Injection device

An injection device for administering a fixed dose of a medication comprising:

• a housing directly engaged with a drive member having a dosing element permanently fixed thereto, is at least partially enclosed by the housing and has an inner surface;
• and
• a piston rod directly engaged with the inner surface of the drive member;
• wherein the engagement between the housing and the drive member is through a combination of a thread and an engaging feature where each is located on one of the housing and the drive member, where the combination is configured to allow only a single predefined fixed dose to be set by rotating the dosing element and the drive member relative to the housing in a dose setting direction(s) such that the drive member moves axially in a proximal direction and the dose can be dispensed by pushing the dosing element in a distal direction towards the housing causing the drive member to directly move the piston rod distally,
• wherein the thread has a dose setting section with a first lead and a dose dispense section having a second lead that is different from the first lead, where the first lead allows rotation of the drive member without movement of the piston rod during dose setting and the second lead allows distal movement of the drive member causing simultaneous distal movement of the piston rod.