Abstract: 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.

Abstract: Plunger sub-assemblies for automatic injectors include a plunger outer having one or more engagement prongs, a plunger inner having one or more engagement slots which correspond with the engagement prongs of the plunger outer, and a retraction biasing member. The retraction biasing member is retained in a first energized state between the plunger outer and plunger inner when the engagement prongs of the plunger outer are releasably engaged with the engagement slots of the plunger inner. The one or more engagement prongs are capable of flexing substantially radially to release from engagement with the engagement slots of the plunger inner to permit the retraction biasing member to expand from the first energized state to a second expanded state. An automatic injector having a plunger sub-assembly includes a housing, an activation mechanism, and a plunger sub-assembly at least partially mounted within a syringe cartridge having a needle assembly.

Abstract: 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.

Abstract: 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.

Abstract: An actuation mechanism for an automatic injector includes a first actuation spring, a first actuation pill, a second actuation spring, and a second actuation pill. In an initial configuration the first actuation spring resides in a compressed, energized state substantially within an upper portion of first actuation pill and the second actuation spring resides in a compressed, energized state between the first actuation pill and the second actuation pill. An automatic injector includes a housing, an activation mechanism, an actuation mechanism, and a syringe cartridge having a plunger and a needle assembly. A retractable syringe may be utilized as a syringe cartridge, such as a prefilled retractable syringe with integrated safety features which retract the needle after use. The automatic injector may be utilized to inject the needle, deliver a drug treatment, and activate retraction of the needle. Methods of assembly and operation are also provided.

Abstract: 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.

Abstract: Plunger sub-assemblies for automatic injectors include a plunger outer having one or more engagement prongs, a plunger inner having one or more engagement slots which correspond with the engagement prongs of the plunger outer, and a retraction biasing member. The retraction biasing member is retained in a first energized state between the plunger outer and plunger inner when the engagement prongs of the plunger outer are releasably engaged with the engagement slots of the plunger inner. The one or more engagement prongs are capable of flexing substantially radially to release from engagement with the engagement slots of the plunger inner to permit the retraction biasing member to expand from the first energized state to a second expanded state. An automatic injector having a plunger sub-assembly includes a housing, an activation mechanism, and a plunger sub-assembly at least partially mounted within a syringe cartridge having a needle assembly.

Abstract: Plunger sub-assemblies for automatic injectors include a plunger outer having one or more engagement prongs, a plunger inner having one or more engagement slots which correspond with the engagement prongs of the plunger outer, and a retraction biasing member. The retraction biasing member is retained in a first energized state between the plunger outer and plunger inner when the engagement prongs of the plunger outer are releasably engaged with the engagement slots of the plunger inner. The one or more engagement prongs are capable of flexing substantially radially to release from engagement with the engagement slots of the plunger inner to permit the retraction biasing member to expand from the first energized state to a second expanded state. An automatic injector having a plunger sub-assembly includes a housing, an activation mechanism, and a plunger sub-assembly at least partially mounted within a syringe cartridge having a needle assembly.

Abstract: 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.

Abstract: 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.

Abstract: Plunger sub-assemblies for automatic injectors include a plunger outer having one or more engagement prongs, a plunger inner having one or more engagement slots which correspond with the engagement prongs of the plunger outer, and a retraction biasing member. The retraction biasing member is retained in a first energized state between the plunger outer and plunger inner when the engagement prongs of the plunger outer are releasably engaged with the engagement slots of the plunger inner. The one or more engagement prongs are capable of flexing substantially radially to release from engagement with the engagement slots of the plunger inner to permit the retraction biasing member to expand from the first energized state to a second expanded state. An automatic injector having a plunger sub-assembly includes a housing, an activation mechanism, and a plunger sub-assembly at least partially mounted within a syringe cartridge having a needle assembly.

Abstract: An actuation mechanism for an automatic injector includes a first actuation spring, a first actuation pill, a second actuation spring, and a second actuation pill. In an initial configuration the first actuation spring resides in a compressed, energized state substantially within an upper portion of first actuation pill and the second actuation spring resides in a compressed, energized state between the first actuation pill and the second actuation pill. An automatic injector includes a housing, an activation mechanism, an actuation mechanism, and a syringe cartridge having a plunger and a needle assembly. A retractable syringe may be utilized as a syringe cartridge, such as a prefilled retractable syringe with integrated safety features which retract the needle after use. The automatic injector may be utilized to inject the needle, deliver a drug treatment, and activate retraction of the needle. Methods of assembly and operation are also provided.