Method indicative of stability for the determination of rifaximin and its degradation products by thin chromatographic

Abstract

Rifaximin is an oral antimicrobial, intestine-selective and non systemic with adverse effects compared to placebo. Rifaximin, until then, does not have standardized analytical methods in most official compendia. Fast, economic, environmentally friendly and selective method indicative of stability by thin chromatographic (TC) for the determination of rifaxmin and its degradation products was designed. The TC method used silica gel as stationary phase and ethyl acetate: ethyl alcohol, 90:10 (v/v), as mobile phase to achieve spots for rifaximin (Rf=0.62) and its degradation products basic (Rf=0.33, 0.49, 0.56), acidic (Rf=0.47, 0.54), oxidative (Rf=0.28) and neutral (Rf=0.32). The plates were visualized in chamber UV at 254 nm. Simultaneously, analysis of high performance liquid chromatography (HPLC) was performed using Eclipse Plus C18 (150 mm x 4.6 mm) column and purified water + 0.1% glacial acetic acid and ethanol in the ratio 52:48 (v/v) as mobile phase at 290 nm. The objective was to verify the interchangeability of TLC and HPLC methods in obtaining the degradation products of rifaximin tablets. In HPLC, as in TLC was observed the rifaximin (RT=5.5) and its degradation products acidic, basic (RT =4.2 and 4.7), oxidative (RT =3.6 min) and neutral (RT =4.7 min). These techniques can be used as methods indicative of stability, because they identify the rifaximin and their degradation products. Therefore they can be effectively applied in quality control of rifaximin in tablets. The study of alternative methods should be encouraged by reducing costs, allowing the use of environmentally friendly solvents, optimize analysts and equipment while providing quality analyzes.