We investigated the optimal blood concentration of voriconazole (VRCZ) based on trough blood concentrations (C) and serological test values in patients. With regard to the regulation of VRCZ dosage (D) to maintain optimal blood concentrations, we investigated the relationship between C and D. Twenty-three patients were enrolled in the present study, and at 28 point data were analyzed retrospectively.
  When the β-D-glucan or the Aspergillus antigen were decreased below the standard set values, it was evaluated as effective. The adverse events were evaluated using the Common Terminology Criteria for Adverse Events ver. 3.0. We found a significant difference (p<0.05) in the average trough blood concentration between patients in whom VRCZ was effective and those in whom VRCZ was ineffective (8.21±2.19 μg/ml vs. 1.01±0.86 μg/ml), and patients presenting with adverse events and those with no adverse events (7.64±2.84 μg/ml vs. 1.49±1.79 μg/ml). There was no significant relationship between C and D (C: D, y=0.018−2.186, r²=0.349).
  Improved efficacy and more adverse events thus occurred with higher blood concentrations. The careful regulation of the dosage must be performed while measuring blood concentration and observing for adverse events. The implementation of therapeutic drug monitoring for VRCZ is a valuable tool for achieving effective fungal infection therapy and should be aggressively investigated in future studies.