Marstacimab is a medicine used to prevent or reduce bleeding episodes in people with haemophilia A or B, generally adults and adolescents without inhibitors to factor VIII or IX. Its purpose is routine prophylaxis, not rapid treatment of an active serious bleed.
The medicine works by blocking tissue factor pathway inhibitor, which helps the body form clots more effectively. It does not replace every haemophilia treatment. A plan for injuries, dental work, surgery and emergency bleeding should be agreed in advance with the haemophilia care team.
Marstacimab is given as a subcutaneous injection, usually once weekly, after proper training. The patient or caregiver should know how to store the medicine, prepare the injection and record doses. Do not change the schedule without advice from your haemophilia centre.
Common side effects include injection site reactions, headache and itching. Rare but important risks include allergic reactions and blood clots. Report chest pain, shortness of breath, sudden swelling of a limb, severe headache, weakness on one side of the body, or widespread hives immediately.