Medication delivery device

A medication delivery device comprising a cartridge assembly having opposite ends and a dosing assembly for setting a desired dose and acting on the cartridge assembly to cause the desired dose to be delivered, wherein:

• the cartridge assembly includes a molded cartridge and a stopper disposed in the cartridge, wherein one end of the cartridge assembly is sealed with a pierceable sealing, wherein the one end includes a first coupling means for releasably mounting a needle assembly having a skin-piercing needle, and wherein the other end of the cartridge assembly includes a second coupling means for engaging the dosing assembly, wherein at least one of the coupling means is unitarily molded with the cartridge, and wherein the dosing assembly includes a housing, a plunger, and a mechanism for setting a desired dose and for moving the plunger relative to the housing in an axial direction for administering a set dose, and wherein the dosing assembly housing includes a coupling member for engaging the second coupling means of the cartridge assembly for securing the housing against axial movement relative to the cartridge assembly such that the plunger engages the stopper for moving the stopper in response to the plunger movement wherein the at least one coupling means of the cartridge assembly is a threaded coupling and wherein the second coupling means is an external threaded coupling.