Sodium Lauryl Sulfate Penetration Research Articles

Percutaneous penetration of sodium lauryl sulphate is increased in uninvolved skin of patients with atopic dermatitis compared with control subjects

Involved regions of the skin in patients with atopic dermatitis (AD) have been shown to have higher transepidermal water loss (TEWL), indicating a compromised skin barrier. Whether uninvolved skin also has diminished barrier characteristics is controversial. To study the penetration of sodium lauryl sulphate (SLS) into uninvolved skin of patients with AD compared with the skin of control subjects. Percutaneous penetration was assessed using the tape stripping technique on the stratum corneum (SC). Twenty patients with AD and 20 healthy subjects were exposed to 1% SLS for 4 h on the mid-volar forearm. After the end of exposure the SC was removed by adhesive tape. The amount of SLS was determined in each consecutive strip. Fick's second law of diffusion was used to deduce the diffusivity and the partition coefficient of SLS between water and the SC. The SC thickness was similar in both groups; however, the TEWL was higher in patients with AD compared with that of the control group (mean+/-SD 8.4+/-4.3 and 6.3+/-2.0 g m-2 h-1, respectively). There was a correlation between SC thickness and TEWL in control subjects but no correlation was found in patients with AD. The diffusivity of SLS through uninvolved AD skin was higher compared with normal skin (mean+/-SD 12.7+/-5.8x10(-9) and 6.2+/-3.0x10(-9) cm-2 h-1, respectively), while the partition coefficient between SC and water was lower (mean+/-SD 137+/-64 and 196+/-107, respectively). The results show a different penetration profile of SLS into the SC of patients with AD compared with control subjects. This indicates that even noninvolved skin in patients with AD has altered barrier characteristics, emphasizing the importance of skin protection and prevention of skin contact with chemicals.

Variation in barrier impairment and inflammation of human skin as determined by sodium lauryl sulphate penetration rate

Skin irritability after a brief exposure to the model skin irritant, sodium lauryl sulphate (SLS), is known to vary considerably between individuals. A difference in the skin barrier to SLS may contribute to this variation. To date, no human in vivo data have been available on SLS penetration into the skin. We studied whether the SLS penetration rate into the stratum corneum (SC) is related to impairment of the water barrier function and inflammation of the skin. The penetration of SLS into the SC was assessed using a noninvasive tape-stripping procedure in 20 volunteers after a 4-h exposure to 1% SLS. Additionally, the effect of a 24-h exposure to 1% SLS on the skin water barrier function was assessed by measuring the transepidermal water loss (TEWL). The accompanying inflammation was quantified by measuring erythema. The mean +/- SD diffusivity of SLS (D) and the SLS permeability coefficient (Kp) were 1.4 +/- 0.6 x 10(-8) cm2 h(-1) and 1.5 +/- 0.7 x 10(-3) cm h(-1), respectively. A multiple regression analysis showed that the baseline TEWL, SC thickness and SLS penetration parameters K (SC/water partition coefficient) and D clearly influenced the increase in TEWL after the 24-h irritation test (explained variance: r2 = 0.80). Change in erythema was mainly influenced by SC thickness. We found that variation in the barrier impairment and inflammation of human skin depends on the SLS penetration rate, which was mainly determined by SC thickness.

The nature of ultrasound–SLS synergism during enhanced transdermal transport

Ultrasound and sodium lauryl sulfate (SLS) exhibit a synergistic effect on transdermal transport, when applied simultaneously on the skin. The synergistic mechanism is not fully understood. Previous studies have shown that application of ultrasound simultaneously with SLS, results in enhanced mass transfer and improved penetration and dispersion of the surfactant. In this study we demonstrate that simultaneous application of ultrasound and SLS leads to modification of the pH profile of the stratum corneum. This pH modification within the stratum corneum's microenvironment, can affect both the structure of the lipid layers and the activity of SLS as a chemical enhancer due to its improved lipophilic solubility. The altered pH profile that results in improved SLS lipophilic solubility, together with improved SLS penetration and dispersion, can explain the synergistic enhancing effect of ultrasound and SLS on transdermal transport.

Differences of skin irritation between Japanese and European women.

After using cosmetics, Japanese women frequently complain about sensitive, stinging skin. We wondered whether Japanese women's skin is more sensitive than that of Caucasians. To examine possible racial differences of skin irritation and subjective sensations. We performed patch testing on the forearm with sodium lauryl sulphate (SLS) at different concentrations (0.25%, 0.5%) and 24-h exposure time. Skin reaction was evaluated by measurement of transepidermal water loss (TEWL), stratum corneum hydration, sebum secretion, laser Doppler flowmetry (LD), content of melanin and erythema. During a stinging test with 10% lactic acid (applied to one side of the cheeks) the subjects were asked to describe the present intensity of any sensation. We used a Chromameter to measure skin colour before and after application of lactic acid. This study was performed in Marburg, Germany, with healthy Japanese and German women living in Marburg. After SLS testing, we found no significant differences of the barrier function in the stratum corneum, but we found significant subjective sensory differences between Japanese and German women. Japanese women may complain about stronger sensations reflecting a different cultural behaviour rather than measurable differences in skin physiology; however, a faster penetration of SLS in Japanese cannot be excluded.

Percutaneous penetration of sodium lauryl sulphate and butoxyethanol as measured by microdialysis in vivo

Percutaneous penetration of sodium lauryl sulphate and butoxyethanol as measured by microdialysis in vivo

Radial spread of sodium lauryl sulfate after topical application.

Since topical application of sodium lauryl sulfate (SLS) has been reported to elevate transepidermal water loss and decrease skin capacitance in areas immediately adjacent to the applied site, studies were carried out to quantify the extent of radial spread of SLS below a topically exposed site in a hairless rat model. Fixed sites were demarcated and the levels of SLS measured around the applied site in the epidermis, dermis and the subcutaneous tissues. Underlying deep tissue penetration and radial spread of SLS in the presence and absence of a vasoconstrictor, phenylephrine, was also quantified. In a typical 24 hour study, the radial spread of SLS was observed to a distance of approximately 0.75 cm from the applied site. The use of phenylephrine (1:20000), did not significantly enhance either the local underlying tissue (apart from underlying epidermis) concentration or radial spread of SLS relative to no vasoconstrictor treatment. Given that SLS impairs barrier function of the skin, its radial spread could be explained by a passive diffusion process. Vasoconstrictor did not remarkably alter SLS penetration and radial spread possibly due to the competing effects of vasodilation (caused by SLS) and vasoconstriction (caused by phenylephrine).

Sodium lauryl sulphate penetration in an in vitro model using human skin

Because of their ability to impair the skin barrier function, detergents constitute a major risk factor for the development of irritant contact dermatitis. Sodium lauryl sulphate (SLS) is a commonly used detergent for experimental studies within the area of irritant contact dermatitis. In the present study, penetration of S35-labelled SLS was studied in an in vitro model using human cadaver skin. The investigations showed that SLS is capable of permeating the skin barrier when applied under occlusion. SLS could be detected in the dermis and the amount of SLS found here was shown to depend on the dose of SLS applied on the skin. Penetration of SLS continued after removal of the SLS applied as a patch test on the skin surface. Considerable inter-individual variation in the penetration of SLS was demonstrated between different donors.

Irritant Patch Testing: Penetration of Sodium Lauryl Sulphate into Human Skin

To clarify the sources of variation in irritant patch testing, variability in delivery of the test substance from the patch test system was studied. An in vitro model was used to study the penetration of sodium lauryl sulphate (SLS) from a patch test system into the skin. Different formulations of SLS applied to the skin for 24 h were studied (aqueous solution and gels), but irrespective of the vehicle used permeation of SLS into the recipient phase was poor. Results were compared to in vivo patch testing in 12 subjects. Approximately 70% of the applied SLS in aqueous solution was released from the patch test system. Release from gels was poorer. High concordance between the in vivo and the in vitro model was found. No correlation was found between the amount of SLS left in the filter disc and the strength of the clinical reaction in vivo.