Interpatient variation in response to subcutaneous versus intravenous low dose erythropoietin

Subcutaneous (SC) recombinant human erythropoietin (EPO) has been reported to correct anemia in hemodialysis patients at lower doses than intravenous (IV) EPO. Those trials involved relatively high doses of EPO or did not control adequately for time-related falls in dose requirements. Therefore, on open-label double-crossover study was performed to compare the hemoglobin (Hb) response to low dose SC versus IV EPO. Ten (4 male) maintenance hemodialysis patients previously stabilised on low dose EPO for 18 +/- 3 months (mean +/- SEM) were given EPO IV for 12 weeks (IV#1), then SC for 24 weeks and then IV for a further 20 weeks (IV#2). Iron status and other factors known to modify response to EPO were kept constant. EPO dose was not changed unless Hb rose above 100 g/l, when the dose was reduced to keep Hb between 90 and 100 g/l. Initial EPO dose was 64 +/- 10 u/kg/week. Mean Hb, measured monthly, was not different during the 3 treatment periods. There was wide interpatient variation in the relative response to IV versus SC EPO. Mean Hb was higher on IV EPO in 5 patients (by 6.1 +/- 2.0 g/l) and higher on SC EPO in 5 patients (by 12.1 +/- 4.1 g/l). The difference in mean Hb during IV versus SC administration was more than 5 g/l in 6 patients, being higher in 3 patients during IV administration (by 8.7 +/- 4.6 g/l) and in 3 during SC (by 17.4 +/- 4.6 g/l). In conclusion, the more efficient route of administration of EPO is not predictable for individual patients, and should be sought to allow possible dose reduction.