A drug reconstitution device comprising a disposable liquid transfer unit (18) and a reusable control and drive unit (16) removably connectable to the liquid transfer unit, the liquid transfer unit including a housing (26), a docking interface (30) configured for coupling at least one of the first and second constituent containers (2, 4) to the housing (10), and a pump engine (28) and fluid flow system (36) configured for transferring liquid from the first constituent container (2) to the second constituent container (4). The control and drive unit comprises a pump drive (22) configured to drive the pump engine during a liquid transfer 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.
