Anatomical Site Differences of Sodium Laurylsulphate Induced Irritation: randomised controlled trial

Summary

Background

Sodium laurylsulphate (SLS) induced contact dermatitis is a commonly used model for testing effects of different topical formulations. Volar forearms are preferred testing site by the guidelines, but other anatomical locations were used in previous research, especially upper back, as the clinically used site for testing different antigens.

Objectives

Aim of the present study was to investigate existence of anatomical variations of skin response to irritation and its' effects on response to treatment.

Methods

Irritation was induced with SLS on symmetrical sites on both forearms and sides of upper back with additional sites exposed to water as controls. Half of the sites were treated with emollient cream while the other half were left untreated. Irritation was assessed using bioengineering methods and clinical scoring.

Results

Upper back skin showed higher reactivity to irritants with stronger barrier disruption (measured by Tewameter, 80·2±18·3 vs 48·0±24·2 gm⁻²h⁻¹), more pronounced erythema (measured by Mexameter, 186·5±88·4 vs 92·1±58·2 AU) and dryness (measured by Corneometer, ‐28·6±14·5 vs 2·7±16·9 AU). Skin recovery rates were also influenced by anatomical location with the upper back showing faster recovery (316·7±223·1 vs 156·2±198·5). Treatment didn't lead to improvement in measured parameters, regardless of anatomical location.

Conclusion

Skins' reaction to irritant and recovery were dependant on anatomical location. Location where testing was conducted should always be reported as treatments tested across different locations could not be directly compared to each other.

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