Efficacy of skin barrier creams (I). The repetitive irritation test (RIT) in the guinea pig.

An animal model for the evaluation of skin protective creams against chemical irritants is described. The irritants were applied daily for 2 weeks to shaved back skin of young guinea pigs: sodium lauryl sulphate (5% aq.; 30 min), sodium hydroxide (0.5% aq.; 2 min), and toluene (20% eth.; 2 min). The barrier cream was applied 2 h prior to and immediately after exposure to the irritant. Control animals were treated with the irritant only. The irritant reaction was scored on a 4-point scale for erythema and quantified with regard to transepidermal water loss (TEWL) by evaporimetry and skin blood flow volume (BFV) by laser Doppler velocimetry. A total of 90 guinea pigs, consisting of individual panels of 5 to 10 animals, was tested. While one barrier cream (Stokoderm) significantly suppressed the irritation due to sodium lauryl sulphate and toluene, the other (Contra-Alkali) failed to do so and even aggravated the response, which was particularly evident with sodium hydroxide. This model may be useful in developing more effective barrier creams.