A suction actuated valve, for a dry powder inhaler, includes a compressed air lumen； a control chamber for providing suction； and a trigger assembly having a displaceable membrane within the control chamber and configured to seal the control chamber such that suction displaces at least a portion of the displaceable membrane to provide an opening force to the trigger assembly for moving from a closed configuration to an open configuration. A trigger is coupled to the displaceable membrane and configured, in the closed configuration, to occlude the compressed air lumen and configured, in the open configuration, to open the compressed air lumen. The trigger has a first cross-sectional area and the displaceable membrane has a second cross-sectional area greater than the first cross-sectional area such that when suction is provided the displaceable membrane provides a mechanical advantage for moving the trigger from the closed configuration to the open configuration.
