Medicament delivery device

A multi-dose medicament delivery device comprising:

• a device front end;
• a device back end;
• a central longitudinal axis;
• a housing having a housing front end and a housing back end;
• a medicament container assembly, the medicament container assembly being configured for accommodating a medicament container with a stopper;
• a dose drum that is supported in the housing via a first threaded connection;
• wherein the dose drum is axially movable with respect to the housing in a backward direction from an initial position to at least one dosing position when rotated in a first direction in order to set a dose to be delivered;
• and
• wherein the dose drum is axially movable with respect to the housing in a forward direction from the dosing position to the initial position when rotated in a second, opposite direction in order to deliver the dose set;
• a plunger rod that is operationally associated with the stopper and supported in the housing via a second threaded connection, wherein the threaded connection is configured to axially guide the plunger rod toward the device front end when the plunger rod is rotated in the second direction, where the plunger rod has an inner surface with an inwardly radial protruding tooth corresponding to a predetermined dosing position;
• and
• an activation assembly comprising:
• a plunger rod rotator that is coupled to the dose drum and has at least one first deflecting member comprising an outwardly radial protruding tooth;
• an activator rod that is axially movable with respect to the plunger rod rotator from an uncoupling position to a coupling position, wherein, when the activator rod is in the coupling position and the dose drum is rotated in the second direction from the dosing position the plunger rod does not rotate until the outwardly radial protruding tooth of the at least one first deflecting member engages the inwardly radial protrusion;
• and
• at least one second deflecting member that is configured to lock the activator rod with respect to the plunger rod rotator in the coupling position until the dose drum reaches the initial position again.