Author(s): Hanaa M. Saleh, Magda M. EL-Henawee, GamalH. Ragab and Omnia F.Mohamed
Three simple, accurate and precise colorimetric methods for the determination of pregabalin in capsules are developed. The first method is based on the reaction of pregabalin with vanillin (Duquenois reagent) in the presence of McIlvain buffer pH 7.5 and the color developed was measured at 394 nm. The linearity range was found to be 20-180 μg ml-1.The second and third mehods are based on condensation of primary amine group of pregabalin with acetylacetone and formaldehyde in presence of acetate buffer pH 5 (Hantzsch reaction) producing a yellow coloured product, which is measured spectrophotometrically at 333 nm or fluorimetrically at 470 nm. Beer’s law was valid within a concentration rang 20-160 μg ml-1 spectrophotometrically and 0.2 -3 μg ml-1 fluorimetrically. All the variables were studied to optimize the reaction conditions. No interference was observed in the presence of common pharmaceutical excipients. The validity of these methods was tested by analyzing pregabalin in its pharmaceutical preparations. Good recoveries were obtained and the results were comparable with those obtained by reported method.