Development of a Validated RP-HPLC Method for Estimation of Ethionamide in Spiked Human Plasma with UV Detection

A simple, rapid and specific RP-HPLC method has been developed and validated as per US-FDA guidelines for estimation of Ethionamide in spiked human plasma using liquid-liquid extraction technique. Ethionamide was well resolved from human plasma interference and internal standard (Guaifenesin) using C 18 (250 × 4.6 mm, 5 μ) column with methanol: water (40: 60%, v/v) as mobile phase, at a flow rate of 1 mL/min. The detection was performed at 275 nm. During calibration experiments, the heteroscedasticity was minimized by using weighted least square regression model with weighing factor 1/x. In accuracy and precision studies, intra-day and interday, % relative error was found between ± 15 and % RSD was less than 15%. Stability experiments indicated that the drug remained stable after three freeze-thaw cycles. The developed method meets the requirements of US-FDA guidelines.