Fig. 2

The LC-MS/MS chromatograms of a drug-free plasma sample (a), plasma sample spiked with 300 ng/mL itraconazole and 300 ng/mL hydroxy itraconazole, 20 ng/mL keto itraconazole and 20 ng/mL N-desalkyl itraconazole (b), and a plasma sample from a patient receiving 200 mg of oral itraconazole once daily at bedtime for prevention of fungal infections, whose concentrations were as follows: itraconazole, 729 ng/mL; hydroxy itraconazole, 859 ng/mL; keto itraconazole, 5.4 ng/mL and N-desalkyl itraconazole, 16.6 ng/mL (c). Peaks of itraconazole, hydroxy itraconazole, keto itraconazole, N-desalkyl itraconazole, and itraconazole-d9 as internal standard, are (1), (2), (3), (4), and (5), respectively. Peaks of isotopes are observed for hydroxy itraconazole and keto itraconazole (6). The MRM transitions are as follows: itraconazole, 706.05/393.05; hydroxy itraconazole, 721.15/408.15; keto itraconazole, 719.10/406.10; N-desalkyl itraconazole, 649.10/376.15; and internal standard, 714.25/401.15