Keratolysis is the separation or loosening of the stratum corneum (SC), and is part of the natural cycle of skin renewal and regeneration. Disordered keratolysis, resulting in skin overgrowth or excessive desquamation, is responsible for various skin disorders. Keratolytics are agents that cause the separation of the SC through proteolysis of the desmosomes between keratinocytes,1, 3 and they therefore are often used to treat ailments that manifest in skin overgrowth. The use of keratolytics dates back to ancient Egypt when hydroxy acids such as lactic, citric and glycolic were commonly used for skin care.4 In fact, Cleopatra once relied on the keratolytic strength of lactic acid in milk to maintain the youthfulness appearance of her skin.4 Currently, keratolytics are employed to treat acne vulgaris, psoriasis, seborrheic dermatitis and warts, among other ailments. Specifically, patients afflicted with mild and severe acne utilize keratolytics such as benzoyl peroxide, retinoic acid and salicylic acid to slough off the outermost layers of excess and damaged skin.
Determining Keratolytic Efficacy
Keratolytic agents vary not only in strength, but also in the type of acne they are most effective in treating. In order to deduce the efficacy of an agent in removing superficial skin layers, many researchers conduct sequential adhesive tape stripping of a skin region and weigh the removed SC with precision balances. However, accurate measurements are time-consuming and may be distorted by water absorption and desorption from the tape or due to artifacts, e.g., applied vehicle and solutes in cases where topical agents are placed over the skin.5, 6 Thus, the authors instead propose evaluating various keratolytic agents by means of in vivo colorimetric protein assay, as described by Dreher et al.5