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V. Vitale, G. De Pasquale, A. Blanco; Netildex® versus Other Fixed Combinations: Tolerability Study. Invest. Ophthalmol. Vis. Sci. 2009;50(13):901.
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To determine the acute ocular toxicity in vivo of Netildex® solution containing 0.3% netilmicin and 0.1% dexamethasone versus Tobradex®, Betabioptal®, Cilodex® and Maxitrol® multidose eyedrops using both intact and mechanically damaged eye models in rabbit.
Forty-eight rabbits (males and female) were divided in two groups (A and B). Group A was used to investigate toxicity in the intact eye and group B was used to examine toxicity in an model of eye damage induced by mechanical scraping of the cornea. All animals received 50 µl of treatments into the fornix of the right eye and for group B in both eyes. Animals were examined (group A - 5 days; group B - 3 days) by slit lamp observation using the modified Draize test. Before sacrifice, eyes from animals of group A were subjected to impression cytology. Histopathological analysis of eyes was made for some animals of group A while scanning electron microscopy (SEM) analysis of corneas was made for some animals of both groups.
Slight conjunctival congestion was seen in some animals from both groups but without any oedema or exudate. However, Maxitrol® treatment evoked irreversible signs of irritation characterised by small superficial fluorescent spots distributed in the cornea (P<0.001 versus Netildex® treatment after 48 hours). Impression cytology and histopathological analysis revealed no differences between groups. Intact eye samples of corneas treated with Netildex® and Cilodex® analyzed with SEM did not show signs of epithelial alteration, whereas with Betabioptal® and Maxitrol® treatment superficial toxicity was evident. Moreover, Tobradex® treatment showed some isolated areas of disepithelization. In the wounded eye, corneas treated with the Netildex® appeared totally repaired with new cells organized and covered by numerous microvilli. New cells disorganized with fewer and shorter microvilli were evident using all other fixed combinations.
All the treatment groups, using modified Draize test, histopathological analysis and impression cytology, appeared tolerated. In contrast, using the more sensitive SEM analysis it was possible to demonstrate on both intact and wounded eye a better safety profile of Netildex® solution respect other fixed combinations used.
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