PubMed · 9118636
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B Santucci, C Cannistraci, E Camera, A Cristaudo, M Picardo. 1996. Thimerosal positivities.. https://doi.org/10.1111/j.1600-0536.1996.tb02422.x
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Cyclodextrins are cyclic oligosaccharides with a hydrophilic outer surface and a somewhat lipophilic central cavity. Cyclodextrins are able to form water-soluble inclusion complexes with many lipophilic water-insoluble drugs. In aqueous solutions drug molecules located in the central cavity are in a dynamic equilibrium with free drug molecules. Furthermore, lipophilic molecules in the aqueous complexation media will compete with each other for a space in the cavity. Due to their size and hydrophilicity only insignificant amounts of cyclodextrins and drug/cyclodextrin complexes are able to penetrate into lipophilic biological barriers, such as intact skin. In general, cyclodextrins enhance topical drug delivery by increasing the drug availability at the barrier surface. At the surface the drug molecules partition from the cyclodextrin cavity into the lipophilic barrier. Thus, drug delivery from aqueous cyclodextrin solutions is both diffusion controlled and membrane controlled. It appears that cyclodextrins can only enhance topical drug delivery in the presence of water.
Treatments currently employed for plantar warts are often painful (electrosurgery, cryotherapy) and not always effective (keratolytic agents). In this paper we investigate the effect of photodynamic therapy (PDT) with topical delta-aminolaevulinic acid (ALA) on plantar warts. In order to remove the superficial hyperkeratotic layer of the warts an ointment containing 10% urea and 10% salicylic acid was applied for 7 days. After gentle curettage, a cream containing 20% ALA was applied under an occlusive dressing for 5 h on 64 warts, while 57 warts (controls) received only the vehicle. Both the ALA-treated warts and the controls were irradiated using a visible light lamp (with a range of 400-700 nm, peaking at 630 nm). The light dose was 50 J/cm(2). Patients were followed-up for 22 months. Two months after the last irradiation session 48 (75.0%) out of 64 ALA-PDT treated warts had resolved. By contrast only 13 (22.8%) of the 57 control warts had done so. During the treatment a few patients complained of a mild burning sensation. The absorption of ALA by the verrucous tissue was demonstrated by in vivo fluorescence spectroscopy. This study shows that topical ALA-PDT can be an alternative treatment for plantar warts. Further studies will be necessary in order to optimize the concentration of ALA and duration of treatment.
The purpose of this study was designed to investigate the in vitro and in vivo skin absorption of capsaicin and nonivamide from hydrogels. Various commercialized creams of capsaicin were also compared with hydrogels. Both skin stripping technique and Mexameter were applied to evaluate the level of capsaicin and nonivamide retained in stratum corneum (SC) and skin erythema in vivo. The partition of drug between skin and the hydrogel matrix was considered to play an important role in the permeation process. The in vitro permeation of capsaicin from hydrogels depends on the physicochemical nature and the concentration of the polymer used. The incorporation of nonionic Pluronic F-127 polymer into hydrogels resulted in a retarded release of capsaicin. On the other hand, the in vitro capsaicin permeation showed higher levels in cationic chitosan and anionic carboxymethyl cellulose (CMC) hydrogels than cream bases. The permeation of nonivamide was retarded at the late stage of in vitro application. The inter-subject variation was more significant in the in vivo study than in vitro skin permeation experiments. The cream induced in vivo skin erythema depending on the drug concentration, however, the dose-dependence was not observed in hydrogels. Nonivamide-treated skin showed stronger erythema than capsaicin-treated skin. The present study indicates that there is a moderate correlation between in vitro skin permeation and in vivo erythema responses of topically applied capsaicin and nonivamide. The correlation between drug amount in SC and skin erythema test in vivo was also observed.