A study of liquid chromatography mass spectral characteristics of efavirenz, emtricitabine and tenorovir and analytical performance characteristics in human plasma

Abstract

The wide spread use of antiretroviral (ARV) drugs have significantly enhanced the quality of life for HIV/AIDS infected populations. However, limitations of the analytical performance characteristics available for therapeutic drug monitoring (TDM) due to extraordinary ability of the virus to adapt to new physiological environments continue to defy efforts made in scaling down the new infections and the post ARV infections. The food and drug administration (FDA) has approved new ARV drug combinations, among them Atripla which is meant to suppress HIV/AIDS. Despite these advances, new analytical performance characteristics for the TDM of ARV drugs are still scanty and marred with limitations alluded to the above. The aim of this study was to unravel the liquid chromatography-mass spectrometry spectral characteristics of the ARVs efavirenz (EFV), emtricitabine (EMT) and tenofovir (TFV) which together and in combination constitute the drug commercially called Atripla. This was in anticipation that the results of the study would stimulate method development for TDM of Atripla. Direct infusion mass spectrometry (DIMS) and liquid chromatography-mass spectrometry (LC-MS) were compared in terms of analytical performance characteristics for the determination of Emtricitabine, Tenofovir and Efavirenz in a sterilised commercial human plasma matrix. Statistical evaluation of data was done. Using the LC-MS, linearities of the analytical growth curves for the three analytes, i.e. EFV, EMT and TFV ranged between 0.930 and 0.999 in the full scan, selected ion monitoring (SIM) and mass spectrometry/mass spectrometry (MS/MS) modes were established. The limits of detection (LODs) ranged between 0.5 μgL-1-11.6 μgL-1. The lower limits of quantification (LLOQs) and the upper limits of quantification (ULOQs) ranged between 0.9μgL-1- 23.2 μgL-1and 1.6μgL-1-38.7μgL-1respectively. Using DIMS, linearities of the analytical growth curves for the three analytes i.e. EFV, EMT and TFV gave similar values to LC-MS, i.e. between 0.930 and 0.999 in the full scan, SIM and MS/MS modes. The LODs ranged between 0.8μgL-1 and114.7 μgL-1. The LLOQ and the ULOQs ranged between 1.6μgL-1 – 29.4 μgL-1 and 2.7μgL-1 – 49.0μgL-1 respectively. On average, the DIMS showed higher sensitivity in comparison to the LC-MS. Statistical analysis using principal component analysis (PCA) and one way - analysis of variance (ANOVA) revealed underlying factors and other statistics related to sources of systematic errors in the study.