Comparison of skin calming effects of cosmetic products containing 4-t-butylcyclohexanol or acetyl dipeptide-1 cetyl ester on capsaicin-induced facial stinging in volunteers with sensitive skin.

OBJECTIVE: To assess and compare the skin calming effect of cosmetic products containing 4-t-butylcyclohexanol (Eucerin(®) UltraSensitive Soothing Care Dry Skin) or acetyl dipeptide-1 cetyl ester (La Roche-Posay Toleriane(®) Ultra Intense Soothing Care) on subjective symptoms of skin sensitivity, a controlled, single-blind, randomized split-face capsaicin-induced stinging test was conducted. METHODS: Thirty-one female test subjects, ranging from 19 to 65 years of age, with self-perceived sensitive to very sensitive skin were enrolled. After a 3-day preconditioning period with no application of facial products and positive reaction to stimulation with a 40 ppm capsaicin cream, the test products were randomly applied to either the right or left nasolabial fold. Burning severity was assessed immediately after capsaicin application, and 1, 2, 5, 10 and 15 min after application of the test products. RESULTS: All 31 subjects reported a stinging/burning sensation on both nasolabial folds after application of capsaicin. Treatment with the 4-t-butylcyclohexanol containing product resulted in significant lower values for burning/stinging after one, and two minutes post-application in comparison to the values for the acetyl dipeptide-1 cetyl ester containing product. No significant difference was determined between the two test products for the point in time with most intense burning sensation, the severity of burning and the duration of burning after capsaicin application and subsequent application of the test products. CONCLUSION: Both products alleviated capsaicin-induced burning during the first 15 min after application. A faster and more pronounced soothing effect in vivo was demonstrated for the 4-t-butylcyclohexanol containing cosmetic product in comparison to the acetyl dipeptide-1 cetyl ester containing cosmetic formulation.

Effective treatment for sensitive skin: 4-t-butylcyclohexanol and licochalcone A.

BACKGROUND: More than 50% of adults report to suffer from sensitive skin. This common condition is characterized by subjective sensations such as prickling, burning, skin tightness or pruritus, and is often accompanied by objective symptoms like inflammation and erythema. OBJECTIVE: The objective of this study was to develop an active ingredient concept for the treatment of sensitive skin. We tested compounds regarding their potential to (i) decrease the release of proinflammatory mediators, which among others induce erythema and (ii) counteract the hyperresponsiveness of nerve fibres and, thus, exert effects on cutaneous neurosensory dysfunction. METHODS: 4-t-butylcyclohexanol, licochalcone A and acetyl dipeptide-1 cetyl ester were analysed in vitro regarding their potential to (i) decrease the release of PGE2 and activation of NFκB and to (ii) inhibit TRPV1 activation or the release of neuronal CGRP. To assess subjective and objective symptoms of skin sensitivity in vivo, two controlled, single-blind, randomized studies were conducted with 4-t-butylcyclohexanol and the combination with licochalcone A. RESULTS: In vitro, 4-t-butylcyclohexanol significantly reduced TRPV1 activation, while acetyl dipeptide-1 cetyl ester had no effect on receptor activation. Licochalcone A significantly decreased NFκB signalling and PGE2 secretion, at lower concentrations than acetyl dipeptide-1 cetyl ester. A formulation containing 4-t-butylcyclohexanol showed a significant immediate anti-stinging/anti-burning effect in vivo, and a cream base containing a combination of 4-t-butylcyclohexanol and a licochalcone A-rich licorice extract reduced shaving-induced erythema. CONCLUSION: In vitro and in vivo data indicate that the combination of the TRPV1 antagonist 4-t-butylcyclohexanol and the potent anti-inflammatory licochalcone A provide an effective active ingredient concept for the treatment of sensitive skin, as the topical application resulted in an immediate relief from symptoms such as erythema and stinging.