PROVENTIL HFA PROVIDES PROTECTION FROM EXERCISE-INDUCED BRONCHOCONSTRICTION COMPARABLE TO PROVENTIL AND VENTOLIN

Introduction: During the 1970s, scientists suggested that the growing use of chlorofluorocarbons (CFCs) was contributing to depletion of the stratospheric ozone layer with potentially harmful results. A committ ee on the ozone layer organized the preparation of the Montreal Protoc ol. This protocol mandated the cessation of production and use of CFCs by January 1, 1996. The primary exemption to this ban is for the use of CFCs as propellants in metered dose inhalers (MDIs) for the treatme nt of asthma. Suitable replacement hydrofluoroalkane (HFA) propellants , such as HFA-134a, for use in MDIs have been identified. Albuterol, a selective beta-adrenergic agonist, currently widely available for inh alation asthma therapy, has been reformulated in HFA-134a (Proventil H FA). Objective: To compare the efficacy of Proventil HFA to Ventolin, Proventil, and placebo (HFA-134a) MDI in protecting asthmatic patients from exercise-induced bronchoconstriction. Methods: This was a random ized, single-blind, placebo-controlled, 4-period crossover study of as thmatic patients with documented exercise-induced bronchoconstriction. Twenty patients self administered two puffs of either Proventil HFA, Ventolin, Proventil or placebo, from an MDI, 30 minutes prior to perfo rming a standardized exercise challenge at the study site. Spirometry was performed predose and 5, 10, 15, 30, 45, 60, 75, and 90 minutes af ter completion of the exercise challenge. Heart rate and blood pressur e were measured just prior to spirometry and a 12-lead ECG was perform ed 15 minutes after completion of the exercise challenge for measureme nt of the QT corrected interval. Results: The primary efficacy variabl e was the smallest percent change from the predose FEV1 following exer cise. The smallest percent change from predose FEV1 for Proventil HFA was 2.0 +/- 9.9 SD, similar to the 2.0 +/- 11.4 SD for Ventolin, and t he 3.6 +/- 10.2 SD for Proventil. The smallest percent change from pre dose FEV1 for each of the active treatments was significantly differen t from placebo, -23.7 +/- 14.5. Twelve of the patients had a greater t han or equal to 20% fall in FEV1 post-exercise with placebo pretreatme nt, but only 1, 1, and 0 had greater than or equal to 20% FEV1 falls a fter treatment with Proventil HFA, Ventolin, and Proventil respectivel y. Changes in heart rate, blood pressure and QT corrected interval wer e similar for the three active treatments following exercise. Conclusi ons: Proventil HFA provides protection against exercise-induced bronch oconstriction comparable to Ventolin and Proventil and protection supe rior to placebo. Proventil HFA has a safety profile similar to Ventoli n when used to prevent exercise-induced bronchoconstriction.