C1-esterase inhibitor, human: clinical use

Prescribing considerations

• Confirm that the selected subcutaneous formulation matches the licensed preventive indication and intended age group.
• Ensure the patient or carer can reconstitute and inject it safely and has an individual plan for breakthrough attacks.
• Assess previous thrombosis and other thrombotic risk factors; licensed subcutaneous use has no established causal association with thromboembolic events.
• Discuss the residual theoretical infection-transmission risk of plasma-derived products and consider hepatitis A and B vaccination for repeated recipients.

Contraindications and cautions

• Previous life-threatening hypersensitivity, including anaphylaxis, to a C1-inhibitor preparation or any excipient.

Monitoring

• Record the product name and batch number for every administration.
• Review injection technique, treatment records and attack control.
• Monitor for hypersensitivity and injection-site reactions.
• Ensure access to appropriate acute treatment.

Clinical pharmacology

Human C1-esterase inhibitor is a plasma serpin that inhibits complement components C1r and C1s, factor XIIa and plasma kallikrein. Replacement restores deficient functional activity and reduces uncontrolled bradykinin-mediated swelling.

Formulation and product differences

• The selected presentation is a powder and solvent reconstituted for subcutaneous injection only; it should not be given by another route or assumed interchangeable with other C1-inhibitor presentations.
• It contains no preservative and should preferably be used immediately after preparation.
• The selected presentation is considered essentially sodium-free.