HEMLIBRA
Clinical safety rating
cautionComprehensive clinical and safety monograph for HEMLIBRA (HEMLIBRA).
Emicizumab is a bispecific monoclonal antibody that bridges activated factor IX (FIXa) and factor X (FX) to restore the function of missing activated factor VIII (FVIIIa) in patients with hemophilia A. It mimics the cofactor activity of FVIIIa, thereby promoting thrombin generation and hemostasis.
| Metabolism | Emicizumab is a humanized monoclonal antibody; it is catabolized by general protein degradation pathways, not by cytochrome P450 enzymes. |
| Excretion | Emicizumab is catabolized via general protein degradation pathways; no specific elimination route data available. In clinical studies, no significant renal or biliary excretion of intact drug has been observed. |
| Half-life | Terminal elimination half-life is approximately 26.7 days (range 20–31 days) in healthy subjects and similar in hemophilia A patients, supporting weekly subcutaneous dosing with a loading period. |
| Protein binding | No protein binding data are available for emicizumab; as a monoclonal antibody, it is not bound to plasma proteins in a specific manner but may be subject to nonspecific binding via Fc receptors. |
| Volume of Distribution | Mean volume of distribution (Vd) is approximately 10.6 L (about 0.14 L/kg for a 70 kg individual), indicating limited distribution primarily to the vascular space. |
| Bioavailability | Subcutaneous administration: Absolute bioavailability is approximately 50–60% after subcutaneous injection. |
| Onset of Action | Subcutaneous injection: Steady-state concentrations are achieved within 4–6 weeks following the loading dose regimen; a clinically relevant effect on bleeding episodes is observed within 24–48 hours after the first dose. |
| Duration of Action | The therapeutic effect persists for at least 28 days after the last dose, due to its long half-life. Dosing every 1–2 weeks maintains effective concentrations. The pharmacodynamic effect is reversible but persists for weeks after discontinuation. |
| Molecular Weight | 149000 |
Subcutaneous loading dose of 3 mg/kg once weekly for 4 weeks, followed by 1.5 mg/kg once weekly; or 3 mg/kg once weekly for 4 weeks, then 3 mg/kg every 2 weeks; or 3 mg/kg once weekly for 4 weeks, then 6 mg/kg every 4 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | No dose adjustment required for mild to moderate renal impairment; not studied in severe renal impairment (eGFR <30 mL/min/1.73 m²) or dialysis. |
| Liver impairment | No dose adjustment required for mild hepatic impairment (Child-Pugh A); not studied in moderate or severe (Child-Pugh B or C). |
| Pediatric use | Weight-based dosing: Same as adult (loading 3 mg/kg weekly x4, then maintenance 1.5 mg/kg weekly, 3 mg/kg every 2 weeks, or 6 mg/kg every 4 weeks) for patients weighing ≥5 kg; no data for <5 kg. |
| Geriatric use | No specific dose adjustment; limited data in patients ≥65 years; use caution due to higher incidence of thromboembolic events. |
| 1st trimester | No adequate human data; based on animal studies, potential fetal harm (IgG1 mAb crosses placenta). Use only if benefit outweighs risk. |
| 2nd trimester | Limited human data; placental transfer increases. May cause fetal coagulation abnormalities. Use only if clearly needed. |
| 3rd trimester | Significant placental transfer; may affect fetal hemostasis. Risk of bleeding in neonate. Avoid unless essential. |
Clinical note
Comprehensive clinical and safety monograph for HEMLIBRA (HEMLIBRA).
| Placental transfer | Emicizumab, a humanized monoclonal antibody (IgG1), is expected to cross the placenta in increasing amounts as pregnancy progresses, especially during the third trimester. Placental transfer is mediated by FcRn receptors. |
| Breastfeeding | Emicizumab is a large molecule likely present in breast milk in low amounts; minimal systemic absorption in infant due to GI degradation. Caution in preterm or neonates with GI issues. |
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | Emicizumab is a recombinant humanized monoclonal antibody (IgG4) that binds to activated factor IX and factor X. As an immunoglobulin G, it is actively transported across the placenta during the second and third trimesters. There are no adequate and well-controlled studies in pregnant women. In animal reproduction studies, no adverse developmental outcomes were observed in cynomolgus monkeys administered intravenous emicizumab at doses up to 30 mg/kg (approximately 0.9 times the human exposure at the maximum recommended human dose of 6 mg/kg/week) during organogenesis. However, based on the mechanism of action and potential for inducing thrombotic events, there is a theoretical risk of fetal harm, including thromboembolism. The drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. |
| Fetal Monitoring | During pregnancy, monitor for signs and symptoms of thrombotic events, including deep vein thrombosis, pulmonary embolism, and thrombotic microangiopathy. In the event of thrombotic complications, emicizumab should be discontinued and appropriate anticoagulant therapy initiated. No routine fetal monitoring specific to emicizumab is recommended; standard obstetric monitoring is appropriate. |
| Fertility Effects | Emicizumab has no known direct effects on human fertility. In animal studies, no effects on male or female fertility were observed in cynomolgus monkeys at doses up to 30 mg/kg. However, data in humans are lacking. Patients of reproductive potential should discuss family planning with their healthcare provider. |
■ FDA Black Box Warning
Thrombotic microangiopathy (TMA) and thromboembolic events: Cases of TMA and thrombotic events (e.g., venous thrombosis, pulmonary embolism) have been reported when emicizumab was used with activated prothrombin complex concentrates (aPCC) for >24 hours or at doses >100 U/kg. Avoid concomitant use of aPCC and monitor for TMA/thrombosis if aPCC is required.
| Serious Effects |
Hypersensitivity to emicizumab or any excipientKnown inhibitor of coagulation factor VIII
| Precautions | Thrombotic microangiopathy (TMA) and thromboembolic events (see black box warning)., Increased risk of bleeding if emicizumab is co-administered with bypassing agents (e.g., aPCC, rFVIIa)., Discontinue concurrent prophylactic use of bypassing agents; reduce dose and monitor for bleeding when using on-demand bypassing therapy., Immunogenicity: Development of anti-emicizumab antibodies may reduce efficacy., Laboratory monitoring: Emicizumab interferes with activated partial thromboplastin time (aPTT)-based coagulation assays; use chromogenic factor VIII activity assay for monitoring. |
| Food/Dietary | No known food interactions. Emicizumab is a monoclonal antibody administered subcutaneously and its absorption and efficacy are not affected by food. Patients may take with or without food. |
| Clinical Pearls | Monitor for thromboembolic events, especially in patients with central venous access devices. Do not mix with other coagulation factor products. Administer subcutaneously once weekly for 4 weeks, then every 2 weeks thereafter. For breakthrough bleeding, use recombinant factor VIIa (rFVIIa) rather than activated prothrombin complex concentrate (aPCC) due to thrombotic risk with aPCC. Do not use for immune tolerance induction. Monitor for thrombotic microangiopathy and venous thromboembolism. Emicizumab is a bispecific monoclonal antibody that bridges factor IXa and factor X, restoring hemostasis in hemophilia A patients with or without factor VIII inhibitors. |
| Patient Advice | Take exactly as prescribed; do not skip doses or change schedule without consulting your doctor. · Report any signs of blood clots (leg pain/swelling, chest pain, shortness of breath, headache, vision changes) immediately. · Inform all healthcare providers that you are taking emicizumab, especially before any surgery or dental procedures. · Do not use emicizumab if you have a history of severe allergic reaction to the drug or its components. · Store emicizumab in the refrigerator at 2-8°C (36-46°F); do not freeze. Protect from light. Do not shake the vial. · If a dose is missed, take it as soon as possible, then resume the regular schedule. Consult your doctor if more than one dose is missed. · Avoid using activated prothrombin complex concentrate (aPCC) unless specifically instructed by your doctor, as it may increase risk of blood clots. · Keep a record of injection dates and sites; rotate injection sites (abdomen, thigh, upper arm) to reduce injection site reactions. |
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