Effects of atenolol vs diltiazem on the haemodynamic effects of an inhaled beta 2‐adrenoceptor agonist.

Abstract

To determine the effects of concurrent beta 1‐adrenoceptor blocker or calcium channel antagonist administration on the haemodynamic sequelae of an inhaled beta 2‐selective adrenoceptor agonist bronchodilator, we examined echocardiographically the effects of fenoterol (400 micrograms) by metered dose inhaler following oral pre‐treatment with (a) placebo, (b) atenolol or (c) diltiazem. Following placebo, fenoterol produced significant decreases in diastolic blood pressure (14% +/‐ 6%), total peripheral vascular resistance (TPR) (31% +/‐ 9%) and end‐systolic stress (ESS) (15% +/‐ 21%). Cardiac output rose significantly (42% +/‐ 23%) as did heart rate (25% +/‐ 13%). After atenolol, responses to fenoterol were significantly blunted. Post‐ fenoterol heart rate, systolic blood pressure, % fractional shortening, stroke volume, ejection fraction, cardiac output and pressure/volume ratio increased significantly less after atenolol pre‐treatment as compared to placebo pretreatment. TPR decreased significantly less. After diltiazem pre‐treatment, the response to inhaled fenoterol was not different from that following placebo pre‐treatment. We conclude that atenolol blunts the haemodynamic changes induced by fenoterol inhalation whereas diltiazem has little effect. 1989 The British Pharmacological Society