The efficacy of darbepoetin alpha in hemodialysis patients resistant to human recombinant erythropoietin (rHuEpo).

Darbepoetin due to longer half life is convenient and effective for long term. This study was done to assess the efficacy of darbepoetin in the treatment of patients on high doses of erythropoietin (EPO) and to compare its efficacy in patients resistant and responsive to EPO. This is a prospective, controlled open label study assessing the efficacy of darbepoetin in 55 hemodialysis patients on high dose EPO and comparing its efficacy in the patients who were "EPO -resistant" (group 1, n= 28) and in those who were "EPO-responsive" (group 2, n= 27). The initial conversion ratio was 380 mcg darbepoetin: 1 U EPO/ week and the dose of darbepoetin was adjusted thereafter at fortnightly intervals with the aim of achieving and maintaining the hemoglobin level between 11-12 g/dL. The patients were followed up for 12 weeks following the introduction of darbepoetin. The impact of gender, baseline PTH, age, Kt/V, duration on dialysis, initial EPO dose on the response to darbepoetin was investigated. Continuous variables were compared using two tailed t-test and non-parametric by Fisher exact test. Overall darbepoetin was effective with 85.5 % of the patients responding and 21.8 % of the patients' able to maintain their hemoglobin with once fortnightly dose by the end of the study. Mean darbepoetin dose and the mean EPO to darbepoetin conversion ratio on completion of the study were 58.2 (42.4) mcg/week (0.983 (0.87) mcg/kg/week) and 384:1 respectively. Hemoglobin levels in groups 1 improved from 9.8 +/- 0.9 g/dL to 12.0 +/- 1.4 g/dL (0.0001) and 2 were and maintained it in group 2 at 11.9 +/- 1.3 g/dL (P= 0.79). The doses of darbepoetin required in groups 1 and 2 were similar (54.3 +/- 33 and 53.9 +/- 47 mcg/week (P= 0.97) respectively and 0.89 +/- 0.6 and 0.98 +/- 1.0 mcg/kg/week (P= 0.8). 22 (78.6 %) of the EPO resistant patients responded to darbepoetin. In conclusion conversion from high dose EPO to darbepoetin proved successful even in patients who were resistant to EPO. The darbepoetin dose required in the EPO resistant and EPO responsive groups did not differ significantly and age, duration on dialysis and baseline PTH level had no impact on responsiveness to EPO or darbepoetin.