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Pharmacokinetics Intravenously administered PROCRIT is eliminated at a rate consistent with first order kinetics with a circulating half-life ranging from approximately 4 to 13 hours in adult and pediatric patients with CRF. Within the therapeutic dose range, detectable levels of plasma erythropoietin are maintained for at least 24 hours. After subcutaneous administration of PROCRIT to patients with CRF, peak serum levels are achieved within 5-24 hours after administration and decline slowly thereafter. There is no apparent difference in half-life between adult patients not on dialysis whose serum creatinine levels were greater than 3, and adult patients maintained on dialysis. In normal volunteers, the half-life of intravenously administered PROCRIT is approximately 20% shorter than the half-life in CRF patients. The pharmacokinetics of PROCRIT have not been studied in HIV-infected patients. The pharmacokinetic profile of Epoetin alfa in children and adolescents appears to be similar to that of adults. Limited data are available in neonates. 17 It has been demonstrated in normal volunteers that the 10,000 U/ mL citrate-buffered Epoetin alfa formulation and the 40,000 U/ mL phosphate-buffered Epoetin alfa formulation are bioequivalent after subcutaneous administration of single 750 Units/ kg doses. Text Continues Below
The Cmax and t1/ 2 after administration of the phosphate buffered Epoetin alfa formulation were 1.80 ± 0.7 U/ mL and 19.0 ± 5.9 hours (mean ± SD), respectively. The corresponding mean ± SD values for the citrate-buffered Epoetin alfa formulation were 2 ± 0.9 U/ mL and 16.3 ± 3. 0 hours. There was minimal accumulation in serum after two weekly 750 Units/ kg subcutaneous doses of Epoetin alfa.
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