RESUMO
BACKGROUND: After the signing of the Montreal Protocol in 1987, new propellants for use in pressurized metered-dose inhalers that are non-ozone-depleting have been developed. OBJECTIVE: This study was designed to compare the efficacy and tolerability of single doses of albuterol/HFA 134a with albuterol/CFC and to demonstrate a dose-response among the different doses of both formulations. METHODS: A single-center, randomized, double-blind, placebo-controlled, cross-over study. Sixty-three adolescent and adult asthmatic patients were randomized to receive at separate treatment visits single doses via a pressurized metered-dose inhaler of either placebo/hydrofluoroalkane (HFA) 134a; 100 microg, 200 microg, or 400 microg albuterol/HFA 134a; 100 microg or 200 microg albuterol/chlorofluorocarbon (CFC). Triplicate measurements of forced expiratory volume in 1 second (FEV1) were made immediately before dosing and 15 minutes, 30 minutes, 1, 2, 3, 4, 5, and 6 hours postdose. The primary efficacy variables were area under the entire 6-hour FEV1 curve, relative to baseline subtracted from the area above baseline (AUC(0-6)) and peak effect (derived from serial FEV1 measurements). RESULTS: Analysis of AUC(0-6) and peak effect showed that all doses of albuterol had a significantly greater effect than placebo (HFA 134a propellant). Comparisons of the two formulations at 100 microg and 200 microg showed no difference in AUC(0-6) (100 microg, -0.23 Lhr, P = 0.114 and 200 microg -0.08 Lhr, P = 0.590) or in peak effect, percentage of baseline (100 microg, -1.3%, P = 0.354 and 200 microg, 0.17%, P = 0.902). There were no differences seen among formulations in the incidence of adverse events or with any of the other safety parameters, including electrocardiograms, vital signs, clinical laboratory assessments, and asthma exacerbations. CONCLUSIONS: The study demonstrated comparability in terms of efficacy and safety between albuterol/HFA 134a and albuterol/CFC.