SKBM02560 MilliporeStrat-M® Membrane, Transdermal Diffusion Test Model, 25mm

Synthetic membranes that are utilized in diffusion studies for topical and transdermal formulations are usually porous thin polymeric sheets for example cellulose acetate (CA) and polysulfones. In this study, the permeability of human skin was compared using two synthetic membranes: cellulose acetate and Strat-M membrane and lipophilic and hydrophilic compounds either as saturated or formulated solutions as well as marketed dosage forms. Our data suggests that hydrophilic compounds have higher permeation in Strat-M membranes compared with lipophilic ones. High variation in permeability values, a typical property of biological membranes, was not observed with Strat-M. In addition, the permeability of Strat-M was closer to that of human skin than that of cellulose acetate. Our results suggest that Strat-M with little or no lot to lot variability can be applied in pilot studies of diffusion tests instead of human skin and is a better substitute than a cellulose acetate.

Polycyclic Aromatic Hydrocarbons are classed as Persistent Organic Pollutants, a large group of compounds that share similar characteristics. They are lipophilic, resistant to degradation in the environment and harmful to human and environmental health. Soil has been identified as the primary reservoir for Polycyclic Aromatic Hydrocarbons in the United Kingdom. This study reviews the literature associated with, or is relevant to, the measurement and modelling of dermal absorption of Polycyclic Aromatic Hydrocarbons from soils. The literature illustrates the use of in vivo, in vitro and in silico methods from a wide variety of scientific disciplines including occupational and environmental exposure, medical, pharmaceutical and cosmetic research and associated mathematical modelling. The review identifies a number of practical shortcomings which must be addressed if dermal bioavailability tests are to be applied to laboratory analysis of contaminated soils for human health risk assessment..

Using a simple solution mixing method, curcumin was dispersed in the matrix of Eudragit® E PO polymer. Water solubility of curcumin in curcumin-Eudragit® E PO solid dispersion (Cur@EPO) was greatly increased. Based on the results of several tests, curcumin was demonstrated to exist in the polymer matrix in amorphous state. The interaction between curcumin and the polymer was investigated through Fourier transform infrared spectroscopy and (1)H NMR which implied that OH group of curcumin and carbonyl group of the polymer involved in the H bonding formation. Cur@EPO also provided protection function for curcumin as verified by the pH challenge and UV irradiation test. The pH value influenced curcumin release profile in which sustained release pattern was revealed. Additionally, in vitro transdermal test was conducted to assess the potential of Cur@EPO as a vehicle to deliver curcumin through this alternative administration route.

(Trans)dermal drug therapy is gaining increasing importance in the modern drug development. To fully utilize the potential of this route, it is important to optimize the delivery of active ingredient/drug into/through the skin. The optimal carrier/vehicle can enhance the desired outcome of the therapy therefore the optimization of skin formulations is often included in the early stages of the product development. A rational approach in designing and optimizing skin formulations requires well-defined skin models, able to identify and evaluate the intrinsic properties of the formulation. Most of the current optimization relies on the use of suitable ex vivo animal/human models. However, increasing restrictions in use and handling of animals and human skin stimulated the search for suitable artificial skin models. This review attempts to provide an unbiased overview of the most commonly used models, with emphasis on their limitations and advantages. The choice of the most applicable in vitro model for the particular purpose should be based on the interplay between the availability, easiness of the use, cost and the respective limitations.

PURPOSE:<br />The usefulness of the synthetic membrane, Strat-M™ as an alternative to human and animal skins was evaluated by estimating the skin permeabilities of chemical compounds.<br />METHOD:<br />Thirteen chemical compounds with molecular weights (M.W.) of 152-289 and lipophilicities (log Ko/w) of -0.9 to 3.5 were selected. Strat-M™, excised human skin, or hairless rat skin was set in a Franz-type diffusion cell and a saturated solution of each chemical compound was applied to determine membrane permeation profiles. The obtained permeability coefficients (log P) were compared among these membranes.<br />RESULTS AND DISCUSSION:<br />Elevations were observed in log P for Strat-M™ with an increase in the log Ko/w of the applied compounds, and similar results were observed with the human and hairless rat skins. A correlation was obtained in log P values between Strat-M™ and human or hairless rat skin. Furthermore, the diffusion and partition parameters of chemicals in Strat-M™ were similar to those in the excised human and rat skins. These results suggest that Strat-M™ could be used as an alternative to animal or human skin in permeation studies.

The toxicity of phthalates is an important concern in the fields of environmental health and toxicology. Dermal exposure via skin care products, soil, and dust is a main route for phthalate delivery. We had explored the effect of topically-applied phthalates on skin absorption and toxicity. Immunohistology, functional proteomics, and Western blotting were employed as methodologies for validating phthalate toxicity. Among 5 phthalates tested, di(2-ethylhexyl)phthalate (DEHP) showed the highest skin reservoir. Only diethyl phthalate (DEP) and dibutyl phthalate (DBP) could penetrate across skin. Strat-M(®) membrane could be used as permeation barrier for predicting phthalate penetration through skin. The accumulation of DEHP in hair follicles was ∼15nmol/cm(2), which was significantly greater than DBP and DEP. DBP induced apoptosis of keratinocytes and fibroblasts via caspase-3 activation. This result was confirmed by downregulation of 14-3-3 and immunohistology of TUNEL. On the other hand, the HSP60 overexpression and immunostaining of COX-2 suggested inflammatory response induced by DEP and DEHP. The proteomic profiling verified the role of calcium homeostasis on skin inflammation. Some proteins investigated in this study can be sensitive biomarkers for dermal toxicity of phthalates. These included HSPs, 14-3-3, and cytokeratin. This work provided novel platforms for examining phthalate toxicity on skin.

Acyclovir, indicated in the treatment of herpes labialis ("cold sores"), is formulated as semisolid topical dosage forms and marketed in numerous countries. Since the formulations of the various acyclovir products may differ from country to country, this study was undertaken to compare the in vitro release of acyclovir from various generic cream products available on the South African and Indian markets using the respective brand/innovator product as the reference product. The in vitro studies were carried out using vertical diffusion cells with a diffusional surface area of 1.767 cm(2) and various commercially available membranes. Normal saline was used as receptor fluid and the temperature maintained at 32 ± 0.5°C. The in vitro release comparisons were based on the recommendations described in the US Food and Drug Administration Draft Guidance for acyclovir ointment and the SUPAC-SS Guidance for non-sterile semisolid dosage forms. The release rates (slope) of the test (T) and the relevant reference product (R) were monitored and compared. The comparative release of acyclovir from the various generic formulations compared with the reference product was found to be within the limits of 75-133.33% with a 90% confidence interval. These experiments indicate that the generic acyclovir cream formulations exhibited release rates that were comparable to the innovator product and could be considered to be bioequivalent.

Capsaicin o/w nanoemulsions with enhanced skin permeation were successfully prepared by controlling the ratios of the surfactant mixtures, oleoresin capsicum as the oil phase, and aqueous phase. Oleoresin capsicum contains 22.67 mg/g of capsaicin, which is an active and oil-soluble ingredient. Nonionic surfactants, Tween 80 and Span 80, were used to optimize the weight ratio of surfactant mixtures (85.98:14.02) by calculating the hydrophile-lipophile balance (HLB) value. The optimal processing conditions for stable nanoemulsions were investigated by using a ternary phase diagram. The mean droplet size of nanoemulsions ranged from 20 to 62 nm. Skin permeation studies were performed using a Franz diffusion cell. The permeation profiles and confocal laser scanning microscopy (CLSM) images supported that capsaicin nanoemulsion could well permeate all skin layers from the stratum corneum to the dermis. The selected nanoemulsions showed great potential as transdermal delivery carriers for enhancing the permeation of core materials.

PURPOSE:<br />This study aimed to assess impact of different vehicles for laser-assisted skin drug delivery. We also tried to uncover the mechanisms by which different vehicles affect laser-aided skin permeation.<br />METHODS:<br />Full-surface ablative (conventional) and fractional lasers were used to irradiate nude mouse skin. Imiquimod and 5-aminolevulinic acid (ALA) were used as lipophilic and hydrophilic permeants. Vehicles employed included water with 40% polyethylene glycol 400 (PEG 400), propylene glycol (PG), and ethanol. Lipid nanoparticles were also utilized as carriers.<br />RESULTS:<br />In vitro permeation profiles showed improvement in imiquimod flux with conventional laser (2.5 J/cm2) producing a 12-, 9-, and 5-fold increase when loading imiquimod in 40% PEG400, PG, and ethanol, respectively, as compared with intact skin. Nanoparticulate delivery by laser produced a 6-fold enhancement in permeation. Fractional laser produced less enhancement of imiquimod delivery than conventional laser. Laser exposure increased follicular imiquimod accumulation from 0.80 to 5.81 μg/cm2. ALA permeation from aqueous buffer, PEG 400, and PG with conventional laser treatment was 641-, 445-, and 104-fold superior to passive control. In vivo skin deposition of topically applied ALA examined by confocal microscopy indicated the same trend as the in vitro experiment, with aqueous buffer showing the greatest proporphyllin IX signaling. Diffusion of cosolvent molecules into ablated skin and drug partitioning from vehicle to skin are two predominant factors controlling laser-assisted delivery. In contrast to conventional laser, lateral drug diffusion was anticipated for fractional laser.