A dry powder inhaler (1) is disclosed comprising first and second medicament reservoirs (2, 2a) and respective rotatable first and second metering members (5, 5a), which are urged into sealing engagement with the respective medicament reservoir (2, 2a) by a compression spring (8) located between the metering members (5, 5a). The inhaler (1) includes an actuator by which the first and second metering members (5, 5a) are rotated in unison from a metering position to a dispensing position. The actuator acts upon the first and second metering members (5, 5a) via a wheel (9) mounted between the first and second metering members (5, 5a). The first and second metering members (5, 5a) are provided with sockets (51) that receive the respective ends of the compression spring (8). The sockets (51) have extensions (52) that project into an axial bushing (92) of the wheel (9), the bushing (92) being provided on its internal surface with formations (94a, 94b, 94c, 94d) that engage the extensions (52) to cause the metering members (5,5a) to rotate when the wheel (9) is rotated.