A drug mixing device is disclosed. The drug mixing device comprises an actuator configured to cause mixing of a first component of a drug with a second component of the drug； and a locking mechanism, having a locked state and a unlocked state. The actuation of the actuator is prevented when the locking mechanism is in the locked state and the actuation of the actuator is permitted when the locking mechanism is in the unlocked state. The locking mechanism is configured to adopt the unlocked state only when the mixing device is oriented in a specific orientation.
