Simultaneous determination of efavirenz, rifampicin and its metabolite desacetyl rifampicin levels in human plasma

A simple and rapid isocratic, high performance liquid chromatography (HPLC) assay employing solid phase extraction (SPE) for the simultaneous determination of the anti HIV drug, efavirenz, the antituberculosis drug, rifampicin and the desacetyl metabolite of rifampicin in plasma from HIV/tuberculosis infected patients has been developed. Using a Zorbax SB-Phenyl reverse-phase analytical column with UV detection, good separation and detection of the drugs was attained within a 10 min run time. Intra- and inter-assay precision RSD values were found to be less than 15% at the concentrations examined (0.1-20 mu g/mL). The LOQ was found to be 0.1 mu g/mL for each agent and the assay was found to generate a linear response up to 20 mu g/mL. This low cost assay can accurately detect efavirenz and rifampicin concentrations within a clinically relevant concentration range using standard chromatography equipment, making it particularly applicable to resource-limited settings. (C) 2011 Elsevier B.V. All rights reserved.