A Reassessment of the in vitro total protein content determination (TPC) with SIRC and 3T3 cells for the evaluation of the ocular irritation potential of shampoos: comparison with the in vivo Draize rabbit test

the aim of this work was to determine the correlation between results obtained from the draize test and from the total protein content determination (tpc) to assess the ocular irritancy potential of 20 shampoos. for tpc, two established cell lines (sirc and 3t3) were used. the concentration that induced 50% inhibition relative to controls (ic50) was calculated for each product. among shampoos tested with sirc, only one had a false positive result. however, for the 3t3, three false-negative results were found. pearson coefficient related to the in vivo value of maximum average score (mas) was -0.58 (p=0.007) with sirc and -0.73 (p=0.007) with 3t3. these results showed that the tpc assay was capable to predict the ocular irritant potential of shampoos, and therefore was a promissory tool to be used as a preliminary assay for the detection of irritant products and to be part of a battery of screening tests to minimize the animal use in the draize test.