Passive water movements through skin of the toad Bufo marinus in air and in water.
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Animals↗
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Results for “Skin Absorption”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
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Potassium uptake across serosal surface of isolated frog skin epithelium.
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Amiloride↗
Skin gas tensions and resistances measured by mass spectrometry in adults.
We used a dual-sampling chamber 2.5 cm in diameter, controlled by an Apple II microcomputer, to measure gas tensions in the skin of adults by mass spectrometry. The tensions of O2, CO2, N2, and water vapor and the resistances to the flows of gases through the skin were calculated from the voltages for the different gases passing through two separate membranes of different permeability. We compared the skin O2 and CO2 tensions with arterial values in 13 patients with lung disease during a standardized exercise test. The skin values followed changes in the arterial values. The regression line relating skin to arterial O2 tension had a slope of 1.05 and that for CO2 a slope of 1.51. We conclude that mass spectrometry is capable of providing measurements of gas tension from the heated skin that are similar to those found using electrochemical methods in adults.
Carbon Dioxide↗
The Sixth International Perspectives in Percutaneous Penetration Conference 1998.
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Animals↗
High-frequency ultrasound in the evaluation of pharmacological effects on the skin.
In 1987, the introduction of two 20-MHz B- (brightness-) scan ultrasound systems with axial and lateral resolution of 200 microm and 75-80 microm, respectively, rendered two-dimensional sonographic imaging in dermatology possible. Since then cutaneous sonography has increasingly been used to investigate drug effects on human skin. Both unwanted and wanted effects have been studied, including skin thinning due to repeated glucocorticoid application and reduction of skin thickening in hyperplastic disorders such as psoriasis vulgaris due to various treatment approaches. The resolution of 20-MHz ultrasound is sufficient for studying pathological changes and pharmacological effects in the dermis and the subcutaneous fat; for assessing the epidermis, frequencies between 50 and 100 MHz may prove to be more effective.
Administration, Cutaneous↗
Iontophoretic transport across the skin.
There have been many attempts to define the key relationships between passive drug diffusion across the skin and the molecular and physicochemical properties of the permeant. At the present time, the importance of lipophilicity (or hydrogen bond donor and acceptor properties) and of molecular volume are well established, and useful predictive relationships for passive percutaneous permeability exist. With respect to iontophoresis, on the other hand, the situation is far less clear and the mechanisms involved have not been completely defined. The roles of electromigration and electroosmosis (current-induced convective solvent flow) are now beginning to be understood and experimentally separated. In turn, this allows the manner in which certain physicochemical parameters influence the efficiency of drug electrotransport to be deduced. An initial examination of a database drawn from the literature and from our own work (for which the experimental conditions employed were reasonably constant) suggests a rather sharp dependence of cationic drug delivery via electromigration upon molecular size. We suggest that the analysis reveals useful paths for further investigation.
Animals↗
Effects of prolonged occlusion on stratum corneum barrier function and water holding capacity.
PURPOSE OF THE STUDY: We aimed to evaluate whether prolonged occlusion can induce stratum corneum barrier damage, alterations in stratum corneum hydration or water-holding capacity (WHC) lasting longer than the occlusion time. MATERIALS AND METHODS: 12 subjects were occluded on the forearm for 24, 48, 72 and 96 h. Two hours after occlusion removal, transepidermal water loss (TEWL) and skin hydration were measured and a sorption-desorption test performed. RESULTS: TEWL showed an increase reaching a plateau on day 2. Hydration and WHC did not show significant changes. Hygroscopicity showed the highest level on day 1, decreasing during the following days. A highly significant correlation between capacitance values and the WHC could be detected (p < 0.0001, r = 0.8206). No correlation could be detected between hygroscopicity and TEWL. CONCLUSIONS: Prolonged occlusion induces barrier damage without skin dryness. Occlusion also induces an increased hygroscopicity. A correlation between these two findings could not be proven.
Adult↗
Comparison of the effects of daily applications between topical corticosteroid and tacrolimus ointments on normal skin: evaluation with noninvasive methods.
OBJECTIVE: To evaluate the skin changes of the neck of normal individuals after repeated applications of moderate-strength corticosteroid or tracrolimus ointment for 3 weeks by use of noninvasive biophysical measurements. METHODS: A 0.12% betamethasone-17-valerate ointment or a 0.1% tacrolimus ointment was applied to the right side of the neck of 8 adult volunteers twice daily for 3 weeks together with control petrolatum applied to the left side of the neck for comparison. Biophysical skin measurements were performed on the neck skin before, 1 and 3 weeks after the start of the treatment and 1 week after the cessation of the treatment. RESULTS: A decrease in hygroscopicity and water-holding capacity of the stratum corneum (SC) when evaluated with the in vivo water sorption-desorption test was found on the corticosteroid-ointment-treated side after 3 weeks of the treatment as compared with the petrolatum-treated side. The erythematous reaction to a topically applied 0.1% aqueous solution of methyl nicotinate, a vasodilator, appeared more slowly on the corticosteroid-ointment-treated skin than on the control skin. No such changes were observed on the skin treated with 0.1% tacrolimus ointment. CONCLUSION: Tacrolimus appears to cause few if any functional changes in the SC of healthy human skin because of its poor permeability into skin with an intact barrier function.
Administration, Topical↗
Molecular skin barrier models and some central problems for the understanding of skin barrier structure and function.
A better understanding of the structure and function of the human skin barrier is a prerequisite for a more rational design of transdermal drug administration systems. The study of biological structural organisation is, however, confronted with many difficulties, and interpretations of skin barrier-related data should therefore be done with caution. The recently developed 'single gel-phase model' constitutes an attempt to interpret structural and functional skin barrier data from a biophysical standpoint.
Humans↗
High plasma levels of 8-methoxypsoralen following bath water delivery in dermatological patients.
With respect to the clinical advantages known for bath PUVA therapy, it was of interest to compare the plasma levels of 8-methoxypsoralen (8-MOP) in bath therapy with those after oral administration for a better insight into the pharmacokinetics of 8-MOP following different modes of application. Considerable high plasma levels of 8-MOP were observed after bath therapy with interindividual variability. The half-life of plasma 8-MOP was markedly shorter after bath PUVA than after oral application. The pharmacokinetic profile of 8-MOP differs according to the mode of application.
Administration, Cutaneous↗
Lateral diffusion of ibuprofen in human skin during permeation studies.
In order to characterize the quality of dermal preparations, permeation studies using human stratum corneum or artificial skin constructs are carried out. For a better understanding of the diffusion processes a method to measure the lateral diffusion in skin samples was developed allowing an estimation of built-up drug depots. By extracting concentric skin segments surrounding the site of application, lateral drug diffusion was determined. Both, excised human skin and artificial skin constructs, showed comparable results with two phases of lateral diffusion (accumulation/redistribution). The use of permeation enhancers promoted lateral diffusion and thus increased the tendency to create a drug depot within the skin.
Biological Transport↗
Using skin models to assess the effects of a protection cream on skin barrier function.
BACKGROUND: There is a basic necessity to understand the mechanisms of the protective effects of emulsions. This would promote the development of protective cosmetics and therefore improve the prevention and treatment of occupational skin diseases. However, for such studies, no reliable skin model is available. OBJECTIVE: An in vitro skin model test was developed to evaluate the protective mechanism of cosmetic ingredients. METHODS: The efficacy of three products was assessed by an in vivo test (Repetitive Occlusive Irritation Test) and then 3-dimensional skin model tests were carried out. RESULTS: In vivo test results demonstrate that the best protection against sodium dodecyl sulphate is offered by a multiple emulsion. In the case of a skin model test, sodium dodecyl sulphate led to cell damage, an increase in pro-inflammatory markers and some barrier lipids. The multiple emulsion increased the content of skin lipids, without inducing irritation or cell death. CONCLUSION: Skin models react similarly to sodium dodecyl sulphate compared to human skin and therefore they are suitable to study barrier repair after sodium dodecyl sulphate damage. It is likely that the superior protective effect of the multiple emulsion in vivo is based on the increased amount of skin barrier lipids.
Administration, Cutaneous↗
Rapid human skin permeation and topical anaesthetic activity of a new amethocaine microemulsion.
We developed a fast-acting, topical, 4% (w/w) amethocaine microemulsion and tested its in vitro permeation in isolated human skin. Comparison with a commercial amethocaine gel (Ametop((R)) ) was performed using Franz diffusion cells. Permeability coefficient (k(p)), flux (J) and percentage permeation after 10 h of microemulsion application were, in all cases, 1.5 times higher than those of the gel. The values obtained for the P(1) parameter [1], 1.06.10(-2) cm (microemulsion) and 0.724.10(-2) cm (gel) indicate that the microemulsion excipients favour amethocaine deposition in the skin, increasing the permeability coefficient, amount of drug retained in the skin, and the flux achieved. Analgesic activity was also examined in rats made hyperalgesic or allodynic after carrageenan-induced inflammation. The rats were distributed into four groups (n = 5-9 per group), each group receiving topically either amethocaine microemulsion, amethocaine gel (Ametop), amethocaine subcutaneous infiltration or nothing (controls). In edematous paws, anti-hyperalgesic activity appeared at 4.2 and 13.8 min after application of amethocaine microemulsion and gel, respectively. These effects are lower than after 0.5% w/w amethocaine infiltration. Amethocaine microemulsion was the only topical formulation with an anti-allodynic effect, although this effect was less than with amethocaine infiltration. These results suggest that microemulsion could be a valuable formula for improving amethocaine permeation and thus bringing rapid pain relief.
Administration, Topical↗
The effect of repeated application of dimethylsulfoxide (DMSO) to paws of rats and guinea-pigs.
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Animals↗
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.
Adult↗
In vivo evaluation of the stratum corneum barrier function in blacks, Caucasians and Asians with two noninvasive methods.
This study compared in man the in vivo barrier function of stratum corneum in three racial groups: black, Caucasian and Asian, by two noninvasive technics. They were transepidermal water loss (TEWL) determination measured with an evaporimeter and laser Doppler velocimetry (LDV) to measure the lag time before the vasodilation induced by application of methyl nicotinate (10 microliters of 0.5% solution in ethanol/propylene glycol 95/5 v/v). Both methods were performed simultaneously on each forearm of 7 black, 8 caucasian and 6 Asian subjects before and after removal of the stratum corneum by stripping. TEWL measurements were higher (p < 0.01) in Asians and Blacks compared to Caucasians. Stripping (8 or 12 strips) increased TEWL in all groups; TEWL increase percentage was higher (p < 0.05) in Asians compared to Caucasians. Vasodilatation lag times assessed by LDV showed that skin permeability was more important in Asians (p < 0.01) and in Caucasians (p < 0.05) than in blacks. Lag times decreased with stripping. After 8 or 12 strips, the order of sensitivity was: Asian > Caucasian > black. Our study showed that, with both noninvasive methods, removal of the stratum corneum increased permeability, with racial differences.
Adult↗
Lipid composition and barrier function of human skin after grafting onto athymic nude mice.
The barrier properties of human epidermis grafted for 1-3 months onto nude mice are compared with normal human skin. Beside penetration studies with tritiated water and measurements of transepidermal water loss (TEWL), we analyzed the epidermal lipids by high-performance thin layer chromatography and evaluated the ultrastructure of the intercorneocyte lipid arrangement by freeze fracture electron microscopy (FFEM). The permeability of human skin for tritiated water and the TEWL exhibit no significant changes after grafting onto nude mice. FFEM analysis showed that grafted epidermis has the same morphological pattern as normal human epidermis. Regular desmosomes and lamellar lipid structures are present. Grafting did not qualitatively affect the lipid composition of human epidermis. Ceramides which contribute largely to the barrier function, have the same distribution profile.
Animals↗