A sensitive validated LC-MS/MS method for quantification of itraconazole in human plasma for pharmacokinetic and bioequivalence study in 24 Korean volunteers.

A rapid and highly sensitive liquid chromatography/electrospray ionization tandem mass spectrometric method (LC/ESI-MS/MS) for itraconazole determination in human plasma was validated and applied to pharmacokinetic and bioequivalence study in humans. In a randomized crossover design with a 1-week period, each subject received a 200 mg itraconazole capsule. The analytical procedures involved a less time-consuming, simple protein precipitation with methyl t-butyl ether and separation by HPLC. The ionization was optimized using electrospray ionization (ESI) with positive ion mode and selectivity was achieved by MS/MS analysis, m/z 705.3 --> 392.4 and m/z 374.3 --> 141.0 for itraconazole and internal standard (IS), respectively. The standard calibration curves showed good linearity within the range of 1 (LLOQ) to 500 ng/mL for itraconazole in human plasma with a correlation coefficient r > 0.9952. The retention times of itraconazole (0.9 min) and IS (0.84 min) suggest the high throughput of the proposed method. No significant metabolic compounds were found to interfere with the analysis. The coefficient of variation values of both intra- and inter-day were below 13.7% and 10.9%, respectively. Intra- and inter-day accuracies were 95.6-108.2% and 86.6-117.5%, respectively. This method was successfully applied for pharmacokinetic and bioequivalence study in 24 healthy human subjects by analysis of blood samples taken up to 72 h after an oral dose of 200 mg of itraconazole.