Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
OMONTYS vs RETACRIT
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Erythropoiesis-stimulating agent; synthetic peptide agonist of the erythropoietin receptor (EPOR) that stimulates erythropoiesis in red blood cell precursors.
RETACRIT (epoetin alfa-epbx) is a recombinant human erythropoietin that stimulates erythropoiesis by binding to and activating the erythropoietin receptor on erythroid progenitor cells, promoting their survival, proliferation, and differentiation into mature red blood cells.
Anemia due to chronic kidney disease (CKD) in adults on dialysis and not on dialysis
Treatment of anemia due to chronic kidney disease (CKD) in patients on dialysis and not on dialysis,Treatment of anemia in HIV-infected patients treated with zidovudine,Treatment of anemia in patients with non-myeloid malignancies where anemia is due to the effect of concomitantly administered chemotherapy,Reduction of allogeneic red blood cell transfusions in patients undergoing elective, noncardiac, nonvascular surgery
45 mg subcutaneously once every 4 weeks (monthly) in adults.
50-100 IU/kg intravenously or subcutaneously three times weekly; initial dose 50 IU/kg three times weekly, titrated to target hemoglobin 10-12 g/d L.
Terminal elimination half-life is approximately 14.5 hours in healthy adults; in hemodialysis patients, half-life is extended to 26.4–29.9 hours, supporting weekly dosing.
Terminal elimination half-life is ~2.5-4.5 hours following intravenous administration; shorter in children; prolonged in hepatic impairment.
Not metabolized by cytochrome P450 enzymes; degraded into small peptides and amino acids via catabolic pathways.
Epoetin alfa-epbx is a protein; metabolism is expected to involve proteolytic degradation via catabolic pathways, similar to endogenous erythropoietin. No specific metabolic enzymes have been identified; clearance is primarily through receptor-mediated uptake and proteolysis.
Primarily eliminated via the reticuloendothelial system; no significant renal or biliary excretion. The iron component is incorporated into hemoglobin or stored as ferritin/hemosiderin.
Primarily hepatic metabolism; ~10% excreted unchanged in urine, remainder via feces as metabolites.
Ferric pyrophosphate citrate moiety: <5% bound to plasma proteins; iron is rapidly transferred to transferrin.
Primarily binds to transferrin; iron is 100% bound to transferrin after dissociation from complex.
Vd approximately 0.47 L/kg (range 0.2–0.8 L/kg), indicating distribution primarily into plasma and interstitial fluid; iron distributes to bone marrow and reticuloendothelial system.
Vd is approximately 0.067-0.22 L/kg; reflects distribution into plasma and extracellular fluid; limited tissue penetration initially.
Not applicable; OMONTYS is administered only intravenously. Oral bioavailability is not relevant.
Not orally bioavailable; administered intravenously (100% bioavailability for IV route).
No dosage adjustment required for any degree of renal impairment, including end-stage renal disease.
For CKD patients, epoetin alfa dosing is independent of GFR; adjust based on hemoglobin response. No specific GFR-based dose adjustments, but start at 50-100 IU/kg three times weekly for dialysis patients.
No dosage adjustment recommended for mild or moderate hepatic impairment (Child-Pugh A or B). Not studied in severe hepatic impairment (Child-Pugh C).
No specific Child-Pugh based adjustments. Use with caution in severe hepatic impairment; monitor for adverse effects.
Safety and efficacy in pediatric patients have not been established; no recommended dose.
0.5-50 IU/kg subcutaneously or intravenously three times weekly, titrated to target hemoglobin. For pediatric CKD, initial dose 50 IU/kg three times weekly.
No specific dosage adjustment needed; consider age-related renal function and individual tolerability.
No specific dose adjustment; initiate at lower end of dosing range (50 IU/kg three times weekly) and titrate slowly, monitoring for hypertension and thrombotic events.
Increased risk of serious cardiovascular events, myocardial infarction, stroke, venous thromboembolism, vascular access thrombosis, and mortality when targeting hemoglobin levels >11 g/d L; increased risk of tumor progression and recurrence in patients with cancer; not indicated for treatment of anemia in cancer patients due to increased risk of death and serious cardiovascular events.
WARNING: INCREASED RISK OF DEATH, MYOCARDIAL INFARCTION, STROKE, VENOUS THROMBOEMBOLISM, THROMBOSIS OF VASCULAR ACCESS AND TUMOR PROGRESSION OR RECURRENCE. Chronic Kidney Disease: In controlled trials, patients experienced greater risks for death, serious adverse cardiovascular reactions, and stroke when administered erythropoiesis-stimulating agents (ESAs) to target a hemoglobin level of 13 g/d L or greater. No trial has identified a hemoglobin target level, ESA dose, or dosing strategy that does not increase these risks. Use the lowest dose sufficient to reduce the need for red blood cell transfusions. Cancer: ESAs shortened overall survival and/or increased the risk of tumor progression or recurrence in clinical studies of patients with breast, non-small cell lung, head and neck, lymphoid, and cervical cancers. To decrease these risks, as well as the risk of serious cardiovascular and thromboembolic reactions, use the lowest dose needed to avoid red blood cell transfusions. Use ESAs only for anemia from myelosuppressive chemotherapy. ESAs are not indicated for patients receiving myelosuppressive chemotherapy when the anticipated outcome is cure. Discontinue following the completion of a chemotherapy course. Perisurgery: Due to increased risk of deep venous thrombosis (DVT), use prophylactic anticoagulation and consider whether benefit of transfusion reduction outweighs increased risk of post-operative thrombotic/vascular events.
Increased mortality, serious cardiovascular events, and thromboembolic events; hypertension; seizures; pure red cell aplasia (PRCA) with neutralizing antibodies; increased risk of tumor progression in cancer patients; hemoglobin monitoring; iron deficiency management; hypersensitivity reactions including anaphylaxis.
Increased mortality, myocardial infarction, stroke, and thromboembolism,Increased risk of thrombosis of vascular access,Increased mortality and/or tumor progression in cancer patients,Hypertension,Seizures,Pure red cell aplasia (PRCA) due to anti-erythropoietin antibodies,Serious allergic reactions,Possible worsening of anemia due to antibody-mediated PRCA,Risk of cardiovascular events when hemoglobin exceeds 11 g/d L,Need for iron supplementation,Monitoring of hemoglobin and blood pressure
Uncontrolled hypertension; history of pure red cell aplasia (PRCA) following erythropoiesis-stimulating agents; known hypersensitivity to OMONTYS or any of its components.
Uncontrolled hypertension,Pure red cell aplasia (PRCA) that begins after treatment with epoetin alfa or other ESAs,Known hypersensitivity to epoetin alfa-epbx or any component of the product
No clinically significant food interactions reported. Administer subcutaneously, independent of meals.
No specific food interactions. Maintain adequate iron intake; consider dietary sources of iron (e.g., red meat, leafy greens) if not on supplements. No restrictions with alcohol or other foods.
OMONTYS (pegcetacoplan) is a complement inhibitor. There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, no adverse developmental effects were observed at maternal exposures up to 20 times the human exposure at the recommended clinical dose. Based on its mechanism of action as a complement inhibitor, there is a theoretical risk of increased susceptibility to infections for the fetus, but no specific teratogenic effects have been identified. The drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Retacrit (epoetin alfa-epbx) is a recombinant human erythropoietin. In animal studies, epoetin alfa did not demonstrate teratogenicity at clinically relevant doses. However, there are no adequate and well-controlled studies in pregnant women. Potential fetal risks include hypertension and thromboembolic events secondary to maternal polycythemia. Use during pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus.
It is unknown whether pegcetacoplan is excreted in human milk, affects the breastfed infant, or affects milk production. No data on the milk-to-plasma (M/P) ratio are available. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
It is not known whether epoetin alfa is excreted in human milk. Endogenous erythropoietin is present in breast milk. M/P ratio not available. Caution should be exercised when Retacrit is administered to a nursing woman. Consider the developmental and health benefits of breastfeeding along with the mother’s clinical need for the drug and any potential adverse effects on the breastfed child from the drug or underlying maternal condition.
No specific pharmacokinetic studies have been conducted in pregnant women. Based on the drug's large molecular weight and subcutaneous route, significant alterations in clearance due to pregnancy-induced physiological changes (e.g., increased blood volume, renal clearance) are possible but not quantified. The recommended dose for non-pregnant adults is 1080 mg subcutaneously twice weekly. No formal dose adjustment is recommended during pregnancy due to lack of data; however, close monitoring for clinical efficacy and safety is advised. Dose adjustments should be guided by therapeutic response and tolerability.
No specific dose adjustments for Retacrit are recommended during pregnancy based on pharmacokinetic changes. However, pregnant women may have increased plasma volume and altered erythropoietin kinetics. The lowest effective dose to gradually increase hemoglobin to the target level (not to exceed 12 g/d L in chronic kidney disease) should be used. Close monitoring of hemoglobin and blood pressure is essential to avoid excessive erythrocytosis and associated risks.
OMONTYS (pegcetacoplan) is a C3 inhibitor approved for paroxysmal nocturnal hemoglobinuria (PNH). Initiate only in patients vaccinated against encapsulated bacteria (Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae type b) due to increased infection risk. Monitor for hemolysis, thrombosis, and breakthrough disease; consider dose adjustments if hemoglobin drops significantly. Do not discontinue abruptly—switch to alternative therapy under medical supervision.
Retacrit (epoetin alfa-epbx) is a biosimilar to Epogen/Procrit. Monitor hemoglobin weekly until stable, then monthly; target Hb 10-12 g/d L. Do not use to replace urgent transfusions. Iron stores must be adequate; check ferritin and transferrin saturation. Increased risk of thrombotic events, especially in patients with cardiovascular disease. Do not shake vial; use one vial per dose; discard unused portion. Administer subcutaneously or intravenously; rotate injection sites.
You must receive vaccinations against meningococcus, pneumococcus, and Haemophilus influenzae type b before starting OMONTYS and maintain up-to-date immunizations.,Report any signs of infection immediately: fever, headache with stiff neck, confusion, chills, or rash.,Do not stop taking OMONTYS without talking to your doctor—sudden discontinuation may cause serious hemolysis.,You may experience injection site reactions; rotate injection sites and avoid injecting into tender or scarred areas.,Store OMONTYS in the refrigerator at 2°C to 8°C (36°F to 46°F). Do not freeze or shake. Protect from light.
This medication helps your body make more red blood cells to treat anemia.,You will have regular blood tests to check your hemoglobin levels and iron stores.,Do not miss scheduled appointments for monitoring; call your doctor if you have symptoms of a blood clot (chest pain, sudden shortness of breath, leg swelling).,It is important to take iron supplements as prescribed while on this medication.,Store Retacrit in the refrigerator; do not freeze or shake the vial.,Report any signs of allergic reaction (rash, itching, swelling).
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about OMONTYS vs RETACRIT, answered by our medical review team.
OMONTYS is a Erythropoiesis-Stimulating Agent that works by Erythropoiesis-stimulating agent; synthetic peptide agonist of the erythropoietin receptor (EPOR) that stimulates erythropoiesis in red blood cell precursors.. RETACRIT is a Erythropoiesis-Stimulating Agent that works by RETACRIT (epoetin alfa-epbx) is a recombinant human erythropoietin that stimulates erythropoiesis by binding to and activating the erythropoietin receptor on erythroid progenitor cells, promoting their survival, proliferation, and differentiation into mature red blood cells.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between OMONTYS and RETACRIT depend on the specific clinical indication. These are both Erythropoiesis-Stimulating Agent agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of OMONTYS is: 45 mg subcutaneously once every 4 weeks (monthly) in adults.. The standard adult dose of RETACRIT is: 50-100 IU/kg intravenously or subcutaneously three times weekly; initial dose 50 IU/kg three times weekly, titrated to target hemoglobin 10-12 g/d L.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between OMONTYS and RETACRIT in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. OMONTYS is classified as Category C. OMONTYS (pegcetacoplan) is a complement inhibitor. There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, no adverse developmental eff. RETACRIT is classified as Category C. Retacrit (epoetin alfa-epbx) is a recombinant human erythropoietin. In animal studies, epoetin alfa did not demonstrate teratogenicity at clinically relevant doses. However, there . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.