Mixing pen needle

1. 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.

2. The medication pen according to claim 1 , wherein each medication compartment comprises a medication cartridge and each dosage plunger engages a respective medication cartridge.

3. The medication pen according to claim 1 , further comprising a check valve on the filler needle preventing backflow from the mixing reservoir into the first and second medication compartments.

4. The medication pen according to claim 1 , wherein the first and second dosing mechanisms comprise first and second rotatable knobs protruding from the proximal end of the pen body.

5. The medication pen according to claim 1 , wherein the movable housing is connected to the pen body by a shaft having a longitudinal axis, the shaft being disposed to slide into the pen body, and the movable housing is rotatable about the axis of the shaft, from a first position in which the filler needle is axially aligned with the first medication compartment to a second position in which the filler needle is axially aligned with the second medication compartment.

6. The medication pen according to claim 1 , wherein the collapsible mixing reservoir includes a stopper moving within and sealing the mixing reservoir, wherein the patient end needle extends through the stopper to access the mixing reservoir, and wherein a sleeve on the exterior of the pen needle assembly is secured to the stopper, so that moving the sleeve in a proximal direction moves the stopper to collapse the mixing reservoir, forcing medication out of the patient end needle.

7. The medication pen according to claim 1 , wherein the first medication compartment contains insulin and the second medication compartment contains GLP.

8. The medication pen according to claim 1 , including a recessed opening on a distal end of the movable housing adapted to receive the proximal end of the pen needle assembly to provide access to the medication compartment.

9. The medication pen according to claim 1 , including a threaded opening protruding from a distal end of the movable housing adapted to receive an internally threaded opening on a proximal end of the pen needle assembly.

10. The medication pen according to claim 1 , comprising a shaft connecting the movable housing and the pen body, said shaft sliding proximally and distally in the pen body from a proximal position in which the filler needle of the pen needle assembly is engaged in one of said medication compartments and a distal position in which the pen needle assembly rotates with respect to the pen body, such that a pen needle installed on the movable housing is moved from 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.

11. The medication pen of claim 1 , wherein the pen needle assembly comprises a first removable cover on the patient end needle which is removed prior to administering an injection.

12. The medication pen of claim 1 , wherein the pen needle assembly comprises a second removable cover on the filler needle which is removed prior to installing the pen needle assembly on the movable housing.

13. The medication pen according to claim 1 , comprising a shaft connecting the movable housing and the pen body, the shaft sliding proximally and distally in the pen body from a distal position in which first and second medication cartridges can be respectively inserted proximally into said first and second medication compartments in the pen body, to a proximal position in which the filler needle of the pen needle assembly is engaged in one of said medication compartments.