Macitentan ACT-132577

Macitentan ACT-132577 is a brominated triazole-sulfonamide derivative featuring a disubstituted benzene ring and a fused pyridine moiety, structurally diverging from Macitentan by incorporating two bromine atoms and a methylsulfonyl group in place of the parent drug’s terminal amide. This impurity arises via bromination of the aromatic core during synthetic processes, introducing steric and electronic perturbations that alter pharmacophore interactions. It serves as an HPLC reference standard for quantifying process-related impurities in Macitentan active pharmaceutical ingredient batches.