Darbepoetin alfa: a new therapeutic agent for renal anemia

Darbepoetin alfa is a super-sialylated analog of human erythropoietin that has a longer circulating half-life in vivo compared to both native and recombinant hormone. It has the same mechanism of action as erythropoietin, stimulating the same surface membrane receptor and triggering the same intracellular chain of events. An extra two N-linked carbohydrate chains, however, gives darbepoetin alfa greater metabolic stability in vivo, and its terminal half-life after intravenous administration is approximately three times longer than for intravenous erythropoietin. This in turn allows injections of the drug to be given less frequently, and studies have shown that once-weekly and once-every-other-week dosing can maintain the hemoglobin concentration in patients with renal anemia. The recommended starting dose for darbepoetin alfa is 0.45 microg/kg once weekly for both IV and SC administration, with subsequent titration based on the hemoglobin concentration. The adverse event profile is very similar to that seen with rHuEPO, and no antibodies have been detected in several thousand patients exposed to the drug, some of whom have been treated for up to five years now. Following a clinical research program that began in November 1996, darbepoetin alfa was finally approved by the European Commission in June 201, and by the FDA in September 201.