ACIDIC HYDROLYSIS OF BROMAZEPAM STUDIED BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY - ISOLATION AND IDENTIFICATION OF ITS DEGRADATION PRODUCTS

A kinetic study on the acidic hydrolysis of bromazepam was carried out in 0.01 M hydrochloric acid solution at 25 and 95 degrees C. A revers ed-phase HPLC method was developed and validated for the determination of bromazepam and its degradation products. Bromazepam degraded by a consecutive reaction with a reversible first step. Two degradation pro ducts were isolated and identified by infrared,H-1 and C-13 nuclear ma gnetic resonance and mass spectroscopy. Spectroscopic data indicated t hat romo-2-(2-pyridylcarbonyl)phenyl)-2-aminoacetamide was the interme diate degradation product of this acid hydrolysis, whereas 2-amino-5-b romophenyl-2-pyridylmethanone was the final one. Therefore, the mechan ism of this acid-catalysed hydrolysis involved initial cleavage of the 4,5-azomethine bond, followed by slow breakage of the 1,2-amide bond. Statistical evaluation of the HPLC method revealed its good linearity and reproducibility. Detection limits were 3.8 x 10(-7) M for bromaze pam, 6.25 x 10(-7 )M for the intermediate and 8.16 x 10(-7) M for the benzophenone derivative. (C) 1998 Elsevier Science B.V. All rights res erved.