The invention relates to a drug delivery device (1), comprising a control unit (2), a drive unit (3), a pressurizing medium container (4) arranged to contain a pressurizing liquid, a drug container (5) arranged to contain a drug and a discharge nozzle (6), wherein the drive unit (3) when controlled and energized by the control unit (2) is arranged to generate a pressure gradient in the pressurizing liquid thereby propagating the pressure to the drug container (5) and at least partially displacing the drug from the drug container (5) through the discharge nozzle (6), wherein the drive unit (3) is arranged as an electro-osmotic actor (3).