Spectrophotometric Estimation of Artemether & Lumefantrine in Pharmaceutical Formulation by Using Mean Centering of Ratio Spectra & H- Point Standard Addition Method

Background: Artemether–lumefantrine is a World Health Organization-recommended artemisinin-based combination therapy for uncomplicated falciparum malaria, marketed as a fixed-dose combination in a 1:6 ratio. Quality-control estimation of both components in combined dosage forms conventionally relies on chromatographic methods that are costly, time-consuming, and solvent-intensive. Objective: To develop and validate two simple, rapid, and economical UV-spectrophotometric methods — mean centering of ratio spectra and the H-point standard addition method — for the simultaneous estimation of artemether and lumefantrine in combined tablet dosage form without prior separation, and to validate them in accordance with ICH Q2 guidelines. Methods: Absorbance measurements were performed in the wavelength range 200–400 nm, with analytical wavelengths of 271 nm (artemether, methanol) and 340 nm (lumefantrine, chloroform); HPSAM was executed at the wavelength pair 280/260 nm. Validation covered specificity, linearity, range, precision (repeatability, intra-day and inter-day), accuracy, limit of detection, limit of quantitation, and robustness. Results: Calibration curves were linear over 5–25 µg/mL for both drugs (regression equations y = 0.1014x − 0.0639, R² = 0.9998 and y = 0.0954x + 0.0886, R² = 0.9961 for artemether and lumefantrine, respectively). All %RSD values for repeatability, intra-day, and inter-day precision were below 2%, as prescribed by ICH. Mean recoveries ranged from 99.06% to 100.80%. Assay results were 99.37% for artemether and 98.40% for lumefantrine, within ICH limits. Conclusion: Both proposed methods are accurate, precise, specific, robust, and economically attractive, and they are suitable for the routine simultaneous determination of artemether and lumefantrine in pharmaceutical dosage forms.