caplacizumab at a glance
Medicine class
Humanised antibody fragment targeting von Willebrand factor
Licensed use
Acute aTTP in eligible adults and adolescents, with plasma exchange and immunosuppression
Routes
Intravenous and subcutaneous injection
Main safety concern
Bleeding, particularly with other treatments affecting clotting
What is caplacizumab used for?
Caplacizumab is licensed with plasma exchange and immunosuppression for an acute episode of aTTP.
Adults
Adolescents aged 12 years or older who weigh at least 40 kg
How does caplacizumab work?
In aTTP, unusually large von Willebrand factor molecules capture platelets and promote tiny clots in small blood vessels. Caplacizumab binds the A1 domain of von Willebrand factor, preventing its interaction with platelets and limiting further microclot formation. It does not directly remove the underlying disease-causing antibodies.
caplacizumab preparations and strengths
Injection
Route: Parenteral
Strengths: 10 mg
How to take caplacizumab
Treatment is started and supervised by a specialist experienced in thrombotic microangiopathies. Intravenous administration is performed by a healthcare professional; a trained patient or caregiver may give subcutaneous injections.
Inject under the skin of the abdomen, avoiding the area around the navel.
Rotate the abdominal injection area.
Reconstitute using the supplied solvent, swirl gently and do not shake.
Use only a clear, colourless or slightly yellow solution without particles.
Follow the supplied instructions and dispose of the syringe and needle safely.
caplacizumab side effects
Common or expected effects
- Nosebleeds or bleeding gums
- Headache
- Fever or tiredness
- Hives
- Bruising
- Injection-site redness, itching, pain or bleeding
- Muscle pain
Get urgent medical advice
- Prolonged, excessive or uncontrolled bleeding
- Vomiting or coughing blood
- Black, tarry or bloody stools
- Blood in the urine
- Heavy or unusual vaginal bleeding
- Sudden severe headache, confusion, weakness, seizures or reduced consciousness
- Shortness of breath, fainting or marked tiredness that could indicate internal bleeding
caplacizumab in pregnancy
Human pregnancy data are unavailable, and the product information advises avoiding caplacizumab as a precaution. Because aTTP is serious, pregnancy requires urgent specialist benefit–risk assessment.
caplacizumab while breastfeeding
It is unknown whether caplacizumab enters human milk, and risk to a breastfed child cannot be excluded. The specialist team should weigh the benefits of breastfeeding against the need for treatment.
caplacizumab interactions
The main clinically important interactions involve treatments that also increase bleeding.
Oral anticoagulants, including warfarin, apixaban and rivaroxaban
Combined use may increase bleeding and requires careful specialist review and close monitoring.
Antiplatelet medicines, including aspirin
Concurrent treatment may increase bleeding risk.
Heparins, including low-molecular-weight heparins
Combined effects on haemostasis may increase bleeding and require monitoring.
Common questions about caplacizumab
Answers are fully visible for fast scanning and source review.
Is caplacizumab a blood thinner?
It is not a conventional anticoagulant. It blocks von Willebrand factor from binding platelets, reducing microclot formation but increasing bleeding risk.
Why is it combined with plasma exchange and immunosuppression?
Caplacizumab rapidly limits platelet-rich microclots, while plasma exchange and immunosuppression address the underlying immune process.
Sources
These sources were used to prepare and review this medicine page.
Prepared and reviewed by the iatroX editorial team.