emicizumab: clinical use

Prescribing considerations

• Initiate under specialist supervision and establish a written plan for breakthrough bleeding and invasive procedures.
• Review prior bypassing-agent use before starting treatment.
• Provide the patient or caregiver guide and patient card, advising that it be shown to all healthcare professionals.
• Assess unexplained increased bleeding for adherence, administration problems and possible neutralising anti-emicizumab antibodies.
• Evidence is limited in infants under one year and in moderate renal or hepatic impairment; severe impairment has not been studied.
• Use particular caution with a personal or family history of thrombotic microangiopathy or relevant concomitant medicines.

Contraindications and cautions

• Hypersensitivity to emicizumab or any excipient.

Monitoring

• Monitor clinical bleed control rather than using routine intrinsic-pathway clotting tests to assess activity.
• If aPCC is required, monitor clinically and with appropriate laboratory tests for thrombosis, thrombotic microangiopathy, renal injury and thrombocytopenia.
• Emicizumab shortens aPTT and affects aPTT-based assays, including one-stage factor VIII assays and clotting-based Bethesda tests; effects may persist for months after stopping.
• Use suitable chromogenic assays containing bovine coagulation factors when endogenous or infused factor VIII activity or inhibitor titres must be assessed.
• Record the product name and batch number for traceability.

Clinical pharmacology

Emicizumab is a humanised, modified IgG4 bispecific antibody that bridges activated factor IX and factor X. It is absorbed after subcutaneous injection and is primarily cleared by proteolytic catabolism rather than renal excretion.

Formulation and product differences

• Ready-to-use single-use vials are supplied at 30 mg/mL and 150 mg/mL.
• The concentrations must not be combined in the same syringe.
• The solution is preservative-free and should not be diluted or shaken.
• Store refrigerated and protected from light; unopened vials have limited permitted storage below 30°C as detailed in the product information.

Injection

Route: Parenteral

Strengths: 30 mg/mL, 150 mg/mL