In vitro deposition and clinical efficacy of two sodium cromoglycate inhalation powders.

In this study, the in vitro deposition as well as the clinical efficacy of two dry powder inhalation preparations containing 20 mg of disodium cromoglycate were evaluated. The preparations were Blacil and Lomudal administered either with I.S.F. or Spinmatic powder inhalers, respectively. The in vitro inhalation study was performed using the cascade impacted method. During the in vitro test, similar fractions of the drug doses were retained in both inhalation devices. A remarkably larger proportion of the pelletized drug powder from the Lomudal preparation was deposited in the imitated upper airway than from the Blacil preparation consisting of the mixture of micronized disodium cromoglycate particles and lactose as a carrier. On the other hand, a larger fraction of the drug dose was deposited in the imitated lung area after the administration of the Blacil preparation than from Lomudal. The clinical study was performed as an exercise test in sixteen asthmatic patients. The preparations tested were statistically equally effective. The decrease in all the values of the pulmonary function parameters (PEF, FEV1) was, however, smaller after the administration of disodium cromoglycate from Blacil than from Lomudal preparation. According to the results of this study, the cascade impaction test seems to be valuable for predicting the efficacy of inhalation powders.