Mixing pen needle

A medication pen comprising:

• a pen body having a distal end and a proximal end, and having a first medication compartment and a second medication compartment;
• first and second dosing mechanisms and first and second dosage plungers engaged in the respective first and second medication compartments;
• a movable housing received on the distal end of the pen body adapted to be received in first and second positions on the pen body;
• a pen needle assembly received on the distal end of the movable housing, said pen needle assembly comprising a patient end needle, a filler needle, and a collapsible mixing reservoir intermediate and accessed by said patient end needle and said filler needle;
• wherein the movable housing is movable between a first position in which the filler needle is in fluid communication with the first medication compartment and a second position in which the filler needle is in fluid communication with the second medication compartment;
• and
• wherein collapsing the mixing reservoir forces medication in the mixing reservoir through the patient end needle during an injection.