A drug delivery device includes a housing releasably coupled with a patient, a pressure chamber disposed in the housing and including a vent, a container at least partially disposed in the pressure chamber for storing a drug connectable in fluid communication with a fluid conduit, an activation mechanism, and a relief mechanism. The activation mechanism releases a pressurized drive fluid into the pressure chamber for expelling the drug from the container into the fluid conduit. The relief mechanism is operably coupled to the fluid conduit and is adapted to open the vent to release the drive fluid from the pressure chamber in response to a predetermined condition.