A medicament delivery device comprises a metering member (25, figure 3) mounted for rotation adjacent a powdered medicament reservoir (22, figure 2) containing a bulk quantity of medicament (21). The metering member is frustoconical and contains cups (27, figure 3) for receiving doses of powder from the reservoir a ratchet mechanism prevents backwards rotation of the metering cone when it is in the filling position. Preferably, the metering cone is coupled to a drive wheel 90 having multiple lugs 93 on its face, spaced every 45 degrees. Two pawls 95 extend resiliently from the circumference of the wheel to sequentially engage with eight formations 102 which taper in the desired direction of rotation and thereby prevent reverse rotation. The wheel may be coupled to a second medicament reservoir (figure 2) and is rotated by the reciprocating translation of a pushrod (74, figure 7) which is part of a pushbutton actuator (70).
