Synthesis and characterization of impurities of barnidipine hydrochloride, an antihypertensive drug substance.

Barnidipine hydrochloride is a long term dihydropyridine calcium channel blocker used for the treatment of hypertension. During the process development of barnidipine hydrochloride, four barnidipine impurities were detected by high-performance liquid chromatography (HPLC) with an ordinary column (Agilent ZORBAX Eclipse XDB-C18, 150 mm×4.6 mm, 5 µm). All these impurities were identified, synthesized, and subsequently characterized by their respective spectral data (MS, 1H-NMR, and 13C-NMR). The identification of these impurities should be useful for quality control in the manufacture of barnidipine.