Does topical application of 5-fluorouracil ointment influence inner ear function?

OBJECTIVE To investigate the effect of 5-fluorouracil (5-FU) ointment on the inner ear of guinea pigs. STUDY DESIGN AND SETTING In group A (n = 7), 5-FU ointment was applied into the left external auditory canal. In group B (n = 10), 5-FU ointment was applied to the left middle ear through myringotomy. In both groups, the right ear served as a control. One week later the endocochlear DC potential (EP) was measured and morphology of the cochleae was examined using scanning electron microscopy (SEM) and light microscopy. RESULTS In group A, there was no significant difference between the EP values of the experimental side and the control side. In group B, there was a statistically significant difference between them (P < 0.05). Morphologic findings showed no damage. CONCLUSION 5-FU ointment application to the external ear seems to be safe but its application to the middle ear may pose some risk of ototoxicity.