A device for storing and administering drug includes a housing, a sealing element (3) and a separate low friction plunger (4) which is substantially-permeable to gas over time. The sealing element (3) is typically broken to allow delivery of the drug. The housing (2) may be filled with the drug through an opening other than the opening through which the pusher (13) enters the housing to move the plunger so as to expel the drug during administration to a patient.