Evaluation of an alternative mucosal irritation test using slugs

The objective of this study was to evaluate an alternative mucosal irritation test using the slug Arion lusitanicus as test organism. The effect of 28 reference substances on the mucosal tissue of the slugs was determined by the amount of mucus produced, the reduction in body weight, and the release of proteins from the body wall. The data of the mucosal irritation test were compared with the available in vivo Draize scores for eye irritation (MMAS). The amount of mucus produced and the reduction in body weight caused by a 60-min contact period were significantly correlated (r = 0.73) with the MMAS score for eye irritation. However, the mucus production was the best endpoint to classify the chemicals into the three categories corresponding the EU classification (NI, R36, and R41). Since irritating alcohols did not induce an increased mucus production and therefore the irritation potential of these molecules was underestimated, two prediction models were developed. For nonalcohols a 60-min contact period with the chemicals was sufficient and the molecules were classified according to the amount of mucus produced. A concordance, specificity, and sensitivity of 65, 100 and 83%, respectively, was obtained. For the alcohols a second 60-min contact period was necessary and the molecules were classified using the protein release as endpoint. Ninety-one percent of the alcohols were correctly classified with a sensitivity and specificity of 100%. We can conclude that the mucosal irritation test using slugs seems to be a reliable and promising method for the evaluation of the irritation potential of drugs instead of diverse tests using different animal models to estimate the irritation on human mucosal tissues.