Adults

For CKD: Initial dose 0.45 mcg/kg administered intravenously or subcutaneously once weekly or 0.75 mcg/kg every 2 weeks. For chemotherapy-induced anemia: 2.25 mcg/kg SC weekly or 500 mcg SC once every 3 weeks. Doses are adjusted to maintain target hemoglobin levels.

Elderly

No specific dose adjustment is typically required for elderly patients, but individual response and comorbidities should be considered.

Renal_impairment

The primary indication is for anemia in CKD patients; dosage is adjusted based on hemoglobin levels and response, as described for adults.

Onset

Erythroid response typically begins within 1-2 weeks, with significant increases in hemoglobin seen over 3-6 weeks.

Excretion

Mainly through receptor-mediated catabolism; minimal excretion of intact drug via kidneys.

Half life

Mean terminal half-life is approximately 49 hours for subcutaneous administration and 21 hours for intravenous administration.

Absorption

Subcutaneous absorption is slow and sustained, with peak concentrations reached in 2-3 days. Bioavailability is approximately 37% (CKD) to 53% (cancer).

Metabolism

Primarily cleared by erythropoietin receptor-mediated uptake and degradation, with minor renal excretion.

No significant direct drug-drug interactions

Darbepoetin alfa is not metabolized by CYP450 enzymes. No formal drug-drug interaction studies have been conducted. Monitor for effects of concomitant medications on blood pressure.