Fungicidal activity plus reservoir effect allow short treatment courses with terbinafine in tinea pedis

Terbinafine, a synthetic allylamine, exerts fungicidal activity against dermatophytes, the causative pathogens of tinea pedis. As proven in numerous clinical trials, tinea pedis can be effectively and safely treated by topical terbinafine. In fact, a 1-week application of terbinafine 1% cream eradicated fungal pathogens at least as effectively as 4-week treatment courses with topical azole derivative antifungals and showed lower relapse rates. A new innovative single-application formulation of terbinafine 1% in a film-forming solution produces a high concentration gradient on the skin surface and enables a prolonged (up to 13 days) exposure of the skin to terbinafine. High drug penetration into the skin results in an otherwise not obtained drug reservoir in the horny layer, the location of dermatophytes in tinea pedis. Although azole antimycotics can also effectively penetrate into the horny layer of the skin, short-term therapy might not be feasible due to its primarily fungistatic activity against dermatophytes. Thus, we conclude that the high efficacy of short-term treatment with terbinafine in patients with tinea pedis is possible due to its fungicidal activity coupled with a distinct reservoir formation in the upper layers of the epidermis. Copyright (C) 2008 S. Karger AG, Basel

Innovative Agents for Actinic Keratosis and Nanocarriers Enhancing Skin Penetration

Actinic keratosis and cutaneous squamous cell carcinoma are of increasing importance with aging and increased ultraviolet light exposure in Western societies. Efficient and well-tolerated therapy is still a matter of concern. As with tumours of other organs, new target sites and innovative drugs selectively addressing them are widely looked for. Due to the relevance for DNA synthesis and thus cell proliferation, human DNA polymerase alpha should be such a target, the more so as the three-dimensional structure of the active site has been proposed based on the application of molecular modelling methods and molecular dynamics simulations. The modelled structure of the active site was used for docking nucleotide analogues in order to design selective inhibitors. Consequently, well-fitting thymidine and guanosine analogues were synthesized and tested in vitro for their influence on normal and transformed human keratinocytes. In fact, the combination of modelling studies and in vitro tests allowed us to design antiproliferative and cytotoxic agents which are new drug candidates for the therapy of skin tumours, given the agents are no relevant substrates of nucleotide transporters (MRP-4, MRP-5) expressed by skin cancer cells. Essential kinases for nucleoside activation were detected, too, corresponding with the observed effects of nucleoside analogues. Due to the rather high molecular weight and poor solubility, however, skin penetration should be poor and thus topical therapy may require carriers to improve the uptake. This becomes feasible by lipidic and non-lipidic nanoparticles which can enhance the uptake of lipophilic agents up to 13-fold. Copyright (C) 2010 S. Karger AG, Base

Morphine Metabolism in Human Skin Microsomes

For patients with severe skin wounds, topically applied morphine is an option to induce efficient analgesia due to the presence of opioid receptors in the skin. However, for topical administration it is important to know whether the substance is biotransformed in the skin as this can eventually reduce the concentration of the active agent considerably. We use skin microsomes to elucidate the impact of skin metabolism on the activity of topically applied morphine. We are able to demonstrate that morphine is only glucuronidated in traces, indicating that the biotransformation in the skin can be neglected when morphine is applied topically. Hence, there is no need to take biotransformation into account when setting up the treatment regimen. Copyright (C) 2012 S. Karger AG, Base

Glucocorticoids for human skin: New aspects of the mechanism of action

Topical glucocorticoids have always been considered first-line drugs for inflammatory diseases of the skin and bronchial system. Applied systemically, glucocorticoids are used for severe inflammatory and immunological diseases and the inhibition of transplant rejection. Owing to the progress in molecular pharmacology, the knowledge of the mechanism of action has increased during the last years. Besides distinct genomic targets, which are due to the activation of specific cytoplasmatic receptors resulting in the (trans-) activation or (trans-) repression of target genes, there are non-genomic effects on the basis of the interference with membrane-associated receptors as well as with membrane lipids. In fact, various glucocorticoids appear to differ with respect to the relative influence on these targets. Thus, the extended knowledge of glucocorticoid-induced cellular signalling should allow the design and development of even more specifically acting drugs-as it has been obtained with other steroids, e.g. estrogens for osteoporosis prevention. Copyright (C) 2005 S. Karger AG, Basel

The Phenion (R) Full-Thickness Skin Model for Percutaneous Absorption Testing

In recent years many efforts have been made to replace dermal toxicity testing of chemicals in the animal by in vitro assays. As a member of a German research consortium, we have previously contributed to the validation of an in vitro test protocol for percutaneous absorption studies on the basis of reconstructed human epidermis and both human and pig skin ex vivo. Aiming to assess the barrier properties of a newly developed reconstructed skin model, this protocol has now been transferred to the Phenion (R) Full-Thickness Skin Model (FT model). The permeation of testosterone and caffeine was quantified in parallel to that of pig skin using Franz-type diffusion cells. In addition, the permeation of benzoic acid and nicotine was studied. As expected, the FT model is more permeable than pig skin, yet its barrier properties are well in accordance with those of reconstructed human epidermis when compared to previous data. In fact, the FT model most efficiently retards testosterone as the compound of highest lipophilicity, which can be explained by an additional uptake by a reservoir formed by the dermis equivalent. Thus, the structure closely parallels human skin. In consequence, the Phenion FT model appears to be suitable for percutaneous absorption studies in hazard analysis and should be subjected to a catch-up validation study. Copyright (C) 2009 S. Karger AG, Base

Morphine Stimulates Cell Migration of Oral Epithelial Cells by Delta-Opioid Receptor Activation

Oral mucositis is one of the most common side effects of chemoradiation regimens and manifestation can be dose-limiting for the therapy, can impair the patient's nutritional condition and quality of life due to severe pain. The therapeutic options are limited; often only an alleviation of the symptoms such as pain reduction by using systemic opioids is possible. Stimulating opioid receptors on peripheral neurons and dermal tissue, potent analgesic effects are induced e.g. in skin grafted patients. Advantageous effects on the cell migration and, thus, on the wound healing process are described, too. In this study, we investigated whether opioid receptors are also expressed on oral epithelial cells and if morphine can modulate their cell migration behavior. The expression of the opioid receptors MOR, DOR and KOR on primary human oral epithelial cells was verified. Furthermore, a significantly accelerated cell migration was observed following incubation with morphine. The effect even slightly exceeded the cell migration stimulating effect of TGF-ß: After 14 h of morphine treatment about 86% of the wound area was closed, whereas TGF-ß application resulted in a closed wound area of 80%. With respect to morphine stimulated cell migration we demonstrate that DOR plays a key role and we show the involvement of the MAPK members Erk 1/2 and p38 using Western blot analysis

Fungicidal activity plus reservoir effect allow short treatment courses with terbinafine in tinea pedis

Terbinafine, a synthetic allylamine, exerts fungicidal activity against dermatophytes, the causative pathogens of tinea pedis. As proven in numerous clinical trials, tinea pedis can be effectively and safely treated by topical terbinafine. In fact, a 1-week application of terbinafine 1% cream eradicated fungal pathogens at least as effectively as 4-week treatment courses with topical azole derivative antifungals and showed lower relapse rates. A new innovative single-application formulation of terbinafine 1% in a film-forming solution produces a high concentration gradient on the skin surface and enables a prolonged (up to 13 days) exposure of the skin to terbinafine. High drug penetration into the skin results in an otherwise not obtained drug reservoir in the horny layer, the location of dermatophytes in tinea pedis. Although azole antimycotics can also effectively penetrate into the horny layer of the skin, short-term therapy might not be feasible due to its primarily fungistatic activity against dermatophytes. Thus, we conclude that the high efficacy of short-term treatment with terbinafine in patients with tinea pedis is possible due to its fungicidal activity coupled with a distinct reservoir formation in the upper layers of the epidermis. Copyright (C) 2008 S. Karger AG, Basel

Ultraviolet B irradiation-induced keratinocyte senescence and impaired development of 3D epidermal reconstruct

Ultraviolet B (UVB) induces morphological and functional changes of the skin. This study investigated the effect of UVB on keratinocyte senescence and the development of reconstructed human epidermis (RHE). Primary normal human keratinocytes (NHK) from juvenile foreskin were irradiated with UVB (30 mJ cm–2) and these effects were compared to NHK that underwent senescence in the late passage. UVB enhanced the accumulation of reactive oxygen species (ROS) and halted cell replication as detected by BrdU cell proliferation assay. The senescence phenotype was evaluated by beta-galactosidase (β-gal) staining and qPCR of genes related to senescent regulation, i.e. p16INK4a, cyclin D2, and IFI27. Senescence induced by high dose UVB resulted in morphological changes, enhanced β-gal activity, elevated cellular ROS levels and reduced DNA synthesis. qPCR revealed differential expression of the genes regulated senescence. p16INK4a expression was significantly increased in NHK exposed to UVB whereas enhanced IFI27 expression was observed only in cultural senescence. The levels of cyclin D2 expression were not significantly altered either by UVB or long culturing conditions. UVB significantly induced the aging phenotype in keratinocytes and impaired epidermal development. RHE generated from UVB-irradiated keratinocytes showed a thinner cross-sectional structure and the majority of keratinocytes in the lower epidermis were degenerated. The 3D epidermis model is useful in studying the skin aging process

pH-Sensitive Chitosan–Heparin Nanoparticles for Effective Delivery of Genetic Drugs into Epithelial Cells

Chitosan has been extensively studied as a genetic drug delivery platform. However, its efficiency is limited by the strength of DNA and RNA binding. Expecting a reduced binding strength of cargo with chitosan, we proposed including heparin as a competing polyanion in the polyplexes. We developed chitosan–heparin nanoparticles by a one-step process for the local delivery of oligonucleotides. The size of the polyplexes was dependent on the mass ratio of polycation to polyanion. The mechanism of oligonucleotide release was pH-dependent and associated with polyplex swelling and collapse of the polysaccharide network. Inclusion of heparin enhanced the oligonucleotide release from the chitosan-based polyplexes. Furthermore, heparin reduced the toxicity of polyplexes in the cultured cells. The cell uptake of chitosan–heparin polyplexes was equal to that of chitosan polyplexes, but heparin increased the transfection efficiency of the polyplexes two-fold. The application of chitosan–heparin small interfering RNA (siRNA) targeted to vascular endothelial growth factor (VEGF) silencing of ARPE-19 cells was 25% higher. Overall, chitosan–heparin polyplexes showed a significant improvement of gene release inside the cells, transfection, and gene silencing efficiency in vitro, suggesting that this fundamental strategy can further improve the transfection efficiency with application of non-viral vectors