Medicament delivery device

A medicament delivery device, comprising:

• an elongated housing having a window and arranged to contain a medicament container that contains a number of doses;
• a dose counter mechanism, comprising a dose drum arranged with dose indicia on an outer surface of the dose drum visible through the window;
• a rotatable driver connected to the dose drum;
• a plunger rod arranged to act on the medicament container for expelling a dose of medicament;
• and
• an actuation mechanism connected to the rotatable driver and to the plunger rod when the medicament delivery device is actuated, the actuation mechanism comprising a toggle sleeve and an actuation button, wherein the actuation button is operably connected to the toggle sleeve that is operably connected to the rotatable driver such that the rotatable driver is rotated when the actuation button is actuated;
• wherein the dose drum includes internal threads for engaging corresponding threads on the rotatable driver, the internal threads having a first pitch;
• and the dose drum includes external threads for engaging corresponding threads arranged in fixed relation to the housing, the external threads having a second pitch that is less than the first pitch of the threads on the rotatable driver, such that when the rotatable driver is rotated a certain angular distance, the dose drum is rotated a lesser angular distance.