A Validated Stability-Indicating Liquid Chromatographic Method for the Simultaneous Determination of Amlodipine and Benazepril in Capsules Dosage Form

Abstract

A simple, sensitive, reproducible and specific stability indicating high performance liquid chromatographic method for the simultaneous estimation of amlodipine besylate (AMD) and benazepril hydrochloride (BEZ) in their combined drug product was developed and validated. Risperidone (RIS) was used as internal standard. AMD and BEZ were separated and quantitated on a Hichrom 5 C8 column (250 × 4.6 mm i.d., 5 μm particle size) using a mixture of methanol-formic acid 0.1 M (63:37, v/v) as a mobile phase and at a flow rate of 0.9 mL min-1. The retention times were about 3.7, 5.3 and 7.3 min for RIS, BEZ and AMD, respectively. Quantification was achieved with an UV detector at 242 nm over the concentration ranges of 0.85-807.0 μg mL-1 for BEZ and 0.32-785.0 μg mL-1 for AMD. The limits of detection were 0.18 and 0.12 μg mL-1 for BEZ and AMD, respectively. The method was validated as per the International Conference on Harmonization (ICH) guidelines. AMD and BEZ stock solutions were subjected to different stress conditions. The degraded product peaks were well resolved from the pure drug peak with significant difference in their retention time values. Stressed samples were assayed using developed HPLC method. The method is also demonstrated to be robust, because it is resistant to small variations of chromatographic variables such as pH, mobile phase composition and flow rate. The proposed method is found to be very sensitive and accurate for the determination of AMD and BEZ in combined capsule dosage form.