WO1990003818A1

WO1990003818A1 - Syringe

Info

Publication number: WO1990003818A1
Application number: PCT/GB1989/001221
Authority: WO
Inventors: Marc Andrew Koska
Original assignee: Agven Medical Corporation
Priority date: 1988-10-14
Filing date: 1989-10-16
Publication date: 1990-04-19
Also published as: GB8824100D0; AU4404889A

Abstract

The specification discloses a syringe (1) which has lost motion means (22), projecting means (16, 17) and outwardly-extending means (26) cooperable with the projecting means to limit the movement of the plunger (6) within the syringe barrel (2). The arrangement is such as to allow only one use whilst being suitable for use with vaccines and other medicines.

Description

SYRINGE

This invention relates to syringes and, in particular, to a syringe that can be used only once.

One use only syringes have been described and illustrated in the specification of Applicant's PCT/GB88/0490 application, the subject matter of which is incorporated into this specification by reference.

The principal object of the present invention is to provide a one use only syringe which is particularly suitable for the injection of medicines, such as vaccines.

With this object in view and in accordance with this invention, we propose a syringe in which lost motion is employed to commit an operator to an injection stroke of the syringe plunger.

In one way of carrying the invention into effect, the plunger stopper is connected to the plunger rod by a lost motion means followed by an outwardly extending means which is engageable with the syringe barrel, and which is co-operable with projection means on the barrel, whereby at the commencement of an injection stroke, with the lost motion means in a retracted position following a withdrawal stroke of the . plunger to draw a liquid into the syringe barrel, the outwardly extending means engage with the projection means to prevent any withdrawal of the plunger piston thereby committing the operator to the injection stroke.

In a preferred embodiment, the lost motion means comprises a piston which is mounted in a receiver for linear motion relative thereto. Conveniently, the receiver is integral with the plunger stopper, or can be integral with a stopper holder member, such as a peg_/ which retains a separate stopper of, for example, elastomeric material. The piston is suitably connected to, or forms part of, the remaining portion of the plunger. The outwardly extending means, which is conveniently associated with the plunger stopper, may be connected to the plunger rod by a breakable means which breaks if the operator attempts to withdraw the plunger after • the outwardly extending means has engaged with the projection means. Alternatively, the outwardly extending means may itself include a breakable means. Both arrangements have been described in Applicant's aforementioned patent specification. In another arrangement, the outwardly extending member may be made in such a way or of such a material that it can pass over the projection means on an advance stroke of the plunger but will engage with the projection means upon any attempt at a withdrawal stroke, thereby committing^*the operator to an injection stroke.

In order to provide for the injection of a fixed dose of say 0.5ml or 1.00ml, an additional projection means may be provided on the syringe barrel. The additional projection means may be positioned at a proximal location on the barrel which is spaced from the first mentioned, distal projection means, with the distance between the distal surfaces of the distal and proximal projection means corresponding to the length of travel or lost motion distance of the lost motion means. The distal projection means may comprise one annular ring, a series of annular rings, or a plurality of spaced-apart annular rings projecting inwardly from the inner wall of the barrel. The proximal projection • means preferably comprises a single annular ring. Angularly-spaced, inwardly-facing 'blips' may be used instead of fully annular rings.

In order that the invention may be more readily understood, reference will now be made, by way of example, to the accompanying drawings in which:

Figure 1 is a sectional side elevation of a syringe constructed in accordance with the invention, showing the assembled syringe plunger in a first position inside the syringe barrel;

Figure 2 is a sectional side elevation corresponding to Figure 1 but showing the syringe plunger in a withdrawn position prior to an injection or advance stroke;

Figure 3 is a sectional side elevation corresponding to Figure 1 but showing the syringe plunger in an intermediate position during an advance or injection stroke;

Figure 4 is a sectional side elevation corresponding ^* to Figure 1 but showing the syringe plunger in a final position after an injection or advance stroke;

Figure 5 is a sectional side elevation corresponding to Figure 1 but showing the result of an attempt to withdraw the syringe plunger after an injection or advance stroke;

Figure 6 is a detailed side elevation, to an enlarged scale, of an outwardly extending means incorporating breakable means, and forming part of the syringe of Figure 1, and;

Figure 7 is a side elevation similar to Figure 6 but showing an alternative outwardly extending means.

Referring to Figures 1 to 5 of the drawings, a syringe 1 has a barrel 2 moulded of plastics material, which comprises an integral distal nose 3 into which a needle 4 is moulded, and an integral proximal peripheral gripping member 5. A plunger 6 of integrally-moulded plastics material is slidably mounted in the barrel 2. The plunger 6 comprises a plunger rod 7, a distal plunger stopper 8 in sliding and sealing cooperation with the inner wall " 9 of the barrel 2, and a proximal peripheral gripping member 10. As best shown in Figure 6, the distal end region of the plunger rod 7 has a stabilizing member 11 which minimises wobble during advance and withdrawal movements of the plunger 6 in the barrel 2.

In known fashion the stopper 8 has a standard peg 12 over which a standard elastomeric cap 13 is frictionally fitted with its open end abutting against a disc 14. The maximum advance (injection) stroke of the plunger is determined by abutment of the stopper 8 with a distal end stop 15.

The barrel 2 has integral distal projection means in the form of a series of annular distal projections 16 located at a predetermined distance from the end^' stop 15. The barrel 2 also has an integral proximal projection means in the form of a single annular projection 17, which is located at a predetermined distance from the most proximal of the distal projections 16.

The stopper 8 is integrally joined to a receiver 18 comprising two axially-extending arms 19 each having a respective inwardly-directed portion 20. The receiver 18 constitutes one part of a lost motion means, the other part comprising a piston rod 23 having a piston 24 which is received in the receiver 18 for axial motion relative thereto. The piston 24 is retained within the receiver 18 by the inwardly-directed portions 20.

The piston rod 23 is integrally joined at its proximal end to the plunger rod 7 via an outwardly extending means 25 which comprises outwardly extending wings 26 and which incorporates breakable means. As best shown in the enlarged view of Figure 6, each wing 26 has an arcuate outer edge and is flexibly joined at two locations to a disc 27, which is integral with the piston rod 23. One, radially outer location 28, where the wing 26 is connected to the disc 27, is adjacent to the inner wall 9 of the barrel 2. The other, radially inner location 29, where the wing 26 is joined to an axial extension 30 of the plunger rod 1 , is adjacent to the plunger axis. Thus, the wings 26 are effectively hinged at the two locations 28 and 29.

• The proximally-facing surface of the disc 27 has a central abutment or stop 31 which is arranged to be engaged by the distally facing surface portions 32 of the wings 26 in axial alignment with the plunger rod extensions 30, and to delimit the amount of axial movement of the plunger rod 7 with respect to the piston rod 23.

In the modification of Figure 7, there are no breakable means and the outwardly extending member comprises an annular elastomeric member 25a having a peripheral projecting rim 26a.

Figures 1 to 5 illustrate the operation of. the syringe in use. Figure 1 shows the condition of the syringe 1 in its 'as-supplied' or assembled state. In this state, the cap 13 of the stopper 8 abuts the end stop 15 of the syringe barrel and the lost motion means 22 is fully extended with the piston 24 abutting the inwardly-extending portions 20 of the arms 19 of the receiver 18. The wings 26 abut against the most proximal of the distal projections 16.

When it is desired to use the syringe 1, the needle 4 is pushed into a phial of a medicine such as a vaccine and the plunger 6 is withdrawn until the proximal parts of the wings 26 abut against the distal surface of the proximal projection 17, at which position further movement in the proximal direction is impossible. In this state, as shown in Figure 2, the lost motion means 22 is in its fully extended position and the medicine occupies the space between the distal end of the stopper 8 and the stop 15 on the barrel 2.

As will be clear, the quantity of liquid drawn into the syringe during the withdrawal stroke depends upon the distance between the proximal projection 17 and the end stop 15 (which determines the starting position of the stopper 8). It should therefore be appreciated that the distance between the proximal projection 17 and the end stop 15 can be selected to vary the amount of liquid as required. The advance (injection) stroke is illustrated in Figures 3 and 4. The first consequence of advancing the plunger 6 is to cause the piston 24 of the lost motion device 22 to move distalwards within the - receiver 18 until it abuts against the distal end of the receiver 18 as shown in Figure 3. At this point, and before the stopper 8 moves distalwards, the wings 26 engage behind the distal surface of the most proximal of the distal projections 16. Any subsequent attempt to withdraw the plunger 6 will be prevented by this interengagement and, if force is used to attempt to break the interengagement, the breakable means incorporated in the outwardly extending means 25 will snap as shown in Figure 5. This renders the syringe unfit for further use, with the axial projections 30 of the plunger rod 7 breaking from the wings 26 at the flexible connections at locations 29.

It will be clear that the range of movement of the piston 24 within the receiver 18 is the same as the distance between the respective distal surfaces of the proximal projection 17 and the distal projections 16. Continued advancement of the plunger 6 causes the plunger stopper 8 to move distalwards, thereby expelling the medicine as the space 40 is reduced until, as shown in Figure 4, the stopper 8 abuts against the stop 15 at which point all of the predetermined quantity of medicine has been expelled.

In the modification shown in Figure T no breakage takes place but, on injection, the annular rim 26a of the outwardly extending members 25a slides over the projections 16 and cannot be withdrawn because of the interengagement of the annular rim with a projection 16.

As will be clear to those skilled in the art, this invention provides a simple and completely effective one use only syringe that is cheap to manufacture and easy to use.

It will also be understood that this invention is not limited to the preferred embodiment described herein, but includes all modifications and variations falling within its scope.

Claims

* 1. A syringe in which a lost motion means is employed to commit an operator to an injection stroke of the syringe plunger.

2. A syringe according to claim 1 wherein the lost motion means is situated between a plunger stopper and a plunger rod.

3. A syringe according to claim 1 or claim 2 wherein the lost motion means includes a piston member mounted within a receiver for linear movement relative thereto through a limited range.

4. A syringe according to any preceding claim, having an outwardly extending means which is cooperable with projecting means on the syringe barrel.

5. A syringe according to claim 4, wherein the projecting means is an annular ring projecting from the inner wall of the barrel. - l3 -

6. A syringe according to claim 4 or claim 5, wherein the projecting means comprises a proximal projection which is positioned to prevent movement of the plunger beyond a fully withdrawn position, by engagement with ^* the outwardly extending means.

7. A syringe according to any of claims 4 to 6, wherein the projecting means comprises a series of distal projections which are positioned to engage with the outwardly extending means in turn from the beginning of an injection stroke, to prevent any withdrawal once the injection stroke has begun.

8. A syringe according to claim 7, wherein the range of movement of the lost motion means, equals the distance between the distal surfaces of the proximal projection and the proximal-most of the series of distal projections.

9. A syringe according to any of claims 3 to 8, wherein the receiver is associated with the stopper and the piston member is associated with the remaining portion of the plunger. - m~ -

10. A syringe according to any of claims 2 to 9, having a breakable means between the rod and the stopper.

11. A syringe according to claim 10, wherein the breakable means is associated with the outwardly extending means.