Variability of Hydroxy-Itraconazole in Relation to Itraconazole Bloodstream Concentrations.

We analyzed the relationship between itraconazole (ITZ) and hydroxy-itraconazole (OH-ITZ) levels in 1,223 human samples. Overall, there was a statistically significant correlation between ITZ and OH-ITZ levels (Pearson's r, 0.7838), and OH-ITZ levels were generally higher than ITZ levels (median OH-ITZ:ITZ ratio, 1.73; range, 0.13 to 8.96). However, marked variability was observed throughout the range of ITZ concentrations. Thus, it is difficult to predict OH-ITZ concentrations based solely on ITZ levels.