The effects of a new serotonin receptor antagonist (ketanserin) on lower urinary tract function in patients with prostatism.

Ten male patients with prostatism, median age 63 years (range 50 to 70 years) were given an intravenous injection of a new serotonin antagonist, ketanserin, at a dose of 10 mg., and were investigated urodynamically before and after injection. A statistically significant increase in maximum and mean flow rates and a statistically significant decrease in urethral pressure profile measurements was observed. Supine CO2 cystometry showed no significant decrease in volumes of first sensation and bladder capacity. No subjective side effects were registered, but we observed a statistically significant decrease in mean blood pressure of 6.5 mm. Hg (range 5 to 14 mm. Hg). The mechanism behind the beneficial effect of ketanserin on micturition in prostatism is not yet known, but the results could explain an alpha blocking effect of the drug.