DRIVE MODULES FOR INJECTORS, AND SYSTEMS AND METHODS FOR USING SUCH DRIVE MODULES

An injection device for delivering an agent into a patient's body including a drive module and an injector module. The drive module includes a canister and puncture mechanism in a first chamber, a plunger in a second chamber communicating with the first chamber, and an actuator that moves the puncture mechanism to cause a puncture pin thereon to penetrate a septum of the canister and cause the gas within the canister to flow through the first chamber into the second chamber. The plunger includes a proximal end including a piston and a distal end and is configured such that gas entering the second chamber causes the plunger to move from an initial position to an extended position for delivering one or more agents from the injector module, the piston including one or more passages that allow gas from the canister to pass through the piston into the second chamber around the plunger.