Effect of commercial cleansers on skin barrier permeability.

BACKGROUND: Addition of hydrophobically modified polymers (HMPs) to cleansers can reduce the negative impact of surfactant-based cleansers. In this study, the effects of a cleanser containing HMPs, a gentle lotion cleanser (GLC), water, and 1% sodium lauryl sulfate (SLS) on barrier permeability, were evaluated in vitro in pig skin and in vivo in humans. METHODS: Skin stratum corneum (SC) barrier function was quantitated by imaging fluorescence intensity of the sulforhodamine B (SRB) in a pig skin model system using 2-photon and conventional fluorescence confocal microscopy. Solutions containing SRB were applied to pig skin in Franz diffusion cells over a period of 2 h. Penetration of SRB into the skin was monitored from 2 µm to 38 µm. In vivo surfactant/cleanser penetration in human skin was determined using tape stripping. RESULTS: After 2 h, water, 1% SLS, and GLC, significantly increased SRB intensity at all depths measured. SRB intensity was reduced in the HMP-cleanser group compared with other groups at each depth. In vivo, the presence of HMP reduced SLS penetration as measured by tape stripping. CONCLUSION: The cleanser containing HMP prevented changes in SC permeability and surfactant penetration, indicating a protective effect on skin barrier properties.

In vitro human nail penetration and kinetics of panthenol.

The in vitro absorption of panthenol into and through the human nail was examined in this study. Panthenol, the alcohol form of pantothenic acid (vitamin B5), is believed to act as a humectant and improve the flexibility and strength of nails. A liquid nail treatment formulated with panthenol (2%) was compared to a solution of panthenol (2%) in water. Fingernail specimens were dosed daily for 7 days with either the nail treatment (non-lacquer film forming) formulation or aqueous solution with sampling performed every 24 h. Panthenol concentrations were determined in the dorsal surface, interior (by drilling and removal) and in the supporting bed under the human nail. Panthenol levels in the dorsal nail (R(2) = 0.87; P < 0.001), nail interior (R(2) = 0.94; P < 0.001) and nail supporting bed (R(2) = 0.79; P < 0.003) showed a significant linear increase with each day of dosing. Significantly more panthenol was delivered into the interior nail and supporting bed by a nail treatment formulation than from an aqueous solution. The film acts not only as a reservoir of panthenol, but also acts to increase the hydration of the nail and the thermodynamic activity of panthenol as well, thereby enhancing diffusion.

Fluorescence excitation spectroscopy for the measurement of epidermal proliferation.

Fluorescence excitation spectroscopy was used to assess cellular turnover in human skin by monitoring changes of endogenous fluorescence. Epidermal proliferation was induced with alpha-hydroxy acids. Commercially available glycolic acid creams (8 and 4% wt/wt concentration) and a vehicle cream (placebo) were applied in a randomized double blinded fashion on subjects' forearms, twice daily for 21 days. Excitation spectra were recorded (excitation 250-360 nm, emission 380 nm) at days 0, 1, 3, 7, 10, 11, 14, 17 and 21. The 295 nm excitation band (assigned to tryptophan moieties) was used in this study as a marker for cellular proliferation. To further reduce the day-to-day variability of the skin fluorescence the intensity of the 295 nm band was normalized to the 334 nm band (assigned to collagen crosslinks). The fluorescence emission intensity from placebo-treated skin remained practically unchanged over the period of the measurements while the fluorescence intensity measured from the glycolic acid-treated skin increased monotonically with treatment. The rate of increase of the excitation intensity with treatment was found to be dose dependent. The epidermal 295 nm band may be used as a quantitative marker to monitor the rate of proliferation of epidermal keratinocytes noninvasively.

Comparative anti-dandruff efficacy between a tar and a non-tar shampoo.

A randomized double-blind clinical study was conducted on two groups of 30 volunteers using either a non-tar shampoo (2% salicylic acid, 0.75% piroctone olamine and 0.5% elubiol) or a 0.5% coal tar shampoo. Subjects were diagnosed as having moderate to marked dandruff. The study consisted of a 3-week washout, followed by a 4-week treatment and a 4-week posttreatment regression phase. The clinical evaluations and subject self-assessments showed that the non-tar shampoo was as effective as the tar shampoo. Both received high approval ratings (> or =70%). Biometrological methods proved to be more sensitive than clinical evaluations to assess the efficacy of the shampoos. The non-tar shampoo yielded a significantly better reduction of Malassezia spp. counts (p<0.02) during the treatment phase and reduced the spontaneous increase in squamometry values (p< 0.01) during the posttreatment phase. It is concluded that a formulation associating salicylic acid, piroctone olamine and elubiol exhibited increased beneficial effects compared to the coal tar shampoo.

Retinoid therapy: compatible skin care.

Topically applied tretinoin (a retinoid) has been used for over 25 years to treat acne and disorders of keratinization. Now, tretinoin emollient cream, 0.05% (Renova(R)), may be prescribed for the treatment of photodamaged and chronologically aged skin, in conjunction with appropriate skin care and sun protection routines. Mild to moderate cutaneous side effects to topical tretinoin, such as xerosis, peeling, erythema and subjective irritation, are experienced by a majority of patients undergoing retinoid therapy. Results of clinical compatibility testing show that concomitant use of effective moisturizers, mild cleansers and daily sunscreens greatly enhance skin tolerance and patient comfort. A frequently prescribed regimen for topical treatment of photodamaged skin includes a combination of tretinoin and glycolic acid. While many clinicians report the use of both these agents for the management of their patients, little information exists in the literature about their compatibility in concomitant use. The results of a double-blind clinical study demonstrate that daytime usage of one of two 8% glycolic acid lotions in addition to nightly applications of Renova was well tolerated as part of a comprehensive skin care and sun protection program.

IL-1alpha and IL-1ra secretion from epidermal equivalents and the prediction of the irritation potential of mild soap and surfactant-based consumer products.

We have previously evaluated the measurement of viability and cytokine release from skin equivalents, for predicting the skin irritation potential of topically applied surfactants and demonstrated that IL-1alpha and interleukin-1 receptor antagonist (IL-1ra) release from epidermal skin equivalents correlates with skin irritation potential. In this study, the utility of the model was confirmed by the evaluation of cleansing bars and cleansing lotions that exhibited varying degrees of irritation potential as determined by exaggerated arm wash human clinical studies. Epidermal equivalents were exposed to increasing concentrations of the cleansing bars and cleansing liquids and viability and release of IL-1alpha and IL-1ra were measured. Loss of viability was used to identify the stronger irritants of the products tested. A linear correlation was demonstrated between IL-1alpha and IL-1ra secretion and human irritation data, demonstrating that the model can correctly predict the irritation potential of soap and surfactant products. These results show that this in vitro model is useful for rank ordering the irritation potential of mild consumer products and for demonstrating enhanced mildness in products with minor differences.