Immediate central and regional haemodynamic effects of a new beta₁-adrenergic stimulating drug, xamoterol (Corwin) in healthy volunteers

Summary

Dose-response curves for heart rate, arterial blood pressure, cardiac output, total peripheral resistance, systolic time intervals, forearm blood flow and forearm vascular resistance were obtained after i.v. administration of seven logarithmically increasing doses of xamoterol to 8 healthy volunteers. The total cumulative dose was 0.2 mg/kg b.w. At rest after the seventh dose of xamoterol heart rate, systolic blood, pressure, cardiac output and forearm blood flow were increased by 10%, 20%, 23% and 41%, respectively. Diastolic blood pressure was unchanged. Forearm vascular resistance was reduced by 21% and total peripheral resistance by 10%. Systolic time intervals were reduced: total electromechanical systole index (QS₂I), left ventricular ejection time index (LVETI), pre ejection period index (PEPI) and PEP/LVET ratio by 4%, 2%, 12% and 14%, respectively. No side-effects were observed. During upright exercise after the seventh dose of xamoterol heart rate was reduced by 11% and systolic BP by 6%. Diastolic blood pressure was unchanged. Thus xamoterol increased the contractility of the heart with only a small increase in heart rate, increased systolic blood pressure and caused vasodilatation in resting skeletal muscle. During exercise the reduction in heart rate and blood pressure suggests beta-adrenoceptor blocking activity of the drug.