The effect of isotretinoin on propylene glycol-induced cholesteatoma in chinchilla middle ears.

Previous studies have shown that propylene glycol causes inflammatory changes and cholesteatoma when applied to chinchilla middle ears. Vitamin A and synthetic analogues are essential for the normal differentiation of epithelial tissues. The purpose of this study was to determine whether the administration of isotretinoin to chinchillas would prevent propylene glycol exposure from inducing middle ear cholesteatomas. Sixteen chinchillas received 90% propylene glycol to the left middle ear and normal saline to the right. Half the animals were placed in the experimental group and received a daily dose of isotretinoin of 2 mg/kg for 7 days prior to propylene glycol administration and then for 6 weeks until killed. At 6 weeks, cholesteatoma was found in six of eight ears treated with propylene glycol in animals receiving isotretinoin. Two animals in the control group died. Three of the remaining eight had cholesteatoma. No ears treated with saline had cholesteatoma. We conclude that isotretinoin, in our chinchilla model, does not prevent propylene glycol-induced cholesteatoma formation.