Macitentan

What it is and how it works

Mechanism of Action Endothelin (ET)-1 and its receptors (ET A and ET B ) mediate a variety of deleterious effects, such as vasoconstriction, fibrosis, proliferation, hypertrophy, and inflammation. In disease conditions such as PAH, the local ET system is upregulated and is involved in vascular hypertrophy and in organ damage. Macitentan is an endothelin receptor antagonist that inhibits the binding of ET-1 to both ET A and ET B receptors. Macitentan displays high affinity and sustained occupancy of the ET receptors in human pulmonary arterial smooth muscle cells.

Mechanism class: Endothelin Receptor Antagonists

Indications

Macitentan tablets are an endothelin receptor antagonist (ERA) indicated for the treatment of pulmonary arterial hypertension (PAH, WHO Group I) in adults to reduce the risks of disease progression and hospitalization for PAH . Pulmonary Arterial Hypertension Macitentan tablets are an endothelin receptor antagonist (ERA) indicated for the treatment of pulmonary arterial hypertension (PAH, WHO Group I) in adults to reduce the risks of disease progression and hospitalization for PAH. Effectiveness was established in a long-term study in PAH patients with predominantly WHO Functional Class II-III symptoms treated for an average of 2 years. Patients had idiopathic and heritable PAH (57%), PAH caused by connective tissue disorders (31%), and PAH caused by congenital heart disease with repaired shunts (8%) .

Dosage and administration (summary)

10 mg once daily. Doses higher than 10 mg once daily have not been studied in patients with PAH and are not recommended . Recommended Dosage The recommended dosage of macitentan tablets is 10 mg once daily for oral administration. Doses higher than 10 mg once daily have not been studied in patients with PAH and are not recommended. Pregnancy Testing in Females of Reproductive Potential Exclude pregnancy before initiating treatment with macitentan tablets in females of reproductive potential .

Contraindications

Pregnancy Hypersensitivity Pregnancy Macitentan tablets may cause fetal harm when administered to a pregnant woman. Macitentan tablets are contraindicated in females who are pregnant. Macitentan was consistently shown to have teratogenic effects when administered to animals. If macitentan tablets are used during pregnancy, advise the patient of the potential risk to a fetus .

Warnings and precautions

ERAs cause hepatotoxicity and liver failure. Obtain baseline liver enzymes and monitor as clinically indicated . Fluid retention may require intervention . Decreases in hemoglobin . Pulmonary edema in patients with pulmonary veno-occlusive disease. If confirmed, discontinue treatment . Decreases in sperm count have been observed in patients taking ERAs . Embryo-fetal Toxicity Based on data from animal reproduction studies, macitentan tablets may cause fetal harm when administered to a pregnant patient and is contraindicated during pregnancy.

Pregnancy

Pregnancy Risk Summary Based on data from animal reproduction studies, macitentan may cause embryo-fetal toxicity, including birth defects and fetal death, when administered to a pregnant female and is contraindicated during pregnancy. There are risks to the mother and the fetus associated with pulmonary arterial hypertension in pregnancy .

Storage and supply

Store at 20°C to 25°C (68°F to 77°F). Excursions are permitted between 15°C and 30°C (59°F and 86°F). . Keep out of reach of children.

Source: Macitentan (Macitentan) — US FDA prescribing information, 2026-06-11, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.