Macitentan ethoxy alcohol

Macitentan ethoxy alcohol is a structurally related impurity derived from the parent drug Macitentan, characterized by the substitution of a terminal ethoxy group (-OCH2CH3) and a hydroxyl (-OH) moiety on the side chain. The compound retains the core pyridine-sulfonamide pharmacophore of Macitentan but features an ethoxy alcohol appendage, introducing steric and electronic modifications that alter its physicochemical properties. This impurity arises via side-chain hydroxylation followed by ethoxylation during synthetic processes. It serves as a critical HPLC reference standard for quantifying process-related impurities in Macitentan active pharmaceutical ingredient batches.