Continuous inhibition of serotonin-induced platelet aggregation during chronic ketanserin administration to man can be detected after plasma pH control.

Ketanserin is a well-known serotonin S2 receptor antagonist but its capacity to inhibit serotonin-induced aggregation ex vivo during chronic administration has been a matter of debate. In vitro evidence is presented that the inhibitory capacity of ketanserin is lowered by increasing plasma pH. Since the pH of plasma kept at the open air increases with time, we studied the effect of chronic administered ketanserin on serotonin-induced platelet aggregation in plasma kept at a lowered pH of 7.

Platelet hypersensitivity to serotonin after prolonged ketanserin intake?

In the present study the effect of acute and short-term ketanserin administration on serotonin (5-HT)-induced aggregation was investigated in eight healthy volunteers. They received 40 mg ketanserin three times a day for 1 week. Blood samples were drawn before (A), 1.