An inhaler including an outlet and a plurality of sealed compartments containing medicament is disclosed. An opening mechanism is provided to open the compartment presently aligned with the outlet. An indexing mechanism sequentially aligns the compartments with the outlet. A latch is provided for latching the opening mechanism in an energized position. The latch cannot latch the opening mechanism before the indexing mechanism has aligned the next compartment with the outlet. A method of priming an inhaler and a method of dispensing a medicament from an inhaler is also disclosed.
