Histopathology of experimental ethambutol intoxication.

Ethambutol was administered to albino rats in their drinking water in doses of 105 to 2,500 mg. per kilogram per day for 18 to 102 days. Sixteen per cent developed bilateral lesions consisting of focal axonal swelling without demyelination, in their optic chiasms and the intracranial portions of their optic nerves.