Effects of Anesthetic Pretreatment and Low Volume Dosage on Ocular Irritancy Potential of Cosmetics: A Collaborative Study

Publisher Website
Google Scholar
Abstract
A collaborative program to modify the Draize irritancy test was conducted at eight industrial laboratories to study (1) the effects of treating rabbit eyes with a topical anesthetic prior to instillation of the test materials, (2) feasibility of reducing ocular response by use of a low dose volume, and (3) ocular response to application of the test materials to the cornea or into the conjunctival sac. Pretreating rabbit eyes with the anesthetic proparacaine or tetracaine had no meaningful effect on the course or intensity of ocular response from treatment with 20% or 100% shampoo, 80% ethyl alcohol, or 100% talc. Comparable irritation responses were produced by 20% shampoo and 80% ethyl alcohol, whether the samples were applied over the cornea or into the conjunctival sac. At the 100-µl dosage volume, ethyl alcohol was more irritating than shampoo, a difference that was not evident at the 10-µ1 dosage. A dose-response study with ethyl alcohol suggested that an intermediate dosage of 50 µl would reduce irritancy without affecting the discriminatory power of the test. Indeed, when the irritancy of 18 cosmetic samples was compared at 50 and 100µl, the response ranking was maintained with a meaningful reduction in irritancy at the low dosage volume (50µl).