Effect of grapefruit juice on pharmacokinetics of itraconazole in healthy subjects

To examine the effect of grapefruit juice on the disposition of oral administered itraconazole in healthy subjects.

Twenty-two healthy male subjects received a single 100 mg dose of itraconazole with either 350 ml grapefruit juice, orange juice or mineral water. Plasma concentrations of itraconazole were measured by HPLC, and pharmacokinetic parameters; Cmax, Tmax, T1/2, AUC, and AUC corrected by human body surface area: AUC/S, were calculated.

Grapefruit juice had no effect on any pharmacokinetic parameter of itraconazole. However, T1/2, AUC, or AUC/S were significantly decreased in orange juice treatment group compared to those in mineral water group (average decrease 56%, p < 0.01, 41%, p < 0.05, and 43%, p < 0.05, respectively).

Coadministration of grapefruit juice did not affect any pharmacokinetic parameter of itraconazole while that of orange juice decreased the parameters of T1/2, AUC, and AUC/S of the drug.