A Review of Anti-Irritants, Part I: Barrier Cream Efficacy on Contact Dermatitis*

By: Howard I. Maibach, MD, University of California School of Medicine; and Hongbo Zhai, MD, University of California

Posted: March 2, 2011, from the March 2011 issue of Cosmetics & Toiletries.

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Protective gel: Lupulescu and Birmingham observed the ultrastructural and relief changes of human epidermis either left unprotected or treated with a protective gel following exposure to acetone and kerosene. Unprotected skin showed cell damage and a disorganized pattern in the upper layers of epidermis. However, skin treated with the protective agent showed substantially reduced ultrastructural and relief changes of epidermis cells when exposed to solvent.

Bioengineering evaluation of BCs: Grunewald et al. evaluated BC protective effects using bioengineering techniques and a sodium lauryl sulfate (SLS) repetitive washing model on 15 human volunteers. All BCs reduced the deterioration of skin functions after one week of repetitive washing. Subsequently, researchers also found that urea and glycerol o/w emulsions provided greater protection than three commercial BCs when tested against the lipophilic irritant toluene after seven days of repetitive irritation.

The effectiveness of BCs was measured on human subjects against dye indicator solutions including methylene blue in water and oil red O in ethanol, where methylene blue was representative of model hydrophilic compounds and oil red O was representative of lipophilic compounds. Each solution was applied at 5% to untreated and BC-pretreated skin with the aid of aluminum occlusive chambers for 0 hr and 4 hr. Post application time, materials were removed and consecutive skin surface biopsies (SSBs) were obtained. The amount of dye penetrating into each strip was determined colorimetrically. Two model creams exhibited protective efficacy but one enhanced the cumulated amount of dye—i.e., it failed to exhibit protective effect against dye indicators.

Four BCs vs. four irritants: Schlüter-Wigger and Elsner compared four commercially available BCs with four standard irritants: 10% SLS, 1% sodium hydroxide (NaOH), 30% lactic acid (LA) and undiluted toluene in a repetitive irritation test (RIT) on humans for 12 days. Irritation was assessed by visual scoring, transepidermal water loss (TEWL) measurements and colorimetry. All products were effective against SLS irritation. Nevertheless, no BC provided significant protection against toluene. Three of the four products tested showed a partially protective effect against all ionic irritants, while the fourth showed less protection against SLS and NaOH, and even amplification of inflammation by toluene.

Petrolatum skin protection: Wigger-Alberti and Elsner evaluated the protective effects of petrolatum utilizing the same model and noted that petrolatum was effective against SLS, NaOH and LA irritation; it also provided moderate protection against toluene. Subsequently, the researchers examined the efficacy of three other BCs and petrolatum against 10% SLS, 0.5% NaOH, 15% LA and undiluted toluene in an RIT on human volunteers for nine days. All BCs exhibited a significant protective effect against irritation by SLS, NaOH and LA, although less efficacy was observed against toluene. In another 12-day RIT study, white petrolatum provided a significant protective effect against SLS, NaOH, and TOL but with less protective effect against LA irritation.