title: The sodium hydroxide erosion assay: a revision of the alkali resistance test.
abstract: Burckhardt proposed the alkali resistance method as a means of assessing the integrity of the stratum corneum barrier in 1947. Researchers after Burckhardt largely found the test unreliable and nonreproducible; it therefore fell into disuse worldwide. We have upgraded the procedure by exposing the skin to 1.0 M sodium hydroxide under strictly specified conditions for successive 1-min periods until the emergence of the first erosions, revealed by staining with nitrazine yellow. Histology showed that the erosions were follicular and limited to the epidermis. The test was highly reproducible and repeatable. We demonstrated the usefulness of the test in the following ways: (1) the erosion time increased with aging, correlating with a thickened horny layer; (2) as few as five Scotch tape strippings greatly decreased the erosion time, although transepidermal water loss was only slightly increased; (3) slight damage to the horny layer by a 24-h exposure to 0.01% sodium lauryl sulfate sharply reduced the erosion time; (4) the erosion time decreased after daily open applications for 3 weeks of clobetasol propionate, corresponding to the thinned horny layer; (5) daily applications of petrolatum increased the erosion time. This new version of the alkali resistance test, renamed the sodium hydroxide erosion assay, promises to be a useful tool for studying the horny layer barrier in healthy and diseased skin.
authors.affiliation: S.K.I.N. Inc., Conshohocken, PA, USA.
authors.forename: L
authors.initials: L
authors.lastname: Kolbe
authors.forename: A M
authors.initials: AM
authors.lastname: Kligman
authors.forename: T
authors.initials: T
authors.lastname: Stoudemayer
mesh_terms: D000287:Administration, Topical; D000328:Adult; D000367:Age Factors; D000368:Aged; D000893:Anti-Inflammatory Agents / Q000494:pharmacology; D002990:Clobetasol / Q000031:analogs & derivatives / Q000494:pharmacology; D003877:Dermatitis, Contact / Q000175:diagnosis* / Q000209:etiology; D004351:Drug Resistance; D005260:Female; D005938:Glucocorticoids; D006651:Histocytochemistry; D006801:Humans; D007509:Irritants / Q000008:administration & dosage / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012867:Skin / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D012882:Skin Tests / Q000379:methods; D012967:Sodium Dodecyl Sulfate / Q000494:pharmacology; D012972:Sodium Hydroxide / Q000008:administration & dosage / Q000009:adverse effects; D013501:Surface-Active Agents / Q000494:pharmacology; D014870:Water Loss, Insensible / Q000187:drug effects / Q000502:physiology
chemical_list: D000893:Anti-Inflammatory Agents; D005938:Glucocorticoids; D007509:Irritants; D013501:Surface-Active Agents; D012967:Sodium Dodecyl Sulfate; D012972:Sodium Hydroxide; D002990:Clobetasol