A Universal Method for the Determination of Amlodipine in Industrial and Extemporaneous Pharmaceutical Preparations

A universal UV spectrophotometric method for determining amlodipine besylate in industrially manufactured and extemporaneously prepared medicinal products in the form of tablets, powders, and oral solutions has been developed and validated. The methodological concept is based on the use of a single analytical model applicable to various dosage forms and dissolution media without modifying the analytical conditions. Spectral studies confirmed the presence of two absorption maxima at (238 ± 2) nm and (365 ± 2) nm, which corresponded to different chromophoric systems of the molecule and could be used to identify the compound; the wavelength of 365 nm was selected as the analytical wavelength, providing improved selectivity for the quantitative determination of the active pharmaceutical ingredient. The method was validated in accordance with pharmacopoeial requirements and ICH guidelines. The procedure is characterized by precision, accuracy, specificity, and linearity in the range of 0.04–0.06 μg mL-1 (80–120% of the nominal concentration) (r > 0.9981) in all solvents proposed. The limits of detection (LOD) and quantification (LOQ) calculated were 0.59% and 0.92% for medicinal products in tablet and powder dosage forms, and 0.84% and 1.09% for the oral solution, respectively. The uncertainty of the method, including contributions from the sample preparation and the final analytical operation, was within acceptable limits for spectrophotometric assay procedures. The method proved to be applicable to industrial tablets, as well as extemporaneous powders and oral solutions, without interference from excipients in different dissolution media. Due to the minimal solvent consumption and the absence of requirements for chromatographic equipment, the approach proposed is an environmentally friendly, affordable and acceptable alternative from the point of view of regulatory requirements for the routine quality control of amlodipine medicinal products, particularly in small-scale production.