Bioavailability of Voriconazole

The bioavailability of voriconazole, based on healthy volunteers, is estimated to be >90%. Due to the high bioavailability of voriconazole, switching between oral and intravenous administration is permitted if clinically allowed. Few data are available for the bioavailability of voriconazole in critically ill patients. However, to obtain a therapeutic concentration of voriconazole (>1.5 mg/L, which is associated with a beneficial response to treatment) one study showed that a higher oral dose is required compared with the intravenous dose, to obtain this therapeutic concentration. Therefore, the pharmacokinetics can be changed in critically ill patients, including bioavailability.

In this study, patients who receive voriconazole orally (prescribed by their attending physician) will receive one intravenous dose of voriconazole instead of the oral dose. The intravenous dose will be the same as the oral dose voriconazole.