Everolimus-coated tympanostomy tube on rat tympanic membrane

Everolimus is an immunosuppressant and an antiproliferative macrolide agent which is used for coronary stent coating for local inhibition of in-stent restenosis. The aim of this study was to evaluate the effect of everolimus-coated tympanostomy tubes in rat tympanic membrane.

Prospective controlled animal study.

Twenty-one Sprague-Dawley rats were included in the study. They were bilaterally myringotomized. An everolimus-coated fluoroplastic tympanostomy tube was inserted into one ear of each of the rats (everolimus-coated TT Group; n=21) and a standard fluoroplastic tympanostomy tube was applied to the contralateral ear of the same rats (Standard TT Group; n=21). Tympanic membranes and tubes were routinely examined otomicroscopically every other day for two months. Then the membranes were harvested and evaluated histologically.

In everolimus-coated tubes, the tube obstruction was found to be significantly lower than in standard tubes (p<0.05). The tube extrusion rate was less for everolimus-coated tubes than for standard tubes, but no statistically significant difference was observed between the two tubes. There was no statistically significant difference in the incidence of otorrhea between two tubes. Histopathological examination under light microscope revealed that everolimus-coated tubes resulted in less fibrosis and less inflammation in tympanic membranes than standard tubes (p<0.01).

The study shows the potential role of everolimus-coating of tympanostomy tubes in reducing tube obstruction. In addition, inflammatory reaction and fibrosis were observed to be significantly less with these tubes.