APPLICATION OF ABSORPTION CORRECTION METHOD AND FIRST ORDER DERIVATIVE SPECTROPHOTOMETRY FOR SIMULTANEOUS DETERMINATION OF ANTI-HYPERTENSIVE COMBINATION (AMLODIPINE AND BENAZEPRIL)

Objective: To develop simple, accurate, precise, reproducible UV Spectrophotometric methods for the simultaneous estimation of Amlodipine besylate (AM) and Benazepril HCl (BZ) in pure and Fixed Dose Combination (FDC). Methods: First method, Absorption Correction Method, involves direct estimation of Amlodipine besylate at 366 nm and Benazepril at 259.4 nm. For estimation of Benazepril, corrected absorbance was calculated at 259.4 nm due to the interference of Amlodipine besylate at this wavelength. The second method was first order derivative spectrophotometry, wavelengths selected for quantification were 390 nm for Amlodipine besylate (zero crossing point for Benazepril) and 228 nm for Benazepril (zero crossing point for Amlodipine besylate). Results: In both methods linearity was observed in the concentration range of 5-50 μg/ml for both the drugs. Recovery study was performed to confirm the accuracy of the methods. The methods were validated as per International Conference on Harmonization (ICH) Q28 guidelines. The proposed method was successfully applied for the simultaneous estimation of both drugs in pharmaceutical dosage form as well as for dissolution study. The results of the marketed formulation assay were found to be 101.4 ± 2.05 % and 98.7 ± 1.94 % for AM and BZ respectively by absorption correction method and 98 ± 2.19 % and 100.9 ± 1.92 % for AM and BZ respectively by first order derivative spectrophotometry. Conclusion: Simple, accurate and precise spectrophotometric methods have been developed and validated for the simultaneous determination of AM and BZ in API and tablet dosage forms without any interference. The methods can be routinely adopted for quality control of these drugs in tablet.