A safety device for use with standard or dental syringes as an add-on feature or as a retrofit in which a safety sleeve moves over the normally exposed front end of a needle to protect users from being accidentally stuck.

A disposable safety syringe has a needle shuttle slidably located within a main syringe barrel. The shuttle has a pair of outwardly extending guide tabs which engage a guide slot formed in the barrel wall. The upper end of the needle shuttle is configured to accept a Wyeth needle cartridge having a needle attached to an ampoule by a carrier. A bushing and rod assembly are mounted in the barrel below the ampoule. After use, the needle shuttle is maneuvered downwardly by the guide tabs to a locking position in which the needle attached to the ampoule is housed within the barrel for safe disposal.

A cartridge syringe with a slideable protective sheath to prevent accidental needle sticks following administration of a an injection is described. The device comprises a syringe cartridge, comprising a constricted distal end region, a piston movably disposed within the barrel, a hub having an axial bore mounted to the constricted distal end region of the barrel, and a hollow needle, the proximal end of the hollow needle projecting through the axial bore of the hub and the distal end of the needle having a pointed tip; and a protective sheath having an inner diameter greater than the external diameter of the syringe cartridge, such that the protective sheath is slideably movable substantially coaxially along the external surface of the cartridge barrel from a first position in which the tip of the needle extends past both ends of the protective sheath, to a second position in which the distal end of the sheath extends past the tip of the needle.

A needle-covering sleeve (14), slidably fitted on the syringe barrel (1), is held in its retracted rest position by means of retaining tongues (10), which hook it at its rear rim (13). At the end of the injection stroke of the plunger (2), a rear flange (8) of the stem (3) of the plunger (2) radially opens the retaining tongues (10) apart, which release thereby the needle-covering sleeve (14). Then, the latter is axially advanced by means of a spring (16), to an advanced safety position, in which it entirely covers the needle (5) and is fastened to a sleeve-clamping ring (18), which is provided at the fore end of the syringe barrel (1). To this purpose, the sleeve-clamping ring (18) has peripheral elastic retaining tongues (19) which interact with matching retaining teeth (20) on the inner part of needle-covering sleeve (14) and prevent any axial backward movement of the needle-covering sleeve (14). Further, the sleeve-clamping ring (18) is a stop abutment, cooperating with an inner projection of the needle-covering sleeve (14) and preventing any further axial forward movement of such sleeve.

A protective assembly for use with needle-bearing injector devices includes a pair of cylindrical sleeve members, initially concentrically disposed relative one another and adapted to be fitted about a conventional hypodermic syringe assembly. Prior to use of the injector device, the protective assembly is slipped over the needle, which is preferably covered by a sheath, until a latch mechanism on an inner one of the sleeves becomes locked between the hub of the needle and the forward portion of the syringe barrel. Following use of the injector device, an outer one of the sleeves is displaced forwardly until a latch mechanism adjacent its rear portion snap-fits within a catch provision on the forward portion of the inner sleeve, thus providing a post-use position wherein the syringe needle is fully peripherally surrounded by the extension of the outer sleeve. Both catch mechanisms are constructed to forestall reverse manipulation of either sleeve member so that not only is the possibility of needle sticks discouraged but also, reuse of the injector device is thwarted.