EPREX-2000 2000IU/0.5ML INJECTION

Indications

• Anemia associated with chronic kidney disease
• Anemia in patients receiving chemotherapy
• Anemia in patients with HIV infection receiving zidovudine
• Anemia due to bone marrow suppression

Dosage

Adults: The usual dosage for adults varies based on the indication and clinical condition. For anemia due to chronic kidney disease, the initial dose is generally 50 to 100 Units/kg administered three times a week. Dose adjustments should be made based on hemoglobin levels, aiming for a target range of 10-12 g/d

Mechanism of action

Epoetin alfa binds to the erythropoietin receptor (EPO-R), activating intracellular signaling pathways. This binding induces a conformational change in the receptor that facilitates the activation of Janus family tyrosine protein kinase 2 (JAK2). JAK2 phosphorylation leads to the activation of transcription factors such as STAT5, which translocate to the nucleus to activate genes responsible for erythroid differentiation and inhibit apoptosis, thus promoting the survival and proliferation of erythroid progenitor cells.

Pharmacodynamics

Epoetin alfa regulates erythrocyte differentiation and maintains physiological erythrocyte levels. It typically increases reticulocyte counts within 10 days of administration, with subsequent increases in red blood cell counts, hemoglobin, and hematocrit observed within 2 to 6 weeks. The response may vary based on the administered dose, and higher doses may not enhance the response in patients undergoing hemodialysis.

Pharmacokinetics

Epoetin alfa is administered via subcutaneous or intravenous injection. It has a half-life of approximately 4 to 13 hours, depending on the route of administration and the patient's condition. It is metabolized by the liver, and its elimination primarily occurs through the kidneys. The pharmacokinetics may be altered in patients with renal impairment, necessitating dose adjustments.

Contra-indications

• Hypersensitivity to epoetin alfa or any of its components
• Uncontrolled hypertension
• Pure red cell aplasia after previous treatment with erythropoietin

Adverse effects

• Hypertension
• Headache
• Nausea
• Vomiting
• Diarrhea
• Fatigue
• Injection site reactions
• Thromboembolic events

Interactions

• Increased risk of thromboembolic events when used with other agents that increase blood viscosity or promote clotting
• Concurrent use with other erythropoiesis-stimulating agents

Precautions

• Monitor blood pressure regularly during treatment
• Use with caution in patients with a history of cardiovascular disease
• Assess for signs of anaphylaxis during the first administration

Pregnancy

Epoetin alfa should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult specific guidelines.

Breast-feeding

Caution is advised when administering epoetin alfa to nursing mothers; the effects on the breastfed infant are unknown.

Storage

Store in a refrigerator at 2 to 8 degrees Celsius. Do not freeze. Protect from light.

Formulations

• Injection solution (various strengths)

Mechanism of action

Erythropoietin or exogenous epoetin alfa binds to the erythropoietin receptor (EPO-R) and activates intracellular signal transduction pathways. The affinity (Kd) of EPO for its receptor on human cells is ∼100 to 200 pM. Upon binding to EPO-R on the surface of erythroid progenitor cells, a conformational change is induced which brings EPO-R-associated Janus family tyrosine protein kinase 2 (JAK2) molecules into close proximity. JAK2 molecules are subsequently activated via phosphorylation, then phosphorylate tyrosine residues in the cytoplasmic domain of the EPO-R that serve as docking sites for Src homology 2-domain-containing intracellular signaling proteins. The signalling proteins include STAT5 that once phosphorylated by JAK2, dissociates from the EPO-R, dimerizes, and translocates to the nucleus where they serve as transcription factors to activate target genes involved in cell division or differentiation, including the apoptosis inhibitor Bcl-x. The inhibition of apoptosis by the EPO-activated JAK2/STAT5/Bcl-x pathway is critical in erythroid differentiation. Via JAK2-mediated tyrosine phosphorylation, erythropoietin and epoetin alfa also activates other intracellular proteins involved in erythroid cell proliferation and survival, such as Shc , phosphatidylinositol 3-kinase (PI3K), and phospholipase C-γ1. Epoetin alfa is a glycoprotein, produced by recombinant DNA technology, that contains 165 amino acids in a sequence identical to that of endogenous human erythropoietin. Recombinant epoetin has the same biological activity as the endogenous hormone, which induces erythropoiesis by stimulating the division and differentiation of committed erythroid progenitor cells, including burst-forming units-erythroid, colony-forming units- erythroid, erythroblasts, and reticulocytes, in bone marrow. Erythropoietin also induces the release of reticulocytes from the bone marrow into the blood stream, where they mature into erythrocytes. Endogenous erythropoietin is produced primarily in the kidney. The anemia associated with chronic renal failure is caused primarily by inadequate production of the hormone. Administration of epoetin corrects the erythropoietin deficiency in patients with chronic renal failure. Epoetin also stimulates red blood cell production in patients who do not have a documented erythropoietin deficiency, i.e., patients with normal or slightly elevated concentrations of endogenous erythropoietin. However, it may not be effective in patients who are anemic despite having significantly elevated concentrations of erythropoietin.

Pharmacodynamics

Erythropoietin and epoetin alfa are involved in the regulation of erythrocyte differentiation and the maintenance of a physiological level of circulating erythrocyte mass. It is reported to increase the reticulocyte count within 10 days of initiation, followed by increases in the RBC count, hemoglobin, and hematocrit, usually within 2 to 6 weeks. Depending on the dose administered, the rate of hemoglobin increase may vary. In patients receiving hemodialysis, a greater biologic response is not observed at doses exceeding 300 Units/kg 3 times weekly. Epoetin alfa serves to restore erythropoietin deficiency in pathological and other clinical conditions where normal production of erythropoietin is impaired or compromised. In anemic patients with chronic renal failure (CRF), administration with epoetin alfa stimulated erythropoiesis by increasing the reticulocyte count within 10 days, followed by increases in the red cell count, hemoglobin, and hematocrit, usually within 2 to 6 weeks. Epoetin alfa was shown to be effective in increasing hematocrit in zidovudine-treated HIV-infected patients and anemic cancer patients undergoing chemotherapy.