Cumulative dose response study comparing HFA-134a albuterol sulfate and conventional CFC albuterol in patients with asthma

Background: As a result of the pending ban on chlorofluorocarbon production , the non-chlorofluorocarbon propellant 1,1,1,2-tetrafluoroethane (HFA-134a ) is being evaluated as a replacement for CFCs in metered-dose inhalers. Objectives: This cumulative dose response study compared the safety and bro nchodilator efficacy of 16 cumulative inhalations of albuterol sulfate in a n HFA-134a, CFC-free propellant system (108 mu g of albuterol sulfate, equi valent to 90 mu g of albuterol base) with that of equivalent doses of albut erol in a conventional CFC propellant system. Methods: Twenty-two patients with at least a 12-month history of stable ast hma, who were currently taken an inhaled beta-adrenergic bronchodilator, an d who had a FEV, between 40% and 80% of predicted, were enrolled in this ra ndomized, modified-blind, two-period crossover study. One, 1, 2, 4, and 8 i nhalations of study drug were self-administered at 30-minute intervals, res ulting in 16 cumulative inhalations. Pulmonary function and safety measures were assessed after each dosing interval. Results: A significant dose response was found for HFA-134a albuterol sulfa te and CFC albuterol with regard to changes in FEV,, serum potassium, heart rate, and blood pressure after 16 cumulative inhalations. No significant d ifferences were demonstrated between HFA-134a albuterol sulfate and CFC alb uterol for any FEV, or safety parameter at any cumulative dose level. No cl inically meaningful laboratory or physical examination abnormalities were f ound with administration of either HFA-134a albuterol sulfate or CFC albute rol. Conclusions: HFA-134a albuterol sulfate provides bronchodilation comparable to CFC albuterol and has a similar safety profile.