Reversibility of bronchospasm in airway obstruction.

In a double-blind, randomized crossover study of 12 patients suffering from chronic bronchitis, the comparative influence of equipotent doses of pindolol (5 mg) and metoprolol (100 mg) on the bronchodilatory potential of inhaled fenoterol (0.4 mg), a beta 2-agonist, was investigated by means of body plethysmography. Neither beta-blocker caused bronchospasm or attenuated the bronchodilation due to fenoterol. The results are not pertinent to the potential risk of bronchospastic complications induced by beta 1-selective or nonselective drugs, but they rule out a therapy-oriented differentiation between pindolol and cardioselective agents as far as the potential response to the bronchodilating activity of inhaled sympathomimetics is concerned.