The effect of ketanserin on blood pressure and biochemical parameters in treated patients with essential hypertension.

17 subjects with essential hypertension (14 male, 3 female - ages: 40-69 years), 13 of whom continued their previous anti-hypertensive therapy, completed a double-blind cross-over trial of ketanserin 40 mg twice daily versus placebo tablets twice daily - each treatment phase was six weeks in duration. For the group as a whole, blood pressure (BP) was reduced in the ketanserin phase compared with the placebo phase; supine mean BP decrease: 4 +/- 1 mm Hg (p less than 0.05); standing mean BP decrease: 7 +/- 1 mm Hg (p less than 0.001). Heart rate (HR) was also significantly decreased in the ketanserin phase by 5 +/- 1 beats/minute (p less than 0.001). When individual subgroups were analysed the reductions in BP and HR were greater in subjects already receiving anti-hypertensives, diuretic and/or beta blockers. Changes were observed in 24 hour urine sodium and potassium excretion - sodium (mmol/day): placebo 137 +/- 17, ketanserin 174 +/- 19 (p less than 0.05); potassium (mmol/day): placebo 74 +/- 8, ketanserin 57 +/- 5. For the group as a whole there were no significant adverse effects during the ketanserin phase, although two subjects had a dose reduction of ketanserin because of drowsiness and dizziness. Two additional subjects withdrew from the study due to adverse effects, one in the placebo phase. In conclusion ketanserin in the dose administered has a modest hypotensive effect which is best seen in subjects already receiving other anti-hypertensive agents.