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Biomedical subjects

B Gabard

Publications and source records attributed to B Gabard.

At least 19 recordsLinked to original sources
PubMed2001

There is no influence of a temperature rise on in vivo adsorption of UV filters into the stratum corneum.

Temperature influences the stratum corneum adsorption of several topically applied compounds. This study was designed to evaluate the influence of the temperature on the stratum corneum adsorption of 3 UV filters. The UV filters were solubilized in two vehicles, an emulsion gel and petroleum jelly and applied at respectively, 31 and 40 degrees C during 30 min. In vivo stratum corneum UV filter content was measured using the tape stripping method. Similar amounts of UV filter were detected in the stratum corneum when comparing applications at the different temperatures. Application of the UV filters in the emulsion gel resulted in higher stratum corneum UV filter concentrations compared with application in the petroleum jelly. The application temperature did not influence the stratum corneum adsorption of the tested UV filters while the nature of the vehicle significantly influenced the amount of UV filters recovered from the stratum corneum.

Adult↗
PubMed2001

Surfactant irritation: in vitro corneosurfametry and in vivo bioengineering.

BACKGROUND/AIMS: Irritant reactions to surfactants, cleansing products, soaps and detergents are common in clinical and occupational dermatology. Mildness has become a major benefit claimed, and testing for mildness now ranks among the first concerns of the manufacturing industry. A wealth of publications deals with this problem, trying to improve the methodology, reduce the costs of testing and facilitate decision-making. Differences in vivo can be measured clinically and/or instrumentally. This is difficult, as commercially available products are generally safe to use and none are harsh in the absolute sense. METHODS: Nineteen different products (syndets, shampoos, personal cleansers), all claiming to be mild, were tested in vitro by a newly introduced method, corneosurfametry. For evaluating the aggressiveness of the products, the calculation of an index of irritation (IOI) was proposed. A concentration-effect curve of sodium lauryl sulfate (SLS) as standard and model surfactant was obtained. Some of the products were further tested in vivo with a flex wash test and with a soap chamber test and compared to SLS. Bioengineering methods (transepidermal water loss TEWL, skin color) were used to evaluate the results. RESULTS AND CONCLUSIONS: The results of the corneosurfametry allowed us to classify the products in three categories, with increasing aggressiveness towards the stratum corneum, according to their IOIs. The in vivo tests were not able to discriminate between the products, but ranks from the results of the bioengineering measurements showed a good correlation between TEWL changes, but not between colour changes, and IOIs from corneosurfametry. Corneosurfametry emerged as a simple, low-cost and fast method for ranking commercial products according to their mildness. However, the skin bioengineering techniques showed that some products could lead to skin reactions, such as erythema, that could not be detected by the in vitro technique.

Colorimetry↗
PubMed2001

Lip sun protection factor of a lipstick sunscreen.

BACKGROUND AND OBJECTIVE: There is a well-documented need for effective human UVA and UVB photoprotection. Since there are important anatomical variations, the sun protection factor (SPF) of a lipstick sunscreen was measured on the anatomical site intended for use. METHODS: The SPF tests were performed according to Federal US and European COLIPA guidelines. Prior to performing a test on the lip, the minimal erythemal dose (MED) of the unprotected back skin was determined. Subsequently, the sunscreen SPF was measured on the anatomical target site (lip). The evaluator was blinded with respect to scoring the SPF of each sunscreen treatment. Individual test sites were assigned to one of the following treatment conditions: (1) no treatment (MED of unprotected skin); (2) test formulation; (3) reference standard. RESULTS: The MED on unprotected back skin was found to be 25% lower than on unprotected lip skin. The SPF of the lipstick sunscreen was measured 2 units lower than the SPF determined in the classical way on the back skin. CONCLUSION: It was hypothesized that the higher MED of the lower lip compared with back skin was due to the adaptation of this tissue to the continuous exposure to UV radiation.

Cosmetics↗
PubMed2001

Microbiological quality of topical drug formulations: efficacy of antimicrobial preservation against Paecilomyces lilacinus.

BACKGROUND: Microbiological quality of topical products comprises both, the microbiological purity of the unopened product and the efficacy of the antimicrobial preservation system. OBJECTIVE: Subsequent to an outbreak of invasive Paecilomyces lilacinus mycosis among patients of an isolation ward, probably caused by a contaminated skin care product, the microbiological quality of different skin care products from the market was investigated. METHODS: The different products were investigated for their efficacy of antimicrobial preservation in general and especially against P. lilacinus according to a pharmacopoeial routine method slightly adopted for the purpose of this investigation. RESULTS: The products did partially not comply with the British Pharmacopoeia 1993 test for efficacy of antimicrobial preservation. The antimicrobial preservation systems were less effective against P. lilacinus than against the pharmacopoeial reference germs. The antimicrobial preservation efficacy decreased towards the end of the shelf-life of the product. A decreased P. lilacinus inoculum dose was related to an increased growth of the micro-organisms. CONCLUSION: Topical products are, unless not labelled otherwise, non-sterile preparations and their preservation systems are only tested against pharmacopoeial key micro-organisms. The microbiological behaviour following contamination with other germs remains unknown.

Administration, Topical↗
PubMed2001

Photostabilization of butyl methoxydibenzoylmethane (Avobenzone) and ethylhexyl methoxycinnamate by bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S), a new UV broadband filter.

It is now well documented that chronic UVA exposure induces damage to human skin. Therefore, modern sunscreens should not only provide protection from both UVB and UVA radiation but also maintain this protection during the entire period of exposure to the sun. UVA filters, however, are rare and not sufficiently photostable. We investigated the effect of the introduction of a new UV filter, bis-ethylhexyloxyphenol methoxyphenyl triazine (Tinosorb S), in oil in water sunscreen formulations on the photostability of butyl methoxydibenzoylmethane (Avobenzone [AVB]) after irradiation with an optically filtered Xenon arc source (UV irradiance adjusted at 1 mean effective dose [MED]/min). With spectrophotometrical methods to assess the sun protection factor (SPF) and UVA ratio and chromatographical methods to determine the amount of UV filters recovered after irradiation we showed that Tinosorb S prevented the photodegradation of AVB in a concentration-dependent way, leading to a sustained SPF and UVA ratio even after irradiation with doses of up to 30 MED. Since AVB was shown to destabilize ethylhexyl methoxycinnamate (EHM) we tested the effect of Tinosorb S in sunscreens containing this UV filter combination. Here too Tinosorb S showed photoprotective properties toward both UV filters. Thus, Tinosorb S can be used successfully to improve the photostability and efficiency of sunscreens containing AVB and EHM.

Benzoates↗
PubMed2000

Efficacy of a barrier cream and its vehicle as protective measures against occupational irritant contact dermatitis.

The actual advantage of barrier creams over bland emollients for skin protection is still hotly debated. In a randomized, double-blinded study, a newly-introduced barrier cream and its moisturizing vehicle were compared regarding their skin compatibility, efficacy and resulting acceptance. Thus, 2 panels of 25 hospital nurses with mild signs of skin irritation were asked to use 1 of the test products provided (verum or vehicle) over a period of 4 weeks. Effects of both types of preparations were studied weekly by clinical examination and the instrumental assessment of bioengineering parameters. Results showed no significant differences between barrier cream and vehicle. In both groups, clinical skin status improved and stratum corneum hydration increased significantly during the study period. Both preparations were tolerated and accepted well, thus showing both skin protection and skin care. These results contribute to the debate as to whether a strict distinction between "skin care" and "skin protection" products is justified. The vehicle alone is capable of positively influencing skin status. Emphasis must be laid on regular, frequent, and correct application of a product for it to be effective.

Adult↗
PubMed1999

Percutaneous absorption of salicylic acid in man after topical administration of three different formulations.

OBJECTIVE: To determine the amount of drug which is absorbed during 1 day following topical application of three different preparations containing salicylic acid. METHODS: Ten grams of the formulations, either (a) Kerasaltrade mark 5% ointment, (b) salicylic acid 5% or (c) 10% in petrolatum, were administered consecutively to a 600-cm2 area on alternating sides of the back of healthy volunteers (n = 9). Thirty minutes after application, a skin area of 2.54 cm2 was stripped with D-Squametrade mark adhesive disks to determine the amount of salicylic acid in the stratum corneum. The entire application site was then covered by a thin gauze bandage and was not washed for the next 24 h. Urine was collected for 26 h following administration, hydrolyzed and assayed by HPLC analysis. RESULTS: The absolute amounts absorbed and excreted were 52.6 +/- 29.4 mg (mean +/- SD), 127.1 +/- 43.9 mg and 208.0 +/- 81.7 mg, and the doses absorbed in relation to the doses applied (500 mg salicylic acid in case of formulations a and b and 1,000 mg for formulation c) were 9.3 +/- 3.8, 25.1 +/- 8.5 and 20.2 +/- 7.7%, respectively. The amounts of salicylic acid in the skin 30 min after application were 36.3 +/- 16.5, 18.2 +/- 11.9 and 31.3 +/- 15.4 microg/ cm2 as determined by the tape stripping procedure. CONCLUSIONS: Significant differences in the doses absorbed were detected between the two formulations a and b (same concentration) with different vehicles (p value < 0.001) as well as between b and c (same vehicle) with different concentrations (p value = 0.018) using Student's paired t test. These results demonstrate that salicylic acid is well absorbed by healthy skin.

Administration, Cutaneous↗
PubMed1999

Effect of topical antioxidants on UV-induced erythema formation when administered after exposure.

BACKGROUND: Photoprotective effects of topically applied antioxidants when applied before ultraviolet radiation (UVR) exposure are well known. Their protective effect when applied after UVR exposure is, however, less established. OBJECTIVE: In a randomized, double-blinded, placebo-controlled human study the short-term photoprotective effects of different antioxidants and of their combinations were evaluated when applied after UVR exposure. METHODS: Melatonin (N-acetyl-5-methoxytryptamine), vitamin E (alpha-tocopherol) and vitamin C (ascorbic acid) were topically administered alone or in combination following UVR exposure as single applications (immediately or 30 min after irradiation, respectively) or as multiple applications (three times: 30 min, 1 h and 2 h after irradiation). The erythemal reaction was evaluated visually and noninvasively with bioengineering methods (skin color and skin blood flow). RESULTS: No significant protective effect of melatonin or the vitamins when applied alone or in combination were obtained when antioxidants were applied after UVR exposure. No improved photoprotective effect was obtained when multiple applications were done. CONCLUSION: UVR-induced skin damage is a rapid event, and antioxidants possibly prevent such damage only when present in relevant concentration at the site of action beginning and during oxidative stress.

Administration, Cutaneous↗
PubMed1998

Topical melatonin in combination with vitamins E and C protects skin from ultraviolet-induced erythema: a human study in vivo.

In this randomized, double-blind human study, the short-term photoprotective effects of different antioxidants and their combinations were evaluated in vivo. Vitamin C (ascorbic acid), vitamin E (alpha-tocopherol) and melatonin (N-acetyl-5-methoxytryptamine) were topically applied, alone or in combination, 30 min before ultraviolet-irradiation of the skin. The erythemal reaction was evaluated visually and non-invasively using different bioengineering methods (skin colour and skin blood flow). The results showed a modest protective effect of the vitamins when applied alone and a dose-dependent photoprotective effect of melatonin. Topical application of combinations of both vitamins, or of melatonin with vitamins, enhanced the photoprotective response. Better protection was obtained by using the combination of melatonin with both vitamins. The role of reactive oxygen species and oxygen-derived free radicals, as well as potential sunscreening properties of the employed antioxidants, are discussed in view of possible mechanisms to explain this elevated photoprotective effect.

Administration, Cutaneous↗
PubMed1996

Skin penetration and sun protection factor of ultra-violet filters from two vehicles.

PURPOSE: In order to improve our knowledge on the efficacy and safety of sunscreen products, we measured the skin penetration profiles of ultra-violet (UV) filters in vitro and in vivo, and the corresponding sun protection factors (SPF) from two vehicles (an O/W emulsion-gel and petroleum jelly). METHODS: The UV filters tested were oxybenzone (5%, A), 2-ethylhexyl 4-methoxycinnamate (7.5%,B), and 2-ethylhexylsalicylate (3%,C). Two mg/cm(2) were applied for 2 min to 6 h. In vitro penetration measurements were performed with static diffusion cells. In vivo, horny layer concentrations were measured after stripping and the SPF evaluated as recommended by the COLIPA-guidelines. RESULTS: Significant differences between vehicles were noticed in vitro as well as in vivo. In vitro, the emulsion-gel generated higher epidermal concentrations than petroleum jelly. Values at 6 h, expressed as percent of the applied dose for A, B, and C were 4, 9, and 7% for the emulsion-gel and 2, 1, and 2% for petroleum jelly. An opposite trend was noticed, mainly for A, in the deeper skin layers with concentrations of 2% in the dermis and 5% in the receptor fluid for petroleum jelly and 0.6% and 1% for the emulsion-gel respectively. In vivo, for each UV filter, maximal stratum corneum levels (15 strips) were obtained at 0.5 h with percentages of the applied doses of 50% for the emulsion-gel and 15 percent for petroleum jelly. SPFs, measured 0.5 h after application amounted to 14 for the emulsion-gel and 5 for petroleum jelly, and decreased in both cases by a factor 2.2 after removal of non penetrated product. CONCLUSIONS: These preliminary results demonstrated that UV filters penetration and retention as well as expected SPF could be optimized by a suitable vehicle.

Chromatography, High Pressure Liquid↗
PubMed1996

Emollients and photo(chemo)therapy: a call for caution.

BACKGROUND: Emollients used for skin care, treatment of a disease or lubrication, before irradiation during the course of phototherapy or photochemotherapy, may significantly interfere with the transmission of UV light and may influence the outcome of the therapy. OBJECTIVE: These experiments should characterize and quantify the possible interactions of usual emollients with UV light transmission. METHOD: The method was an in vitro technique similar to the one already used for the determination of sun protection factors of topical sunscreen preparations. RESULTS: Among the products tested, two showed a significant photoprotection capable of interfering with the course of therapy. Oils enhanced UV light transmission significantly. CONCLUSIONS: Emollients may show significant interference with UV light transmission during phototherapy or photochemotherapy. The outcome and course of the therapy could thus be significantly modified.

Contraindications↗
PubMed1996

Measurement of sodium lauryl sulfate-induced skin irritation.

Besides visual evaluation, skin irritation induced by sodium lauryl sulfate (SLS) may be characterized by bioengineering measurements, such as skin colour reflectance, transepidermal water loss (TEWL) or hydration. Short application times or low concentrations of the irritant usually do not modify the visual aspect of the skin, and the measurements described above are unchanged or only slightly altered. We were looking for a suitable method to measure cutaneous changes not detectable by usual bioengineering procedures. Therefore these measurements were compared to those of dynamic function testing of the stratum corneum, namely sorption-desorption and moisture accumulation tests. Different concentrations of SLS (0.1%, 0.5%, 2.5%), application times (15 min, 24 h) and times of testing (1 h, 24 h after patch removal) were investigated on the ventral forearm of human subjects. When SLS was applied for a short period (15 min), 1 h after patch removal skin colour, TEWL and hydration were not modified, while increases in hygroscopicity, water-holding capacity and water accumulation were detected depending on the applied concentration. Increase of hygroscopicity was closely correlated with the alteration of epidermal barrier function (TEWL). We demonstrated that sorption-desorption and moisture accumulation tests performed on SLS-treated areas for a short period, without visible modifications, could evaluate changes of the stratum corneum properties. We consider these tests as useful complementary methods to skin colour, TEWL and hydration measurements, particularly in the detection of subclinical skin injuries.

Adult↗
PubMed1996

[Helicobacter pylori eradication therapy with bismuth citrate/amoxycillin combination therapy].

The efficacy of a new combination preparation containing bismuth citrate and amoxicillin in one tablet was compared with the efficacy of bismuth citrate monotherapy in a randomised double-blind study on the eradication of Helicobacter pylori. The study involved 70 H. pylori positive (antrum biopsies showing a positive urease test) patients with non-ulcer dyspepsia and chronic gastritis. The treatment period was 14 days; 35 patients in group 1 received 2 tablets tid containing the bismuth citrate amoxicillin combination (BIAM tablet; 250 mg amoxicillin base and 120 mg bismuth); 35 patients in group 2 were treated with 2 tablets tid containing bismuth citrate (BI tablet; 120 mg bismuth). Total daily dose was therefore 1500 mg amoxicillin + 720 mg bismuth in group 1 patients resp. 720 mg bismuth in group 2 patients. 4 weeks after therapy H. pylori could not be histologically detected in the antrum of 22 patients (63%) in group 1 and 8 patients (24%) in group 2. Thus in group 1 (BIAM) a significantly higher eradication rate (p < 0.001) was shown than in group 2 (BI). Inflammation characterized by the infiltration of polymorphonuclear cells was significantly (p < 0.01) less pronounced in group 1 (BIAM) than in group 2 (BI) 4 weeks after the end of treatment. Gastrointestinal distress was quantified by evaluation of 13 different symptoms using a fourpoints scale at the beginning of the study and after 2 and 6 weeks. The sum of scores decreased by 81% in group 1 (BIAM) and 71% in group 2 (BI) after 6 weeks.

Adult↗
PubMed1995

Comparison of the bioavailability of dexibuprofen administered alone or as part of racemic ibuprofen.

Two bioavailability studies of S(+)-ibuprofen (dexibuprofen) were conducted in healthy volunteers to define the relationship between the bioavailability of the drug after administration of dexibuprofen alone or as part of ibuprofen racemate. Enantioselective plasma drug analysis was used throughout. In the first study, the bioavailability of dexibuprofen from a 400 mg tablet formulation was compared with that from 400 mg in aqueous solution. The tablet formulation did not influence the bioavailability of the drug and dexibuprofen was well absorbed from the gastro-intestinal tract. The second study was divided into three identical parts. Bioavailability of dexibuprofen 200, 400 and 600 mg was compared with its bioavailability from ibuprofen racemate 400, 800 and 1200 mg. The second study showed that the mean relative bioavailability of dexibuprofen to ibuprofen racemate was 0.66, thus enabling the estimation of clinically useful dexibuprofen doses from the usual doses of the racemate. The 95% confidence interval limits did not include 0.5, leading to the conclusion that administering half of the racemate dose would not provide patients with an adequate amount of therapeutically active drug.

Adult↗
PubMed1995

Stratum corneum dynamic function measurements after moisturizer or irritant application.

Two simple tests were conducted which allowed the quantification of parameters that characterize the stratum corneum (SC) dynamic functions in vivo under physiological conditions after moisturizer applications for 1 h and after irritation with different concentrations of sodium lauryl sulphate (SLS; 0.5-4%) applied under occlusion for 15 min or 24 h. Both tests, the sorption-desorption test (SDT) and the moisture accumulation test (MAT), were performed with a Nova Dermal Phase Meter 9003. The following parameters were quantified: prehydration state (SDT, MAT), hygroscopicity, water-holding capacity (SDT), water accumulation velocity and water accumulation (MAT). These procedures allowed the demonstration of the water-holding effect of urea contained in moisturizers. Differences between the long and the short application time of SLS were characterized by differences in SC dynamic functions while the hydration state was not changed. An effect on transepidermal water loss (TEWL) was noted only after the long application time, although the MAT clearly showed dynamic parameters to be changed after 15 min of treatment. These tests were simple in practice and allowed the demonstration of functional modifications of the SC while other parameters remained unchanged. They gave insight into possible action mechanisms of urea and SLS in the SC.

Adult↗
PubMed1994

Evaluation of barrier creams: an in vitro technique on human skin.

A method was developed to measure in vitro on human skin the effectiveness of barrier creams against three dyes (eosin, methyl-violet and oil red O) with different n-octanol/water partition coefficients (0.19, 29.8 and 165, respectively). Some galenic properties (water washability, water content and viscosity) of the products were also evaluated to try to understand the mechanisms of such a protection. The barrier creams were assayed by measurements of the dyes in the epidermis of protected skin samples after an application time of 30 min. Whereas some products showed some degree of protection, as claimed on the packaging, we demonstrated in several cases disagreement with the manufacturer's information. Surprisingly, petrolatum was found to provide the best protection of all tested products in our in vitro model. There was no correlation between the galenic parameters of the assayed products and the level of protections, indicating that neither the water content nor the consistence of the formulations influenced the protection effectiveness. In conclusion, regarding the possible skin effects of some irritants, our results stress that barrier creams should be used with caution, knowing the protection limits of some of the formulations marketed.

Administration, Cutaneous↗