Quantification of voriconazole in plasma by liquid chromatography-tandem mass spectrometry

A convenient liquid chromatography-tandem mass spectrometry method
for the quantification of the triazole antifungal agent
voriconazole in plasma samples is described. Fenbuconazole is used
as an internal standard. After protein precipitation, automated
solid-phase extraction is applied. Electrospray ionization in the
positive mode is used and the following mass transitions are
recorded: voriconazole, 350 -> 127; and fenbuconazol, 337 ->
125. The analytical run time is 4 min. The response was linear from
78 to 5000 mu g/L. The total coefficient of variation (n=16) was
12.6% for a low-concentration pool (143 mu g/L), 4.7% for a
medium-concentration pool (419 mu g/L), and 5.0% for a
high-concentration pool (4304 mu g/L). The method is proposed for
future investigations that should be performed to test the
hypothesis that therapeutic drug monitoring of voriconazole is
clinically useful.