Abstract: The present invention is a hypodermic syringe pre-filled with a volume of a desired solution. A plug member is positioned within the hypodermic syringe in between the pre-filled fluid and the lumen of the syringe's cannula. The presence of the plug member within the hypodermic syringe separates the cannula from the pre-filled fluid thereby leaving the cannula unaffected by the presence of the fluid within the syringe. As the plunger of the hypodermic syringe is engaged, the pressure of the pre-filled fluid is increased. The fluid pressure acts upon the plug member, displacing the plug member when a predetermined fluid pressure is achieved. Once the plug member is displaced, the occlusion between the pre-filled fluid and the cannula is removed and the pre-filled fluid is free to flow through the lumen of the cannula.

Abstract: A pre-filled hypodermic syringe includes a retractable needle and detachable plunger shaft so the syringe can be selectively rendered inoperable. A liquid held within the syringe is held in place by a elastomeric stop that surrounds the discharging tip of the needle. When the syringe is to be used, the needle stop is removed and the plunger is advanced within the syringe barrel until the liquid is displaced through the needle. When the plunger contacts the base of the needle within the syringe barrel, the plunger becomes capable of being rotated. The rotation of the plunger connects the plunger to the needle and the needle can be retracted into the syringe barrel with the plunger. Once fully retracted, the needle cants and the plunger shaft can be destructively disconnected from the plunger, rendering the syringe inoperable.

Abstract: A syringe and needle assembly having a piston that is formed to engage and retract the needle assembly into the syringe barrel. The piston includes a spring member that is elastically deformed by the attachment of the piston to the needle assembly. The spring member causes the needle assembly to be spring biased into a canted position so that, once retracted into the syringe barrel, the needle assembly cants to an inoperable position.