[Beta-receptor blocking drugs and the bronchial system. A comparative study of pindolol and metoprolol (author's...

Effects of the beta 2-receptor stimulating drug fenoterol were investigated after administration of beta-receptor blocking agents in 12 patients with obstructive respiratory disease and a hyperreactive bronchial system (positive acetylcholine test). In a double blind trial pindolol (universal beta-receptor blocking drug) and metoprolol (a cardioselective substance) were compared after administration of equally effective doses of 5 and 100 mg respectively. Whole-body plethysmography showed that both beta-receptor blocking drugs caused no bronchial constriction; the bronchodilating effects of fenoterol were not reduced. These findings must cast doubt on the differentiation between cardioselective and non-cardioselective beta-receptor blocking agents as far as practical therapeutic implications are concerned.