Biomaterials

A biomaterial is essentially a material that is used and adapted for a medical application. Biomaterials can have a benign function, such as being used for a heart valve, or may be bioactive . Used for a more interactive purpose such as hydroxy-apatite coated hip implants (the Furlong Hip, by Joint Replacement Instrumentation Ltd, Sheffield is one such example - such implants are lasting upwards of twenty years). Biomaterials are also used every day in dental applications, surgery, and drug delivery (a construct with impregnated pharmaceutical products can be placed into the body, which permits the prolonged release of a drug over an extended period of time)

Transdermal and buccal delivery of methylxanthines through human tissue in vitro

We examined the in vitro permeation of central nervous stimulants-caffeine, theophylline, and theobromine across human skin with the aid of six chemical enhancers. It was found that oleic acid was the most potent enhancer for all three methylxanthines. Further optimization studies with different solvents showed that caffeine transport could be enhanced to give flux values up to 585 μg/cm2.hr-1. Theobromine and theophylline delivery rates proved insufficient. An additional study involving a buccal tissue equivalent showed that this membrane was more permeable than skin for all model actives tested and would offer an alternate way of delivery

Enhanced iontophoretic delivery of buspirone hydrochloride across human skin using chemical enhancers

Buspirone hydrochloride (BH) is a structurally and pharmacologically unique anxiolytic that is used to treat a variety of different anxiety conditions. The marketed product is named BuSpar®. The in vitro iontophoretic delivery of BH through human skin was investigated in order to evaluate the feasibility of delivering a therapeutic dose of BH by this route. We also examined the influence of co-formulations of chemical enhancers (Azone®, oleic acid, menthone, cineole, and terpineol) on BH permeation, both without iontophoresis and with iontophoresis—to look for possible synergistic effects. By applying iontophoresis at 0.5 mA/cm2, it was possible to achieve a BH steady state flux of approximately 350 μg/cm2 h, which would be therapeutically effective if clinically duplicated. Importantly, 24 h of iontophoresis at 0.5 mA/cm2 did not affect skin morphology and after the current was switched off, the skin’s permeability to BH rapidly reverted to its pre-iontophoretic level. Without iontophoreis, BH transdermal flux was significantly enhanced by the application of 2.5% (v/v) concentrations of Azone®, oleic acid, or menthone but not cineole or terpineol. Furthermore, this paper identified a synergistic transport enhancement effect developing when very low current (0.025 mA/cm2) iontophoresis was applied in conjuction with Azone® treatment

An investigation of the mechanism by which aluminium and other polyvalent cations inhibit eccrine sweating

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