f Voriconazole concentrations display a large variability, which cannot completely be explained by known factors. Inflammation may be a contributing factor, as inflammatory stimuli can change the activities and expression levels of cytochrome P450 isoenzymes. We explored the correlation between inflammation, reflected by C-reactive protein (

f Voriconazole (VCZ) exhibits great inter-and intrapatient variability. The latter variation cannot exclusively be explained by concomitant medications, liver disease or dysfunction, and genetic polymorphisms in cytochrome P450 2C19 (CYP2C19). We hypothesized that inflammatory response in patients under VCZ medication might also influence this fluctuation in concentrations. In this study, we explored the association between inflammation, reflected by the C-reactive protein (CRP) concentration, and VCZ trough concentrations over time. A retrospective analysis of data was performed for patients with more than one steady-state VCZ trough concentration and a CRP concentration measured on the same day. A longitudinal analysis was used for series of observations obtained from many study participants over time. The approach involved inclusion of random effects and autocorrelation in linear models to reflect within-person cross-time correlation. A total of 50 patients were eligible for the study, V oriconazole (VCZ) is the first-line treatment for invasive aspergillosis (1-3). It undergoes extensive hepatic metabolism, principally by cytochrome P450 2C19 (CYP2C19) and to a lesser extent by CYP3A4 and CYP2C9 (4, 5). It is catalyzed into inactive metabolites, with VCZ N-oxide being the principal circulating metabolite (6). The trough concentration of VCZ under steady-state conditions in relation to the MIC is used for practical reasons as the predictive pharmacokinetic/pharmacodynamic parameter (7).VCZ exhibits nonlinear pharmacokinetics in adults with a large inter-and intrapatient variability of drug exposure. These variations might be caused by many factors, including the use of concomitant medications, liver disease or liver dysfunction (1, 3, 5, 8), and, especially, genetic polymorphisms of CYP2C19 (8). However, none of these factors provides a complete explanation of the variability in VCZ concentrations observed in previous studies (9, 10).Data are now emerging that identify a decrease in the capacity of metabolic pathways to handle drugs during infections and diseases that involve an inflammatory response (11)(12)(13)(14). We were the first to associate inflammation, reflected by the C-reactive protein (CRP) concentration, with the VCZ trough concentration (15), as well as finding an association between the CRP concentration and the VCZ N-oxide/VCZ ratio (16), identifying a possible explanation for some of the variability in VCZ concentrations.Previously, the relationship between CRP and the VCZ trough concentration was evaluated at a single point in time (15). However, the inflammatory response represents a coordinated set of physiological events, while the metabolic and inflammatory status of each patient is different and may vary over time during VCZ treatment. Therefore, to detect changes in VCZ trough concentrations of the patients at both the group and the individual levels, the studies should be extended beyond a single moment in time in order to explore all sequences of events.To further explore the intrap...

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