Macitentan
Macitentan is an endothelin receptor antagonist used to treat pulmonary arterial hypertension (PAH) by blocking the action of endothelin-1, a substance that causes blood vessels to narrow. By inhibiting both endothelin A and B receptors, it helps relax and widen the pulmonary arteries, improving blood flow and exercise capacity in patients with PAH.
Macitentan treats pulmonary arterial hypertension by blocking endothelin receptors to reduce vasoconstriction and improve pulmonary blood flow.
This medication carries a boxed (black box) warning — the strongest type of FDA warning. Review the full prescribing information before use.
Key facts at a glance
- ATC
- C02KX04
- RxNorm
- 1442132
- Generic
- Macitentan
- Class
- atc-c02
- Brands
- Opsumit, Opsynvi
- Availability
- rx
- Lactation
- unknown
- Routes
- oral
- Forms
- tablet
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Treatment of pulmonary arterial hypertension (PAH) to improve exercise capacity, delay disease progression, and reduce the need for hospitalization. May be used as monotherapy or in combination with other PAH medications.
Macitentan is a dual endothelin receptor antagonist that blocks both endothelin A (ETA) and endothelin B (ETB) receptors. Endothelin-1 is a potent vasoconstrictor that promotes fibrosis, inflammation, and vascular cell proliferation. By blocking these receptors, macitentan counteracts the excessive endothelin activity seen in PAH, leading to vasodilation and reduced vascular remodeling in the pulmonary arteries.
Macitentan is contraindicated in pregnancy due to teratogenic effects. Monthly liver function monitoring is required as hepatotoxicity may occur. Common side effects include anemia, fluid retention, and upper respiratory infections. Requires REMS program enrollment. May cause spermatogenesis reduction in male patients.
Official drug label
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This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy