Bioequivalence study of two formulations of 100 mg capsule of itraconazole. Quantification by tandem mass spectrometry.

The purpose of this study is to compare the bioavailability of two itraconazole (CAS 84625-61-6) capsule formulations. An open, randomized, two-period crossover study with a 7-day washout interval was conduced in 32 healthy volunteers. The plasma samples were obtained up to 96 h after drug administration. A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the determination of itraconazole in human plasma. Itraconazole and ketoconazole (internal standard) were extracted from the plasma by liquid-liquid extraction using diethylether : dichloromethane (70 : 30) as extraction solvent and separated on a C8 analytical column (150 mm x 4.6 mm I.D.) maintained at 40 degrees C. The elution was performed by a constant flow rate of 1.2 mL/min and the mobile phase consisted of acetonitrile and acetic acid 0.1% (85 :15 v/v). The mass spectrometer equipped with an electrospray source in positive mode, was set up in multiple reaction monitoring, to detect parent --> production 705.0 392.0 (itraconazole) and 531.0 --> 81.70 (ketoconazole). The chromatographic separation was obtained within 3.5 min and was linear in the concentration range of 5 to 600 ng/mL. Bioequivalence between the products was determined by calculating 90% confidence intervals for the ratio of C(max) (95.02%-109.48%), AUC(0-t) (81.41%-107.77%) and AUC(0-inf) (80.85%-106.86%). These values for the test and reference products are within the 80-125% interval, proposed by FDA and EMEA. It was concluded that the proposed method was successfully applied to a pharmacokinetic study in healthy human volunteers, and results showed that the two itraconazole formulations are bioequivalent in their rate and extent of absorption.