Prediction of ocular irritancy of prototype shampoo formulations by the isolated rabbit eye (IRE) test and bovine corneal opacity and permeability (BCOP) assay.

The isolated rabbit eye (IRE) test and bovine corneal opacity and permeability (BCOP) assay were evaluated for their ability to predict the eye irritation potential of a range of hair shampoo formulations, some containing a novel non-surfactant ingredient known to be an ocular irritant. The additional endpoints of corneal swelling and histological examination were incorporated into the standard BCOP protocol. Historic Draize data were available for several of the formulations and served as a reference. The standard BCOP assay (without histology) failed to distinguish between shampoos of low and high irritant potential, when exposure times of 10 and 60 min were employed (for undiluted and 10% dilution of the shampoos, respectively) and the in vitro score classified the majority of formulations as mild. The incorporation of the histological endpoint to the BCOP protocol allowed discrimination between formulations of differing irritancy, and should be included to augment the standard BCOP protocol. Corneal swelling values did not, however, correlate with the irritant potential of the shampoos tested. The IRE which includes the endpoints of corneal swelling and histopathological scoring produced classifications of irritancy that were fairly consistent with in vivo data and distinguished between the high and low irritant potential shampoos.