Beta-adrenergic blockade of the lung. Dose-dependent cardioselectivity of tolamolol in asthma.
Beta-adrenergic blocking agents are widely used to treat disorders of cardiac rhythm and rate, angina, and hypertension. Propranolol is the most widely used beta-adrenergic blocking agent in this country. Because of its nonselective beta-adrenergic blocking effect, propranolol may be associated with significant bronchoconstriction in asthmatic subjects and in some patients with chronic obstructive pulmonary disease. Since tolamolol, a new beta-adrenergic blocking agent, has cardioselectivity in animals, we studied asthmatic subjects for six hours on three separate days in a double-blind crossover comparison of oral therapy with 40 mg of propranolol, its beta-adrenergic blocking equivalent dose of tolamolol (50 mg), and a high dose of tolamolol (100 mg). All three dosages had equipotent effects on heart rate and systolic pressure. The 50-mg dose of tolamolol had no effect on pulmonary function over six hours; however, both propranolol (40 mg) and the 100-mg dose of tolamolol had equivalent deleterious effects on airway resistance and on rates of expiratory flow. We conclude that the cardioselectivity of tolamolol is dose-limited but is present at the dosage of 50 mg, which is equivalent to the usual antiarrhythmic beta-adrenergic blocking dose of propranolol (40 mg).
D000328:Adult; D000403:Airway Resistance / Q000187:drug effects; D001249:Asthma / Q000188:drug therapy*; D002986:Clinical Trials as Topic; D004311:Double-Blind Method; D004341:Drug Evaluation; D005540:Forced Expiratory Flow Rates; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008875:Middle Aged; D011412:Propanolamines / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D011433:Propranolol / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D012119:Respiration / Q000187:drug effects*; D013997:Time Factors
D011412:Propanolamines; D011433:Propranolol