Abstract: A retractable syringe, plunger and releasable needle assembly including a retractable needle, a needle seal, a retaining member and an ejector member. The retaining member has a mating surface for mounting to a complementary mating surface of an interior wall of a syringe barrel. The plunger comprises a plunger outer, a plunger rod frangibly connected to a controlling member, a spring and a unitary plunger seal capable of engaging the retractable needle, wherein the plunger rod, plunger outer and the controlling member co-operate to releasably maintain the spring in an initially compressed state. After delivery of fluid contents of the syringe, the plunger forces the ejector member to release the retractable needle from the retaining member. Decompression of the spring at the end of depression of the plunger facilitates retraction of the retractable needle when engaged with the unitary plunger seal.

Abstract: A barrel adapter mountable to a syringe barrel includes a barrel tip, a biasing member, a locking mechanism, and a needle assembly. A safety syringe includes a barrel, a plunger assembly, and a barrel adapter. The needle assembly includes a needle, a needle hub, and a needle seal. The needle is configured to pass-through the needle assembly, locking mechanism, biasing member, and barrel tip such that, at one end the needle is within the barrel and at another end the needle passes through an aperture in the barrel tip. The barrel may be substantially cylindrical, having along its longitudinal axis a distal end for drug injection, a proximal end for injection control, and at least a portion of the barrel interior for drug containment. The barrel adapter provides needle retraction mechanisms to the barrel to form a safety syringe. Methods of assembling, manufacturing, and using such syringes are also provided.

Abstract: A dose control mechanism for a syringe includes a plunger having a coarse pitch screw on its exterior surface, a housing having a corresponding coarse pitch guide along the interior surface of the housing, a screw having a fine pitch screw which interfaces with a fine pitch nut of an adapter, wherein the plunger has an internal annular space within which screw at least partially resides. An accurate dose drug delivery syringe includes such a dose control mechanism, a barrel, a plunger seal, and a barrel adapter assembly having a barrel tip and a needle. The syringe may be a fill-at-time-of-use syringe, a pre-filled syringe, or a safety syringe having integrated needle retraction or needle sheathing safety features, or a combination thereof. Methods of assembly, manufacturing, and operation are similarly disclosed.