Regional Differences of Cutaneous Irritation and Its Effect on Skin Barrier Recovery

Regional Differences of Cutaneous Irritation and Its Effect on Skin Barrier Recovery: A Randomised, Controlled Trial

Irritant contact dermatitis induced by sodium lauryl sulphate (SLS) is often used as a model for testing efficacy of various topical preparations. Aforementioned model is standardized and described in guidelines, but it is not explicitly stated where the irritation should be induced. Published clinical trials usually irritate volar aspect of forearms or upper back. Also, lower back and dorsal aspect of forearm are sometimes used. Skin parameters vary depending on anatomic location of measured skin. There is a difference in stratum corneum thickness, hydration and transepidermal water loss across different locations, including between volar forearm and upper back. Furthermore, regional difference in skin response to irritation by tape stripping and benzalkonium chloride were observed. Such differences are also possible in SLS irritation model. One study has shown higher, but not statistically significant, response of back in comparison to forearms, but it had a very small sample size (n=9). Moreover, there are regional variations of topical preparations absorption. Hydrocortisone had 1,7 times higher absorption when applied to upper back in comparison to forearms. Those variations could be explained by different corneocyte size and number of their layers between back and hands. Skin baseline properties and response to irritation seem to be dependent on anatomic position. Those differences could mean different response to treatment. Since published trials only tested efficacy of various preparations on one anatomic location, it is possible their results would be different if tested on other body parts. It could limit validity and usefulness of conducted trials. The aim of this study is to determine if there are regional differences of skin response to irritation and emollient cream treatment in irritant contact dermatitis model.

Sodium lauryl sulphate will be applied to specified skin sites according to randomization protocol to induce irritation. 60 uL of 2% w/v SLS will be applied to skin under occlusion by large Finn chamber for 24 hours as described in the guidelines by Standardization group of European Society of Contact Dermatitis.

Commercially available topical emollient cream will be applied by each participant to treatment sites according to randomization protocol.

Corneometer will be used to estimate skin dryness. It is a relative measurement and uses arbitrary units (AU).

Mexameter will be used to assess erythema. It is a relative measurement and uses arbitrary units (AU).

Skin response to irritation and treatment will be assessed using a five-point scale to describe changes in skin erythema, roughness, scaling, oedema, and fissures.

Inclusion Criteria: young, healthy volunteers who gave written informed consent Exclusion Criteria: skin disease, skin damage on measurement sites, use of corticosteroids and immunomodulators a month prior the inclusion and during the trial, use of emollients three days prior the inclusion in the trial, non-adherence to the trial protocol, exposure to artificial UV radiation, pregnancy and lactation

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