title: Bronchial and cardiac beta-adrenoceptor blockade--a comparison of atenolol, acebutolol and labetalol.
abstract: Bronchial and cardiac beta-adrenoceptor blockade have been compared in six normal subjects after three beta-adrenoceptor antagonists. Single and double doses of atenolol (50 and 100 mg), acebutolol (100 and 200 mg) and labetalolol (150 and 300 mg) were studied on separate occasions. 2 Salbutamol airway dose-response curves were obtained by measuring the airway response as the change in specific airway conductance (sGaw) after increasing doses of inhaled salbutamol. Bronchial beta-adrenoceptor blockade was assessed after each drug as the dose of salbutamol needed to cause a 50% increase in sGaw (sGaw D50). 3 Cardiac beta-adrenoceptor blockade was assessed after the same doses of each beta-adrenoceptor antagonist, by measuring the percentage reduction in exercise heart rate from control, after exercise for 5 min at 70% of the subject's maximum work rate. 4 Atenolol 50 and 100 mg caused least bronchial beta-adrenoceptor blockade and the greatest reduction in exercise heart rate. 5 Acebutolol 100 and 200 mg and labetalol 150 and 300 mg produced more bronchial beta-adrenoceptor blockade than atenolol. 6 With this approach new beta-adrenoceptor antagonists can be assessed without putting asthmatic patients at risk.
mesh_terms: D000070:Acebutolol / Q000494:pharmacology*; D000403:Airway Resistance / Q000187:drug effects; D001262:Atenolol / Q000494:pharmacology*; D001980:Bronchi / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004983:Ethanolamines / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007741:Labetalol / Q000494:pharmacology*; D005082:Physical Exertion; D011412:Propanolamines / Q000494:pharmacology*; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*
chemical_list: D004983:Ethanolamines; D011412:Propanolamines; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D001262:Atenolol; D000070:Acebutolol; D007741:Labetalol