Pharmacology of darbepoetin alfa.

The distinct molecular structure of darbepoetin alfa, in both its amino acid sequence and its carbohydrate content, results in a biologic profile with lower binding affinity, longer circulating half-life, and higher in vivo potency compared with the epoetins. The mechanisms responsible for these differences in biological effects have not been fully explained. Pharmacokinetic investigations of darbepoetin alfa using prolonged blood sampling times established that the mean terminal half-life after subcutaneous (SC) administration is 70 to 105 hours. Pharmacodynamic studies were conducted to assess the suitability of darbepoetin alfa for use in weekly or less frequent (once every other week or once a month) dosing regimens to maintain haemoglobin levels in patients with anaemia of renal disease. Regardless of dialysis status, route of administration, or prior treatment with an erythropoiesis-stimulating agent, darbepoetin alfa administered at extended intervals was able to raise or maintain hemoglobin levels to target. More rigorous studies will be needed to confirm these findings.