WO1984003840A1

WO1984003840A1 - Multi-dose syringe and cannulae therefor

Info

Publication number: WO1984003840A1
Application number: PCT/GB1984/000110
Authority: WO
Inventors: Anthony Roger Jones
Original assignee: English Glass Co Ltd
Priority date: 1983-03-31
Filing date: 1984-03-29
Publication date: 1984-10-11
Also published as: GB8308966D0; GB8508775D0; GB2155555B; GB2155555A; EP0169845A1

Abstract

A multi-dose syringe (1) has a plurality of cannulae (5, 40, 41, 42)stacked on it. One of them may be integral with the body of the syringe. They are held together by claw detents (47) engaging annular shoulders (37, 51) in such a way that at any given time only the cannula (e.g. 42) endmost in the stack is removable. Tear-off tabs (12, 13, 14, 15) define the stroke of a piston (7, 8) of the pump of the syringe for the dispensing of respective doses through all of the canulae at that time on the syringe. The syringe is particularly for veterinary use and allows multiple doses to be given from a single precharged syringe without risk of cross-infection, since an endmost used cannula can be removed before a next dose is given.

Description

MULTI-DOSE SYRINGE AND CANNULAE THEREFOR

This invention relates to syringes, and concerns multi-dose syringes and also removable cannulae therefor. They are usable for example in domestic, catering, medical or, particularly, in veterinary environments.

In medical and more particularly veterinary usage it is frequently necessary for a number of people or animals to be given an identical treatment. We are particularly concerned with the need to dose all the members of a herd of animals with some prophylactic or curative medicine or with some food-stuff supplement. Oral doses have been given in the shape of pills, balls or ^• drenches, and injections by means of conventional syringes, usually disposable syringes.

In many circumstances it is preferable to use a syringe. An example is in the treatment of mastitis in milking cows. This can be done by in raraammary injection. Currently this is done with pre-filled single .shot disposable syringes. During packaging, each filled syringe is fitted with a cannula cover cap and subsequently packed in a heat sealed plastic envelope prior to bulk packaging in an outer cardboard container.

At the time of treatment it is necessary to follow the following procedure:

1. Open the outer cardboard container and remove a syringe in a plastic envelope;

2. Open the plastic envelope, remove the syringe from it and dispose of the envelope;

3. Remove the cannula cover cap and dispose of it;

-i . Inject, and dispose of the syringe. For each injection, steps 2 to A must be repeated. In the treatment of mastitis each of the four teats of the cow must be injected. Consequently, this routine must be gone through many times during treating a herd.

We have realised that this procedure could be simplified if the syringes were multi-dose.

In this case it would not be necessary to dispose of the syringe, take out and open another plastic envelope, and remove a fresh syringe between each injection. However, in developing a multi-dose syringe we have realised that there is a danger of cross- infection from the syringe.

We are now proposing that a syringe should be fitted with a plurality of separable stacked cannulae. The syringe may have an integral cannula with one or more additional cannulae stacked upon it. Alternatively, the syringe may be without an integral cannula, but with two or more separable S E stacked cannulae attached to it.

In use, the syringe will normally be pre-filled with a sufficient quantity of preparation for a plurality of doses, conveniently for the same 5 number of doses as there are cannulae on the syringe, or as there are animals to be treated. A dose is injected through the stacked cannulae, and whenever it is desired to eliminate cross-infection, normally between each injection, the endmost cannula 0 is removed before the next injection is administered. In this way the injection is given with an uncontam- inated cannula, even though it is not the first injection to be given with that syringe.

Preferably the stackable and separable cannulae

■ 5 are so designed that when they are stacked, only the endmost can be removed from the stack. In this way it is made easy for the user to work through the cannulae in succession. He does not need to take care to separate the stack in ° the correct place because it will not separate in any other. This can be achieved by clipping adjacent cannulae together with detents on each cannula which must move if that cannula is to ,ce separated from its adjacent cannula away from 5 the end of the stack. If each cannula, when in position in a stack, covers the detents of the next one away from the end of the stack so that its detents cannot move, then only the endmost cannula, whose detents are not covered, can be removed.

It is advantageous to provide means for the regulation of the size of each dose administered with the multi-dose syringe. The syringe may be graduated, or more preferably its plunger may be provided with one or more removable tabs so that the plunger can only - be pushed in initially by a predetermined distance; the tab is then broken off, and the plunger can then be pushed in by another predetermined distance.

The present invention also covers the individual stackable and separable cannulae per se.

An embodiment of the invention, given by way of example, will now be described with reference to the accompanying drawings, in which:

Figure 1 shows partly in diametrical section and partly in elevation a multi-dose syringe with stack¬ able and seperable cannulae embodying the invention;

Figure 2 is a section on the line II-II, Figure 1; Figure 3 is a diametrical section through an end portion of the body of the syringe showing an integral cannula;

Figures 4 and 5 are diametrical sections in mutually orthogonal planes through a separable cannula; and

Figure 6 is an end view of the syringe on the arrow VI of Figure 1.

OMPI_ The syringe 1 has a generally cylindrical body 2 at one end of which is an approximately rectangular flange 3 by which the body may be held by the fingers of the user. At the other end the body tapers at 4 and in this embodiment terminates in an integral cannula 5 which will be described in more detail later. The internal volume of the body is sufficient to hold a plurality- of doses of a liquid or pasty material to be dispensed. Dispensing is assured by a pump which in this case is a piston assembly 6 working in the cylinder of the body. The piston has a double head 7,8 which are one-piece mouldings of an essentially rigid plastic material of which, however, an extremely narrow periphery distorts to engage the inner surface of the cylindrical body 2 in a fluid-tight manner.

The stem 9,10 of the piston is made up of crossed webs (Figure 2) and terminates in a disc 11 which can be pushed by the palm or thumb of the user whose fingers are engaged around the plate 3. Frangible tabs are formed on opposite edges of one of the webs of the cross. These tabs 12_.13,14,15 are integrally formed with the rest of the web and the piston assembly but are joined to it by comparatively localised weak lines 16. Otherwise, they are separated from the rest of the piston assembly by gaps 17.

The tabs are to act as stops to define the successively permissible strokes of the piston whereby to dispense successive doses of the material. Tab 12 which bears upon it embossed or inset indicia, such as the number "1" for example, has a front end 20 which abuts against a face of the plate 3. While this tab is in position the piston cannot move further into the cylinder. To dispense a first does therefore the tab 12 is twisted by the user, his grip on the tab being assisted by a ribbed area 21 so that the lines of weakening 16 are torn and the tab is removed. The pump may then execute a stroke until the front shoulder 22 of the tab 13 abuts against the plate 3. A second dose may be dispensed when that tab 13 has been torn off and so forth. The stroke after removal of subsequent tabs to allow for the fact that the material will usually have been packed in the syringe with a certain amount of included air.

To minimise the entrapment of air, however, a bleed slot 23 is provided at the initial portion of the inner cylindrical surface of the body.

The doses of material expressed by the pump pass from the syringe by a path defined by at least one cannula.

The relevant end portion of the body 2 and the structure of the integral cannula are best seen from Figure 3. At the narrow end of the taper portion 4 is an annular boss 30 having a sharp ridge 31 on its cylindrical surface. Beyond that boss a tapered portion 32 forms a -first end portion of the cannula 5. This leads to a frusto-conical transition 33 and a second taper portion 34 leading to the outlet nozzle 35 of the cannula. An annular ridge 36 on the taper portion 34 defines on one face 37 an annular shoulder.

At least one additional cannula is provided which is stackable onto the integral one 5. in Figure 1 three additional cannulae 40, 41 and 42 respectively are shown but any reasonable number may be provided. When the cannulae are stacked in a manner which will be described they together form the unique path by which material is expressed from the syringe, and normally the total number of cannulae will equal the number of doses contained in the syringe and the number of stops defining the strokes of the plunger.

Each additional cannula, then, is identical, has a first tapered portion 43 generally analogous to portion 32, a frusto-conical transition 44 and a second and end taper portion 45 leading to a nozzle 46. The portion 45 has on its outer surface 53 an annular ridge 52 defining a continuous shoulder 51. The taper portion 43 is interrupted by detents by which the cannula may be engaged positively with a next cannula in a stack. The detents include a radially inwardly projecting claw 47 mounted on an arm 48 which by virtue of the nature of the material from which the cannulae are made is somewhat flexible. The arm and claw are defined by a U-shaped aperture 49. - There are two such claws diametrically opposed to each other. Each claw has a back surface 50 of which the angle corresponds to the angle of the annular shoulder 37 of the first cannula, and also corresponds to the angle of the shoulder formed on the additional cannulae. Since the shoulders 37,51 are continuous the cannulae may be stacked, and the detents be engaged, in any relative rotational orientation. Each additional cannula has a rounded annular ridge 54 near its widest end to assist in gripping and handling.

The conicity of an inner surface 55 of the taper portions 45 is exactly the same as that of its outer surface 53 and the dimensions are arranged such that when the claws 47 of the detents of one cannula are engaged behind the shoulder of a next with the surface 50 in contact with the shoulder of the next, the outer surface 53 of the end taper portion of the inner cannula and the inner surface 55 of the outer one fit tightly together and form a hydraulic seal over all the length from the nozzle 46,35 of the inner cannula to the start of the frusto-conical transition 44 of the next outer one. The position of an inner cannula when nested is indicated at 45' in dotted lines in Figure 5.

The appearance of the completed stack of four cannulae (one integral and three additional) is seen in Figure 1. Since each successive cannula in the stack forms a hydraulic seal with the next, a leak-proof path is defined all the way to the nozzle 46 of the endmost cannula 42.

It can also be seen from Figure 1 that the inner surface 38 of the taper portion 43 of each successive cannula engages against the outer surface 39 of the arm 48 and the claw 47 of the next adjacent cannula whereby holding that one positively engaged with the one within it. For example the inner surface of portion 43 of cannula 42 holds in the arm 48 and the claw 47 of cannula 41 which is thereby held engaged behind the shoulder 51 of the ridge 52 on the cannula 40. Only on the outermost, (endmost) cannula at any given time is there the possibility of flexion of the arm 48 so that the claw 47 may move outwardly and become disengaged from the shoulder of the cannula below it. Therefore, at any given time only the endmost cannula of the stack, that one at the end furthest in the stack from the body of the syringe can be detached from the stack.

To enable the syringe together with its stack of cannulae to be sent out from the factory fully assembled and charged, a cover cup 60 of rubber or other elastomeric material, e.g. a thermoplastics material such as polyethylene, is fitted over it. This has an open conical end 61 which is to fit flush against the outer end surface of the transition 4 on the body and at its root there is an annular r-acess 62 which is for engage¬ ment with the ridge 31 on the boss 30.so as to hold the cover cup securely to the body until it is deliberately removed. A cylindrical portion of the cover cup 63 has a handling ridge 64 on its outside and leads to a bellows part 65 leading to a taper end part 66. The bellows part allows for slight variation in the length of a stack. of cannulae. - At the extreme end of the part 66 is a wall 67 with an inwardly projecting plug 68 which is to enter into the nozzle 46 of the endmost cannula the stack. Positioning ridge 69 holds the end portion snugly to the outer portion of the cannula, and engagement of the inner surface of the taper part 66 against the arm 48 and claw 47 of the endmost cannula 42 causes that to be held in positive engagement with the rest of the stack.

To use the syringe, the protective cup is stripped off and discarded, the first tab broken away and the first dose dispensed through the cannula 42. Further dose(s) may also be dispensed through that cannula but usually it will be taken from the end of that stack after a first dose has been dispensed so that the next dose, made available by detachment of the second tab 13, will be dispensed through the next cannula 41 to diminish the risk of cross-infection. Cannulae nearer to the body 2 than the one remotest from it cannot be accidentally stripped off for the reasons which have been explained.

The first cannula that is nearest to the body need not be integral -with the body as described here but may be attachable to it. The body may, preferably when a different form of -pump is used, be usable with a plurality of stacks of cannulae fitted onto it in succession. Each of the parts (the body, the piston assembly, cover cup, and the respective cannulae) can be one-piece integral mouldings in a suitable plastics material such as Alkathane (Trade Mark^' for a polyethylene).

I

Claims

CLAIMS :

1. A multiple-dose syringe (1) having a body (2) for containing material to be dosed and a pump (6) for expressing the material from the body in doses through a path defined by a cannula (5) , characterised in that

5 a plurality of cannulae (5,40,41,42) are provided in a stack to define the said path so that each dose issues through the cannula (5,40,41,42) at the end of the stack remote from the body.

2. A multiple-dose syringe according to Claim 1° 1, wherein the cannulae (5,40,41,42) of the stack are held together by a detent (47), only the detent (47) of the cannula (e.g. 42) endmost in the stack at a given time being releasable.

3. A multiple-dose syringe according to Claim 5 2, wherein the detent (47) is an inwardly projecting, flexibly mounted integral claw an outer surface (39) of which is, in the detaining position of the claw, engaged by an inner surface (38) of a next cannula in the stack.

4. A multiple-dose syringe according to Claim 0 3, wherein the said claw (47) engages behind a continuous annular shoulder (37,51) on a cannula next in the stack towards the body (2) .

5. A multiple-dose syringe according to Claim 1, Claim 2, Claim 3 or- Claim 4, wherein the pump has stops

^■25 (12,13,14,15) for permittinσ the expression of successive doses.

6. - A multiple-dose syringe according to Claim 5, wherein the stops are frangible tabs (12,13,14,15) respectively defining a stroke length of a piston (7,8) of the said pump (6) for the expression of respective doses.

7. A multiple-dose syringe according to Claim 6, wherein a first said tab (12) prevents movement of the piston (7,8 ) .

8. A multiple-dose syringe according to Claim

1, Claim 2, Claim 3 or Claim 4, wherein a first cannula (5) of the stack nearest to the body (2) is integral with the body.

9. A cannula (40,41,42) for mounting on a syringe (1) and form thereby a path for expression of material in a dose from a body of a syringe by a pump ( 6 ) of the syringe characterised in that the cannula (40,41,42) is stackable with at least one other cannula (5,40,41,42) to define a said path extending through the complete stack.

10. A cannula according to Claim 9 which has an inwardly projecting flexibly mounted integral claw (47) detainingly engageable behind a continuous annular shoulder (37,51) on a said other cannula (5,40,41,42) next adjacent in the stack in one direction along the stack, an outer surface (39) of the claw being contactable by a surface (38) of a further cannula next adjacent in the stack in the opposite direction along the stack to prevent retraction of the claw (47) and hence its disengagement from the said shoulder (37,51)