Evaluation of eye irritation potential of experimental cosmetic formulations containing glycolic acid, salicylic acid and ethanol using the Bovine Corneal Opacity and Permeability Assay

Abstract

Objective

Prototype cosmetic formulations containing short-chain acids and alcohols intended to be applied in the proximity of the eyes are sometimes evaluated for ocular irritation potential using the validated Bovine Corneal Opacity and Permeability Assay (OECD TG 437). We evaluated the eye irritation potential of nine experimental cosmetic formulations designed and prepared by Avon Global Reserach and Development to differ only in the concentrations of Ethanol, Glycolic Acid and Salicylic Acid.

Methods

We analysed the data generated using the BCOP assay. The opacity and permeability values obtained following the exposure of bovine corneas to experimental cosmetic formulations were combined into a single In Vitro Irritancy Score used to rank eye irritation potential. Histopathological examination of treated corneas was used to provide additional information about the depth and degree of the injury and to support the prediction of eye irritation potential of each experimental cosmetic formulation.

Results

The In Vitro Irritancy Scores and histopathological analysis showed that experimental formulations containing only Ethanol, Glycolic Acid, or Salicylic Acid alone had, at most, a mild ocular irritation potential. The experimental formulations containing both Ethanol and Glycolic Acid had a mild ocular irritation potential, while the experimental formulations containing both Ethanol and Salicylic Acid had a moderate ocular irritation potential. Severe ocular irritation potential was induced by an experimental formulation containing a combination of Glycolic Acid and Salicylic Acid and it was further accentuated by the addition of Ethanol to the formulation. Our data indicate a possible synergistic effect on eye irritation potential of Ethanol, Glycolic Acid and Salicylic Acid in at least some experimental cosmetic formulations. Further, our results provide insight on an apparent concentration-dependent ocular irritation potential effect of combinations of Glycolic Acid, Salicylic Acid and Ethanol in at least one experimental cosmetic formulation.

Conclusions

The results presented herein emphasise the need to consider in vitro testing of prototype cosmetic formulations containing combinations of Ethanol, Glycolic Acid and Salicylic Acid rather than relying on any predicted additive effect on ocular irritation based solely on previously generated results of similar formulations containing Ethanol, Glycolic Acid or Salicylic Acid alone. Further work is required to understand the significance of these observations and to elucidate the mechanisms responsible for the apparent synergistic effects of Glycolic Acid, Salicylic Acid and Ethanol and eye irritation potential suggested by our results.

Keywords:

• Eye irritation
• BCOP (Bovine Corneal Opacity and Permeability Assay)
• cosmetic formulations
• histopathology
• short-chain acids and alcohols

Acknowledgments

The authors thank Allison Hilberer (IIVS) for the pictures included in Figure 1 and Jennifer R. Nash (IIVS) for the histological analysis included in Figures 2 and 3. The authors also thank Kimberly Tran and Megan Madrid (IIVS) for conducting the additional experiment and taking the associated pictures of corneas included in Supplementary Fig. 1.

Disclosure statement

At the time of writing this manuscript, the authors Ramez Labib and Stephen Gettings were employees of Avon Global Research and Development which formulated the experimental cosmetic formulations evaluated in this study. The authors Kayla Cantrell, Hans Raabe and Gertrude-Emilia Costin are employees of the Institute for In Vitro Sciences, Inc. (IIVS) which tested the experimental cosmetic formulations evaluated in this study.

Additional information

Funding

This work was sponsored by Avon Global Research and Development (U.S.A.).