Simple and Sensitive Colorimetric Method for the Determination of Milnacipran in Bulk and Swellable Matrix Tablets

Abstract

Milnacipran, a serotonin and adrenaline reuptake inhibitor used to treat fibromyalgia and major depression, is difficult to quantify analytically at shorter UV wavelengths. This necessitates the development of a sensitive, precise and accurate colorimetric method for the determination of milnacipran hydrochloride in bulk and swellable matrix tablets. The drug was derivatized with ninhydrin reagent prepared by two methods using direct heating on flame and in glycerol bath at 110°C. The drug -(milnacipran)- ninhydrin complex (Ruhemman’s Purple) showed an absorbance maximum at 570 nm. The method exhibited linearity in a concentration range of 4 to 400 μg/mL with a correlation coefficient of 0.9999. As per ICH guidelines, the method showed good sensitivity (LOD = 0.550 μg/mL and LOQ = 1.667 μg/mL), intraday accuracy and precision (4.713%), and interday accuracy and precision (2.569%). The method was applied to determine the drug in swellable matrix tablets. The obtained results indicate that the proposed method of milnacipran hydrochloride determination in bulk and swellable matrix tablets is simple, accurate and precise, and can be used in less equipped laboratories.