Effect of intratympanic application of efinaconazole 10 % solution in the guinea pig

Efinaconazole 10 % solution is a new triazole antifungal agent developed for the topical treatment of fungal infections of the nails. The current study examined the effect of intratympanic application of efinaconazole 10 % solution in the guinea pig ear. Sixteen male Hartley guinea pigs (weight 501–620 g) were divided into 3 groups to be treated with efinaconazole 10 % solution, gentamicin (50 mg/mL), or saline solution. Topical solutions of 0.2 mL were applied through a small hole made at the tympanic bulla once daily for 7 consecutive days. Post-intervention auditory brainstem responses were obtained 7 days after the last treatment. The extent of middle ear damage and hair cell loss was investigated. The efinaconazole- and gentamicin-treated groups showed severe deterioration in auditory brainstem response threshold. Middle ear examination revealed extensive changes in the efinaconazole-treated group and medium changes in the gentamicin-treated group. Hair cells were preserved in the efinaconazole- and saline-treated groups, but severe damage was seen in the gentamicin group. In conclusion, efinaconazole 10 % solution applied intratympanically to the guinea pig middle ear caused significant middle ear inflammation and hearing impairment.