Drug reconstitution system

A drug reconstitution device comprising a single use disposable liquid transfer unit (18) and a reusable control and drive unit (16) removably connectable to the liquid transfer unit, the disposable liquid transfer unit including a housing (26), a docking interface (30) configured for coupling at least one of first and second constituent containers (2, 4) to the housing (10), and a pump engine (28) and fluid flow system (37) configured for transferring liquid from the first constituent container (2) to the second constituent container (4), the control and drive unit comprising a pump drive (22) configured to drive the pump engine during a fluid pumping action, the pump drive comprising a transmission output coupling (34) removably engaged with a transmission input coupling (50) of the pump engine (28) when the liquid transfer unit and control and drive unit are connected, wherein the pump engine is configured as a rotary pump and comprises a rotor rotatably moveable in a stator and integrated with said transmission input coupling (50), the transmission input coupling removably engageable with a transmission output coupling of the pump drive.