Darbepoetin alfa is a novel erythropoiesis-stimulating protein developed for the treatment of anaemia associated with chronic kidney disease.In single-dose studies in patients undergoing dialysis,the mean terminal half-life forintravenous darbepoetin alfa was approximately 3-fold longer than for intravenous recombinant human erythropoitin (r-HuEPO,epoetin alfa; 25.3 vs 8.5 hours).The mean terminal halflife after subcutaneous administration of darbepoetin alfa was 48.8 hour.In randomised nonblind trials in patients undergoing dialysis, darbepoetin alfa (0.45 μg/kg) given once weekly for the correction of anaemia increased haemoglobin (Hb) levels to a similar extent as darbepoetin alfa three times weekly or r-HuEPO two or three times weekly.A double-blind, randomised clinical trial reported that switching patients from a three-times weekly regimen of r-HuEPO to once weekly darbepoetin alfa with additional placebo twice weekly (all intravenously) maintained Hb levels between 9.0 and 13.0 g/dl to a similar extent as continued treatment with r-HuEPO three times weekly.In a randomised nonblind study, r-HuEPO-naive patients with chronic renal insufficiency received either subcutaneous darbepoetin alfa once weekl.y.or r-HuEPO twice weekly.93% of patients receiving darbepoetin alfa and 92% of patients receiving r-HuEPO achieved a Hb increase of ≥ 1.0 g/dl from baseline and the mean increase in Hb level over the initial 4 weeks was similar for both treatments.The number and frequency of adverse events, withdrawals and deaths reported in clinical trials did not differ between patients receiving darbepoetin alfa and patients receiving r-HuEPO.There have been no reports of immune responses to darbepoetin alfa in 1534 patients receiving treatment for up to 2 years.