Liquid Chromatographic Studies of the Stability of Benazepril in Pure Form and in Tablets

Abstract

Selective, linear (coefficient of linear correlation = 0.999) and accurate HPLC method for evaluation of stability of benazepril (BEN) in solid phase has been applied. Liquid chromatography was performed with a column Hypersil MOS (5 µm particle size, 250 mm × 4 mm, Merck), the mobile phase used was mixture of acetonitrile–phosphate buffer (50:50 v/v), flow rate of 1.1 mL/min, and internal standard: cetirizine dichloride (methanolic solution 0.3 mg/mL). The effluent was monitored on a UV detector at 215 nm. The influence of humidity and temperature on the stability of BEN in solid phase has been studied. The thermodynamic parameters, at 293 K of degradation of BEN hydrochloride in solid phase, E _a (kJ/mol) = 121.16 ± 15.7, ΔH ^≠(kJ/mol) = 118.67 ± 15.7, ΔS ^≠ [J/(K × mol)] = −28.99 ± 44.5 for RH = 76.4% and E _a (kJ/mol)= 85.2 ± 15.9, ΔH ^≠ (kJ/mol) = 82.7 ± 15.9, ΔS ^≠ [J/(K × mol)]= −139.2 ± 41.3 for RH = 0% have been calculated.

Keywords:

• Benazepril hydrochloride
• Cetirizine dichloride
• HPLC and HPLC‐MS method
• Stability in solid phase

Acknowledgments

The author wishes to thank Novartis International Pharmaceutical Ltd for supplying benazepril hydrochloride (CIBACEN) pure substance. This study was financially supported by the grant no. 501‐3‐05‐05.