A Novel Quantitative Method for the Simultaneous Assay of Rifampicin (RIF), Isoniazid (INH), Ethambutol (EMB), and Pyrazinamide (PYP) in 4-FDC Tablets

This paper presents the development and validation of a new ultra high performance chromatography (UHPLC) procedure for the simultaneous determination of isoniazid (INH), rifampicin (RIF), pyrazinamide (PYP), and ethambutol hydrochloride (EMB.2HCl) in four fixed-dose combination (4-FDC) anti-tubercular tablets. It is a dual wavelength single method in which, INH, RIF, and PYP were detected at 230 nm, whereas EMB was detected at 210 nm. The chromatographic separation was performed on Water’s Acquity BEHC18 (50 mm x 2.1 mm, 1.7 μm particle size) column at a flow rate of 0.4 ml/min, 40oC temperature, and a mobile phase consisting of triethylamine in phosphate buffer of pH 6.8, 95% and acetonitrile 5%. The proposed method was validated in terms of linearity, interday and intraday precision, recovery, specificity, and robustness. The results of the assay of the active constituents in two different batches of tablets were 102.3±1.5, 104.9±1.2, 101.0±1.4, 100.2±1.6, and 104.8±1.3, 103.8±1.1, 101.4±1.7, and 99.9±2.1, for INH, RIF, PYP, and EMB, respectively. The proposed method proves that the application of UHPLC technique is rewarding and additional economic benefits are gained as a result of reduction of analysis time and the consumption of the expensive HPLC grade materials.