Single-injection device

Abstract

A single-injection syringe, including a liquid container to be filled with the medicament, and holding at its sealed lower end a shortened or long syringe body which, in its interior, carries a movable needle support and forms with a piston rod a sterile chamber.

Description

The present invention relates to a single-injection device consisting of a liquid container of special shape to be filled with a liquid medicament. The sealed lower end of the container holds a syringe body which, however, may also cover the liquid container over its full length. The interior of the syringe body is provided with a movable needle support and forms a sterile chamber together with a piston rod.

So-called "ready-to-use" syringes used for a single injection are already widely employed in the medicinal administration technique. Owing to the many individual parts of such wholesale articles, the assembly to be made under sterile conditions involves considerable cost. Since a ready-to-use syringe is destined for one injection only, the manufacturer will strive to keep the production costs thereof as low as possible.

Prior art knows injection devices, in which the medicament to be injected is stored in a liquid container, shaped as an ampoule which is pushed into a syringe body. In the final assembly, the ampoule placed in the syringe body will be pushed in only to such a point that the assembled injection cannula which reaches into the interior of the syringe body does not pierce the seal at the front end of the ampoule. An essential disadvantage of that syringe is the injection needle fixed in the syringe body, since the needle portion which projects into the syringe body and the portion of the ampoule facing it have to be kept sterile. Because of the resulting space between the liquid container and the syringe body, however, micro-organisms can penetrate into the sterile zone within a certain length of time in storage.

The present invention makes it a point to provide a sterile zone for the injection needle not in the syringe body but in a sealed and separate part of the device. This is achieved by mechanically deforming the syringe body proper into engagement with the liquid container, thus providing a sealed sterile chamber.

The syringe, constructed in accordacne with the present invention, will now be described in greater detail by way of example only with reference to the accompanying drawings, in which:

FIG. 1 is a side view of the syringe;

FIG. 2 is a longitudinal cross sectional view of the syringe with the syringe body shortened;

FIG. 3 is a longitudinal cross sectional view of the syringe with the syringe body covering the liquid container;

FIG. 3a is a top view of the upper end of the syringe as shown in FIG. 3.

Referring to the drawings, FIG. 2, A and FIG. 3, B show the syringe body in its shortened form and in its long form respectively, the finger support 5 in the first case being part of the liquid container, whereas in the second case it is part of the syringe body.

If the liquid container to be filled with the medicament has such a shape that no means is provided for a firm connection with the syringe body, the preferred method for securely fastening the container according to the invention is provided by thermically and mechanically deforming a projecting portion of the rim 4 (FIG. 3) of the syring body made of a suitable plastic material by means of a punch moved in the direction of the container axis so as to form beads 20 (FIGS. 3 and 3a) to retain the container. These retaining beads prevent the liquid container from being removed, while compensating for differences in the total length of the liquid container, as do also various securing means of injection devices as presently used, for example stoppers with annular sealing lamellae or threads or so-called bayonet-type sealings.

To overcome the above-mentioned disadvantages I have now developed a new syringe system comprising essentially the following three main parts, as shown in FIG. 1: A container 1 to be filled with a liquid medicament, a shortened and/or a long syringe body 2 and a piston rod 3 mounted on the syringe body.

Referring to FIGS. 2 and 3, the liquid container is sealed in a familiar manner at its rear end by means of a movable piston stopper 6 and at its lower end by means of an aluminium cap 7 having a central aperture, under which a rubber disk or a rubber stopper 8 is inserted. The sealing plug of the rubber stopper is advantageously provided with a conical cavity, through which air bubbles, which frequently form in the interior of the container filled with the liquid medicament prior to the application, can simply be removed by pressing the piston rod.

The liquid container 1 may be separated from a bore 9 holding the needle support 10, with a cannula 11 passing through, by means of a plastic membrane 12, which may be injection-molded onto the syringe body 2, which is made of a plastic material. Moreover, the surface of the needle support 10 is provided with an annular projection 13 which engages an annular groove 14 cut in the bore 9, thus securing the needle support 10 in its initial position. This prevents premature perforation of the membrane 12 and the piercing of the rubber disk or stopper 8 placed under the aluminium cap 7. Four stabilizing fins 15, running perpendicular to the plane of the annular projection 13 on the needle support 10, assure pefect centering in the bore 9.

The lower end of the needle support 10 is frustroconical, preferably shaped as a record frustrum 16, and has a shoulder 17, so that a plastic socket 18 projecting in the interior of the piston rod 3 can engage the needle support 10. In the case of a long cannula which, as the same time, is the injection needle, a frustrum 18 is not required.

The syringe body 2 with the piston rod 3 screwed on and the needle support 10 located inside it may be sterilized in ways already known, for example by using gamma rays. The device is secured against inadvertent twisting of the piston rod 3 by spot welding, which also presents the advantage of tamper-proof sealing.

In order to operate the syringe of the invention, the piston rod 3 is turned until retained by a stop 21. The projecting end of the cannula 11 thereby pierces the plastic membrane 12 and the rubber sealing 8, thus establishing a communication to the injection solution. The piston rod 3 is then removed by simple reversed turning and screwed into the piston stopper 6 placed at the upper end of the medicament container 1.

The injection needle, the size of which depends on the intended injection, is then placed on the record frustrum 16 of the needle support 10. It is also possible to use the injection cannula 11, which projects beyond the frustrum and is firmly connected to the needle support 10, as an injection needle. The injection device of the invention is then ready for a single injection of the medicament in the usual manner.

Compared with the single-injection devices made in accordance with the present state of the art, the device of the invention has the advantage that the whole cannula is located in a sterile chamber, that fractionation of the rubber disk or stopper and thus clogging of the cannula are avoided to a large extent and that, in the case of a long syringe body, provision of retaining beads ensures a locking effect which is superior to conventional types and, inter alia, ensures perfect aspiration. The retaining beads provide a reliable means of preventing the liquid container from falling out of the syringe or being exchanged unintentionally.

Claims

I claim:

1. A single-injection syringe, comprising a container for a medicament; said container having first and second open end positions; said first end portion of the container having a penetrable seal mounted therein for sealing said first end portion, and said second end portion having a piston inserted therein to define with said seal a chamber for containing the medicament; a syringe body mounted on and surrounding said first end portion of the container; said syringe body having a penetrable end wall extending across said first end portion of the container and an elongated generally cylindrical sleeve integrally formed with and extending from said wall; said sleeve having an elongated bore formed therein extending from said end wall to an open end located in spaced relation from said end wall and a threaded external periphery; a needle support mounted in said bore for movement between first and second positions therein; said needle support having a diameter which is slightly less than the diameter of said bore and including an annular projection formed thereon and at least four stabilizing fins extending perpendicularly thereto into engagement with the bore; a needle mounted in said support having an end portion located within said bore in the first position of the needle support and piercing said end wall and said seal as it is moved to its second position; said bore of said sleeve having a pair of spaced annular grooves formed therein respectively defining the first and second positions of said needle, said groove receiving and cooperating with said annular projection on the needle support to hold the needle support in its respective positions against inadvertent movement in the sleeve; and a hollow plunger including a first end portion threadably engaged with said threaded sleeve and operatively engaged in bearing engagement with said support, and a second end portion having means formed on the exterior thereof for engaging said piston when the plunger is removed from the sleeve; said needle support also including an annular shoulder formed thereon; and said plunger having an annular socket formed therein at its first end portion operatively engaging said annular shoulder in bearing engagement to urge said support towards the syringe body to cause the needle to pierce the end wall and seal upon rotation of the plunger on the sleeve when the plunger is rotated on the sleeve in a direction to move it towards the syringe body, said plunger having an elongated chamber formed therein receiving said needle, whereby said needle support forms, with the end wall of said syringe body an enclosed sterile chamber for the needle and is moved from its first to its second position to cause said needle to pierce said end wall and said seal when said plunger is threaded on the sleeve in a direction to move it towards the syringe body.

2. A syringe as claimed in claim 1 wherein said seal is a rubber stopper and has a conical cavity formed therein opening towards said chamber at the position at which the needle will pierce the seal.

3. A syringe as claimed in claim 1 wherein said syringe body extends only about said first end portion of the container and the liquid container has a flanged-out finger support formed thereon.

4. A syringe as claimed in claim 1 wherein the syringe body surrounds the entire container and has, adjacent the second end portion of the container, radially inwardly extending beads overlying the container for retaining the liquid container in the syringe body.