KETANSERIN LOWERS ERYTHROPOIETIN CONCENTRATION IN HEMODIALYZED PATIENTS TREATED WITH THE HORMONE

Ketanserin, an antagonist of peripheral serotonin receptors when given to hemodialyzed patients treated with recombinant human erythropoieti n (rHuEpo) corrects some changes in hemostasis but also apparently del ays an increase in hematocrit. We wished to elucidate the effects of o ral administration of ketanserin on serum Epo, some hematological and biochemical blood parameters, arterial blood pressure (BP), and bleedi ng time in hemodialyzed patients receiving rHuEpo therapy. We noted a 33% decrease in Epo concentration (p < 0.05) after a 4-week ketanserin trial in patients in the initial stage of rHuEpo therapy. Although a concomitant decrease in erythrocyte count and hemoglobin did not reach statistical significance, these changes correlated positively with de creasing Epo level (r = 0.749 and 0.787, respectively). Ketanserin adm inistered for 14 days to patients between 32 and 34 weeks of rHuEpo th erapy also produced a decrease of 26% in Epo concentration (p < 0.005) . This decrease correlated (r = 0.629) with a decrement in the red blo od cell (RBC) count (p < 0.005). Hemoglobin concentration followed the same pattern (p < 0.005). However, the decreases in the reticulocyte count did not reach statistical significance. The decrease in hormone concentration resulted in a concomitant thrombocyte decrease (p < 0.05 ) only in patients who received ketanserin in the interval between 8 a nd 12 weeks of rHuEpo therapy. The previously normal bleeding time was significantly prolonged (p < 0.05) in both groups of patients. There were no changes in leukocyte count, iron status parameters, or calcium , phosphorus, or bilirubin concentration. Administration of ketanserin even for 4 weeks did not influence BP in the patients. It is highly p robable that the observed decrease in Epo concentration and the concom itant inhibition of erythropoiesis and thrombocytopoiesis are the resu lts of diminished endogenous hormone synthesis caused by ketanserin.