Injection device for delivering a fixed dose of liquid drug

A method for delivering a predetermined fixed dose of liquid drug from an injection device, the method comprising:

• providing a device comprising:
• a base member,
• a variable volume reservoir adapted to contain the liquid drug and comprising an outlet,
• a piston rod defining a longitudinal axis and being adapted to cooperate with a piston in causing the predetermined fixed dose to be delivered from the variable volume reservoir,
• a first tubular member operatively coupled with the base member and movable to set the predetermined fixed dose,
• a second tubular member operatively coupled with the first tubular member and the piston rod, and
• means for preventing setting of a new dose once the predetermined fixed dose has been set and the ejection has commenced until the entire predetermined fixed dose has been ejected,
• rotating the first tubular member from a zero dose position to a predefined dose setting stop to set the predetermined fixed dose, and
• non-rotationally advancing the first tubular member along the longitudinal axis to eject the predetermined fixed dose through the outlet.