SINGLE-SHOT UNIT SPRAY TESTING OF METERED-DOSE INHALERS

An apparatus has been developed for the collection of single shots of drug delivered through the actuator of metered dose inhalers. The equi pment is constructed from readily available components and affords com plete drug recovery in 50 ml solvent. The apparatus has been evaluated with three drugs commonly administered from metered dose inhalers; be clomethasone dipropionate, salbutamol and sodium cromoglycate. Assays at the single shot level are highly reproducible, with coefficients of variation of typically 5 %. The use of the apparatus provides a direc t measure of the dose of drug available for inhalation by the patient.