Effects of therapeutic doses of albuterol on β2-adrenergic receptor density and metabolic changes

beta (2)-Agonist drugs at inhaled supratherapeutic doses or when given orally or parenterally alter peripheral lymphocyte beta (2)-adrenoceptor density (beta AR) and have demonstrable metabolic effects. However, it is not known whether these changes occur at therapeutic inhaled doses. We therefore studied the effects of therapeutic doses of inhaled albuterol in five asthmatic subjects (mean age 23.0 +/- 2/4 years) and six normal subjects (mean age 28.3 +/- 3.3 years). Subjects were studied in a randomized, double-blind protocol in which each subject received either inhaled albuterol (270 mug four times daily) for 2 weeks followed by placebo or vice versa in two sequential 2-week periods separated by a 2-week washout period. In the asthmatics, baseline FEV1 increased significantly (p < 0.05) after 2 weeks of inhaled albuterol treatment compared to the initial visit and after 2 weeks of placebo (mean FEV1: 3.2 L +/- 0.7 L, 2.9 L +/- 0.5 L, and 3.0 L +/- 0.7 L, respectively). Baseline peripheral lymphocyte <beta>AR was not significantly different (p > 0.05) between the asthmatic (mean: 757 +/- 176) and normal subjects (mean: 732 +/- 251). However, in neither group was there any significant change (p > 0.05) in beta AR or plasma potassium, insulin, or glucose, either acutely or after 2 weeks of albuterol therapy. The present study confirms that there is no difference in peripheral lymphocyte beta AR between asthmatic and normal subjects and shows that at therapeutic doses of inhaled albuterol, there are no significant changes in beta AR or metabolic effects.