Effects of intravenous ketanserin on severely hypertensive patients with double-blind crossover assessment of central side-effects.

Ketanserin, the specific S2 serotonin antagonist, is undergoing evaluation for the therapy of hypertension of all degrees of severity. We studied 20 patients with severe hypertension [diastolic blood pressure (DBP) greater than 120 mm Hg after 40 min of supine rest]. In the first dose-ranging study on eight patients, multiple i.v. injections of 5 mg ketanserin were administered every 4 min (mean 38 mg). Only 4 patients responded adequately (DBP less than 100 mm Hg), 2 responded partially, and 2 did not respond to ketanserin. The major adverse effect of ketanserin, found in all patients, was severe dose-dependent sleepiness. A second double-blind crossover study with ketanserin and placebo (12 patients) assessed neural side effects. The supine DBP dropped from a mean of 134 +/- 4 mm Hg to 112 +/- 4 mm Hg 20 min after ketanserin when the sedation score rose from 0 to 1.2 +/- 0.3 (range 1-3) and the dizziness score from 0.1 +/- 0.1 to 1.4 +/- 0.3 (range 1-3; both p less than 0.01 vs. 1-2 min after ketanserin). Only 7 of 12 patients responded adequately to ketanserin. Twelve of the 20 patients were subsequently given nifedipine 10 mg sublingually; the DBP fell from a mean of 128 +/- 3 mm Hg to 101 +/- 4 mm Hg (p less than 0.001) after 40 min without side effects. Ketanserin does not appear to be a suitable agent for the acute therapy of severe hypertension because of: the imperfect and short-lived blood pressure control; the variability of the hypotensive effect; and sleepiness and dizziness as significant side effects.