A breath actuated dry powder inhaler, comprising a substantially disc
shaped air circulation chamber for de-agglomeration of entrained powdered
medicament using the energy of the inspiratory air stream. The chamber
has a substantially circular or polygonal sidewall extending about a
central axis between top and bottom walls of the chamber so that the
height of the chamber is smaller than its diameter. A plurality of air
supply channels disposed about the circumference of the chamber, which
channels extend from joint or separate air inlets and which channels
enter the chamber substantially tangentially to its sidewall. At least
one of the supply channels extends through a powder dose supply region of
the inhaler. The chamber further comprises an air outlet axially
extending from a discharge opening in the centre of the top or bottom
wall of the chamber and connects to a discharge channel that extends to a
mouthpiece. The inhaler comprises at least one further air circulation
chamber for de-agglomeration of entrained powdered medicament, the
chambers being connected to the mouthpiece in parallel.