Can fluconazole concentrations in saliva be used for therapeutic drug monitoring?

The saliva/plasma concentration ratio of fluconazole was investigated in 22 HIV-1-infected individuals with an oropharyngeal Candida infection to dete rmine whether saliva fluconazole concentrations could provide useful inform ation for therapeutic drug monitoring in this population. Steady-state pair ed plasma and saliva samples were obtained after approximately 1 week of tr eatment with 50- or 100-mg fluconazole as capsules. A significant correlati on between plasma and salivary levels of fluconazole was observed. The medi an saliva/plasma concentration ratio was 1.3 and was independent of the ing ested dose and the plasma fluconazole concentration. The prediction of fluc onazole concentrations in plasma from the concentrations in saliva was, alt hough unbiased, not precise. From these findings, the authors conclude that although stimulated salivary fluconazole concentrations are significantly correlated with plasma concentrations, it is not possible to predict plasma fluconazole levels from the salivary concentrations with adequate precisio n. However, saliva fluconazole concentrations have sufficient value to test for compliance and even semiquantitative prediction of plasma concentratio ns.