Hematinic drugs: Erythropoietin agents

Erythropoietin agents

Epoetin alfa and darbepoetin alfa are glycopro-teins that stimulate RBC production (erythro-poiesis).

Pharmacokinetics

Epoetin alfa and darbepoetin alfa may be given subQ or I.V. After subQ administration, serum levels of epoetin alfa peak in 5 to 24 hours, while serum levels of darbepoetin alfa peak in 24 to 72 hours.

The circulating half-life of epoetin alfa is also shorter at 4 to 13 hours, compared to 49 hours for darbepoetin alfa. The therapeutic effect of these agents lasts for several days after ad-ministration.

Pharmacodynamics

Epoetin alfa and darbepoetin alfa boost the production of erythro-poietin, thus stimulating RBC production in bone marrow. Nor-mally, erythropoietin is formed in the kidneys in response to hy-poxia (reduced oxygen) and anemiaPatients with conditions that decrease production of erythropoietin typically develop normocytic anemia. This anemia canusually be corrected after 5 to 6 weeks of treatment with an erythropoietin agent.

Pharmacotherapeutics

Epoetin alfa is used to:

• treat patients with anemia associated with chronic renal failure

• treat anemia associated with zidovudine therapy in patients with human immunodeficiency virus infection

• treat anemia in cancer patients receiving chemotherapy

• reduce the need for allogenic blood transfusions in surgical patients.

Darbepoetin alfa is used to treat anemia associated with chronic renal failure.

Drug interactions

No known drug interactions exist with either drug, although they can cause some adverse reactions. (See Adverse reactions to erythropoietin agents.)