Epoetin Alfa
Common Brand Names: Epogen, Procrit
Therapeutic Class: A biosynthetic form of the blood modifier glycoprotein hormone erythropoietin
Common Injectable Dosage Forms:
Injection: 1 mL vials containing 2,000, 3,000, 4,000, 10,000, 20,000, or 40,000 units
Dosage Ranges:
The initial dose in chronic renal failure is 50-100 units/kg 3 times weekly until hematocrit reaches 30-33% or hemoglobin is 10 g/dL. Doses should then be reduced by 25 units/kg and titrated to response. Further dosage adjustments are generally based on keeping the hematocrit in a target range around 35% with dosage adjustments only every 2-6 weeks to allow time to adequate response.
For zidovudine-induced anemia, usual dosage is initiated at 100 u/kg IV or SQ 3 times weekly for 8-12 weeks.
Chemotherapy-induced anemia is usually treated with 150 u/kg SQ 3 times weekly.
Administration and Stability: Epoetin may be given undiluted by either subcutaneous or direct IV injection. The vials should NOT be shaken prior to administration to prevent foaming and denaturation of the glycopeptide structure. Do not further dilute with other solutions. Vials should be stored refrigerated, do not freeze. pH 5.8-7.2
Pharmacology/Pharmacokinetics: Epoetin alfa induces the production of erythrocytes in an identical manner to endogenous erythropoietin. While rate and extent of absorption vary widely with SQ vs. IV administration, the clinical importance of this seems rather unimportant. The drug has a volume of distribution approximately equaling that of plasma. While much remains to be learned about its metabolic fate, it appears the drug is both metabolized and eliminated at multiple sites (kidney, bone marrow, spleen).
Drug and Lab Interactions: Concurrent administration with desmopressin results in additive reduction of bleeding times. Androgens have been shown beneficial as an adjunct to increasing erythropoiesis. Probenecid may inhibit the renal tubular secretion of epoetin.
Contraindications/Precautions: Contraindicated in patients with uncontrolled hypertension, known sensitivity to mammalian cell-derived products, or sensitivity to human albumin. Should be used with caution in patients with porphyria, suspected myeloid malignancies, and in patients with unstable angina, or a history of recent myocardial infarction. Careful and periodic monitoring of hematocrit should be a cornerstone of therapy to keep levels within desired range. Pregnancy Category C.
Monitoring Parameters: Blood pressure, hematocrit, hemoglobin, CBC with diff., transferring saturation, and ferritin.
Adverse Effects: The most prevalent adverse effects with epoetin have been hypertension, venous fistula clotting, and functional iron deficiency. Other rare reports include thrombocytosis, sweating, and bone pain.
Common Clinical Applications: Stimulates erythropoiesis in anemic patients with chronic renal failure, including both patients on dialysis and those who do not require regular dialysis.
