A pharmaceutical suspension formulation suitable for aerosol administration having from 0.0025 to 0.1 %w/w of micronized Formoterol, or an acid addition salt thereof, from 0.1 to 5.0 % w/w ethanol, HFA 134a, HFA 227 or a mixture of HFA 227 and HFA 134a, and optionally a surfactant other than a monoacetylated or diacetylated monoglyceride, the formulation being further characterized in that it exhibits substantially no growth in particle size or change in crystal morphology of the drug over a prolonged period, is substantially and readily redispersible, and upon redispersion does not flocculate so quickly as to prevent reproducible dosing of the drug.
