Tolerability of long-term fluconazole therapy

Background Fluconazole is a commonly prescribed first-generation triazole antifungal. Although the toxicity profile of fluconazole has been evaluated in clinical trials, there are scant data regarding its tolerability with long-term therapy. Treatment guidelines for coccidioidomycosis recommend fluconazole therapy and severe or disseminated infections can require lifelong treatment. Objectives To assess the prevalence of long-term fluconazole adverse effects, their consequences for antifungal therapy, time to adverse effects and the association between dosing regimen or fluconazole serum level and adverse effect status. Methods We conducted a single-centre, retrospective study of adult patients (18years) with proven or probable coccidioidomycosis receiving long-term fluconazole therapy for an intended duration of 28days. Results Out of 124 patients included, 64 (51.6%) experienced adverse effects. The most common adverse effects were xerosis (16.9%), alopecia (16.1%) and fatigue (11.3%). Of the 64 patients experiencing adverse effects, 42 (65.6%) required a therapeutic intervention such as dose reduction, discontinuation or switch to a new antifungal. Patients experiencing adverse effects were prescribed higher total daily fluconazole doses (6.7 versus 5.7mg/kg; P<0.01). The median therapeutic drug levels did not differ significantly between patients who experienced adverse effects and those who did not (36.1 versus 28.1mg/L; P=0.35). Conclusions A significant number of patients receiving long-term fluconazole therapy for coccidioidomycosis experienced adverse effects. Of these, around two-thirds required a therapeutic change. We believe these findings are representative of the adverse effect profile of long-term fluconazole therapy as it is used in clinical practice for coccidioidomycosis as opposed to use in clinical trials.