A drug delivery device for delivering to a patient a drug composition from a container which contains the drug composition where the container is adapted to be placed in a dispensing mode thereof on application of an actuating condition thereto is disclosed. The device includes a dispensing unit adapted to receive the container, the dispensing unit having an actuating mechanism operable to apply the actuating condition to the container and an outlet through which the drug composition is dispensable from the device, and a removable casing unit for the dispensing unit. The dispensing and casing units have securing features for releasably, fixedly securing the units together, and the dispensing unit is operable to apply the actuating condition to the container when fixedly secured to the casing unit and when independent from the casing unit.