Efficacy of Protective Creams in a Modified Repeated Irritation Test. Methodological aspects.

Abstract

The effect of 3 protective creams and petrolatum was tested in a repetitive irritation test. On 15 healthy volunteers;the irritants (sodium lauryl sulfate 10%;sodium hydroxide 0.5%;lactic acid 15%;and toluene undiluted) were applied on the paravertebral skin of the mid-back after 30 min pretreatment with the products tested. The volunteers were treated for 9 days. The irritant cutaneous reactions were quantified by erythema score;transepidermal water loss;and chromametry. The results showed a specific profile of efficacy against the 4 irritants used. For all creams a significant protective effect was obtained against irritation by sodium lauryl sulfate;sodium hydroxide and lactic acid in different degrees. Less efficacy was observed against toluene. Even an amplification of inflammation by pretreatment with 1 product could be demonstrated. The results indicate that a 1-week period of cumulative irritation might be enough to evaluate the efficacy of protective creams against most irritants.