This invention provides a process for preparing an inhalable dry powder pharmaceutical formulation comprising the step of heating a sealed wrapper containing a desiccant and an inhaler or a capsule, the inhaler or capsule further containing a dry powder formulation comprising an inhalable active pharmaceutical ingredient and a carrier, wherein the wrapper forms a barrier to the ingress of moisture and wherein heating the sealed wrapper and its contents is performed at a temperature of 30-50° C.
