A device is disclosed for dispensing a fluid supplied from a fluid source(22). The device comprises a transducer adapted to receive a fluid from thefluid source, and a collapsible linkage and trip link (502) coupling thetransducer and the fluid source. The linkage has a collapsible joint (66)inhibiting discharge of the fluid source when in a locked orientation. Thedevice further comprises a moveable member coupled to the linkage such thatinhalation forces on the device cause the linkage to collapse thereby-discharging the fluid from the fluid source. The device may further include adose counter coupled to the fluid source for registering the amount of dosesadministered from the fluid source.