Toxicity of intravitreal interferon alpha-2b in the rabbit.

OBJECTIVE

To investigate the toxicity of single doses of intravitreally administered interferon alpha-2b in the New Zealand white albino rabbit.

INTERVENTIONS

One eye each of six rabbits received an intravitreal injection of 1000, 10,000, 100,000, 500,000, 1 million or 2 million units of interferon alpha-2b reconstituted in 0.1 mL of balanced salt solution. The fellow eye of the first three rabbits received an intravitreal injection of the same volume of balanced salt solution.

OUTCOME MEASURES

Media opacities, toxic effects to the retina, optic nerve or other ocular structures.

RESULTS

The injection of 2 million units of interferon alpha-2b elicited an immediate dense vitreous haze that largely cleared within 24 hours as well as numerous intraretinal hemorrhages that were no longer visible 7 days after injection. Histopathological study of this eye 14 days after injection showed a diffuse mixed inflammatory cell infiltrate with retinal vacuolation and ganglion cell dropout. In the remaining eyes, to dosages of 1 million units, the agent produced no clinically or pathologically evident toxic ocular effects.

CONCLUSIONS

Interferon alpha-2b appears to be safe and well tolerated up to dosages of 1 million units.