Inhaled salmeterol and salbutamol in asthmatic patients. An evaluation of asthma symptoms and the possible development of tachyphylaxis.

Salmeterol (SM) is a new beta 2-adrenoceptor agonist for inhaled use that has been shown to produce long-lasting bronchodilation in asthmatic patients. In the present study, evaluating efficacy and possible development of tachyphylaxis after SM, 12 patients with stable asthma were included after the demonstration of reversibility in FEV1 of at least 15% to 200 micrograms salbutamol (SB) or 20% to 500 micrograms SB. At inclusion all patients were receiving treatment with inhaled beta 2-agonists, and 11 of the 12 patients were also receiving inhaled corticosteroids. The patients were treated for two 2-wk periods with either inhaled SM 50 micrograms twice a day or SB 200 micrograms four times a day, following a double-blind, double-dummy, randomized design. The treatment periods were separated by a washout period of 1 wk. Dose-response curves to inhaled SB were obtained the day before and the day after each treatment period. On each of these days, basal FEV1, tremor, heart rate, and blood pressure were recorded and were then followed after the inhalation of 100 + 300 + 900 micrograms SB to obtain a cumulative dose-response curve. During the treatment periods, as well as during the washout week after each treatment, the patients recorded their morning and evening peak expiratory flow (PEF) each day before the inhalation of the study drug. Subjective asthma symptoms were monitored by a visual analog scale after each treatment period. The dose-response curves to SB revealed no signs of a reduced response to SB after any of the treatments, but significant increases in basal FEV1 and FVC were seen after the SM period (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)