A low retraction activation force plunger sub-assembly for an automatic injector includes: a plunger outer having one or more engagement prongs, a plunger inner having a shoulder, and a plunger biasing member retained in a first energized state between said plunger outer and plunger inner when the engagement prongs of the plunger outer are releasably engaged with the shoulder of the plunger inner. An automatic injector includes a housing, an activation mechanism, an actuation mechanism, and a syringe cartridge having the plunger sub-assembly and a needle assembly, wherein the actuation mechanism includes comprises an actuation biasing member residing in an initial energized state substantially within an upper portion of an actuation pill. A method of assembling the automatic injector includes the steps of: assembling the plunger sub-assembly and inserting the plunger sub-assembly into the housing such that a proximal end of the plunger sub-assembly contacts the actuation pill.

A mixing device and a retractable syringe comprising same are provided. The mixing device comprises concentric outer and inner barrels that form an outer chamber, the inner barrel having an inner chamber. A mixing plunger is slidably located in the outer chamber. A seal located in the outer chamber is capable of axial movement, in response to depression of the mixing plunger, from a first position in sealing engagement with one or more apertures in the inner barrel to a second position intermediate the apertures and vents in the outer barrel. This allows depression of the mixing plunger to force a first substance from the outer chamber through the apertures to mix with a second substance in the inner chamber. The mixed substance in the inner barrel is then delivered by the syringe with subsequent needle retraction.

A combination plunger, a mixing device and a mixing syringe including the same are provided. The mixing syringe includes concentric outer and inner barrels that form an outer chamber, the inner barrel having an inner chamber. The combination plunger includes a mixing plunger and a delivery plunger and a biasing means. The mixing plunger is slidably located in the outer chamber and translated by coordinated depression of the delivery plunger to transfer a first substance from the outer chamber to mix with a second substance in the inner chamber. After the mixing stage is complete, the delivery plunger is disengaged from the mixing plunger and permitted, such as by rotation, to be further depressed in the axial direction to deliver fluid contents of the mixing syringe to a recipient. The mixing syringe needle is then retracted as result of engagement by the delivery plunger and activation of the biasing means.

An injection device comprises a barrel having a proximal end for a needle to protrude therefrom; a needle assembly having a double-pointed hollow needle and a biasing means operable to bias the double-pointed hollow needle away from the proximal end of the barrel; a cartridge; and a mechanism operable to cause the cartridge to be punctured by the first end of the needle, and to cause the second end of the needle to protrude from the proximal end of the barrel and to be locked in the protruded position.

Methods and systems for an injection system are provided. An example injection system includes a container for a pharmaceutical that is sealed at a proximal end with a plunger having a pushing surface for engaging an inner surface of the hollow body. A plunger rod extends axially from the proximal end of the container and is covered with a plunger rod cover. Removal of the cover activates the system and allows for delivery of the pharmaceutical product from the container by advancing the plunger within the container towards the seal.

Methods and systems for an injection system are provided. An example injection system includes a container for a pharmaceutical that is sealed at a proximal end with a plunger having a pushing surface for engaging an inner surface of the hollow body. A plunger rod extends axially from the proximal end of the container and is covered with a plunger rod cover. Removal of the cover activates the system and allows for delivery of the pharmaceutical product from the container by advancing the plunger within the container towards the seal.

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.

An automatic injection device for use with a syringe, including a housing element; at least one resilient element arranged to be located within the housing element; a needle guard slidably positionable with respect to the housing element; a control unit configured to be fixedly coupled with the housing element; a plunger rod biased axially forwardly under an urge of the at least one resilient element and configured to engage the control unit in a storage operative orientation, in which the plunger rod is prevented from forward axial displacement relative to the control unit under the urge of the at least one resilient element; and upon axial rearward displacement of the needle guard with respect to the housing element, the plunger rod is disengaged from the control unit and is permitted to be axially forwardly displaced relative to the control unit under the urge of the at least one resilient element.