The present invention relates to an medicament delivery device (10) having a proximal (11) and distal end (12) and intended for use in combination with a disposable container (20) having a distal and proximal end and comprising at least one chamber in the proximal end for a liquid medicament encapsulated in the container (20) by a movable plunger (26). The medicament delivery device (10) comprises: an elogated housing comprising a proximal housing section (13) and a distal housing section (14), said proximal housing section is configured to accomodate the disposable container (20) an elongated plunger rod (30) configured to be in contact with said movable plunger (26) and a drive mechanism arranged in said distal housing section (14) in order to, when the medicament delivery device (10) is activated, apply a force in a proximal direction via said plunger rod (30) acting on said movable plunger (26), wherein said elongated plunger rod (30) comprises an outer periphery in which at least two axially separated recesses and/or cut-out portions (36) are arranged to prevent that leaking fluid is flowing along the plunger rod to the drive mechanism.本發明有關一藥物輸送裝置(10),具有近側端(11)與遠側端(12),且意欲供與用完即丟之容器(20)組合地使用,該容器(20)具有一遠側與近側端,並在該近側端中包括用於藉由可運動柱塞(26)被封裝在該容器(20)的液體藥物之至少一室。該藥物輸送裝置(10)包括瘦長的外殼,包括一近側外殼區段(13)與一遠側外殼區段(14),該近側外殼區段被建構成容納該用完即丟之容器(20);瘦長的柱塞桿(30),被建構成將與該可運動柱塞(26)接觸;及驅動機件,被配置在該遠側外殼區段(14)中,以便當該藥物輸送裝置(10)被作動時,於近側方向中經由作用在該可運動柱塞(26)上之柱塞桿(30)施加一力量,其中該瘦長的柱塞桿(30)包括一外周邊,至少二軸向分開的凹部及/或切口部分(36)被配置在該外周邊中,以防止該滲漏流體正沿著該柱塞桿流動至該驅動機件。26‧‧‧柱塞30‧‧‧柱塞桿31‧‧‧滑動面32‧‧‧較薄區段33‧‧‧突出部分34‧‧‧旋轉器35‧‧‧溝槽36‧‧‧切口部分37‧‧‧核心38‧‧‧外周邊
