[Ketanserin decreases erythropoietin concentration in hemodialyzed patients on rHuEPO therapy].

Serotonergic mechanisms are partially responsible for changes in haemostasis and blood pressure rise in haemodialyzed patients treated with recombinant human erythropoietin (rHuEPO). Ketanserin--an antagonist of platelet and blood vessel serotonin receptors, given concomitantly to patients on rHuEPO therapy, prevents certain changes in haemostasis. Preliminary observations suggest that ketanserin also inhibits an increase in haemoglobin and haematocrit. So far there have been no reports on ketanserin affecting erythropoiesis. We studied an influence of the 2-week oral ketanserin administration on some haematologic parameters, serum erythropoietin concentration, blood pressure and relevant biochemical blood indexes in 15 haemodialyzed patients treated with rHuEPO for 32 weeks. We found a significant fall in serum EPO concentration (p < 0.005) measured with the ELISA technique that correlated positively (r = 0.629) with a decrease in erythrocyte count (p < 0.005). Haemoglobin concentration followed the same pattern (p < 0.005). The previously normal bleeding time prolonged significantly (p < 0.02) after ketanserin therapy. There were no changes in plasma iron and ferritin concentration, total iron binding capacity, transferrin saturation index, calcium, phosphorus and bilirubin concentration nor reticulocytosis. The decrement in EPO concentration did not affect peripheral blood platelet or leukocyte counts. The 14-day treatment with ketanserin did not influence arterial blood pressure in the patients. The study shows that ketanserin administered to haemodialyzed patients on long-term rHuEPO therapy induces a decrease in erythropoietin concentration and inhibits erythropoiesis. This phenomenon seems to result from diminished endogenous hormone synthesis caused by ketanserin.