Isolation and characterization of some potential impurities in ropinirole hydrochloride.

Abstract Three impurities in ropinirole hydrochloride drug substance at levels ∼0.06–0.15% were detected by reverse-phase high performance liquid chromatography (HPLC). These impurities were isolated from the drug substance. These impurities were analyzed using reverse-phase HPLC. Based on the spectral data (IR, NMR and MS), structures of these impurities were characterized as 4-[2-(propylamino) ethyl]-1,3-dihydro- 2H -indol-2-one hydrochloride (impurity-A), 5-[2-(diropylamino) ethyl]-1,4-dihydro-3 H -benzoxazin-3-one hydrochloride (impurity-B) and 4-[2-(diropylamino) ethyl]- 1H -indol-2,3-dione hydrochloride (impurity-C). Synthesis of these impurities is discussed.