ABSTRACT
Dry powder inhalers contain usually pure drug and a carrier. Usually the diameter of the carrier substance particles is greater that the pure drug. In order to ensure that only the drug is labelled, it has to be labelled prior to mixing with the carrier. To achieve this the drug has to be suspended in a solvent which dissolves the label but not the drug. The radiolabel is added to the drug suspension, which is then evaporated. The drug particles are disaggregated, blended with carrier and loaded into the inhaler.
