A method to evaluate the safety of an OTC ophthalmic solution in normal human volunteers

Methods of evaluating eye preparations from a human safety standpoint have remained somewhat obscure. Toxicology and predictive irritancy studies in animal models can be readily retrieved from the literature (1-4), but methods for human testing are not as available. The rabbit is the species of choice for the preliminary evaluation of potential ocular irritation from toiletties, cosmetics and household products, as well as for proprietary and ethical ophthalmic preparations because the rabbit eye is more sensitive to irritation than the human eye (5). In addition, the standardization which exists for rabbit ocular irritation studies is well documented (6). Although the data generated in the rabbit model can prove most interesting and is extremely useful for predicting the potential for human ocular irritation, every eye product should be subjected to subsequent human safety testing prior to release to the marketplace. The reformulation of an over-the-counter ophthalmic solution (Ocusol © NorwichEaton Pharmaceuticals) created the need for the evaluation of its ocular irritation potential.