Immediate haemodynamic effects of a novel partial agonist, beta 1- adrenoceptor blocking drug ICI 141,292 after intravenous administration to healthy young volunteers and patients with ischaemic heart disease.

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Abstract
1. ICI 141 292 is a new .beta.1-adrenoceptor blocking drug. The .beta.1-adrenoceptor antagonistic effect of ICI 141 292 was examined in a double-blind, randomized crossover study in eight healthy young volunteers and compared with atenolol. Three doses of ICI 141 292 (1, 2 and 4 mg) and atenolol 5 mg were administered intravenously. The attenuation in exercise induced tachycardia varied between 16.0 and 21.2% (P < 0.01). A significant reduction in blood pressure could be demonstrated following all three doses of ICI 141 292 and atenolol during exercise. 2. At rest in the sitting position HR decreased approximately 8% following all three doses of ICI 141 292 and 14.9% after atenolol 5 mg. No changes in blood pressure were observed under resting conditions after any of the drugs. 3. In six patients with ischaemic heart disease the intrinsic sympathomimetic activity following intravenous administration of four sequential doses (0.5, 0.5, 1.0 and 2.0 mg) of ICI 141 292 was examined. HR decreased 7% (P < 0.05) following ICI 141 292 1 mg with no further decrease following the succeeding doses. Cardiac output decreased 5.2% (P < 0.05) following a cumulative dose of 4 mg. 4. No significant changes were observed in mean arterial blood pressure, stroke volume or total peripheral resistance whereas an increase in supine resting mean pulmonary arterial pressure of 3.4 mm Hg (P < 0.05) could be demonstrated. 5. ICI 141 292 seems to be a potent (at least five times as potent as atenolol) .beta.1-adrenoceptor blocking agent possessing intrinsic sympathomimetic activity.