PubMed · 12465536
Psoriasis affects patients to varying degrees, and may seriously impair their quality of life. Treatments minimise symptoms but cannot cure the condition.
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Janet Blake. 2002. Psoriasis.. https://pubmed.ncbi.nlm.nih.gov/12465536/
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In the present study, the influence of vesicle size on the penetration of two fluorescently labeled substances into the human skin was investigated. For the measurements either a hydrophilic fluorescent compound [carboxyfluorescein (CF)] or a lipophilic one [1,1'-dioctadecyl-3,3,3',3'-tertramethylindocarbo-cyanine perchlorate (DiI)] were encapsulated into vesicles. Liposomal formulations were prepared by extruding the vesicles through polycarbonate membrane filters with pores of different sizes. In vitro penetration studies into human abdominal skin were performed by using the Franz diffusion cell and a standardized skin stripping technique in attempt to find an optimum size for topical drug delivery by liposomes. Confocal laser scanning microscopy (CLSM) was used to visualize the effect of penetration ability of liposomal DiI. The maximum DiI fluorescence in the skin was observed with smaller liposomes of 71 nm diameter. The liposomes with a size of 120 nm diameter showed statistically enhanced penetration of CF into the skin as compared to larger ones. The results indicated that the CF penetration was inversely related to the size of the liposomes, which was confirmed by the data of the confocal laser scanning microscopy studies.
The aim of this study was to prepare solid lipid microspheres (SLM) of octyl methoxy cinnamate (2-ethylhexyl-p-methoxy cinnamate; OMC) to achieve controlled release, decrease penetration of this UV absorber from skin and improve its photostability. The influence of the carrier on the rate of release was studied in vitro with a cellulose acetate membrane and in vivo from excised rat skin with Franz diffusion cells. The release rate was decreased by up to 13-80% with the SLM formulation. In vivo, penetration of OMC into skin was investigated by HPLC method. It was found out that the rate of penetration is significantly dependent upon the formulation and could be decreased by up to 77% in SLM formulations. When different topical vehicles were compared, OMC was released and penetrated into rat skin more quickly and in greater amount from vehicles containing free OMC than in SLM form. Additionally, photostability was shown to be improved in SLM form.
3-l-Menthoxypropane-1,2-diol (MPD) is a derivative of l-menthol, which has an enhancement effect on drug permeation through skin. In this study, the effect of MPD on drug permeation through skin was compared with that of l-menthol. MPD or l-menthol at final concentrations of 3% in 40% ethanol was added to the drugs indomethacin or antipyrine and each mix then applied to Yucatan micropig skin in vitro. Drug concentrations in the skin were higher in the presence of either MPD or l-menthol, however, only l-menthol shortened the lag time of permeation. MPD enhanced the skin permeation of the drugs only by increasing the skin concentration of the drugs. In contrast, l-menthol enhanced the skin permeation of the drugs by increasing both the skin concentration and the diffusion rate in skin. The infrared (IR) spectra and X-ray diffraction patterns of stratum corneum after treatment with MPD did not differ from those of intact stratum corneum. A change in the IR spectra of stratum corneum after treatment with l-menthol was observed at the CH band, and the peaks representative of the lipid structure in the X-ray diffraction patterns decreased in intensity. These results suggest that l-menthol, but not MPD, disrupts the intercellular lipid structure of stratum corneum. Thus, MPD is expected to be a moderate skin permeation enhancer.