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A Review of Anti-Irritants, Part I: Barrier Cream Efficacy on Contact Dermatitis*
By: Howard I. Maibach, MD, University of California School of Medicine; and Hongbo Zhai, MD, University of California
Posted: March 2, 2011, from the March 2011 issue of Cosmetics & Toiletries.
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BC protection against water: De Fine Olivarius et al. determined the efficacy of various BC and moisturizers in protecting skin against water. An aqueous solution of crystal violet was applied to the skin after pretreatment with different formulas and its color intensity was evaluated. The BC with particles gave the best immediate protection (dorsal 76%, volar 69%). The moisturizer was intermediately protective (dorsal 57%, volar 34%), while little protection was found for the silicone-containing cream (dorsal 16%, volar 10%).
Lipophilic BC protection from acute ICD: Fartasch et al. investigated the protective capacity of a lipophilic BC on acute ICD by TEWL measurement. Application of the BC before and during irritation showed a decrease TEWL enhancement with 0.5% SLS by 58% (back) and 49% (arm), and after irritation with 0.75% SLS by 56% (back) and 43% (arm).
PFPE irritant protection: Elsner et al. evaluated o/w emulsions containing 0.5%, 1.0%, 2.0% and 4.0% perfluoropolyethers (PFPE) against four irritants: 10% SLS, 0.5% NaOH, 15% LA and undiluted toluene in an RIT on the human back. Irritation was assessed by visual scoring, TEWL and colorimetry. All PFPE preparations significantly suppressed irritation caused by SLS and NaOH. However, only the 4% PFPE preparation was significant against LA and toluene.
In vivo protectant screening: Zhai et al. introduced an approach for screening protectants in vivo in human subjects. Two acute irritants, SLS and the combination of ammonium hydroxide (NH4OH) and urea, were used in addition to one allergen, Rhus (poison ivy). The model irritants and allergen were applied with an occlusive patch for 24 hr. Inflammation was scored with an expanded 10-point scale at 72 hr post application.
Most test protectants statistically suppressed SLS irritation and Rhus allergic reaction but not NH4OH- or urea-induced irritation. The researchers further utilized this model to evaluate putative skin-protective formulations. All formulations failed to inhibit NH4OH and urea irritation. Only paraffin wax in cetyl alcohol significantly reduced Rhus-allergic contact dermatitis (ACD). Three commercial formulationsa–c markedly suppressed SLS-ICD.