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Biomedical subjects

L Duteil

Publications and source records attributed to L Duteil.

11 recordsLinked to original sources
PubMed1992

Colorimetric assessment of the effects of azelaic acid on light-induced skin pigmentation.

A 20% azelaic acid (AZA) cream is currently used as a therapeutic agent in the treatment of acne vulgaris. Therefore, this product is intended to be applied on frequently or continuously sun-exposed skin. In certain disorders of hyperpigmentation, AZA has been reported to have a depigmenting effect as well, while showing no significant activity on normal skin. It has been suggested that AZA selectively inhibits hyperactive or malignant melanocytes. Knowing that light-stimulated melanocytes are in a state of hyperactivity, it seemed worthwhile to investigate AZA activity on light-induced skin pigmentation. This study aimed to assess the activity of 20% AZA cream on light-induced skin pigmentation in 10 subjects. There were 5 test zones, all located on the middle of the back: 2 were treated with AZA cream, 2 others with the vehicle and 1 was left untreated. Each product was applied twice daily, 5 days a week, for 4 weeks on one zone, and for 5 weeks on the other. In the middle of the fourth week, the tested zones were exposed to ultraviolet B (UVB) + UVA + visible light, with a total of 3 times the minimal erythema dose distributed progressively over 3 consecutive days. Seven and 10 days after the last irradiation, the induced photopigmentation was assessed by colorimetric and visual means. Compared with its vehicle, the AZA cream had neither a depigmenting effect nor a preventive effect on the light-acquired skin pigmentation. Moreover, interrupting or continuing the AZA treatment after skin irradiation had no influence on the resulting pigmentation.

Adult↗
PubMed1991

Processing and statistical analysis of laser Doppler data applied to the assessment of systemic anti-inflammatory drugs.

Continuous laser Doppler measurements of methyl nicotinate-induced skin inflammation have been used to evaluate the activities of three oral non-steroidal anti-inflammatory drugs, indomethacin 50 mg (Indocid), tiaprofenic acid 100 mg (Surgam) and sodium acetylsalicylate 1 g (Catalgine). They were compared in a single-blind, randomized, intra-individual comparison (N = 16) versus placebo (lactose). One hour after each drug was ingested, four concentrations of methyl nicotinate were applied to the subject's forearms. Simultaneous skin blood flow (SBF) measurements were then carried out on the four tested zones, by use of four calibrated laser Doppler flowmeters. Computerized processing of recorded SBF levels provided data related to flow amplitude, kinetics and magnitude (area under the curve) of the reactions. A detailed statistical analysis was performed to establish the selectivity of this type of test and the following points were demonstrated: adjustment of SBF data to baseline did not improve precision, data had to be log-transformed before analysis, and magnitude data gave the best product discrimination. Under the conditions of this study, i.e. one hour after oral administration and for the indicated doses, the tested products could be classified, in terms of anti-inflammatory activity, as follows: Lactose less than Indomethacin 50 mg = Tiaprofenic acid 100 mg less than Sodium acetylsalicylate 1 g.

Adult↗
PubMed1990

Objective assessment of topical corticosteroids and non-steroidal anti-inflammatory drugs in methyl-nicotinate-induced skin inflammation.

The aim of this study was to compare the activities of the two main classes of topical anti-inflammatory drugs in methyl-nicotinate-induced skin inflammation, using a new methodology based on laser-Doppler velocimetry. Six topical non-steroidal anti-inflammatory drugs (NSAIDs) (bufexamac, diclofenac, ibuprofen, indomethacin, phenylbutazone and niflumic acid) and three topical corticosteroids (clobetasol propionate, hydrocortisone and hydrocortisone butyrate) were tested. Drugs were commercially available (except indomethacin) and were applied under occlusion for 4 h to the forearms of 16 healthy male volunteers. Thirty minutes after excess drug removal, skin inflammation was induced by a 1-min application of methyl nicotinate (3 mM). This was repeated 44 h later. Each methyl-nicotinate application was followed by continuous skin blood flow recordings over 1 h. Overall, NSAIDs proved more effective than corticosteroids in inhibiting methyl-nicotinate-induced increases in skin blood flow. Diclofenac and indomethacin showed a potent prolonged inhibitory effect. Different types of activity were observed in the corticosteroid group: (a) At 30 min, hydrocortisone and hydrocortisone butyrate moderately inhibited methyl-nicotinate reactions whereas clobetasol propionate produced no detectable effects; (b) at 44 h, clobetasol propionate produced a significant inhibition whereas hydrocortisone butyrate and hydrocortisone exhibited either weak or no inhibitory action at all. These pharmacodynamic discrepancies between the corticosteroids tested could be related to differences in drug affinity to cutaneous receptors and in vasoconstrictive potency.

Adult↗
PubMed1990

Objective assessment of topical anti-inflammatory drug activity on experimentally induced nickel contact dermatitis: comparison between visual scoring, colorimetry, laser Doppler velocimetry and transepidermal water loss.

Four topical anti-inflammatory drugs were investigated for their effect on allergic contact dermatitis. Nickel dermatitis was chosen for its high incidence in European healthy volunteers. Experimental lesions were treated twice daily with two steroids, two non-steroidal anti-inflammatory drugs and a blank base for 4.5 days without occlusion. The influence of treatments was assessed by daily visual grading and one site was left untreated for comparison over the same period. To quantify drug activities objectively, skin colour (colorimetry), skin blood flow (laser Doppler velocimetry) and transepidermal water loss (evaporimetry) were measured before drugs were first applied, then 6 hr after the last application. As expected, only Dermoval cream significantly improved the spontaneous clinical evolution in comparison with the other creams (Hydrocortisone Aster à 1%. Parfenac, indomethacin 2.5% and Skinbase) and the untreated site. Colorimetric parameter a* (redness) and L* (luminance) showed more differences between treatments than the other criteria and a close relationship was obtained between these two parameters and skin blood flow, all three being highly correlated to visual grading. Transepidermal water loss appeared less related to clinical improvement but this parameter could prove helpful for detecting compounds which could be irritant to diseased skin.

Administration, Topical↗
PubMedDate not supplied

[Clinical trials in dermatology. The phase I trials].

Application of the new topical product on the diseased skin should be preceded by its safety evaluation on the healthy skin in human volunteers. We propose here guidelines for the evaluation of the irritation, sensitization, phototoxicity and photoallergy potentials for topical products. The methods for evaluation of percutaneous absorption are also discussed. The studies presented here are not the object of any regulations. Therefore, we propose here an approach for the safety evaluation of topical products in human volunteers.

Administration, Topical↗
PubMedDate not supplied

[Clinical trials in dermatology. Evaluation of the tolerability and efficacy of a topical antifungal agent in the treatment of superficial mycoses].

There is no single method for evaluating topical antifungal drugs. The localisation and the type of fungal, determine the treatment duration (from few days to several months). The main methodological characteristics of clinical trials in tinea pedis treatment (athlete's foot type) are reported. Aspects related to other clinical forms such as tinea versicolor and onychomycosis are also described. In any case, the main criteria of activity remains the mycological examination based on KOH microbiology and culture performed at the end of the treatment and again afterwards.

Administration, Topical↗
PubMedDate not supplied

[Clinical trials in dermatology. Statistical support].

To determine the efficacy or safety of new topical treatments, more or less standardized studies must be performed. This article presents several examples of statistical analyses of the data currently seen in the dermatology area, and some guidelines for study sample size determination. More importantly, it indicates, for as soon as phase I studies, the need for preliminary informations such as development strategy, historical data, literature references or pilot studies, to determine or adapt appropriate designs and sample sizes. This need can be filled by close collaboration among clinicians, statisticians and sponsor.

Clinical Trials as Topic↗