Pharmacokinetics of several subcutaneous doses of erythropoietin: potential implications for blood transfusion.

1. The aim of the present study was to assess the effectiveness of repeated subcutaneous low-dose recombinant human erythropoietin (rHuEPO) on parameters associated with improved procurement of autologous blood; a procedure regularly used to preclude the need for homologous blood transfusion at the time of elective surgery. 2. Three groups of three volunteers each (n = 9) were administered one of three low doses of rHuEPO (30, 60 or 100 IU/kg bodyweight, s.c.) on days 1, 4 and 8. The plasma pharmacokinetic profile of rHuEPO was studied after the first and third injections. Statistical evaluations were intragroup and intraindividual comparisons. 3. There was a linear relationship between maximum plasma concentration (Cmax) and dose. In the overall study group, Cmax and area under the curve (AUC) were significantly decreased, while the mean residence time (MRT) and elimination half-life (t1/2beta) were significantly increased on day 8 relative to day 1. Significant and sustained increases in reticulocytes were observed after rHuEPO administration, which were maintained above the predose values throughout the study period. 4. In conclusion, rHuEPO, by subcutaneous repeat-dose, was eliminated more slowly and remained longer in the circulation, despite lowered plasma concentrations. Repeated low rHuEPO administration at doses > or = 60 IU/kg bodyweight stimulated modest but sustained reticulocyte concentrations, suggesting that cost may be substantially decreased in autologous blood donation or perioperative treatment programmes.