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  • 11
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 134 (1996), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Topically applied all-trans retinoic acid (RA) is often associated with skin irritation. A detailed quantification of RA-induced functional changes in stratum corneum is. however, still limited. U sing noti-invasive bioengineering techniques of measurements of transepidermal water loss (TEWL), stratum corneum hydration and cutaneous blood flow (CBF). we quantified the irritant effects of 0·05% and 0·1% RA in ethanol on normal skin compared with 1% sodium lauryl sulphate (SLS) in water as a model irritant in a 24-h occlusive patch-test assay. Additionally, in order to document data possibly related to the mechanism of action, skin responses to both compounds applied in tandem was also investigated over 18 daysThe extent of the irritant response to 0·05 and 0·1% RA, respectively, were similar, implying analogous irritation potency. While RA caused more intense scaling than SLS. other skin responses to RA were significantly weaker than those due to SLS. An increase in TEWL. on day 7. in RA-exposed sites indicates a secondary delayed impairment of the stratum corneum (SC) barrier. In a tandem-design assay, pretreatment with RA appeared to reduce the irritant effects of SLS on SC hydration and CBF. In contrast, pre-exposure to SLS showed a synergestic response in erythema, scaling and TEWLOur results demonstrate that RA, like SLS. is capable of impairing SC water barrier function, which may be responsible, in part, for the irritation associated with its topical use. However, the distinctive biological responses to these compounds suggest a different mode of action of RA and SLS. In addition, the precise reason for the unique results observed in the tandem-design assays is not clear.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 148 (2003), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  When evaluating transepidermal water loss (TEWL) in patch testing, the occlusive effect of the patch must be considered as an important artificial impairment of the measurement.Objectives  To investigate the time course of effects of occlusion.Methods  Epicutaneous patches with sodium lauryl sulphate (SLS) 0·25%, SLS 0·5%, water and an empty test chamber (control) were applied on the volar forearm for different time intervals (12, 24, 48 h). Test reactions were evaluated by measurement of TEWL immediately, every 15 min during the first hour, every 30 min during the following 3 h and 24 h after patch removal.Results  After patch removal, TEWL values showed a steep increase. When compared with basal values, TEWL values after SLS patch testing remained increased for 24 h, whereas TEWL values on water patch sites were only significantly increased for up to 180 min, and on empty patch sites for only up to 120 min after patch removal. The prolonged increase in TEWL values in SLS patch testing seemed to be induced by barrier function damage caused by SLS itself, as shown in various earlier studies. After the initial increase, TEWL values showed a significant decrease for all patches from 0 to 120 min after patch removal. Patch testing with water gave a significant decrease in TEWL values up to 180 min, and for empty chambers (control) up to 150 min after removal of patches. These data suggest that the occlusive effect on TEWL in patch testing ends 3 h after the removal of test chambers.Conclusions  We recommend TEWL measurement in SLS patch testing after a period of at least 3 h after patch removal. For practical purposes a 24-h period after patch removal may be useful.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 145 (2001), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background It is well known that the degree of skin reaction to an irritant depends on its concentration and exposure time. Objectives To determine the interrelationship between the concentration of sodium lauryl sulphate (SLS) and exposure time in both weak (subclinical) and severe reactions. Methods Patch testing with SLS was performed at different concentrations (0·125%, 0·25%, 0·5%, 1·0% and 2·0%) and with different exposure times (3, 6, 12, 24 and 48 h). Evaluation was conducted by measurement of transepidermal water loss and by laser-Doppler flowmetry both 30 min and 24 h after patch removal. Results We found more reliable and constant skin reactions 24 h after patch removal, and a higher correlation between SLS concentration and skin reaction. Conclusions We conclude that the concentration of SLS influences the test outcome to a larger degree than the exposure time. We present formulae by which the outcome of SLS patch testing at various SLS concentrations ranging from 0·125% to 2% and any exposure time between 3 and 24 h can be estimated.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental dermatology 20 (1995), S. 0 
    ISSN: 1365-2230
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Patients with toe-nail onychomycosis were treated with terbinafine (250 mg daily, n= 20) for either 6 or 12 weeks in a randomized double-blind study. Plasma and distal nail clippings were taken before initiation of therapy and 1, 6, 12, 18, 24, 36 and 48 weeks thereafter.Analytical data of terbinafine extracted from nail clippings or plasma were obtained by high-performance liquid chromatography (HPLC). Nail extracts and isolated HPLC terbinafine peaks were analysed using a combined gas chromatography - mass spectroscopy system (GC-MS) for unequivocal identification of the drug.Terbinafine could be detected in the distal nail in the majority of the patients within 1 week of starling therapy. Maximum terbinafine levels of 0·52 and 1·01 μg;g were measured after 18 weeks in the 6- and 12-week treatment groups, respectively.While plasma levels decreased rapidly after termination of therapy terbinaiine was detected in the nails as long as 36 weeks (6 weeks treatment) and 36 weeks (12 weeks treatment) after termination of therapy at a range of 0·–0·19 μg/g. The drug concentrations measured at all time points are well above the minimum inhibitory concentration (MIC) tor dermatophytes and other fungi, These data suggest that the drug readies the nail plate rapidly and persists there for several months after cessation of active treatment.
    Type of Medium: Electronic Resource
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