Spectrophotometric Determination of Nor-Epinephrine Serotonin Reuptake Inhibitor (SNRI) Drug Milnacipran in Pure and in Dosage Forms

Abstract

Milnacipran hydrochloride is an antidepressant drug belonging to the class of serotonin and nor-adrenaline reuptake inhibitors. Rapid and cost effective UV-spectrophotometric methods were developed for the estimation of milnacipran hydrochloride in bulk, pharmaceutical formulations and in vitro release samples. Milnacipran hydrochloride was estimated at 220 nm wavelength in the phosphate buffer (pH = 6.8 buffer) and hydrochloric acid buffer (pH = 1.2 buffer). Linearity range was found to be 5-30 μg mL^-1 in both medium. The regression equations were found to be: absorbance = 0.0405 × concentration in μg mL^-1 + 0.0198 (r2 = 0.998) in the pH 6.8 buffer and absorbance = 0.03904 × concentraion in μg mL^-1 + 0.0598 (r2 = 0.999) in pH 1.2 buffer. The apparent molar absorptivity was found to be 1.148 × 10⁴ mol^-1 cm^-1 in pH 6.8 buffer and 1.105 × 10⁴ mol^-1 cm^-1 in pH 1.2 buffer. In both the proposed methods Sandell's sensitivity was found to be about 0.025 μg cm^-2/0.001A. These methods were tested and validated for various parameters according to ICH guidelines and USP. The quantitation limits were found to be 1.6046 and 0.9653 μg mL^-1 in pH 6.8 buffer and pH 1.2 buffer, respectively. The results demonstrated that the procedure is accurate, precise and reproducible (relative standard deviation < 2 %), while being simple, cheap and less time consuming and can be suitably applied for the estimation of milnacipran hydrochloride in routine analysis.