The present invention relates to a dose setting mechanism for a drug delivery device and a method of using same. The mechanism comprises a housing, a mechanism member movable in a first axial direction relative to the housing during dose setting and movable in a second, opposite axial direction relative to the housing during injection, wherein the mechanism member is designed and arranged such that the mechanism member is able to change its condition between a first condition preventing movement in the second axial direction and a second condition allowing movement in the second axial direction, and a switching member forcing the mechanism member to change from its second condition into its first condition at a predefined position of the movement in the first axial direction during dose setting.本發明係有關一用於藥物傳輸裝置之劑量設定機構及其使用方法。該機構係包含一殼體,一機構構件,其在劑量設定期間相對於殼體可移動於一第一軸向方向且在注射期間相對於殼體可移動於一第二相對軸向方向,其中機構構件係設計且配置為使機構構件能夠改變其狀況於一防止第二軸向方向的運動之第一狀況與一容許第二軸向方向的運動之第二狀況之間,及一切換構件,其迫使機構構件在劑量設定期間於第一軸向方向的運動之一預定位置從其第二狀況改變成其第一狀況。5‧‧‧驅動器7‧‧‧撓性碟元件9‧‧‧縮小直徑段L‧‧‧長度
