Retractable needle syringe with unitary propellant release module

A modular retractable needle assembly for engagement with a barrel of a retractable needle syringe having a plunger, the modular retractable needle assembly comprising:

• a body having an upper chamber at a proximal end thereof;
• a propellant chamber defined within the body, the propellant chamber having an inside wall and an outside wall provided by the body;
• a seal sealingly engaged over an upper proximal edge of each of the inside wall and the outside wall of the propellant chamber to seal a propellant in the propellant chamber;
• a retention member initially engaged within the upper chamber, the retention member being moveable in a distal direction in response to an application of a post-injection force to the plunger by a user;
• a needle hub initially engaged within the retention member, the needle hub being engageable with a retractable locking tip of the plunger upon the application of the post-injection force to the plunger by the user;
• a needle for injecting medicament into a patient engaged with the needle hub and projecting distally from the body;
• and
• a rupturing member projecting in the distal direction, the rupturing member being moveable in the distal direction in response to the application of the post-injection force to the plunger by the user to rupture the seal and thereby release propellant into the upper chamber.