High Performance Liquid Chromatographic–Diode Array Detector Method for Simultaneous Determination of Aspirin, Caffeine and Ephedrine in Weight Loss Formulations, Human Plasma and in vitro Drug–Drug Interaction Studies

Abstract

A simple, rapid and accurate stability-indicating reversed-phase liquid chromatographic method was developed and validated for the simultaneous determination of aspirin, caffeine and ephedrine in weight loss formulations, human plasma and for the study of in vitro drug−drug interactions. Optimum chromatographic separation for aspirin, caffeine and ephedrine was achieved within 4.5 min on a Teknokroma C18 column (250 × 4.6 mm, 5 μm) with a mobile phase consisting of acetonitrile and water (55 : 45) at pH 3.18 with the flow rate of 1 mL/min with detection wavelengths of 210 and 254 nm. The method was validated in accordance with the ICH guidelines with respect to linearity, accuracy, precision, robustness, specificity, limits of detection and quantitation. Regression analysis showed good correlations (R2 > 0.998) in the concentration ranges of 100–1000, 50–500 and 20–100 μg/mL for aspirin, caffeine and ephedrine, respectively. The study of in vitro drug−drug interaction showed that the interaction of ephedrine with aspirin and caffeine was pH dependent. The proposed method is suitable for routine quality control analysis of related weight loss formulations and for stability studies.