New, simple and validated UV-spectrophotometric methods for the estimation of drotaverine hydrochloride in bulk and formulations

摘要

New, simple and cost effective, accurate and reproducible UV-spectrophotometric methods were developed for the estimation of drotaverine hydrochloride (DHC) in bulk and pharmaceutical formulations. The drug was estimated at 242 nm in 100 mM hydrochloric acid (pH 1.2), 242 nm in methanol: 100 mM phosphate buffer pH 7.4 (25:75), and 243 nm in ethanol: 100 mM phosphate buffer pH 7.4 (25:75). Linearity range was found to be 2-18 μg mL–1 (regression equation: absorbance = 0.052 × concentration in μg mL–1 + 0.0163; r2 = 0.9999) in the hydrochloric acid medium (pH 1.2), 5-25 μg mL–1 (regression equation: absorbance = 0.0347× concentraion in μg mL–1 + 0.0058; r2 = 0.9999) in methanol: 100 mM phosphate buffer, pH 7.4 (25:75) and 7-25 μg mL–1 (regression equation: absorbance = 0.0435 × concentraion in μg mL–1 + 0.0002; r2 = 0.9998) in ethanol: 100 mM phosphate buffer, pH 7.4 (25:75). The apparent molar absorptivity was found to be 2.22 × 104 l mol−1 cm−1, 1.48 ×104 l mol−1 cm−1 and 1.88 × 104 l mol−1 cm−1. The quantitation limits were found to be 0.23, 0.31 and 3.56 μg mL–1 in the respective media. These methods were tested and validated for various parameters according to ICH guidelines and USP.