title: Assessment of beta-adrenoceptor antagonists in asthmatic patients.
abstract: 1 Bronchial smooth muscle, skeletal muscle and cardiac beta-adrenoceptor antagonism have been compared in twelve asthmatic patients after three beta-adrenoceptor antagonists at two dose levels. The non-selective antagonist propranolol (40 and 160 mg), the non-selective antagonist with partial agonist activity pindolol (5 and 20 mg) and the beta 1-selective antagonist atenolol (50 and 200 mg) were studied on separate occasions. 2 Six placebo days were used in this double-blind crossover study to allow interpretation of individual as well as group results. 3 Bronchial smooth muscle effects were assessed by resting spirometry, histamine inhalation test and spirometric response to inhaled fenoterol. Skeletal muscle effects were assessed by resting tremor and fenoterol induced tremor. 4 Cardiac beta-adrenoceptor antagonism was assessed by measuring the effect on resting heart rate and on maximum heart rate in a standard exercise test. 5 Pindolol tended to cause least change from placebo in resting spirometry, caused significant tremor response, inhibited the fenoterol airway response, and tended to protect against inhaled histamine. 6 Atenolol 60 mg was the only drug to allow a fenoterol airway response similar to placebo. Atenolol increased the inhaled histamine responsiveness. 7 Propranolol 160 mg caused the most reduction in spirometry but also tended to cause the maximum reduction in exercise heart rate. Propranolol caused increased inhaled histamine responsiveness. 8 Initial sensitivity to inhaled histamine did not necessarily predict significant reduction in an asthmatics' spirometry by a beta-adrenoceptor antagonist. The effect of a beta-adrenoceptor antagonist on histamine responsiveness does not correspond to its effect on inhaled beta 2-adrenoceptor agonist responsiveness.
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000009:adverse effects / Q000494:pharmacology*; D000328:Adult; D001249:Asthma / Q000503:physiopathology*; D001262:Atenolol / Q000494:pharmacology; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D005082:Physical Exertion; D010869:Pindolol / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013997:Time Factors; D014202:Tremor / Q000139:chemically induced
chemical_list: D000319:Adrenergic beta-Antagonists; D001262:Atenolol; D011433:Propranolol; D010869:Pindolol