Abstract: An auto injector including: a housing; an outlet portion with a needle (110) moveable relative to the housing; a container (104) within the housing for containing medicament; and an actuatable deployment mechanism configured to deploy the outlet portion by moving the outlet portion relative to the housing and to eject medicament contained in the container through the outlet portion. The auto injector is configured to store a volume of fluid and includes a filling mechanism configured to expel the volume of fluid from the outlet portion and subsequently to draw medicament through the outlet portion and into the container. An adaptor (112) fits to the auto injector so as to cover the needle and includes a puncture member configured to puncture a vial, the puncture member providing fluid communication to the needle.