Influence of ketanserin (serotonin antagonist) on bladder and urethral function

As it is known that serotonin or 5-hydroxytryptamine can enhance bladder activity, we studied urodynamically the effect of ketanserin, a serotonin antagonist, in 17 patients, in the hope that this drug might be useful in treating unstable bladders. However, a relaxant effect on bladder contractility could not be demonstrated. On the contrary, a significant decrease of the urethral pressure was observed, suggesting that ketanserin might still have a possible role in promotion of bladder emptying. The relaxant effect on the urethra suggests some alpha-sympathicolytic activity of ketanserin.