An inhaler for dispensing a dose of an active agent to the respiratory tract of a patient, which inhaler comprises a housing defined by an upper part and a lower part and a mouthpiece which is attached or is adapted to be attached to said housing wherein said housing includes storage means for storing an active agent and an airway for delivering said dose from the storage means to the mouthpiece in a stream of air or other gas for administration to a patient, characterised in that said upper part and said lower part of the housing are joined together in a substantially airtight fashion by means of a mechanical fixing, such that a gas flow rate of no more than about 45 litres/minute, preferably no more than about 40 litres/minutes, is required in order to propel a dose of said active agent from the reservoir to the mouthpiece for administration to the patient.
