Inhalation apparatus

A cartridge (32) for use in an inhalation apparatus (20) comprising a mouthpiece (26) comprising a central bore (40), the cartridge comprising a head portion, a tail portion, at least one portion for receipt in a central bore of the inhalation apparatus, and a chamber (110) for storing an inhalable substance; wherein the cartridge is movable from a first position, where the chamber is closed to an ambient environment, to a second position, where a flow pathway from the ambient environment through the chamber has been opened, when the cartridge is engaged with the inhalation apparatus, and wherein the cartridge comprises structures (45,154) configured to engage with the inhalation apparatus and retain the second position once the second position has been reached.