Clinical studies with the beta-adrenoceptor agonist BRL 26830A.

BRL 26830A is a beta-adrenoceptor agonist drug that shows a high degree of selectivity for thermogenesis and has potential as an antiobesity agent. We undertook a double-blind trial in 40 obese subjects who received either BRL 26830A or placebo for 18 wk. All were prescribed a 3.35 MJ (800 kcal) diet. Weight loss was 15.4 +/- 6.6 (SD) kg on BRL 26830A compared with 10.0 +/- 5.9 kg on placebo (P less than 0.02). The relative weight losses were 0.93% and 0.61%/wk, respectively. Urinary nitrogen excretion was similar in both groups and skinfold measurements indicated a 4-kg difference in fat lost, suggesting that weight loss was mainly from adipose tissue. Psychological assessments showed that BRL 26830A had no adverse effect on mood and no effect on hunger or satiety. Tremor was experienced by 12 of 16 treated subjects who completed the study. It was generally rated as mild, occurred 1 h after dosing, and tended to diminish with time on treatment. Subsequent analysis of the tremor suggested that it is an exaggeration of physiological tremor mediated through skeletal muscle beta 2 adrenoceptors.