Quantification of rifampicin and rifabutin in plasma of tuberculosis patients by micellar liquid chromatography

A Micellar Liquid Chromatographic method is described to determine Rifampicin and Rifabutin in plasma from Tuberculosis patients. Samples were diluted in mobile phase and then directly injected, avoiding long and tedious extraction steps. The analytes were resolved from the matrix without interferences from endogenous compounds using a mobile phase of sodium dodecyl sulfate 0.15 mol L-1-6%(v/v) 1-pentanol and phosphate buffer at pH 3, running at 1 mL min−1 through a C18 column at 25 °C. Detection was carried out by UV absorbance at 270 nm. Under these conditions, the final chromatographic analysis time was 22 min. The analytical methodology was validated following the FDA 2018 Bioanalytical Method Validation Guidance for Industry. The response of the drugs in plasma was linear in the 0.05-5 μg/mL range, with r2 > 0.9993. Trueness and precision were <14% for both substances. Carry over and matrix effects were negligible. Dilution integrity, robustness and stability were also investigated. Method was reliable, economic, eco-friendly, safe, easy-to-conduct, and with a high sample throughput, thus useful for routine analysis. Finally, the analytical method was used to determine both antituberculosis drugs in incurred plasma samples of Tuberculosis patients.