Determination of Saliva Trough Levels for Monitoring Voriconazole Therapy in Immunocompromised Children and Adults

To evaluate the reliability and practical use of saliva for therapeutic drug monitoring of the antifungal agent voriconazole in immunocompromised patients, a paired-sample study was conducted. Plasma and saliva trough levels were measured in seven children and nine adults who required treatment for the prevention or therapy of systemic fungal infections. The pediatric patients received a voriconazole dosage of 7 mg/kg intravenously twice a day. Adults were treated with two loading doses of 6 mg/kg intravenously followed by a maintenance dose of 4 mg/kg intravenously twice a day. Based on 104 paired plasma/saliva specimens, we found a significant correlation between the voriconazole concentrations in blood and saliva (r > 0.95). The median saliva/plasma voriconazole concentration ratio was 0.34 in children and 0.40 in adults. Intra- and interpatient variability in the saliva/plasma ratios were 22% and 23% in children and 16% and 24% in adults, respectively. Thirty-three percent of plasma trough levels were below 1.0 μg/mL or above 6.0 μg/mL and occurred in six pediatric and four adult patients. Monitoring of salivary concentrations proved to be a realistic alternative in patients when blood drawing is difficult. Especially in therapeutic drug monitoring, an easier sample collection being noninvasive and painless is more acceptable to patients, particularly children.