1,721,045 research outputs found
Effect of hydroxypropyl-beta-cyclodextrin on butyl-methoxydibenzoylmethane from lipid microparticles
No full textButyl methoxydibenzoylmethane (BMDBM), the most widely used UVA absorber has been shown to be photo-unstable and to exhibit appreciable permeation into human stratum corneum and viable epidermis. In earlier investigations we demonstrated that complexation of BMDBM with hydroxypropyl--cyclodextrin (HP--CD) reduced the sunscreen degradation under simulated sunlight although no significant influence on the percutaneous penetration of the UVA filter was observed. The purpose of this study was to evaluate whether the encapsulation of the BMDBM/HP--CD complex into lipid microparticles could affect the skin permeation of the sunscreen agent. Microparticles loaded with free BMDBM or its complex with HP--CD were prepared by the melt emulsification technique using tristearin as lipidic material and hydrogenate phosphatidylcholine as the surfactant. The lipoparticles loaded with free BMDBM or BMDBM/HP--CD complex were incorporated in a model O/W emulsion and their influence on the UV filter percutaneous penetration was assessed in vivo on humans by the tape-stripping technique. Compared to the formulation with the non-encapsulated sunscreen agent (percentage of the applied dose penetrated, 9.7%±2.5), the amount of BMDBM diffusing into the stratum corneum was increased by the formulations containing the BMDBM/HP--CD complex (17.1% ± 3.2 of the applied dose) or the microparticles loaded with BMDBM only (15.1% ± 2.7 of the applied dose). On the contrary, a significant reduction in the level of UV filter retained into the stratum corneum was achieved by the formulation containing the microencapsulated BMDBM/ HP--CD complex (percentage of the applied dose penetrated, 6.0%±1.5). Differences were detected among the formulations also in the sunscreen distribution in the horny layer, statistical significance being measured in the intermediate part of the stratum corneum (strips 5-7). The reduced BMDBM percutaneous penetration achieved by the lipid microparticles incorporating the sunscreen in the cyclodextrin complex form, should enhance the UV filter efficacy and limit potential toxicological risks
Influence of penetration enhancers and lipid nanoparticles on in vivo human skin penetration of quercetin
No full textQuercetin has been shown in animal and human skin to inhibit, in vitro an in vivo, the adverse effects caused by the sun UV rays. However, the skin protective activity of quercetin is hampered by its inefficient percutaneous penetration. Object of this study was the comparative evaluation of emulsions containing penetration enhancer or lipid noanoparticles on the skin penetration of the flavonoid.The study indicated that the nanoparticles achieved a targeting effect, favouring the localisation of the flavonoid in the superficial skin layers
Effect of the vehicle on in vitro skin permeation of glycolic acid loaded liposheres
No full textPurpose: To evaluate the effect of the microencapsulation in lipospheres on glycolic acid percutaneous absorption from different vehicles.
Methods: Lipospheres loaded with glycolic acid, prepared by the melt method using tristearin as the lipid phase and hydrogenated soybean phosphatidylcholine as the emulsifier, were introduced in three different cosmetic formulations (petrolatum jelly, W/O and O/W emulsions) obtaining a 10% glycolic acid concentration. The study of percutaneous absorption was carried out by means a properly adapted diffusion chamber through a lipophilized membrane simulating the horney layer. The data were compared with those obtained by assaying the formulations containing the unencapsulated active substance.
Results: The entrapment of glycolic acid in lipospheres (loading level 27.2 4.1 % w/w) produced a significant decrease in glycolic acid skin penetration rate. Unlike the unencapsulated substance, showing a clear dependence on vehicle properties, the in vitro skin penetration behaviour from lipospheres resulted uneffected by the formulation.
Conclusions: Lipospheres loaded with glycolic acid, characterized previously both in vitro for morphology, size, loading level and release and in vivo for skin tolerance and cell renewal efficacy, showed the capability to retain glycolic acid regardless its partitioning between the vehicle and the lipophilized membrane. Therefore, the microparticle structure, having a predominant role on the vehicle, can determine the modulation of the cutaneous absorption and, consequently, decrease glycolic acid side local effects
Santo Stefano in Arce
No full textIl saggio presenta il caso della chiesa di Santo Stefano in Arce sul colle Cidneo a Bresci
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Una “città da ferro” all’ombra del Castello: gestione dell’ordine pubblico e rapporti con la Dominante nella Brescia secentesca
No full textIl documento tratta della storia e della gestione del Castello di Brescia durante il periodo della dominazione veneziana nel XVI e XVII secolo. In particolare viene analizzato il suo ruolo alla luce delle politiche della difesa veneziane in Terraferm
Formulations containing Ursodeoxycholic acid for the improvement of the dissolution behaviour of the drug
No full textSolid Lipid Nanoparticles for the sustained release of a prodrug of Zidovudine by its conjugation with ursodeoxycholic acid
No full textPurpose: We report a study of encapsulation and release from solid lipid microparticles (SLMs) of a prodrug of zidovudine (AZT), an antiviral agent, obtained by its ester conjiugation with a bile acid, the ursodeoxycholic acid (UDCA). We have demonstrated that this prodrug is able to elude the active efflux systems expressed on physiological barriers.
Results: The mean diameters of tristerain and stearic acid loaded microparticles were 7 and 14 micron, respectively. The shape of the SLMs was spherical and their prodrug loading was 0.57% (tristearin based) and 1.84% (stearic acid based). The tristearin SLMs were able to control the release of the prodrug, whereas the stearic acid SLMs induced a significant increase of the dissolution rate of the free prodrug obtained in the presence of Twwen 60.
Conclusions. The developed SLMs were represent a good candidate for the local delivery of UDCA-AZT in the nose and its potential uptake in the brain
In vitro and in vivo skin permeation of glycolic acid
No full textEvaluation in vitro skin permeation of glycolic acid from two different skin formulation and comparison the in vitro data with those obtained in vivo by means tape-stripping technique in humans. As far as the vehicle influence, in vivo glycolic acid skin permeation extent was predicted by the in vitro data. On the contrary, the in vitro assay provided an overestimation of absorption that can be probably explained by glycolic acid penetration into the unremoved stratum corneum layers
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