The present invention relates to a dose setting mechanism for a drug delivery device and a method of using same. The mechanism comprises a drug delivery device housing(205), a dose dial component(104) positioned in the housing(205) and rotatable during dose setting and dose delivery, a clutch(105) rotatable during dose setting and non-rotatable during dose delivery having, preferably located at a distal end, clutch teeth(109), and a clutch ring(102) engaged with the housing(205) in a first rotatable configuration and in a second non-rotatable configuration.本發明係有關於用於一藥物輸送裝置的一劑量設定機構以及其一使用方法。該機構包含一藥物輸送裝置外殼(205)，一劑量標度組件(104)，其係配置在該外殼(205)中，並可在劑量設定與劑量輸送期間轉動，一離合器(105)，其可在劑量設定期間轉動，以及在劑量輸送期間不可轉動，較佳地在一遠端處其具有離合器齒件(109)，以及一離合器環件(102)，其與該外殼(205)在一第一可轉動構形以及一第二不可轉動構形中嚙合。
