Cassette for an autoinjector and related methods

A cassette fer a drug delivery device, the cassette comprising:

• a housing:
• a drive mechanism disposed at least partially within the housing and comprising a plunger rod configured to move relative to the housing during a drug extrusion operation;
• and
• a cassette comprising:
• a sleeve having a proximal end and a distal end;
• a syringe disposed in the sleeve, the syringe comprising a barrel having a distal opening adjacent to the distal end of the sleeve;
• a plunger-stopper slidably disposed within the barrel;
• an end cap coupled to the distal end of the sleeve adjacent the distal opening of the barrel to secure the syringe in the sleeve;
• and
• a spacer disposed distally of the plunger-stopper having a diameter approximately equal to a diameter of the plunger-stopper, the spacer configured and sized to be slidably moved within the barrel and adapted to be engaged by the plunger rod of the drive mechanism to slide within the barrel and engage the plunger-stopper, wherein, following assembly of the cassette within the housing and until the drug extrusion operation, the spacer is spaced from the plunger-stopper by a gap, and wherein the spacer is brought into initial contact with the plunger-stopper by movement of the plunger rod when the plunger rod moves to expel a drug from the syringe during the drug extrusion operation.