US Patent 9345834 Autoinjector

Described is an autoinjector comprising a case, a drive carriage disposed in the case, and a plunger coupled to the drive carriage. The plunger is adapted to releasably engage a needle retraction mechanism in a syringe. Translation of the drive carriage in a distal direction relative to the case causes the plunger to engage the needle retraction mechanism and translation of the drive carriage in a proximal direction relative to the casing case the plunger to needle retraction mechanism the stopper.