IN VITRO SKIN IRRITATION TEST: INCREASING THE SENSITIVITY OF THE EPIDERM SKIN IRRITATION PROTOCOL EVALUATED IN THE ECVAM SKIN IRRITATION VALIDATION STUDY.

This study by scientists at MatTek Corp. demonstrated that a modification of the common Skin Irritation protocol that extended the exposure time from 15 minutes to 60 minutes for MatTek’s EpiDerm in vitro human skin tissue model produced a significant increase in sensitivity without decreasing the specificity of the method. During 2001-2004, refined EPISKIN and EpiDerm in vitro skin irritation protocols were developed showing good correlation between in vivo and in vitro data. Both methods were based on the idea of a common protocol, comprised of 15 minute application and 42 hour post-exposure period. In 2004, these protocols proceeded into the ECVAM validation study with the aim of replacing the rabbit in vivo test (OECD TG 404). Based on results published by Faller and Bracher (2002), and comparing the outcomes of the EpiDerm and EPISKIN optimization studies, there is evidence that the more robust barrier of the EpiDerm model caused false negative outcomes in the common protocol design. Therefore, a modification of the common protocol was introduced by extending the exposure time from 15 min to 60 min for the EpiDerm model. With this change, MatTek scientists obtained a significant increase in sensitivity without decreasing the specificity of the method. This presentation summarizes results obtained with the original (15 min/ 42 hr) and modified protocol (60 min/ 42 hr). Results are compared to in vivo rabbit data as well as results from a recently performed human patch study.

ECVAM Skin Irritation Validation, EpiDerm, MTT, MTT auto-reduction, MTT reducers, Skin corrosive chemicals, Skin irritation

1,1,1-Trichloroethane, 1,2-diaminopropane, 1,6-Dibromohexane, 1-(2-Aminoethyl) piperazine, 1-Bromo-4-chlorobutane, 1-Bromohexane , 1-Bromopentane, 1-Decanol, 1-chloro-3-nitrobenzene, 10-Undecenoic acid, 2-Methyl-4-phenyl-2-butanol, 2-ethoxy ethyl methacrylate, 2-isopropyl-2-isobutyl-1,3-dimethoxy propane, 2-tert. Butylphenol, 20% SLS, 3,3'-Dithiodipropionic acid, 3,4-dimethyM-H-pyrazole , 4,4-Methylene bis-(2.6-di -tert-butyl) phenol, 4-Amino-1.2.4-triazole, 4-Methylthio-benzaldehyde , Allyl heptanoate, Allyl phenoxy acetate, Alpha terpineol, Benzyl acetate, Benzyl benzoate, Benzyl salicylate, Benzylalcohol, Boron trifluoride dihydrate, Butyl methacrylate , Carvacrol, Cinnamaldehyde, Cis-Cyclooctene, Cyclamene aldehyde, Decanoic acid, Di-n-propyl disulphide, Di-propylene glycol , Diethyl phtalate, Dimethylisopropylamine, Dodecanoic acid (lauric acid) , Erucamide, Eugenol, Ferric chloride, Heptaldehyde, Heptyl butyrate , Hexyl salicylate, Hydroxycitronellal , Isopropanol, Isopropyl myristate, Isopropyl palmitate, Lilestralis/Lilial, Linalool, Linalyl acetate, Methacrolein, Methyl laurate, Methyl palmitate, Metyl stearate, Mixture of isomers: 1-(2-isopropylphenyl)-1-phenylethane, 1-(3-isopropylphenyl)-1-phenylethane, 1-(4isopropylphenyl)-1-phenylethane, Mixture of isomers: 1-(spiro[4.5]dec-7-en-7-yl)pent-4-en-1-one ,1 - (spiro[4.5]dec-6-en-7-yl)pent-4-en-1 -one, N.N-Dimethyldiprolylenetriamine, Nonanolc acid, Octanoic acid, Phosphorous tribromide, Potassium hydroxide (5%), Sodium bicarbonate, Sodium lauryl sulphate (50%), Sulphuric acid 10 %, Terpinyl acetate , Tetrachloroethylene, Tri-isobutyl phosphate, bis[(1-methylimidazol)-(2/ethyl-hexanoate)]lzinc complex, d-Limonene, n-Heptylamine, naphthalene acetic acid , â-Citronellol