DRY POWDER INHALERS ARE BIOEQUIVALENT TO METERED-DOSE INHALERS - A STUDY USING A NEW URINARY ALBUTEROL (SALBUTAMOL) ASSAY TECHNIQUE

Metered-dose inhalers (MDIs) are extensively used to deliver drugs to the lungs but are driven by chlorofluorocarbon (CFC) propellants. The worldwide phasing out of CFCs within the next 5 to 10 years presents d ifficulties to the pharmaceutical industry. The mean +/- SD relative l ung bioavailability of albuterol to the lung following inhalation of 4 00 mu g of albuterol from an MDI, the Rotahaler and Diskhaler in 10 we ll-trained volunteers, was 2.83 (0.78), 1.72 (0.99), and 2.84 (1.23)%, respectively, expressed as a percentage of the nominal dose. The deli very of albuterol to the lungs from the MDI and Diskhaler was similar. In nine asthmatic subjects, the relative lung bioavailability of albu terol following inhalation with the MDI and Diskhaler was 1.19 (0.79) and 2.38 (1.46)%, respectively, expressed as a percentage of the nomin al dose. There was no difference in reversibility 30 min after adminis tration of the dose by the two methods. Similar lung deposition from t he Diskhaler in volunteers probably is due to efficient MDI technique, which was absent in the asthmatic subjects. The Diskhaler does not re ly on coordination during inhalation and therefore is easier to use.