Patent ID: 7033338

Claim:
A cartridge for use in a medication pump, comprising: a cylindrical barrel comprising an open end and a closed end, wherein the closed end defines an orifice, wherein the open end has an outer edge that is symmetrical about a central longitudinal axis extending from the open end to the closed end; a plunger slidably received within the barrel, the plunger comprising a cylindrical wall having an interior cylindrical wall face, wherein a first tab projects inwardly from the interior wall face; and a removable cartridge rod comprising a shaft and an interface cylinder at one end of the shaft, the interface cylinder defining a first channel for receiving and retaining the first tab of the plunger wherein the first channel of the interface cylinder includes an axial portion disposed parallel to an axis of the shaft and a locking portion disposed in a circumferential direction around an outer surface of the interface cylinder.