Effective administration of erythropoietin for renal anemia

The erythropoietic effects of erythropoietin (EPO) have been investigated in the different administration schedule and injection routes. EPO was intravenously, intramuscularly or subcutaneously injected to partially nephrectomized anemic rats in 3 types of prescriptions (300 units of EPO per kg of body weight was respectively given in a dose at the first day, in 4 divided doses every 4 days, and in 7 divided doses every 2 days for 2 weeks). Repeated injections of EPO in divided doses caused stronger erythropoiesis than single injection. Especially, seven repeated injections promoted the strongest erythropoiesis. The serum iron concentration and reticulocyte counts suggested that erythropoiesis was continued less than 2 weeks after single injection but erythropoiesis in repeated injection groups had been accelerated for 2 weeks. Intravenous injections were less effective than either intramuscular or subcutaneous injections at 2 weeks after 7 repeated injections of 300 units of EPO per kg of body weight in 7 divided doses. Erythropoietic effects of EPO on the same total dose are dependent on the frequency of EPO injection and the durability of serum EPO concentration. On EPO usage, one bolus intravenous injection of excessive dose is considered to be wasteful and the repeating injections to maintain plasma EPO concentration is expected for the rational treatment of uremic anemia.