Prolongation of the QT interval by ketanserin

Abstract

In hypertensive patients single doses of kentanserin 40 mg prolonged the corrected QT interval (QT(c)) for at least 8 hours, with a maximal increase of 35 ms (P < 0.001, n = 6) after 2 hours. During chronic dosing (20 and 40 mg b.d.) the QT(c) was further prolonged, by 46 and 45 ms respectively. QT(c) prolongation after treatment with a mean dose of 73 mg/day for 7 weeks (n = 26) was significantly related to body weight (r = -0.58, P < 0.01), adn to the dose of kentaserin corrected for body weight (r = 0.63, P < 0.01), but not to plasma concentrations of kentanserin, kentanserinol, potassium or calcium. High doses of kentanserin (mean dose 167 mg/day, n = 9) increased the QT(c) by 40 ms (P < 0.001), with prolongation of up to 80 ms in individual patients. Treatment with kentanserin at doses proposed for clinical use (40-80 mg/day) may carry a risk of ventricular arrhythmias.