Determination of itraconazole in human plasma by high-performance liquid chromatography with solid-phase extraction

A practical, simple, high-performance liquid chromatographic (HPLC) method is needed for the determination of itraconazole in clinical plasma samples.

Itraconazole and bifonazole (internal standard) were extracted from plasma using a C8-bonded solid-phase cartridge, separated by C8 reversed-phase HPLC, and quantified by ultraviolet absorption at 263 nm.

This new method enabled the determination of itraconazole in the concentration range of 10.0-500.0 microg/L. The detection limit of itraconazole was 5.0 microg/L. The mean recovery of itraconazole added to plasma was more than 89.1%, with a coefficient of variation of less than 6.9%. We applied this method for the determination of plasma itraconazole in volunteers treated daily with a 200 mg oral capsule of itraconazole for four days. We monitored the plasma level of itraconazole for the following 24 h and obtained the mean area under the plasma concentration-time curve from 0 to 24 h (AUC(0-24) ) value of 4358.9 +/- 1933.4 microg h/L.

Our new method will be clinically useful for accurately monitoring the plasma concentration of itraconazole in patients under treatment.