A medicament delivery device configured to provide a variable single dose of medicament is disclosed. The medicament delivery device includes a main body and a syringe arranged in the main body, wherein the syringe comprises a medicament. The medicament delivery device further includes a removable cap and a plunger rod operatively arranged to eject the medicament through a delivery member i.e. an injection needle attached to the syringe. Still further, the medicament delivery device includes a tubular member coupled to the plunger rod. The tubular member is configured to rotate during removing of the removable cap, and the rotation releases the plunger rod thereby allowing the plunger rod to travel a predetermined distance so as to prime the medicament delivery device.被建構來提供一可變單一劑量藥物之藥物輸送裝置被揭示。該藥物輸送裝置包括主要本體及被配置在該主要本體中的注射器，其中該注射器包含藥物。該藥物輸送裝置另包括可移除蓋子及柱塞桿，該柱塞桿被操作地配置來經過輸送構件、亦即被附接至該注射器之注射針排出該藥物。又再者，該藥物輸送裝置包括被耦接至該柱塞桿的管狀構件。該管狀構件被建構來在移除該可移除蓋子期間旋轉，且該旋轉釋放該柱塞桿，藉此允許該柱塞桿行進一段預定距離，以便引動注給該藥物輸送裝置。
