GB2241893A - Hypodermic syringe - Google Patents

Abstract

A non-reusable hypodermic syringe comprises a barrel 1 of elastomeric material with a diaphragm 4 inserted near the end further from the needle. A separate plunger 5 is a loose sliding fit within the barrel. The syringe may be filled by squeezing the barrel, or it may be supplied already prefilled and sterilised. The end nearest the needle may be strengthened or reinforced. <IMAGE>

Description

Hypodermic syringe This invention relates to hypodermic syringes, and, in particular to hypodermic syringes so designed that they cannot readily be re-used.

Hypodermic syringes nowadays are normally of the disposable kind, pre-packed in sterile packaging, and intended to be discarded after a single use. However, sometimes such syringes are often retrieved for further use, for example for the illicit administration of drugs, or for re-use in mass vaccination programmes under primitive conditions where equipment is in short supply. Such re-use is highly undesirable, since it carries a risk of transmitting blood-borne diseases such as hepatitis and AIDS.

An object of the present invention is to provide a syringe which is inexpensive to manufacture in large numbers, readily capable of being sterilised, and which cannot readily be re-used for further injection.

The invention is defined in the claims which follow.

The invention will be described with reference to the accompanying drawings, in which Figure 1 shows, in diagrammatic outline, a syringe according to the invention, and Figure 2 indicates a method of filling the syringe.

Referring first to Figure 1, the syringe comprises a barrel 1 of elastomeric material, preferably transparent, with projections or a collar at one end to provide a finger grip 2 and having a hypodermic needle 3, or a mount for such a needle, at the other.

Preferably the needle is integral with the barrel, the upper end of the needle being moulded into the material of the barrel during manufacture, so that neither the body of the syringe nor the needle is recoverable for re-use.

A diaphragm 4 is a sliding fit within the barrel, the fit being tight enought to ensure that it is liquid-tight so as to prevent the contents of the barrel from leaking past it. Initially the diaphragm is positioned within the barrel near its upper end, that is to say the end farthest from the needle. A separate plunger, 5, shown very diagrammatically in Figure 1, is a loose sliding fit within the barrel.

The syringe body and plunger are hermetically sealed within a package, which is then sterilised.

When the syringe is to be used, the package is opened and the needle inserted through the sterilised rubber seal of an ampoule of vaccine or other material to be injected. Then, by repeatedly squeezing the flexible wall of the barrel, as indicated by the arrows in Figure 2, sterile air is expelled from the syringe barrel into the ampoule and is replaced by the vaccine. When the required quantity has been transferred the needle is withdrawn, the plunger inserted, any excess air remaining within the syringe is expelled, and injection is carried out in the usual way.

After use the plunger is at the bottom of the barrel in the position shown in Figure 1, making it difficult or impossible to re-use the syringe. To add further to the difficulty of restoring the syringe to a usable condition the lower end of the barrel may be strengthened, for example by making it thicker or by reinforcing it with rigid material, so preventing the diaphragm from being manipulated through the barrel wall.

In an alternative form of the invention the syringe is pre-loaded during manufacture with a medicament to be injected, and supplied in a sterile packaged condition ready for immediate use.

Claims (5)

1. A non-reusable hypodermic syringe comprising a barrel of elastomeric material with a diaphragm inserted near the end remote from the needle or needle mount, the diaphragm being a liquid-tight sliding fit in the barrel, in combination with a plunger which is a loose sliding fit within the barrel.

2. A non-reusable hypodermic syringe according to claim 1 in which the material of the barrel is transparent.

3. A non-reusable hypodermic syringe according to claim 1 or claim 2 in which the needle is moulded integrally into the end of the barrel.

4. A non-reusable hypodermic syringe according to any preceding claim prefilled with a substance for injection

5. A non-reusable hypodermic syringe according to any preceding claim in which the end of the barrel nearest the needle is strengthened or reinforced so that the diaphragm cannot be manipulated through the barrel.