METERED-DOSE INHALERS .3. METAPROTERENOL SULFATE - PARTICLE-SIZE DISTRIBUTION AND DOSE UNIFORMITY

Three American products and one Canadian product were examined for con tent uniformity and particle size distribution. The results showed tha t not all products performed equally well. Some of the products exhibi ted high sprays early in the canister lifetime and all products demons trated loss of prime. The particle size distributions were determined using the Andersen cascade impactor (USP Induction Port) and the fine particle fraction was determined using the twin impinger. The results showed that three of the four products had similar particle size distr ibution profiles. Both the Andersen cascade impactor and the twin impi nger yielded the same trends in the amount of drug substance delivered to the fine particle fraction. (C) 1997 Published by Elsevier Science B.V.