1. In a double-blind placebo-controlled crossover study a 4 week treatment with ketanserin was shown to reduce systolic and diastolic blood pressure markedly and significantly in 10 patients with essential hypertension. Heart rate remained virtually unchanged during the whole observation period. Systolic time intervals, reflecting cardiac output, did not change during the ketanserin phase, whereas these values deteriorated during the placebo period.
2. Ketanserin, a novel 5-hydroxytryptamine (5HT2)-receptor antagonist with a high selectivity for blood vessels and thrombocytes, most probably acts by decreasing the venous capacitance bed constriction, and by counteraction of the amplifying effects of serotonin on noradrenaline and other vasoactive amines.