New aspects of the Slug Mucosal Irritation (SMI) assay: Detecting ocular stinging, itching and burning sensations

Abstract

Abstract Purpose Our eyes are one of the most important senses. They are very sensitive and irritations may occur easily. A screening method for ocular discomfort would be very helpful in the development and refinement of formulations. In the past, the Slug Mucosal Irritation (SMI) assay demonstrated a relation between an increased mucus production (MP) in slugs and an elevated incidence of stinging, itching and burning (SIB) in human eyes. The aim of this study is to compare subjective ocular discomfort caused by shampoos evaluated in volunteers with results of the SIB‐procedure. Methods The stinging potency of 1 artificial tear and 10 shampoos was evaluated with the SIB‐procedure by placing 3 slugs per treatment group 3 times on 100 µl of the test item. After each 15 min contact period, MP was measured. Evaluation of the results is based upon the total MP during 3 repeated contact periods. Experiments were repeated 3 times. A Human Eye Irritation test with the same test items will be set up (12‐period cross‐over study, 24 volunteers, study approved by an independent Commission for Medical Ethics, associated with Ghent University Hospital). The participants are dripped 10 µl of a 5% or 10% shampoo dilution in water or the artificial tear in 1 eye, while in the other eye 10 µl of water is administered. The evaluation of the test substances is done both by participants and the ophthalmologist at several time points. Conclusion With the obtained results we will be able to improve the newly developed protocol and examine the predictability with reference to non‐ and mildly irritating formulations in humans. We hope to conclude that the SIB‐procedure is a good tool to predict clinical ocular discomfort.