Macitentan (3 brand names, 1 dosage form, 1 route)
Available dosage forms: TABLET.
Routes of administration: ORAL.
Brand Names
- MACITENTAN
- OPSUMIT
- OPSYNVI
Boxed Warning
Macitentan tablets are contraindicated for use during pregnancy because it may cause fetal harm based on animal data [see Contraindications ( 4.1), Warnings and Precautions ( 5.1 )], Use in Specific Populations (8.1 )]. Therefore, for females of reproductive potential, exclude pregnancy before the start of treatment with macitentan tablets. Advise use of effective contraception before the initiation of treatment, during treatment, and for one month after stopping treatment with macitentan tablets [see Dosage and Administration (2.2), Use in Specific Populations (8.3)]. When pregnancy is detected, discontinue macitentan tablets as soon as possible [see Warnings and Precautions (5.1)].
Adverse Reactions
Clinically significant adverse reactions that appear in other sections of the labeling include: Embryo-fetal Toxicity [see Warnings and Precautions (5.1)] Hepatotoxicity [see Warnings and Precautions (5.2)] Fluid Retention [see Warnings and Precautions (5.3)] Decrease in Hemoglobin [see Warnings and Precautions (5.4)]
Mechanism of Action
Endothelin (ET)-1 and its receptors (ETA and ETB) 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 ETA and ETB receptors. Macitentan displays high affinity and sustained occupancy of the ET receptors in human pulmonary arterial smooth muscle cells. One of the metabolites of macitentan is also pharmacologically active at the ET receptors and is estimated to be about 20% as potent as the parent drug in vitro. The clinical impact of dual endothelin blockage is unknown.
Overdosage
Macitentan has been administered as a single dose of up to and including 600 mg to healthy subjects (60 times the approved dosage). Adverse reactions of headache, nausea and vomiting were observed. In the event of an overdose, standard supportive measures should be taken, as required. Dialysis is unlikely to be effective because macitentan is highly protein-bound.