Non-invasive Bioengineering Methods Research Articles

Use of a novel Indentometer to evaluate skin induration in localized scleroderma and psoriasis vulgaris.

Diseased skin in localized scleroderma (LS) and plaque psoriasis (PPs) is characterized by induration that can be evaluated by non-invasive bioengineering methods. In this study, we applied a new measurement device based on indentometry to determine the changes of skin mechanical properties in patients with LS and PPs. A total of 30 sclerodermatous plaques in 12 patients with LS and 46 psoriatic plaques in 19 patients with PPs were measured with Indentometer IDM 800 (Courage + Khazaka, Cologne, Germany). The device measures the penetration depth of the probe indenter (pin) into the skin in mm. We used two probes with pin diameters 3 and 5mm, respectively. The stiffer the skin, the less deep is the displacement by the indenter. The smaller the diameter, the deeper the pin will go into the skin when using the same force. The measurements were made on diseased skin and in adjacent normal skin served as control.In addition, the psoriatic plaques were measured before and after treatment. The sclerodermatous skin and the psoriatic skin showed lower Indentometer values compared to adjacent normal skin as measured with both probes. This suggests that diseased skin is stiffer than healthy skin. The values of psoriatic plaques increased after treatment applied that correlates with the clinical improvement. The Indentometric readings significantly negatively correlated with clinical scores of skin induration. There was a significant correlation between the measurements with probe 3mm and probe 5mm. The non-invasive method used is appropriate for objective and quantitative determination of the degree of skin induration in LS and PPs as well as for assessment of the disease evaluation and treatment efficacy.

Hydration and Barrier Potential of Cosmetic Matrices with Bee Products.

Honey, honey extracts, and bee products belong to traditionally used bioactive molecules in many areas. The aim of the study was primarily to evaluate the effect of cosmetic matrices containing honey and bee products on the skin. The study is complemented by a questionnaire survey on the knowledge and awareness of the effects and potential uses of bee products. The effect of bee molecules at various concentrations was observed by applying 12 formulations to the skin of the volar side of the forearm by non-invasive bioengineering methods on a set of 24 volunteers for 48 h. Very good moisturizing properties have been found in matrices with the glycerin extract of honey. Matrices containing forest honey had better moisturizing effects than those containing flower honey. Barrier properties were enhanced by gradual absorption, especially in formulations with both glycerin and aqueous honey extract. The observed organoleptic properties of the matrices assessed by sensory analysis through 12 evaluators did not show statistically significant differences except for color and spreadability. There are differences in the ability to hydrate the skin, reduce the loss of epidermal water, and affect the pH of the skin surface, including the organoleptic properties between honey and bee product matrices according to their type and concentration.

Impact of chemical peeling combined with negative pressure on human skin.

In vivo changes in skin barrier function after chemical peeling with alpha hydroxyacids (AHAs) have been previously reported. However, the additional effects of physical treatment with chemical agents on skin barrier function have not been adequately studied. This study measured the degree of acute skin damage and the time required for skin barrier repair using non-invasive bioengineering methods in vivo with human skin to investigate the additional effect of a 4% AHA chemical jet accelerated at supersonic velocities. Thirteen female subjects (average age: 29.54 ± 4.86 years) participated in this study. The faces of the subjects were divided into half according to the block randomization design and were then assigned to receive AHA peeling alone or AHA peeling combined with pneumatic pressure on each side of the face. Transepidermal water loss (TEWL), skin colour and skin blood flow were evaluated at baseline and at 30 min, 2, 5 and 7 days after treatment. The TEWL and skin blood flow were significantly increased after 30 min in chemodermabrasion compared with chemical peeling alone (P < 0.05). The TEWL and skin blood flow recovered to baseline after 2 days, and TEWL was significantly decreased at 7 days compared with chemical peeling alone (P < 0.05). Chemodermabrasion can temporarily impair skin barriers, but it is estimated that it can enhance the skin barrier function after 7 days compared to the use of a chemical agent alone. In addition, chemodermabrasion has a more effective impact in the dermis and relatively preserves the skin barrier.

Randomized, double-blinded, vehicle-controlled, split-face study to evaluate the effects of topical application of a Gold Silk Sericin/Niacinamide/Signaline complex on biophysical parameters related to skin ageing.

To investigate the effects of topical application of a Gold Silk Sericin (GSS) complex on biophysical parameters related to skin ageing. A range of non-invasive bioengineering methods were deployed in an 8-week randomized, double-blinded, vehicle-controlled, split-face study among 40 female subjects aged 40-70. Endpoints measured included expert grades of skin condition, stratum corneum (SC) hydration, SC barrier function, elasticity and surface topography. The GSS complex produced significant single-variable (P < 0.05) improvements in SC hydration, barrier function, elasticity and surface topography compared with the Vehicle control. The GSS complex examined in this study represents an interesting new cosmetic topical technology with which to address multiple aspects of aged/photoaged female facial skin.

Nonlesional skin in atopic dermatitis is seemingly healthy skin - observations using noninvasive methods.

IntroductionAtopic dermatitis (AD) is a chronic and relapsing skin disorder, which is characterized by abnormal skin barrier function within the entire skin surface. Several noninvasive bioengineering methods have been commonly used to quantify disease severity. High-frequency ultrasonography (HF-USG) is an important contribution to this field.AimTo evaluate noninvolved skin during the external treatment in relation to involved regions in patients with AD skin using noninvasive methods.Material and methodsTransepidermal water loss (TEWL), capacitance and erythema assessment and HF-USG were performed in 55 AD patients within 2 regions (involved and uninvolved skin) before and after therapy. The clinical severity of the disease process was based on the eczema area and severity index (EASI) score. A control group consisting of 15 subjects was also included.ResultsOn the basis of 4 bioengineering methods our study revealed that uninvolved skin in AD presents subclinical disturbances and significantly changes during therapy. The HF-USG detects inflammation in the upper dermis in AD patients in the form of a hypoechoic band, which may also be observed to a lesser extent within normal-appearing skin.ConclusionsNonlesional skin differs significantly from lesional skin in AD and from skin of healthy subjects. Noninvasive methods are able to measure subclinical skin disturbances within normal-appearing skin, which are not evaluated using standard clinical scores. They are objective and may facilitate communication between different research groups.

Medical management of cutaneous sulfur mustard injuries

Background Sulfur mustard (2,2′-dichlorodiethyl sulfide; HD) is a potent vesicating chemical warfare agent that poses a continuing threat to both military and civilian populations. Significant cutaneous HD injuries can take several months to heal, necessitate lengthy hospitalizations, and result in long-term complications. There are currently no standardized or optimized methods of casualty management. New strategies are needed to provide for optimal and rapid wound healing. Objective The primary aim of this research was to develop improved clinical strategies (treatment guidelines) for optimal treatment of superficial dermal (second degree) cutaneous HD injuries, with the goal of returning damaged skin to optimal appearance and normal function in the shortest period of time. Methods Superficial dermal HD injuries were created on the ventral abdominal surface of weanling pigs. At 48 h post-exposure, lesions were laser debrided and a treatment adjunct applied. Cultured epithelial allografts and 11 commercial off-the-shelf (COTS) products were examined for their efficacy in improving wound healing of these injuries. Clinical evaluations and a variety of non-invasive bioengineering methods were used at 7 and 14 days post-surgery to follow the progress of wound healing and evaluate various cosmetic and functional properties of the wounds. Measurements included reflectance colorimetry to measure erythema; evaporimetry to examine transepidermal water loss as a method of evaluating barrier function; torsional ballistometry to evaluate the mechanical properties of skin firmness and elasticity; and two-dimensional high frequency ultrasonography (HFU) to monitor skin thickness (e.g., edema, scar tissue). Histopathology and immunohistochemistry were performed 14 days following surgery to examine structural integrity and quality of healing. Logical Decisions ® for Windows was used to rank the 12 treatment adjuncts that were studied. Results The most efficacious treatment adjuncts included (1) Vacuum Assisted Closure™, V.A.C. ®, involving application of topical negative pressure, (2) Amino-Plex ® Spray (biO 2 Cosmeceuticals International, Inc., Beverly Hills, CA), a nutritive cosmeceutical product that is designed to increase oxygen in cells, stimulate ATP synthesis, improve glucose transportation, stimulate collagen formation, and promote angiogenesis, and (3) ReCell ® Autologous Cell Harvesting Device (Clinical Cell Culture Americas LLC, Coral Springs, Florida), an innovative medical device that was developed to allow rapid harvesting of autologous cells from a thin split-thickness biopsy followed by spray application of a population of skin cells onto wounds within 30 min of collecting the biopsy, without the need of culturing the keratinocytes in a clinical laboratory. Conclusions Complete re-epithelialization of debrided HD injuries in 7 days is possible. In general, shallow laser debridement through the basement membrane zone (100 μm) appears to provide better results than deeper debridement (400 μm) with respect to early re-epithelialization, cosmetic appearance, functional restoration, and structural integrity. Of the 12 treatment adjuncts examined, the most promising included Vacuum Assisted Closure™, Amino-Plex ® Spray, and ReCell ® Autologous Cell Harvesting Device.

Evaluation of Natural Change of Skin Function in Split-Thickness Skin Grafts by Noninvasive Bioengineering Methods

BACKGROUND Autologous split-thickness skin grafts (STSGs) are considered the mainstay for the treatment of large full-thickness wounds. There have been few studies reporting the natural change of the skin function in STSGs after procedure, however. OBJECTIVE The objective was to evaluate the natural change of the skin function in STSG using noninvasive bioengineering methods. METHODS Eighteen patients were eligible for the study. The skin functions of the graft and the control site were evaluated by an evaporimeter, corneometer, mexameter, and cutometer at Postoperation Days 0.5, 1, 2, 3, 6, 9, and 12 months. RESULTS Transepidermal water loss (TEWL) of the graft was maintained around that of the normal skin. The values of the skin hydration testing generally decreased during the follow-up period. Erythema was highly maintained for the whole period. For the pigmentation, the ratio tended to increase after 6 months. The skin pliability of the graft was abruptly decreased at 0.5 month, and it recovered from 3 to 12 months. The value did not reach that of the normal skin, however. CONCLUSION Our results showed that the STSGs had changed within the frame of the skin function, including the TEWL, epidermal hydration, color, and pliability, throughout 1 year after surgery.

Evaluation of Natural Change of Skin Function in Split-Thickness Skin Grafts by Noninvasive Bioengineering Methods

Autologous split-thickness skin grafts (STSGs) are considered the mainstay for the treatment of large full-thickness wounds. There have been few studies reporting the natural change of the skin function in STSGs after procedure, however. The objective was to evaluate the natural change of the skin function in STSG using noninvasive bioengineering methods. Eighteen patients were eligible for the study. The skin functions of the graft and the control site were evaluated by an evaporimeter, corneometer, mexameter, and cutometer at Postoperation Days 0.5, 1, 2, 3, 6, 9, and 12 months. Transepidermal water loss (TEWL) of the graft was maintained around that of the normal skin. The values of the skin hydration testing generally decreased during the follow-up period. Erythema was highly maintained for the whole period. For the pigmentation, the ratio tended to increase after 6 months. The skin pliability of the graft was abruptly decreased at 0.5 month, and it recovered from 3 to 12 months. The value did not reach that of the normal skin, however. Our results showed that the STSGs had changed within the frame of the skin function, including the TEWL, epidermal hydration, color, and pliability, throughout 1 year after surgery. The authors have indicated no significant interest with commercial supporters.

Skin capacitance mapping of psoriasis

The pathobiological dynamics of psoriatic lesions are complex and difficult to perceive by clinical inspection alone. Non-invasive bioengineering methods may prove to be useful in this field. To identify some subtle capacitance variations in the stratum corneum of chronic psoriasis lesions. The newly developed method of skin capacitance imaging was used to provide non-optical images of the hydration of the superficial layers of the stratum corneum. Compared to the uninvolved skin, psoriatic lesions usually showed an overall lowered capacitance, admixed with foci of moderately higher capacitance. Still other sharply circumscribed blotches with higher capacitance were present. The latter aspect corresponded to inflammatory areas. Sweating appeared markedly impaired inside the lesions. The fingerprint of some patients was altered, thus potentially interfering with the current biometric security procedures using the same method. Skin capacitance imaging is a non-invasive, non-optical method that distinguishes three contrasting levels of stratum corneum hydration in psoriatic lesions. The lowest capacitance level probably corresponded to xerotic orthokeratosis. The medium capacitance level presumably identified foci of parakeratosis and clumps of neutrophils. The highest capacitance level suggested exsudation at the site of prominent vessel dilation and dermal inflammation. Impaired sweating in the psoriatic lesions may potentially interfere with body thermoregulation.

Assessment of anti‐inflammatory activity of Poria cocos in sodium lauryl sulphate‐induced irritant contact dermatitis

In the present study, we evaluated the anti-inflammatory activity of Poria cocos (PoCo) on experimentally induced irritant contact dermatitis (ICD) in a repeated sodium lauryl sulphate (SLS) irritation model. The anti-irritative effect of PoCo was evaluated with a visual score and quantified by non-invasive bioengineering methods, namely chromametry and transepidermal water loss. Three concentrations of PoCo in base cream DAC (amphiphilic emollient; German pharmacopoeia) were tested in a 4-day repetitive irritation test using SLS. A statistically significant anti-inflammatory activity was observed for PoCo by all three methods when applied in parallel to the induction period of ICD. Application of PoCo after induction of ICD once a day for 5 days, starting just at the end of 4 days, was without any effect. An anti-inflammatory efficacy of PoCo on the elicitation phase of the ICD induced by repeated SLS test could be observed and quantified by three independent, non-invasive biophysical assessment parameters. This effect can be explained by its influence on pro-inflammatory enzymes, namely phospholipase A2.

Age-related changes in skin topography and microcirculation

Skin topography and microvasculature undergo characteristic changes with age. Although several non-invasive bioengineering methods are currently available to measure them quantitatively, few publications have referred to their relationship with age in different anatomical sites. This study was carried out to observe the age-related changes of the skin topography and skin microcirculation. The microrelief was assessed with special processing software from scanning by interference fringe profilometry of silicone replicas performed on two sites (volar forearm and back of hand) on 50 female volunteers (aged 20-74 years who consisted of ten probands in each decade). The superficial vascular network of both sites was assessed by videocapillaroscopy, and the subpapillary vascular plexus was studied with laser Doppler flowmetry. Skin color, which is affected by blood flow, was observed by colorimeter. The skin roughness and the mean height between peak and valley increased with age. There were statistically significant differences between the evaluated sites. This study also shows that the capillary loops in the dermal papillae decrease but the subpapillary plexus increase with age. The interference fringe profilometry associated with videocapillaroscopy may be useful and accurate to measure the efficacy of medical or cosmetic products to delay skin aging.

The Objective Severity Assessment of Atopic Dermatitis (OSAAD) score: validity, reliability and sensitivity in adult patients with atopic dermatitis

The Objective Severity Assessment of Atopic Dermatitis (OSAAD) score is a recently developed scale for evaluation of severity of atopic dermatitis, constructed from the assessment of epidermal barrier function, and properties using noninvasive bioengineering methods and computer-assisted estimates of disease extent. The method has been validated for use in infants and children with atopic dermatitis and compared with a referent scoring system. The aim of the present study was to test the validity, reliability and sensitivity of the OSAAD score as an objective tool for the assessment of the severity of atopic dermatitis in adult patients. Thirty-two adult patients with atopic dermatitis were included in the study. To assess the validity of the OSAAD score we tested it against the Severity Scoring of Atopic Dermatitis (SCORAD) index of the European Task Force on Atopic Dermatitis as a referent clinical severity scale, and the serum levels of interleukin (IL)-16 as a laboratory variable for monitoring the activity of atopic dermatitis. Responsiveness to change was assessed in a longitudinal study comparing OSAAD, SCORAD and serum levels of IL-16 before and after treatment. To test the reliability of the OSAAD score we studied the interobserver variability of the score recorded by three independent board-certified dermatologists in 16 patients and compared it with SCORAD. We report a significant correlation between the OSAAD and the SCORAD index as an acknowledged referent severity scale. The OSAAD score correlated significantly with the serum levels of IL-16 in the acute stage of atopic dermatitis. In a longitudinal study, the OSAAD score decreased significantly, parallel with improvement of the skin findings and a significant decrease in the SCORAD score and IL-16 serum levels. We report improved interobserver variability for the OSAAD score compared with SCORAD. This is the first study validating the OSAAD score as a sensitive and reliable tool for the assessment of the severity of atopic dermatitis in adult patients.

Correlation of clinical features and skin barrier function in adolescent and adult patients with atopic dermatitis

Xerotic changes in atopic skin are considered to be related to a decrease in the water permeability barrier. Whether abnormal skin barrier function is the main cause of atopic dermatitis (AD) or a secondary change of the disease is still controversial. Noninvasive bioengineering methods, including the measurement of the transepidermal water loss (TEWL) and water capacitance, have been commonly used to evaluate skin barrier function. To evaluate the correlation between the clinical features of each evaluation site (severity of AD) and skin barrier function. TEWL, capacitance, and pH were checked on five evaluation sites: postauricle, forearm, abdomen, thigh, and popliteal fossa. The subjects included 25 patients, both adolescents and adults, with AD and 25 age-matched normal controls. The clinical severity, from 0 (no clinical manifestation) to 3 (severe), was also scored for erythema, induration/papulation, lichenification, and xerosis on each evaluation site of the AD patients. Based on the data, we found that the clinical severity score was correlated with TEWL and capacitance in more than one-half of the evaluation sites. Erythema and induration/papulation showed a statistically significant correlation with TEWL in most cases (P < 0.05, four sites). Lichenification and xerosis showed a significant correlation with capacitance in most cases (P < 0.05, four sites). In most cases, severity scoring of the clinical features did not show a significant correlation with skin pH. The patients showed higher TEWL and lower capacitance than normal controls (P < 0.05, all five sites). The results of our study suggest that skin barrier function, measured by TEWL and capacitance, and clinical severity show a statistically significant correlation in patients with AD.

Protective Effects of Different Marigold (Calendula officinalis L.) and Rosemary Cream Preparations against Sodium-Lauryl-Sulfate-Induced Irritant Contact Dermatitis

In the present study, we evaluated the protective action of cream preparations containing seven different types of marigold and rosemary extracts in vivo in healthy volunteers with experimentally induced irritant contact dermatitis (ICD). Marigold and rosemary extracts in base cream DAC (Deutscher Arzneimittel-Codex = German Pharmaceutical Codex) were tested in a 4-day repetitive irritation test using sodium lauryl sulfate. The effect was evaluated visually and quantified by noninvasive bioengineering methods, namely chromametry and tewametry. When the test products were applied parallel to the induction period of ICD, a statistically significant protective effect of all cream preparations was observed by all methods. This effect, although not statistically significant, was superior to control by undyed marigold und faradiol ester-enriched extracts in chromametry and by dyed and undyed rosemary extracts in tewametry. The sequential treatment (postirritation) once a day for 5 days was without any effect. Thus, a protective effect of some marigold and rosemary extracts against ICD could be shown in the elicitation phase.

Effects of Three Anesthetic Regimens on Bioengineering Methods Conducted on Ventral Abdominal Skin of Weanling Swine

Background/Purpose: A weanling swine model was previously developed to study healing of cutaneous injuries induced by the blistering chemical warfare agent sulfur mustard. Noninvasive bioengineering methods are used in the model to monitor the progress of wound healing and evaluate the efficacy of treatments. It is necessary to anesthetize the animals to facilitate bioengineering data collection from ventral abdominal wound sites. As anesthetic agents affect cardiac output and deep vascular and cutaneous microcirculation in many species, there was a need to identify an anesthetic regimen with minimal effects on baseline measurements. The effects of three anesthetic regimens on reflectance colorimetry, transepidermal water loss, and laser Doppler perfusion imaging were studied in unexposed control animals. Methods: The following regimens were tested on six female Yorkshire swine (weanlings, 8–11 kg): repeated, separate intramuscular (i.m.) injections of ketamine HCl and xylazine HCl (K/X, at 20 ± 2 mg/kg a...

Damage and recovery of skin barrier function after glycolic acid chemical peeling and crystal microdermabrasion.

Superficial chemical peeling and microdermabrasion have become increasingly popular methods for producing facial rejuvenation. However, there are few studies reporting the skin barrier function changes after these procedures. To evaluate objectively the degree of damage visually and the time needed for the skin barrier function to recover after glycolic acid peeling and aluminum oxide crystal microdermabrasion using noninvasive bioengineering methods. Superficial chemical peeling using 30%, 50%, and 70% glycolic acid and aluminum oxide crystal microdermabrasion were used on the volar forearm of 13 healthy women. The skin response was measured by a visual observation and using an evaporimeter, corneometer, and colorimeter before and after peeling at set time intervals. Both glycolic acid peeling and aluminum oxide crystal microdermabrasion induced significant damage to the skin barrier function immediately after the procedure, and the degree of damage was less severe after the aluminum oxide crystal microdermabrasion compared with glycolic acid peeling. The damaged skin barrier function had recovered within 24 hours after both procedures. The degree of erythema induction was less severe after the aluminum oxide crystal microdermabrasion compared with the glycolic acid peeling procedure. The degree of erythema induced after the glycolic acid peeling procedure was not proportional to the peeling solution concentration used. The erythema subsided within 1 day after the aluminum oxide crystal microdermabrasion procedure and within 4 days after the glycolic acid peeling procedure. These results suggest that the skin barrier function is damaged after the glycolic acid peeling and aluminum oxide crystal microdermabrasion procedure but recovers within 1 to 4 days. Therefore, repeating the superficial peeling procedure at 2-week intervals will allow sufficient time for the damaged skin to recover its barrier function.

Measuring skin moisturization: influence of emulsion type on test data and its implications

Dry skin conditions are commonly seen in the dermatologist’s office. Many products claim to moisturize the skin and ameliorate the condition, citing data from one of several common non-invasive bioengineering devices as an indication of skin hydration state. These devices estimate skin hydration indirectly by measuring the electrical properties of the stratum corneum, but can produce misleading information depending on the properties of the formulation. Because of the insulating effects of oils, emulsions that have oil in the external phase (i.e. water-in-oil emulsions) can interfere with the ability of the device to make electrical measurements, and thus produce false negative results. Conversely, products that have water in the external phase (oil-in-water emulsions) give comparatively high measurements, and may appear to be far more efficacious than water-in-oil products. Other methods directly measure water in the skin (e.g. NMR), but are not readily available due to the expense of the equipment. Ideally, moisturizing efficacy is best evaluated by a multi-dimensional approach such as non-invasive bioengineering methods, clinical and subjective assessments, as well as short and long-term study designs. The aim of this study was to compare data obtained for water-in-oil and oil-in-water emulsion systems, and demonstrate technical problems that can generate misleading results regarding product efficacy.

Damage and Recovery of Skin Barrier Function After Glycolic Acid Chemical Peeling and Crystal Microdermabrasion

BACKGROUND Superficial chemical peeling and microdermabrasion have become increasingly popular methods for producing facial rejuvenation. However, there are few studies reporting the skin barrier function changes after these procedures. OBJECTIVE To evaluate objectively the degree of damage visually and the time needed for the skin barrier function to recover after glycolic acid peeling and aluminum oxide crystal microdermabrasion using noninvasive bioengineering methods. METHODS Superficial chemical peeling using 30%, 50%, and 70% glycolic acid and aluminum oxide crystal microdermabrasion were used on the volar forearm of 13 healthy women. The skin response was measured by a visual observation and using an evaporimeter, corneometer, and colorimeter before and after peeling at set time intervals. RESULTS Both glycolic acid peeling and aluminum oxide crystal microdermabrasion induced significant damage to the skin barrier function immediately after the procedure, and the degree of damage was less severe after the aluminum oxide crystal microdermabrasion compared with glycolic acid peeling. The damaged skin barrier function had recovered within 24 hours after both procedures. The degree of erythema induction was less severe after the aluminum oxide crystal microdermabrasion compared with the glycolic acid peeling procedure. The degree of erythema induced after the glycolic acid peeling procedure was not proportional to the peeling solution concentration used. The erythema subsided within 1 day after the aluminum oxide crystal microdermabrasion procedure and within 4 days after the glycolic acid peeling procedure. CONCLUSION These results suggest that the skin barrier function is damaged after the glycolic acid peeling and aluminum oxide crystal microdermabrasion procedure but recovers within 1 to 4 days. Therefore, repeating the superficial peeling procedure at 2-week intervals will allow sufficient time for the damaged skin to recover its barrier function.

The Influence of Anti‐irritants on Captopril Hydrophilic Gel

In this study, we compared the irritation inhibition of various types of anti‐irritants such as antihistamines (cyprohetadine, diphenhydramine, and promethazine), alpha‐hydroxy acids (gluconolactone and gluco‐δ‐lactone), corticosteroids (betamethasone and clobetasol), and ion channel modulating agents (amiloride, ethacrynic acid, nifedipine, and verapamil) on the adverse dermatological reaction caused by captopril gel using noninvasive bioengineering methods including measuring the transepidermal water loss (TEWL) and the color change of skin surface [such as change chroma (delta C) and difference in color (delta E) between the gel‐treated site and the untreated site]. In addition, the influence of these anti‐irritants on the penetration capacity of captopril through the rabbit skin was also investigated. The results showed that the TEWL, change chroma (delta C), and difference in color (delta E) of skin were significantly reduced via incorporating diphenhydramine and clobetasol, indicating that both substances had potent irritation inhibition activity. Moreover, these substances had no effect on the percutaneous absorption of captopril gel. However, flux of the captopril with anti‐irritants was about 480 µg/cm2/h and the required minimum administration area to obtain the minimum effective concentration was about 15 cm2, indicating that this formulation could possibly be developed for a transdermal drug delivery system.

In vivo Tolerance Assessment of Skin after Insertion of Subcutaneous and Cutaneous Microdialysis Probes in the Rat

The purpose of the study was to evaluate the trauma induced by insertion of the linear microdialysis probe in the subcutaneous and dermal tissue in the rat and to check if the microdialysis probe insertion affects transdermal drug delivery. Non-invasive bioengineering methods (TEWL, Laser Doppler Velocimeter, Chromameter) as well as histology were combined to characterize these effects. The results showed that the dermal and subcutaneous insertion of microdialysis probes did not change skin permeability, blood flow and color, confirming the safety of this technique. The probe depth did not influence the trauma. No significant physical damage after probe insertion was noticed. Thus, the present work validates the use of microdialysis in dermatopharmacokinetics studies after topical or systemic drug delivery.