Increased stratum corneum turnover induced by subclinical irritant dermatitis

Multifaceted Design and Emerging Applications of Tissue Adhesives

Tissue adhesives can form appreciable adhesion with tissues and have found clinical use in a variety of medical settings such as wound closure, surgical sealants, regenerative medicine, and device attachment. The advantages of tissue adhesives include ease of implementation, rapid application, mitigation of tissue damage, and compatibility with minimally invasive procedures. The field of tissue adhesives is rapidly evolving, leading to tissue adhesives with superior mechanical properties and advanced functionality. Such adhesives enable new applications ranging from mobile health to cancer treatment. To provide guidelines for the rational design of tissue adhesives, here, existing strategies for tissue adhesives are synthesized into a multifaceted design, which comprises three design elements: the tissue, the adhesive surface, and the adhesive matrix. The mechanical, chemical, and biological considerations associated with each design element are reviewed. Throughout the report, the limitations of existing tissue adhesives and immediate opportunities for improvement are discussed. The recent progress of tissue adhesives in topical and implantable applications is highlighted, and then future directions toward next-generation tissue adhesives are outlined. The development of tissue adhesives will fuse disciplines and make broad impacts in engineering and medicine.

Prospective observational study to assess hand skin condition after application of alcohol-based hand rub solutions

BACKGROUND

The use of alcohol-based hand rub solutions (ABHRSs) in health care settings has been associated with increased hand hygiene compliance and reduced rates of nosocomial infection. Deterioration in hand skin condition leads to impaired barrier function, changes in skin flora, and increased bacterial shedding. Thus, poor skin condition can increase the risk of infection. This study evaluated the hand skin condition and dermal tolerance among health care workers (HCWs) after ABHRS application.

METHODS

The study group comprised 231 HCWs (34% nurses, 22% nurse assistants, and 15% hospital cleaners). The mean participant age was 40 years. Stratum corneum hydration and superficial sebum content and surface pH of the skin were measured on the back and palm of each participant's dominant hand before and after ABHRS use. A self-assessment questionnaire was administered to collect information about the participants, their skin problems, and their perception of the ABHRS.

RESULTS

The study group was 83% females. Skin hydration at the 2 assessment sites was markedly increased after ABHRS use (P < .0001). The mean pH value did not change significantly on the back of the hand, but did change significantly on the palm (P = .012). The superficial sebum content decreased significantly on the palm (P < .0001), but not on the back of the hand. HCWs reported excellent or good skin tolerance of ABHRS in 73% of cases.

CONCLUSION

ABHRSs are well tolerated and do not dry the skin. pH and superficial sebum values decreased slightly, but these decreases did not affect skin barrier function. Values remained within the physiological range.

Three-dimensional analyses of individual corneocytes with atomic force microscope: morphological changes related to age, location and to the pathologic skin conditions

BACKGROUND/AIMS

The past morphological studies on individual corneocytes have so far mainly focused on their two-dimensional characteristics, particularly on their projected area, which have been widely employed for the estimation of the turnover rate of the stratum corneum because of the practical use. However, sometimes a poor correlation has been reported between the projected area of corneocytes and actually measured turnover time of the stratum corneum. The objective of the present study is to perform detailed three-dimensional measurements of individual corneocytes with atomic force microscope. Through analyses of the obtained data, we tried to find morphological parameters that reflect more closely the differentiation process of the corneocytes in the stratum corneum than the frequently used two-dimensional projected area.

METHODS

We measured such morphological parameters as the volume, average thickness and real surface area of individual corneocytes isolated from the covered skin (the flexor surface of the upper arm) and the exposed skin (the cheek) of 12 healthy individuals belonging to different age brackets, in addition to their projected area. We further introduced a new parameter, a flatness index calculated by dividing the projected area of corneocytes by their thickness. Similarly, we measured corneocytes obtained from eight patients with atopic dermatitis (AD) and psoriatic patients.

RESULTS

Obtained results showed that most of these morphological parameters varied greatly depending upon the anatomical location and age of the subjects. Needless to say great differences were found between healthy skin and lesional skin of atopic dermatitis or psoriasis. However, the volume and thickness of corneocytes collected from the same location of normal skin of the covered area (upper arm) with tape-strippings were noted to decrease as they differentiated in the stratum corneum, showing an increase in their surface area and projected area with a resultant increase in the flatness index. Moreover, the corneocyte collected from the lesional skin of AD or psoriasis showed a great decrease in flatness index, reflecting their poor differentiation in the stratum corneum due to its enhanced turnover rate. Most of all, we found a poor correlation between the projected area and the various three-dimensional morphologic parameters of the corneocytes, indicating that the projected area does not reflect the volume or thickness of corneocytes that are also greatly influenced by the differentiation process of corneocytes in the stratum corneum.

CONCLUSIONS

To estimate the differentiation speed of the corneocytes, we suggest using their flatness index rather than the two-dimensional cell surface area, because the former is a concept that takes into account the three-dimensional characteristics of corneocytes.

Skin benefits from continuous topical administration of a zinc oxide/petrolatum formulation by a novel disposable diaper

BACKGROUND

Diaper dermatitis is a common childhood affliction. Aiming to help reduce the prevalence of this problem, we have advanced in our development of a novel diaper that delivers dermatological formulations to help protect the skin from over-hydration and irritation.

OBJECTIVE

To determine the clinical benefits of a novel disposable diaper designed to deliver a zinc oxide and petrolatum-based formulation continuously to the skin during use.

METHODS

All studies were independent, blinded, randomized clinical trials. Study A was conducted to confirm transfer of the zinc oxide/petrolatum (ZnO/Pet) formulation from the diaper to the child's skin during use. Children wore a single diaper for 3 h or multiple diapers for 24 h. After the use period, stratum corneum samples were taken from each child and analysed for ZnO/Pet. Study B evaluated the prevention of skin irritation and barrier damage from a standard skin irritant (SLS) in an adult arm model. Study C evaluated skin erythema and diaper rash in 268 infants over a 4-week usage period. One half of the infants used the ZnO/Pet diaper, while the other half used a control diaper that was identical except for the absence of the ZnO/Pet formulation.

RESULTS

The ointment formulation and ZnO transferred effectively from the diaper to the child's skin during product use. Transfer of ZnO increased from 4.2 microg/cm2 at 3 h to > 8 microg/cm2 at 24 h. Exposure to the formulations directly on adult skin prior to an irritant challenge was associated with up to a 3.5 reduction in skin barrier damage and skin erythema. Greatest reductions were seen for the ZnO containing formulations. Wearing of the formulation treated diaper was also associated with a significant reduction in skin erythema and diaper rash compared to the control product.

CONCLUSIONS

The results demonstrated the clinical benefits associated with continuous topical administration of a zinc oxide/petrolatum-based formulation by this novel diaper.

Subclinical, non-erythematous irritation with an open assay model (washing): sodium lauryl sulfate (SLS) versus sodium laureth sulfate (SLES)

Compared to exaggerated hand washing procedures, an open non-exaggerated assay better approximates consumer surfactant use. Our goal was to observe skin surface modifications induced by an open test with regard to discriminating between surfactant solutions. This human in vivo assay provided information about the effect of only three washes at the laboratory and a week of at-home use. Dorsal hand and volar forearm were compared. The results demonstrated that this clinical model permits exploration of subclinical surfactant-induced irritation. Both the volar forearm and the dorsal hand are capable of discriminating between the effects of sodium lauryl sulfate (SLS) and sodium laureth sulfate (SLES). Squamometry proved to be a sensitive assessment technique for detecting surfactant-induced subclinical skin surface alterations and for differentiating surfactant effects in this open application assay, in as few as three washes.

Guidelines on sodium lauryl sulfate (SLS) exposure tests. A report from the Standardization Group of the European Society of Contact Dermatitis

This report reviews the clinical and histopathological reactions caused by sodium lauryl sulfate (SLS), and the non-invasive methods that can characterize these reactions. Furthermore, SLS exposure techniques and factors that may influence the outcome of these exposures are discussed. Finally, guidelines are introduced for each exposure technique in order to have a uniform approach to SLS testing in man. Since different study aims warrant different testing conditions, we have proposed 2 categories, namely susceptibility testing and provocative testing, tailored to the aim with which the study is performed.

The influence of hard water (calcium) and surfactants on irritant contact dermatitis

Although the induction of irritant contact dermatitis has been extensively studied for surfactants, the role of the environmental factor water hardness (i.e., calcium content) on the induction process has not received attention. Our objective was to investigate differences in surfactant-induced irritant skin reactions from cumulative exposure to 3 different personal cleansing agents and determine whether the irritation potential can be affected by the hardness of the water. 2 commonly used exaggerated washing procedures were variously employed to evaluate representative sodium soap, triethanolamine-soap, or synthetic detergent cleansers under conditions where the water hardness varied from 0-grain to 11-grain (gr). Subjects were clinically evaluated for skin dryness, skin redness, and instrumentally for hydration. Soap binding to skin was quantified using Fourier transform infrared reflectance spectroscopy. Using the more mild wash procedure, skin sites treated under conditions of hard, 11 gr water were significantly drier, had more erythema, and were less hydrated than corresponding sites treated with deionized 0 gr water. All 3 surfactant cleanser behaved similarly. We also found the hardness of the rinse water to be the more significant factor versus that of the wash water. Effect of water hardness on soap binding to skin revealed a similar outcome. Under a more exaggerated wash condition the relationship between water hardness and irritation broke down.

Effects of phospholipids on the in vitro percutaneous penetration of prednisolone and analysis of mechanism by using attenuated total reflectance-Fourier transform infrared spectroscopy

We investigated the effects of 10 phospholipids on the in vitro percutaneous penetration of prednisolone (PR) through the dorsal skin of guinea pigs. A marked enhancing effect of PR penetration was observed in the presence of phospholipids that have unsaturated acyl chains. A maximum of 68-fold enhancement was observed compared to that of control. On the contrary, phospholipids that have saturated acyl chains did not significantly increase the amount of PR passing to the receptor side. Attenuated total reflectance-Fourier transform infrared spectroscopy was used to monitor the outer several microns of stratum corneum (SC) surface. It was observed that phospholipids that have unsaturated acyl chains induced higher and broader absorbance shifts in the C-H bond stretching region while phospholipids that have saturated acyl chains induced lower and sharper absorbance shifts in the C-H bond stretching region. A significant parallel between the amount of PR penetrated and the lipid-chain fluidity of the SC was found. These results suggest that phospholipids may influence the percutaneous penetration of PR by changing the lipid-chain fluidity of the SC.

Sensitive skin and stratum corneum reactivity to household cleaning products

Products intended for individuals with sensitive skin are being increasingly developed by formulators of household cleaning products. However, there is currently no consensus about the definition and recognition of the biological basis of sensitive skin. We sought to determine the relation between the nature of environmental threat perceived as aggressive by panelists, and the stratum corneum reactivity to household cleaning products as measured by the corneosurfametry test. Results indicate substantial differences in irritancy potential between proprietary products. Corneosurfametry data show significant differences in stratum corneum reactivity between, on the one hand, individuals with either non-sensitive skin or skin sensitive to climate/fabrics, and, on the other hand, individuals with detergent-sensitive skin. It is concluded that sensitive skin is not one single condition. Sound information in rating detergent-sensitive skin may be gained by corneosurfametry.

Baseline transepidermal water loss in patients with acute and healed irritant contact dermatitis

To examine the skin barrier function of patients with acute and healed irritant contact dermatitis (n = 80) baseline transepidermal water loss (TEWL) was quantitatively measured using an evaporimeter. Healthy subjects served as controls (n = 40). Test areas were the forearm and the thigh. A significant increase in TEWL was observed in the patients with acute and with healed irritant contact dermatitis (ICD) as compared to healthy volunteers (P < or = 0.01). TEWL values in both test areas were comparable and markedly correlated (P < or = 0.01) with each other in every group. Thus, it is possible that basal TEWL depends more on the intrinsic skin barrier function of the subjects rather than the 2 anatomical regions examined. TEWL at the forearm with acute ICD was significantly higher (P < or = 0.01) than that of the group with healed ICD, but not for TEWL at the thigh suggesting that ICD may aggravate the barrier function of the adjacent uninvolved skin. It is assumed, that increased basal TEWL in patients with ICD may reflect a constitutional deviation of epidermal barrier function. This event seems to be comparable with the well-known symptom of atopic individuals. Using a detailed atopic scoring system in such a study may clarify the question of whether a proportion of patients with hand ICD may indeed be atopic individuals.

The sodium lauryl sulfate model: an overview

Irritant contact dermatitis is a complex entity with several clinical forms (acute, cumulative, etc.) and multiple mechanisms. Sodium lauryl sulfate (SLS), the most widely utilized model for studying acute and cumulative irritation, has proved highly practical and informative for such studies. This article summarizes several decades of investigation, and provides details of dosing, application method (closed versus open), and biologic endpoints (visual grading, transepidermal water loss) that may be utilized in future studies.

Damage to the skin by repetitive washing

Damage to the skin following the repeated use of 2 different wash solutions was investigated. Stratum corneum capacitative resistance, stratum corneum lipids, transepidermal water loss, skin surface pH, laser Doppler flow and skin reddening were determined. All skin function parameters already showed a marked change after a single wash (e.g., the median of TEWL values increased by more than 0.5 g/m2 h). Repetitive washing for 1 week led to a further deterioration of TEWL and corneometry values (e.g., TEWL increased for about 2.9 g/m2 h after repetitive washing with sodium lauryl sulfate). The rate of skin function regeneration after repetitive washing was unaltered compared to regeneration after a single wash. The surfactants used showed quantitatively differing effects on corneometry, TEWL and laser Doppler flow (e.g., after repetitive washing with Geliderm, the median of TEWL values increased only up to 1.55 g/m2 h). However, damage arising from repetitive washing could not be completely prevented by the selection of a mild surfactant. Skin function regeneration showed no difference with the 2 surfactants used.

Surfactant-induced skin irritation and skin repair: evaluation of a cumulative human irritation model by noninvasive techniques

BACKGROUND

Although surfactant-induced acute irritant dermatitis has been extensively studied, our understanding about the induction and repair of the clinically more relevant chronic form is limited.

OBJECTIVE

Our purpose was to investigate qualitative and quantitative differences in surfactant-induced irritant skin reactions from cumulative exposure to structurally unrelated surfactants and to compare the maximal irritant responses from this model with corresponding reactions noted in a previously reported acute irritation model.

METHODS

Sodium lauryl sulfate (SLS), dodecyl trimethyl ammonium bromide (DTAB), and potassium soap were the model irritants. Surfactant solutions (7.5%) were applied for 20 minutes daily (for 8 consecutive days excluding the weekend) to the volar aspect of the forearm of 11 volunteers. Irritant reactions were repeatedly assessed until complete healing was indicated by visual assessment and by measurements of transepidermal water loss (TEWL), erythema (skin color reflectance), and stratum corneum hydration (electrical capacitance). Maximum irritant responses were compared with corresponding reactions from an acute irritation model.

RESULTS

TEWL was increased by SLS and DTAB to the same extent, but erythema was significantly higher in DTAB-treated skin. Skin dryness, as demonstrated by decreased capacitance values and increased scores for scaling and fissuring, was significantly more pronounced than in an acute irritation model for SLS and DTAB, although no difference was detected between the two surfactants. Potassium soap led to a slight increase in TEWL, whereas the remaining features were not significantly changed.

CONCLUSION

This chronic irritation model appears to represent the clinical situation of irritant contact dermatitis with pronounced skin dryness more closely than the acute irritation model. The present study confirms that an extended time is needed for complete healing of irritant skin reactions. We also demonstrated that the evaluation of the irritation potential of diverse surfactants depended significantly on the feature evaluated (erythema vs electrical capacitance and TEWL), on the mode of application (acute vs cumulative), and, in the cumulative model, on the point of observation.

The modulation of skin irritation

Irritant contact dermatitis (ICD) is a multifactorial disease, the onset and modulation of which depend on both endogenous and exogenous factors. Among the former, age, race, site, sex and history of dermatitis may all be important. Such variables can now readily be quantified by objective noninvasive techniques, such as measurement of transepidermal water loss (TEWL). Moreover, effects of irritants on the epidermis are related to the particular chemical properties of each molecule, contributing further to clinical heterogeneity. Release of cytokines and mediators may be initiated by a number of cells, including living keratinocytes and those of the stratum corneum, thus modulating inflammation and repair. Furthermore, differences in mechanisms of inflammation between acute and chronic ICD may exist, the former being characterized predominantly by inflammation, the latter by hyperproliferation and transient hyperkeratosis. These findings may explain the complexity and difficulty of investigating ICD. Better understanding and quantification of these mechanisms may lead to identification of high-risk individuals and more effective prevention and treatment.

Organization of stratum corneum lipids in relation to permeability: influence of sodium lauryl sulfate and preheating

The role of the structural organization of intercorneocyte lipids in the barrier function of human stratum corneum was evaluated by treatment with heat and sodium lauryl sulfate. Measurement of transepidermal water loss in treated samples was used to quantify variations in stratum corneum permeability. Thermodynamic transition of lamellar lipids and their degree of organization were evaluated by differential scanning calorimetry and small-angle X-ray diffraction, respectively. Progressively preheating stratum corneum samples from 75 degrees C to 90 degrees C increased stratum corneum permeability to water vapor, while the fusion temperature of lamellar lipids and the intensity of the X-ray diffraction peaks of the polar lipids decreased. Sodium lauryl sulfate induced similar variations of these three parameters. These results support the hypothesis that, in addition to the chemical nature of intercorneocyte lipids, their structural arrangement and thermodynamic properties play an important role in the barrier function of the stratum corneum to water vapor.

Surfactant-induced skin irritation and skin repair. Evaluation of the acute human irritation model by noninvasive techniques

BACKGROUND

Although the induction of irritant dermatitis by surfactants has been extensively studied in recent years, our understanding of the repair phase of irritant dermatitis is limited.

OBJECTIVE

We investigated qualitative and quantitative differences in surfactant-induced irritant skin reactions from short-term exposure to three structurally different surfactants.

METHODS

Sodium lauryl sulfate (SLS), dodecyl trimethyl ammonium bromide (DTAB), and potassium soap were the model irritants. Surfactant solutions (0.5%) were applied for 24 hours to the volar aspect of the forearm of 11 volunteers. Irritant reactions were assessed until complete healing was indicated by visual assessment and by various aspects of skin function, that is, transepidermal water loss (TEWL), erythema (skin color reflectance), and stratum that is, transepidermal water loss (TEWL), erythema (skin color reflectance), and stratum corneum hydration (electrical capacitance).

RESULTS

SLS and DTAB induced similar degrees of erythema, whereas SLS induced significantly higher TEWL increase. Although both erythema and TEWL were highest 1 hour after exposure to surfactants, skin dryness was a symptom with delayed onset, justifying the long observation period in this study. Minimum hydration values were measured as late as 7 days after surfactant exposure. Dryness was significantly more pronounced in areas exposed to SLS than in areas exposed to DTAB. Complete repair of the irritant reaction induced by either SLS or DTAB was achieved 17 days after surfactant exposure. Stratum corneum hydration was the last feature to return to baseline values. Potassium soap did not significantly influence any skin function.

CONCLUSION

We emphasize the importance of extended periods needed before a patient with irritant contact dermatitis can be reexposed to irritant substances. The evaluation of the irritation potential of diverse surfactants depended significantly on the feature (erythema vs hydration and TEWL) measured.

Study of cumulative irritant contact dermatitis in man utilizing open application on subclinically irritated skin

We evaluated the effect of subclinical irritation on the cutaneous reaction elicited by cumulative short-term (30-min) application of sodium lauryl sulphate (SLS), by measuring transepidermal water loss (TEWL) and assigning visual scores. 11 healthy adult volunteers, free of skin disease and with no history of atopic dermatitis, were treated with SLS solution (1%, 2%, 5%, 7.5%). On a Monday, we applied 80 microliters of 1% SLS solution and deionized water (control), using large aluminium chambers with filter paper discs, for 30 min. We measured TEWL values 2 x before and after patch application of control and 1% SLS solution, and then applied 80 microliters of SLS solution (2%, 5%, 7.5%) using filter paper discs. From Tuesday to Friday, we applied 80 microliters of each solution, using filter paper discs, and measured TEWL before and after open application of test solutions. Compared with each corresponding group, TEWL values of SLS patch groups (S-2.0, S-5.0, S-7.5) were higher than those of water patch groups (W-2.0, W-5.0, W-7.5), respectively. TEWL values of each groups increased stepwise and the final (hour 97) TEWL values were higher than those of baseline (hour 0) TEWL. The mean visual scores of the vehicle control were lower than those of other test groups, but there were no statistically significant differences in visual scores between each test group. These findings suggested that impaired skin barrier function, elicited by subclinical irritation from short-duration contact with some irritants, might augment the cumulative irritant contact dermatitis caused by repeated open exposure to other surfactants.(ABSTRACT TRUNCATED AT 250 WORDS)

Dansyl chloride labelling of stratum corneum: its rapid extraction from skin can predict skin irritation due to surfactants and cleansing products

The irritation potential of surfactants and body cleansing products was determined by evaluating the removal of dansyl chloride from the skin. Dilute solutions (2% active ingredient, w/v) of surfactants and soap extract fluorescence from the skin within 30 min. This is probably a physicochemical effect as it is too rapid to be due to a modification of epidermal cell turnover rate. Such an extraction of the fluorescent dye occurs without any clinical sign of irritation. However, it may represent an early phase of the skin irritation process, because it is related to the ranking of irritant products as determined by other assessment methods.

Electrical impedance index in human skin: measurements after occlusion, in 5 anatomical regions and in mild irritant contact dermatitis

The electrical impedance in 23 healthy volunteers at 2-6 different skin sites was measured with a new impedance device, which makes possible non-invasive local measurements to a controlled depth. In 11 subjects, the test sites were occluded for 24 h using empty Finn Chambers and chambers with water, physiological saline, a paper disc or 0.002% sodium lauryl sulfate (SLS). In the normal skin of 10 subjects, the electrical impedance was measured from 5 different body areas for 5 consecutive days. In 3 subjects, daily measurements for 1 month were done, both from normal skin and from skin following the application of 2% SLS. The results show that the irritation index based on electrical skin impedance gives little day-to-day variation at one and the same test site, in comparison to the variations between different test sites on the same subject and the interindividual variations observed. Significant differences in impedance values between different anatomical regions of normal skin were found. Occlusion does not affect readings taken 24 h or later after removal, but increases variance for readings taken 1 h after removal. Effects on the skin of mild irritation and its recovery phase are easily monitored with the new device. Technology based on electrical impedance, in its newly presented form, with the advantages of improved geometrical definition and depth control, can be used as an objective tool to measure skin irritation. For detection of subclinical irritant contact dermatitis, repeated readings taken over several days may be needed.

An arm immersion model of compromised skin (I). Influence on irritation reactions

Patch testing and safety evaluation processes to assess the allergic or irritant potential of substances are usually performed on normal skin. However, the reactivity of compromised skin may be different. Consequently, it is important to have a test procedure which acts as a model for compromised skin and which reproduces on the target sites the cumulative insult which results from repeated exposure, working temperatures, hydration and the action of surfactants. The procedure described uses regular immersion of forearm skin in an aqueous solution of sodium dodecyl sulphate until an identifiable alteration of skin condition is produced. In this first report, the model system has been described in detail and the influence of skin compromise on the response to 3 irritants, citral, sodium dodecyl sulphate and nonanoic acid, has been assessed. The irritation potential of the materials varied, but each irritant produced a greater degree of reaction on skin compromised to be within the normal clinical range one might expect from housework.

The influence of daily dish-washing with synthetic detergent on human skin

The effects of regular dish-washing on the stratum corneum barrier function, as determined by transepidermal water loss (TEWL), and objective and subjective skin parameters, were investigated in a 'use test' performed by 18 healthy volunteers. Hands were soaked in a 0.05% solution of a commercial dish-washing product (three times/day, for 15 min, at 37 degrees C) over a period of 3 weeks; one hand was unprotected and the other was protected with a commercial rubber glove. TEWL increased in 13/18 volunteers by more than 25% above baseline on exposed hands within the first 2 weeks of the study. Objective skin signs (erythema, scaling, fissures) and subjective symptoms (itching, dryness, smarting) occurred almost exclusively in subjects with substantial TEWL increases and were most prominent 1-2 weeks following peak TEWL values. There was a highly significant correlation between cumulative relative symptom scores and TEWL changes. TEWL increase and symptom scores were not correlated with a history of inhalant allergy and/or elevated serum IgE levels. Three volunteers, who had shown the highest increase of TEWL values and the most intense clinical reactions to the detergent were subjected to a control experiment in which one hand was soaked in warm tap-water following the same experimental protocol. No significant effects on TEWL values or skin symptoms were observed. We conclude that regular exposure to low concentrations of detergents as used for dish-washing is capable of inducing skin lesions in a substantial proportion of individuals.

Effect of sodium lauryl sulfate-induced skin irritation on in vivo percutaneous penetration of four drugs

The influence of sodium lauryl sulfate-induced irritant contact dermatitis on in vivo percutaneous penetration was investigated for four 14C-labeled compounds with diverse physicochemical properties: hydrocortisone (HC), indomethacin (IM), ibuprofen (IB), and acitretin (AC). Hairless guinea pigs were pretreated for 24 h with either 0.5% sodium lauryl sulfate (SLS) to induce irritant contact dermatitis or with water (controls). Twenty-four hours after pretreatment, 450 microliters saturated solutions of HC, IM, IB, or AC in isopropylmyristate were applied to the pretreated skin for 24 h. Systemic absorption was determined by urinary and fecal excretion of compounds. Drug concentrations in stratum corneum (obtained by tape cellophane stripping after decontamination of the application site) and in epidermis/dermis (punch biopsy) were also investigated. Systemic absorption of topically applied drugs (as evaluated by urinary and fecal excretion) in SLS-irritated skin was significantly increased for HC (factor 2.6) followed by IB (1.9 times) and IM (1.6 times) but not increased for AC. However, drug concentrations in the viable epidermis and dermis were 70% lower in SLS-irritated than normal skin for HC, but not different for IB, IM, and AC. Thus, the influence of the state of the skin (irritant dermatitis versus healthy) on percutaneous penetration was different for diverse drugs. The general assumption that percutaneous penetration and drug tissue concentrations were higher in diseased versus healthy skin was not found to be true in our irritated-skin model.

Effect of sodium lauryl sulfate-induced skin irritation on in vitro percutaneous absorption of four drugs

The influence of irritant contact dermatitis on percutaneous penetration was investigated for four 14C-labeled compounds with diverse physicochemical properties: hydrocortisone (HC), indomethacin (IM), ibuprofen (IB), and acitretin (AC). Hairless guinea pigs were pretreated in vivo for 24 h with either 0.5% sodium lauryl sulfate (SLS) to induce irritant contact dermatitis or with water (controls). Twenty-four hours after pretreatment animals were sacrificed. Percutaneous penetration was then measured using in vitro diffusion cells and the removed (pretreated) skin. The following parameters were determined: cumulative amount of compound penetrated, steady state flux, lag time, and permeability coefficient, skin concentration per unit area, and the relative amount of drug remaining in the skin (as a percentage of the cumulative amount of compound penetrated through the skin). SLS pretreatment resulted in moderate irritant dermatitis in all animals and increased in vivo transepidermal water loss 4.5 times. Flux was increased in SLS-pretreated skin as compared with controls for all four compounds, with the greatest enhancement for hydrocortisone (HC) (5.9 times), followed by indomethacin (IM) (4.6 times), ibuprofen (IB) (3.9 times), and acitretin (AC) (3.4 times). Skin concentrations increased to a smaller degree from 1.6 times (IB) and 2.6 times (HC) to 3.4 times (IM). However, AC skin concentrations were not different between the two groups. Thus, percutaneous penetration parameters were equivocally influenced by SLS-induced irritation. Increased skin concentrations were paralleled by even higher increases in flux.