Comparison of the antifungal effect of voriconazole and fluconazole on oral candidiasis before and during radiotherapy

Head‑and‑neck radiotherapy can change oral Candida species and cause candidiasis resistance to common antifungals by making the changes to the oral cavity environment. Voriconazole is a synthetic azole with extensive antifungal activity. The current study aimed at comparing the antifungal activity of fluconazole and voriconazole on Candida species isolated from the oral cavity of patients undergoing head‑and‑neck radiotherapy.

The present in vitro study was performed on samples isolated from patients undergoing head‑and‑neck radiotherapy, before and during radiotherapy. After the identification of the species, the antifungal effect of fluconazole and voriconazole was determined by the microdilution method, and the minimum inhibitory concentration (MIC), the minimum fungicidal concentration, and the antifungal susceptibility of the isolated strains were also measured. The data were analyzed by the Chi‑squared and then two‑sided Fisher’s exact tests. P < 0.05 was considered statistically significant.

The study findings showed no significant difference in the susceptibility of Candida albicans to voriconazole and fluconazole before and during radiotherapy. Before radiotherapy, both voriconazole and fluconazole had similar effects on Candida tropicalis, but after radiotherapy, voriconazole was less effective. However, both before and during radiotherapy, fluconazole had a greater antifungal effect than voriconazole on Candida glabrata strains. The MICs of voriconazole and fluconazole for both Candida parapsilosis and Candida krusei isolates were within the susceptible or dose‑dependent range.

The current study results showed that voriconazole was not more effective than fluconazole in the treatment of oral candidiasis in patients undergoing head‑and‑neck radiotherapy.