Experimentally induced chronic irritant contact dermatitis to evaluate the efficacy of protective creams in vivo.

Abstract

Widely accepted in vivo models to evaluate the efficacy of protective creams (PCs) are still missing. The effect of petrolatum's ability to protect against irritation was tested in a repetitive irritation test to optimize the concentration of irritants against which PCs are tested and to evaluate the necessary cumulative application time. On 20 healthy volunteers, the irritants (sodium lauryl sulfate 5% vs 10%, sodium hydroxide 0.5% vs 1%, lactic acid 20% vs 30%, and toluene undiluted) were applied daily for 2 weeks on the ventral forearms after 30 minutes of pretreatment with petrolatum. The irritant cutaneous reactions were quantified by erythema score, transepidermal water loss, and chromametry. For petrolatum, a significant protective effect was obtained against irritation by sodium lauryl sulfate, sodium hydroxide, and toluene in different degrees. Less efficacy was observed against lactic acid. It was concluded that a 1-week period of cumulative irritation is enough to evaluate the efficacy of PCs against most irritants, even if lower concentrations of irritants are used.