syringes without adequate sterilization between consecutive users is a major factor in the transmission of Human Immunodeficiency Virus (HIV) and hepatitis, with its attendant severe repercussions by the victim and the high cost to society of supporting and providing medical care to the victim.

In addition, medical professionals may be exposed to used syringes, which can lead to inadvertent needle stick injuries and may lead to exposure to infectious pathogens or other contaminants.

In response to this problem, retractable syringes have been developed with the purpose of preventing reuse of the syringe and/or needle stick injuries of used syringes.

Disclosure of Invention

During the development of retractable syringes, particularly for mass production and distribution, the aim is to reduce the manufacturing costs and/or to maintain the ease of use and/or the safety of the syringe. These are all important factors if the safety syringe is to be used in large scale production, especially in third world countries with low medical budgets.

It is therefore a preferred object of the present invention to provide a user-friendly and safe retractable syringe while keeping manufacturing costs to a minimum, thereby facilitating mass distribution of retractable syringes.

Another preferred object is to provide a retractable syringe which efficiently delivers fluid substance, thereby minimizing waste of said fluid substance.

A particularly preferred object is to provide a prefilled retractable syringe.

In a first aspect, the present invention provides a plunger for a retractable syringe, said plunger comprising a plunger rod, a plunger outer, a control member and a biasing member, wherein said plunger rod, said plunger outer and said control member cooperate to releasably maintain said biasing member in an initially energized state.

In a second aspect, the invention provides a retractable syringe comprising a barrel, a retractable needle and a plunger engageable with the retractable needle, the plunger comprising a plunger rod, a plunger outer, a control member and a biasing member, wherein the plunger rod, the plunger outer and the control member cooperate to releasably retain the biasing member in an initially energized state.

In a third aspect, the present invention provides a releasable needle holding system, the system comprising: a retractable needle and a retaining member mounted to, or integrally formed with, the inner wall of the syringe barrel, the retaining member being capable of initially retaining the retractable needle at the needle end of the barrel until the retractable needle is engaged by the plunger to facilitate retraction of the retractable needle.

In a fourth aspect, the invention provides a retractable syringe comprising a barrel; a releasable needle retaining system comprising a retractable needle and a retaining member mounted to, or formed integrally with, an inner wall of a syringe barrel; and a plunger engageable with the retractable needle; the retaining member is capable of initially retaining the retractable needle at the needle end of the barrel until the retractable needle is engaged by the plunger to facilitate retraction of the retractable needle.

Suitably, the syringe according to the above aspect is a pre-filled syringe.

Preferably, the plunger further comprises a plunger seal capable of engaging the retractable needle.

In a preferred embodiment, the plunger seal is a one-piece plunger seal.

Suitably, the control member facilitates control of the rate of retraction of the retractable needle when engaged with the plunger and is detachable from the plunger after needle retraction.

Suitably, the control member comprises one or more mating portions which initially engage the plunger outer to facilitate maintaining the biasing member in an initially energized state.

In one embodiment, the control member includes one or more arm members that initially engage the plunger outer to facilitate maintaining the biasing member in an initially energized state.

In another embodiment, the control member includes one or more cutaways, notches or recesses that initially engage the plunger outer to facilitate maintaining the biasing member in an initially energized state.

Suitably, retraction of the retractable needle is facilitated by the biasing member, such as a spring, resilient means or other means for storing energy.

Preferably, the biasing member is a spring.

In a preferred embodiment, the spring is initially compressed, such that decompression of the spring facilitates retraction of the retractable needle.

In a preferred embodiment, the retaining member comprises a mating surface that is complementary to a mating surface of the inner wall of the syringe barrel.

In a preferred form, the releasable needle retention system further comprises a needle seal.

Preferably, the retractable needle comprises a retractable needle body and a cannula.

In a particularly preferred embodiment, the releasable needle retaining system further comprises an ejector member which facilitates release of the retractable needle from the retaining member, thereby facilitating retraction of the retractable needle when engaged by the plunger.

According to the above aspect, typically, although not exclusively, the cylinder is formed from glass.

Preferably, said barrel further comprises a collar having one or more release members which facilitate release of said control member from said plunger outer.

Preferably, said syringe or said plunger comprises at least one locking system which prevents reuse of the syringe after needle retraction is complete.

In one embodiment, one said locking system comprises respective elements of said barrel and said plunger outer. Preferably, according to this embodiment, the locking system comprises elements of said collar and of said plunger outer rim.

In another embodiment, another of said locking systems comprises elements of said plunger rod and said plunger outer.

Preferably, the syringe comprises two of said locking systems.

In a particularly preferred, non-limiting embodiment, the present invention provides a prefilled retractable syringe comprising:

(i) a glass cylinder comprising an inner wall and a collar, the collar having a release ring;

(ii) a releasable needle retention system, comprising: a needle assembly comprising a retractable needle and a needle seal; a retaining member comprising a mating surface that is complementary to a mating surface of the inner wall; and an ejector member for releasing the retractable needle from the retaining member;

(iii) a plunger engageable with said retractable needle, said plunger comprising a plunger rim, a plunger rod frangibly connected to a control member, a spring and a unitary plunger seal, said control member comprising one or more mating portions, said unitary plunger seal being engageable with said retractable needle, wherein said plunger rod, plunger rim and said control member cooperate to releasably retain said spring in an initially compressed state, said one or more mating portions of said control member engaging said plunger rim until said release ring disengages said one or more mating portions from said plunger rim after compression of said plunger is complete to facilitate decompression of said spring and retraction of said retractable needle when engaged with said unitary plunger seal; and

(iv) a plurality of locking systems respectively formed between said plunger outer rim and said collar member; and between the plunger rod and an element of the plunger outer; these locking systems are operable to prevent reuse of the syringe after needle retraction.

It will also be appreciated that in other aspects the invention also relates to a method of assembling the above-described plunger, releasable needle holding assembly and/or syringe, and to a method of using the above-described syringe.

In a preferred embodiment, the method of assembling the syringe comprises the sequential steps of:

(i) mounting a releasable needle holding assembly to a syringe barrel;

(ii) filling the cylinder with a fluid substance;

(iii) inserting the plunger seal into the barrel; and

(iv) coupling the plunger to the plunger seal.

Throughout this specification, unless otherwise indicated, the terms "comprises," "comprising," and "including" are open-ended and not closed-ended expressions such that a stated integer or group of integers may include one or more other unstated integers or groups of integers.

Drawings

Non-limiting embodiments of the present invention are described with reference to the following drawings, in which

FIG. 1 is a cross-sectional view of a retractable syringe embodiment;

FIG. 2 is a cross-sectional view of an embodiment of the plunger;

FIG. 3 is another cross-sectional view of an embodiment of the plunger;

FIG. 4 is a cross-sectional view of an embodiment of a unitary plunger seal;

FIG. 5 is a cross-sectional view of an embodiment of the needle seal, retractable needle, ejector member and retaining member;

FIG. 6 is another cross-sectional view of the embodiment of the needle seal, retractable needle, ejector member and retaining member mounted at the needle end of the syringe barrel showing engagement between the barrel and retaining member;

FIG. 7 is a top view of an embodiment of a retaining member;

FIG. 8 is a side perspective view of an embodiment of a retaining member;

FIGS. 9A-C are sectional views showing progressively the engagement of the retractable needle by the unitary plunger seal prior to retraction;

FIG. 10 is a cross-sectional view showing engagement between the outer edge of the plunger and the control member toward the end of plunger compression;

FIG. 11 is a side elevational view of the syringe showing retraction of the plunger rod and control member after disengagement between the plunger outer and control member and decompression of the spring;

FIG. 12 is a cross-sectional view of the locking system after needle retraction;

FIG. 13 shows a cross-sectional view of another locking system prior to needle retraction;

FIG. 14 shows a cross-sectional view of the alternative locking system after needle retraction;

FIG. 15 provides a perspective view and a cross-sectional view of an alternative embodiment of a retaining member of the releasable needle retainer system;

FIG. 16 provides a perspective view and a cross-sectional view of another alternative embodiment of a retaining member of the releasable needle retainer system;

FIGS. 17A-C illustrate an alternative embodiment of a retractable needle engaged with a needle seal of a releasable needle retention system;

FIG. 18 shows another alternative embodiment of a releasable needle retainer system;

fig. 19 shows a perspective view and a cross-sectional view of an alternative embodiment of the control member and the plunger rod.

Detailed Description

Referring to fig. 1, an embodiment of retractable syringe 10 includes barrel 11 and plunger 20, plunger 20 having plunger seal 80 mounted to plunger 20. Barrel 11 is formed of glass and includes plunger end 14 and needle end 15, collar 13 is located at plunger end 14, and releasable needle holding system 90 is mounted within needle end 15, releasable needle holding system 90 including retractable needle 40, needle seal 43, expelling member 60 and retaining member 30, wherein said retractable needle 40 includes cannula 41 and retractable needle body 42. Needle end 15 also has a protective cover 12 for cannula 41. Collar 13 may be mounted or assembled to barrel 11 or co-molded with barrel 11.

Barrel 11 also includes an inner wall 18, which inner wall 18, together with needle seal 43 and plunger seal 80, defines a fluid space 105 inside barrel 11. The retaining member 30 has a relatively smooth Outer Diameter (OD) that includes a mating surface that flush fits with a complementary mating surface of the inner wall 18 of the cylinder. Preferably, the holding member 30 is glued or bonded to the glass cylinder 11. This arrangement eliminates the need for complementary grooves, ribs or co-moulding (for example) included in the barrel 11 to support the retaining member 30, thereby enhancing the ease of manufacture and assembly of the retractable syringe 10.

In use, plunger 20 is axially movable into fluid space 105 to facilitate delivery of fluid substance of retractable syringe 10. In a preferred embodiment, fluid space 105 is prefilled with a fluid substance to be delivered by retractable syringe 10. Non-limiting examples of such fluid materials are low molecular weight heparin, such as enoxaparin sodium (e.g.,)。

with particular reference to fig. 2 and 3, the plunger 20 comprises a plunger rod 21 and a plunger outer 22, the plunger outer 22 having a cap member 23. A control member 50 is releasably engaged with the plunger 20, the control member 50 including a button 51, an arm 52 and a shaft 53. Plunger 20 further comprises a compression spring 70 mounted between plunger rod 21 and plunger outer 22, which compression spring 70 is held in compression between annular ledge 27 of plunger rod 21 and bottom 28 of plunger outer 22.

Plunger rod 21 further comprises a sealing engagement member 26, in this embodiment sealing engagement member 26 is a threaded protrusion that engages a complementary recess 82 of plunger seal 80. In an alternative embodiment, the seal engaging member 26 may be in the form of a snap lock projection that engages a complementary recess in the plunger seal 80.

As best shown in fig. 3, the control member 50 is releasably coupled to the plunger rod 21 by a shaft 53, said shaft 53 comprising a frangible connection 24 to the plunger rod 21. The frangible engagement between the control member 50 and the plunger rod 21 applies minimal stress to the frangible connection 24.

Control member 50 is also releasably engaged with plunger outer 22, which maintains spring 70, which is held between annular ledge 27 of plunger rod 21 and bottom 28 of plunger outer 22, in an initial compressed state. Initially, the ledge 54 of the arm 52 abuts the rim 29 of the cap member 23 of the plunger skirt 22, thereby retaining the space member 50 and preventing axial movement of the control member relative to the plunger skirt 22. However, the arms 52 of the control member 50 are resiliently flexible and movable in the direction of the solid arrows shown in FIG. 3, which will disengage the control member 50 from the plunger outer 22, thereby promoting decompression of the spring 70, as will be described in more detail below.

Referring now to FIG. 4, plunger seal 80 is of unitary construction and is mounted to plunger 20 to provide a fluid seal between plunger 20 and inner wall 18 of barrel 11. Plunger seal 80 includes a sealing body 84 and circumferential ribs 85A, 85B, 85C that effect a fluid seal between plunger 20 and inner wall 18 of barrel 11.

Plunger seal 80 further includes a recessed seat 81 and a needle recess 86, the recessed seat 81 receiving a bottom 405 of retractable needle body 42, the needle recess 86 receiving a sleeve end 141 that is compressed toward plunger 20 before retraction of retractable needle 40, as will be described below.

In fig. 5 and 6, boot 12 has been removed and retractable syringe 10 is ready for use. The needle end 15 of the barrel 11 is fitted with a releasable needle holding system 90, the releasable needle holding system 90 comprising a releasable needle 40 and a needle seal 43, said releasable needle 40 having a cannula 41 and a releasable needle body 42. The end 141 of the cannula 41 is in fluid communication with the fluid substance in the fluid space 105 of the cylinder 11. As is evident in fig. 5, needle seal 43 includes complementary steps 46 forming bore 44 which respectively receive steps 45 of retractable needle body 42 so that bottom 405 of retractable needle body 42 is initially seated in bore 44. In a similar manner to the needle seal described in international publication WO 2006/108243, and as best shown in fig. 5, retractable needle body 42 advantageously has a tapered cross-section tapering towards cannula 41 and includes a plurality of steps 45. The stepped configuration means that the amount of movement required to remove retractable needle 40 from needle seal 43 is minimised. This taper may assist in centering retractable needle 40 as it is withdrawn from needle seal 43 because the resistance to withdrawal of retractable needle 40 is effectively reduced as retractable needle body 42 of tapered cross-section is withdrawn through bore 44 of needle seal 43.

Needle seal 43 also has an annular rib 47 and an annular base 48 that cooperate with the inner wall 18 of barrel 11 to promote improved sealing and prevent inadvertent leakage of fluid material.

As previously mentioned, the retaining member 30 is mounted inside the needle end 15 of the barrel 11, as best shown in FIG. 6, with a "smooth" mating surface to promote adhesion to the "smooth" mating surface of the inner wall 18 of the needle end 15 of the barrel 11. This is the preferred embodiment when retractable syringe 10 is made of glass. In an alternative embodiment particularly suited for a plastic retractable syringe 10, the retaining member 30 is mounted to the inner wall 18 of the barrel 11 by a circumferential rib (not shown), the inner wall 18 of the barrel 11 engaging a circumferential groove (not shown) on the retaining member 30. In another alternative embodiment of plastic retractable syringe 10, retaining member 30 may be co-molded to needle end 15 of barrel 11.

Needle end 15 also has an ejector member 60, which ejector member 60 comprises an ejector ring 61 and a bottom 62. The expelling member 60 is engaged by the annular stop 63 with the circumferential recess 420 of the retractable needle body 42. Unlike the arrangement corresponding to international publication WO 2006/108243, the expelling member 60 is not fixed or mounted or engaged with the needle seal 43, but merely abuts against the needle seal 43. Alternatively, the needle seal 43 and the expelling member 60 may be co-molded as a unitary structure.

Referring again to fig. 6, and also to fig. 7 and 8, the sleeve 41 and retractable needle body 42 project through the central bore 33 of the retaining member 30. Retaining member 30 includes a cylindrical body 35 and fingers 31A, 31B, 31C, fingers 31A, 31B, 31C including angled faces 32A, 32B, 32C, respectively (visible in FIG. 8), angled faces 32A, 32B, 32C abutting against a ledge 491 of head 49 of retractable needle body 42 to releasably retain retractable needle 40 in position during operation of retractable syringe 10. Cylindrical body 35 of retaining member 30 further includes internally tapered bosses 34A, 34B and 34C which engage head 49 of retractable needle body 42 to prevent retractable needle body 42 from being pushed out of barrel 11.

Figures 9A-C show a sequence of events by which retractable needle 40 is disengaged from retaining member 30, thereby facilitating retraction of retractable needle 40.

Typically, retractable syringe 10 is prefilled with a fluid substance for delivery. Thus, plunger 20 is disposed in an initial position ready to be compressed to deliver fluid substance of retractable syringe 10.

As shown in fig. 9A-C, at or near the end of plunger 20 compression (in the direction indicated by the solid arrow), plunger 20 moves plunger seal 80 coupled to plunger 20 against needle seal 43 at needle end 15 of barrel 11. This causes the ejection member 60 to move so that it engages the retaining member 30. Plunger 20 continues to move in the direction of the solid arrow so that recessed seat 81 receives bottom 405 of retractable needle body 42 and needle recess 86 receives cannula end 141. This effectively couples retractable needle body 42 to plunger 20.

A characteristic of this design is that plunger seal 80 "squeezes out" the final portion of the delivered fluid because bottom 405 of retractable needle body 42 engages recessed seat 81. Tests have shown that the dead space (the amount of fluid remaining in retractable syringe 10 after injection) is on average less than 0.001 grams, which is far superior to the acceptable level of drug delivery.

Continued axial movement of plunger 20 along the solid arrow in fig. 9 causes plunger seal 80 to abut needle seal 43 and force needle seal 43 further toward needle end 15 of barrel 11 so that discharge ring 61 of discharge member 60 moves fingers 31A, 31B, 31C of retaining member 30 out from behind ledge 491 of head 49 of retractable needle body 42 in the direction indicated by the solid arrow in fig. 7. This releases retractable needle 40 for retraction. One particular advantage of the releasable needle retainer system 90 is that: the expelling member 60 permanently deforms the fingers 31A, 31B, 31C of the retaining member 30, thereby facilitating prevention of re-use of the syringe after release of the retractable needle 40.

To retract retractable needle 40, compression spring 70 must be decompressed, which decompression is facilitated by disengaging plunger rod 21 from plunger outer 22. Referring to fig. 10, axial movement of the plunger 20 in the direction of the solid vertical arrow causes the arms 52 of the control member 50 to abut against the release ring 136 of the collar 13 at the plunger end 14 of the barrel 11 (not shown for clarity). The release ring 136 may be mounted or assembled to the barrel 11, or may be co-molded with the collar 13 and barrel 11.

The release ring 136 forces the arm 52 to move laterally in the direction of the horizontal solid arrow and out of engagement with the rim 29 of the cap member 23 of the plunger outer 22. This disengagement causes compression spring 70 to decompress and push ledge 27 of plunger rod 21, thereby retracting plunger rod 21 and control member 50 coupled to plunger rod 21. The disengagement may also be accompanied by an audible and/or tactile signal (e.g., a "click") that tells the user that retraction is about to occur. As depicted in fig. 9, retractable needle 40 is coupled to plunger seal 80 and is thus retracted within barrel 11 in the direction of the arrow in fig. 11 with plunger rod 21 so as to be completely enclosed by and contained within barrel 11. Although retraction of the needle 40 is "automatically" actuated by decompression of the spring 70, the user can release pressure (e.g., by thumb pressure) against the button 51 of the control member 50 to control the rate of retraction.

At the end of retraction of plunger rod 21 and retractable needle 40, control member 50 may be broken off of plunger rod 21 at frangible connection 24 and manually removed from retractable syringe 10 and discarded as "clean" waste.

One advantage of this embodiment of the plunger 20 is that when the control member 50 is snapped off the plunger rod 21, it constitutes a relatively short piece of material for subsequent "clean" disposal.

Another advantage of this embodiment of plunger 20 is that once control member 50 is snapped off plunger rod 21, only a little, if any, of plunger 20 protrudes out of barrel 11 in an attempt to force plunger 20 back into barrel 11 and re-engage the needle (not shown).

Retractable syringe 10 may also include a first locking system 95A and a second locking system 95B to prevent reuse of retractable syringe 10.

Fig. 12 shows an embodiment of locking system 95A in which plunger outer 22 locks into collar 13 to prevent retraction of plunger 20 from barrel 11, thereby removing retracted needle 40 and thereby preventing reuse of retractable syringe 10. In this embodiment, and as is evident in fig. 10, a complementary circumferential groove 137 of the collar receives the cylindrical lip 119. The connection 138 between the cylinder 11 and the collar 13 is coated with an adhesive or glue. Plunger outer 22 includes locking arms 299A, 299B that engage locking edges 139 in collar 13, respectively. The locking arms 299A, 299B are oriented approximately 150 degrees from one another to maximize the strength of the plunger outer 22.

Fig. 13 and 14 show an embodiment of a locking system 95B.

Referring to fig. 13 and 14, the plunger 20 of the retractable syringe 10 includes a plunger rod 21, a control member 50 and a plunger outer 22. The control member 50 also includes a recess 57, the recess 57 initially engaging the flexible tab 25 of the plunger outer 22. The plunger rod 21 and the control member 50 are releasably connected together by a frangible connection 24. Preferably, the recess 57 and flexible tab 25 are molded into the control member 50 and plunger outer 22, respectively.

The compression of the plunger 20 for expelling the fluid substance of the retractable syringe 10 is substantially the same as previously described. As shown in fig. 13 and 14, decompression of the spring 70, together with the angled face of the flexible tab 25 and its height (i.e., preventing engagement in the frangible connection 24) causes the flexible tab 25 to ride over the retracting control member 50 and plunger rod 21 until the flexible tab 25 of the plunger outer 22 engages the notch 27 on the plunger rod 21, thereby forming a second locking system. The second locking system is arranged such that the plunger rod 21 and the control member 50 coupled to the plunger rod 21 cannot be retracted towards the inside of the plunger outer rim 22 in the direction of the solid arrow in fig. 14. This prevents re-exposure of the retracted needle (not shown).

It will be appreciated that the retractable syringe 10 provides a number of manufacturing and design advantages, and that numerous variations are contemplated within the broad scope of the present invention, which are primarily conducive to manufacture and design.

Typically, barrel 11 is formed of glass, with lip 119 at plunger end 14 rather than finger grips. As previously described (as shown in fig. 10 and 12), the collar 13 may have finger grips 139A, 139B incorporated therein and glued or bonded to the glass cylinder 11. One advantage is that the underside of the collar 13 will be a smooth continuous surface (without any clips protruding under the glass finger grips), which is important in fluid fill lines where the syringe is guided and positioned by the handling of the underside of the finger grips 139A, 139B.

Fig. 15 and 16 show alternative embodiments of retaining member 30, which, although requiring more complex tooling (slides), result in savings in overall length. Fig. 15 shows the needle retainer member 330 with the needle retainer member 330 self-locking and assembled to the needle end 315 of the syringe 310. This may provide potentially greater resistance to inadvertently pushing retractable needle 430 into barrel 311 during an injection. Fig. 16 shows another smaller retaining member 430, the retaining member 430 being self-locking but terminally assembled to the needle end 415 of the syringe 410.

The releasable needle retainer system 90 may also be modified. For example, retractable needle 40, and in particular retractable needle body 42, can be modified as shown in fig. 17A, B and C, wherein bottom 530 of retractable needle body 542 protrudes through needle seal 543 into cylindrical fluid space 5105. As previously described, this may stagger system forces and/or reduce the overall plunger travel distance and/or provide reduced force to cause a plunger seal (not shown) to engage retractable needle body 542.

In another embodiment shown in fig. 18, the releasable needle retainer system 690 comprises a needle seal 643 at the needle end 615 of the barrel 611, an expelling member 660, the expelling member 660 holding the retractable needle body 642 in place, and a retaining member 630 for retaining the retractable needle body 642 against forward movement. Upon retraction, the expelling member 660 is pushed around the retractable needle body 642 away from the detent 6409, leaving the retractable needle body 642 free to be retracted (rather than unlocking the fingers 31A, 31B, 31C on the retaining member 30 as previously described), thereby retracting the needle 640. This eliminates the need for any radial orientation during assembly and is not affected by changes in the internal glass cylinder geometry, and also reduces the length, which contributes to ease of manufacture.

In another alternative embodiment of the plunger 720, the shaft 573 may include a connector that releasably engages a recess in the plunger rod 721, or is arranged as described in fig. 2 and 3. Fig. 19 shows an example in which the control member 750 includes a recess (not shown) that receives a snap ring connector 729 on the plunger rod 721.

The preferred manner of assembly of the prefilled retractable syringe 10 is as follows, in accordance with the description of the preferred embodiment of retractable syringe 10 set forth above. Both the holding member 30 and the collar 13 are glued to the cylinder 11, the cylinder 11 then being siliconized. The retractable needle 40, the expelling member 60 and the needle seal 43 of the releasable needle holding system 90 are fitted into the needle end 15 of the barrel 11. These three parts are held together as an assembly by the head 405 of the retractable needle 40, said retractable needle 40 being held by the needle seal 43 and the discharge member 60, the discharge member 60 engaging the circumferential recess 420 on the retractable needle body 42 by the annular detent 63. Retractable needle body 42 is also clipped into fingers 31A-C of retaining member 30. The boot 12 is then assembled to the barrel 11 at the needle end 15. Next, cylinder 11 is filled with the fluid substance, and then plunger seal 80 is inserted into cylinder 11 at an insertion position adjacent to the fluid substance without pressurizing the fluid substance. Typically, a nitrogen gas gap is located between the fluid substance and plunger seal 80. Thus, the assembly of the plunger 80 provides a sterile container for the fluid substance. The plunger outer 22, the plunger rod 21 with the control member 50 and the spring 70 are pre-assembled into a plunger 20 assembly which is then screw fitted into the plunger seal 80.

The parts of retractable syringe 10 are designed to provide ease of manufacture by: plastic parts require only open-close machining (e.g., no slides), which not only makes machining cheaper and less complex, but also makes the open/close tool more reliable in mass production.

Assembly of retractable syringe 10 requires a minimum of orientation. Only two parts need to be oriented to fit together (control member 50 to plunger outer 22), but they are easily oriented in an automated assembly process and this orientation is verified by functional advantages.

The retractable syringe 10 is designed to take into account the manufacturing tolerances of the wider glass cylinder (as compared to the plastic molding tolerances), which is +/-0.5mm in length. To overcome the wide length tolerances, retractable syringe 10 has been designed to allow retaining member 30 to be bonded to barrel 11 at needle end 15 with a tolerance of + -0.05 mm, with reference to collar 13 at plunger end 14 of barrel 11. This reduces the tolerance effect of glass cylinder 11 to provide a more secure actuation of the retractable needle 40 retraction mechanism which is actuated by the release of the release ring 136 of trigger spring 70 while the retractable needle 40 is released from the retaining member 30.

Furthermore, the expelling member 60 merely sits on the needle seal 43 and also engages the retractable needle body 42 by means of the annular detent 63, which effectively locks the assembly of needle seal 43, expelling member 60 and retractable needle 40 together for assembly as a unit into the glass cylinder 11. When the assembly is moved to a position within barrel 11, retaining member 30 has been glued into position (at a set distance from collar 13) for positioning of retractable needle 40.

For ease of assembly, the plunger 20 as described above comprises the plunger rod 21 and the control member 50 as a single part, wherein the control member 50 is broken off at the frangible connection 24 after retraction. This reduces the number of parts and eliminates details of the connection between the two parts.

From the foregoing, it will be appreciated that the present invention provides a relatively simple, rugged and inexpensive syringe which automatically fails with little or no user assistance, thereby preventing or at least minimizing needle stick injuries from re-use of the syringe and/or from used syringes.

In addition, by controlling or adjusting the speed of needle retraction, the likelihood of blood splash is reduced, thereby enhancing the "user-friendliness" and commercial appearance of the retractable syringe.

The components of the retractable syringe are all designed to ensure the only accurate timing and effective delivery of the fluid substance, engagement of the plunger with the retractable needle and needle retraction as unique features of the syringe described herein. The compression of the plunger rod "presses" the plunger seal against the needle seal in the length direction, which needle seal presses against the expelling member to ensure that the expelling member has deployed the fingers of the holding member sufficiently to allow the retractable needle to retract freely, but not before the final part of the fluid substance has been delivered and the retractable needle is firmly engaged.

As previously mentioned, manufacture and assembly of the retractable syringe is facilitated by the features described herein. In the case of a pre-filled syringe, sterility is readily maintained, and a sub-assembly of a retractable syringe (including a barrel fitted with a releasable needle holding system and a plunger and separate plunger seal) can be provided for subsequent completion of filling and assembly of the fluid substance.

Throughout this specification the aim has been to describe the preferred embodiments of the invention without limiting the invention to any one embodiment or specific collection of features. Various changes and modifications may be made to the embodiments described and illustrated without departing from the present invention.

The disclosures of each patent and scientific literature, computer programs, and algorithms referenced in this specification are hereby incorporated by reference in their entirety.

Claims (15)

1. A releasable needle holding system mountable to a syringe barrel, the system comprising: a retractable needle comprising a needle body and a sleeve, and a retaining member comprising a mating surface complementary to a mating surface of the inner wall of the barrel, the retaining member comprising a cylindrical body and two or three fingers to enable releasable retention of the needle body during operation of the syringe to initially retain the retractable needle at the needle end of the barrel until the retractable needle is engaged by the plunger to facilitate retraction of the retractable needle.

2. The releasable needle holding system of claim 1, further comprising a needle seal.

3. The releasable needle holding system of claim 1 or 2 mountable to a glass cylinder.

4. The releasable needle retaining system of claim 1, further comprising an ejector member that facilitates release of the retractable needle from the retaining member.

5. The releasable needle retaining system of claim 4, wherein the ejector member is capable of deforming fingers of the retaining member to facilitate preventing reuse of the syringe after release of the retaining member.

6. A retractable syringe comprising a barrel, a plunger and the releasable needle retaining system of any one of claims 1 to 5.

7. The retractable syringe of claim 6, wherein the plunger comprises a plunger rod, a plunger outer, a control member and a biasing member, wherein the plunger rod, the plunger outer and the control member cooperate to releasably maintain the biasing member in an initially energized state.

8. The retractable syringe of claim 7, wherein the plunger rod comprises a unitary seal capable of engaging the retractable needle.

9. The retractable syringe of claim 7 or 8, wherein the control member comprises one or more mating portions which initially engage the plunger outer to facilitate maintaining the biasing member in an initially energized state.

10. The retractable syringe of claim 7, wherein the biasing member is a spring.

11. The retractable syringe of claim 7, wherein the plunger rod and control member are releasably connected.

12. The retractable syringe of claim 11, wherein the plunger rod and control member are frangibly connected.

13. The retractable syringe of claim 7, further comprising a locking system comprising elements of the plunger outer and the plunger rod.

14. The retractable syringe of claim 7, which is a pre-filled syringe.

15. The retractable syringe of claim 14, filled with an injectable solution of low molecular weight heparin.