Abstract
Three percent N-acetylcysteine ophthalmic solution (PAPITEIN®, Senju pharmaceutical Co., Ltd., Osaka) is widely known to be useful for the treatment of canine and feline corneal lesions in traumatic keratitis and corneal ulcer by its anti-collagenase effect. On the other hand, it is also known that repeated instillations of a highly concentrated N-acetylcysteine solution remove the ocular surface mucin in rabbits. Therefore, we investigated whether 3% N-acetylcysteine ophthalmic solution led to damage on the ocular surface by repeated instillations of it into the left eye and of saline into the right eye of beagle dogs at intervals of 2 hours, 6 times a day for 2 weeks. During instillation period, anterior ocular findings were evaluated by vital staining with fluorescein on cornea and with lissamine green on cornea and conjunctiva, and histopathological findings of isolated cornea were also evaluated after 2 week repeated instillations of them. No adverse effects on the ocular surface were observed by both vital staining and histopathological findings with a microscope and a scanning electron microscope. These findings suggest that 3% N-acetylcysteine ophthalmic solution does not reduce mucin covered on the ocular surface and does not induce the damage of corneal epithelium in dogs when the solution is repeatedly instilled 6 times a day for 2 weeks.
