The EYTEX system and the neutral red uptake inhibition assay in cultured Hep G2 cells as alternative methods for in vivo eye irritation following the EEC protocol

By Dierickx, P.J. - Gordon, V.C.

The neutral red uptake inhibition assay and the EYTEX(TM) system were investigated as alternative methods for the assessment of eye irritation, determined according to the EEC protocol. The 17 test chemicals used were mainly organic solvents. The xenobiotics were applied to Hep G2 cells for 24 hours at different concentrations. Neutral red uptake inhibition was then measured. The results are expressed as the NI50 value, which is the concentration of test compound required to induce a 50% reduction in neutral red uptake. The same chemicals were also tested as coded samples by the EYTEX(TM) test according to the manufacturer's directions. A nearly identical quantitative correlation was found for both in vitro methods with corneal opacity scores: r = 0.84 for EYTEX(TM) scores and r = 0.83 for log N150, expressed in micrograms/ml. Whilst these correlations are certainly not perfect, it is clear that both in vitro methods can be used as valuable prescreening methods.