Flucytosine: Correlation Between Toxicity and Pharmacokinetic Parameters

Flucytosine (5-fluorocytosine, 5-FC) is a systemic antimycotic drug the major toxicities of which are bone marrow depression and hepatotoxicity. The purpose of this observational and retrospective study was to assess a possible relationship between toxicity and 5-FC pharmacokinetics within a group of 53 intensive care unit patients. The presented results reveal that thrombocytopenia is associated with a decreased 5-FC clearance and that the thrombocyte nadir is linearly related to the 5-FC clearance. Furthermore, patients experiencing 5-FC levels exceeding 100 mg 5-FC/l were found to be at a higher risk of developing thrombocytopenia and hepatotoxicity as compared to those not exceeding this level.