The present invention is generally directed to a drug delivery device for selecting and dispensing a number of user variable doses of a medicament. The device comprises a housing (10) having a tubular portion (12) with an inner thread, a piston rod (30) having a threaded portion (31) and a distal end, and a bearing (140) having a distal face and a proximal face. The bearing (140) comprises a retaining stem (142) protruding from the proximal face. The piston rod (30) comprises a distal portion having an outer diameter which is smaller than the inner diameter of the inner thread of the tubular portion (12) and comprising at its distal end at least one retaining clip (33, 33') engaging the retaining stem (142). The axial length of the tubular portion (12) is smaller than or equal to the axial distance between the proximal face of the bearing disc (141) and the distal end of the threaded portion (31) of the piston rod (30). During manufacturing of the device, the retaining clip (33, 33') engages the retaining stem (142) prior to the inner thread of the tubular portion (12) engages with the threaded portion (31) of the piston rod (30).本發明總體涉及用於選擇和分配多個用戶可變藥劑劑量的藥物輸送裝置。該裝置包括具有帶內螺紋的管狀部分(12)的殼體(10)、具有螺紋部分(31)和遠側端的活塞桿(30)，以及具有遠側面和近側面的支承件(140)。支承件(140)包括從近側面突出的保持桿(142)。活塞桿(30)包括外徑小於管狀部分(12)的內螺紋的內徑的遠側部，並且在其遠側端包括接合保持桿(142)的至少一個保持夾(33，33')。管狀部分(12)的軸向長度小於或者等於支承盤(141)的近側面和活塞桿(30)的螺紋部分(31)的遠側端之間的軸向距離。在製造裝置期間，保持夾(33，33')在管狀部分(12)的內螺紋接合活塞桿(30)的螺紋部分(31)之前接合保持桿(142)。
