Comparative Clinical and Electrometric Assessments of the Impact of Surfactants on Forearm Skin

Abstract

Surfactant-based skin care products can induce minimal to severer alterations of the human stratum corneum (SC). These changes can be conveniently assessed using electrometric devices. Four different surfactant-based solutions were applied to the forearms of 10 healthy volunteers following a soap chamber test method. The 2-day patch testing was followed by a 2-week follow-up. Clinical and instrumental assessments were performed at 7 time points. Data generated by the Corneometer^® CM820, the Dermalab Moisture Module^® and the Nova Dermal Phase Meter^® (DPM) 9003 were compared. The significant differences between the product aggressiveness to the SC were similarly disclosed by the Corneometer and the Dermalab Moisture Module. The ranking of product aggressiveness given by the 3 devices 5 days after patch removal was similar to that given by the clinical assessment of erythema. A high level of correlation was found between the values yielded by the immediate and continuous mode assessments using the Dermalab Moisture Module with the pin probe, while the correlation was weaker with the Nova DPM. This finding may be related to the fact that the Nova DPM is influenced by the accumulation of the transepidermal water loss in the continuous mode assessment while there is no significant occlusion effect of the Dermalab Moisture pin probe that is more representative of the initial level of SC hydration. In conclusion, the Corneometer and the Dermalab Moisture Module respond similarly to changes in the SC content. This finding is different from some previous reports.

Repair Kinetics of the Stratum corneum under Repeated Insults

“…Emollient-based lubrication and moisturization typically make the SC soft, supple and fl exible. In general, bioengineering methods are needed in order to disclose and measure some structural and functional alterations and repair of the SC [4][5][6][7][8][9] . The evidence for a positive effect of skin care products on the epidermal structure and functions can be sought in vivo by a variety of experimental and clinical study designs looking at the SC.…”

Silicon Image Sensor Technology for in vivo Detection of Surfactant-Induced Corneocyte Swelling and Drying

“…Hence, most individuals with sensitive skin find it necessary to select a suitable skin cleanser using a trial-and-error approach [26]. Many in vitro and in vivo predictive methods have, however, been described for rating the potential irritancy of surfactants [5, 6, 7, 8, 26, 27, 28, 29, 30]. Searching for more sensitive methods is one of the goals in this field of research.…”

“…This contrasts with the usual methods for irritation assessment because they are less sensitive at this stage of irritation dynamics. They are better suited to detect the later decrease in skin surface hydration [7]. …”

“…Several instrumental methods can indirectly assess some specific aspects of cutaneous irritation on human SC. In particular, the apparent SC dehydration can be assessed in vivo using devices measuring some electrical properties of skin at different frequencies and at different depths inside the SC [2, 3, 4, 5, 6, 7]. The impaired desquamation can be conveniently measured by squamometry [8, 9, 10].…”

“…One of the earliest events following protein denaturation is perceived as corneocyte swelling [15, 16, 17, 18, 19]. This leads to a paradoxical and transient SC hydration following surfactant challenge in vivo [7, 20]. …”