Topical dermatological drug delivery: quo vadis?

Skin disease (dermatological conditions') affects at least one-third of the US population and has been cited as one of the top 15 medical conditions for which prevalence and healthcare spending increased in the last decade. The outcome of topical dermatological drug treatment is significantly influenced by the choice of vehicle or delivery system. Advancements in the life sciences coupled with a growing market for dermatologicals have facilitated the emergence of improved topical formulations and drug delivery systems.

Short-term iontophoretic and post-iontophoretic transport of model penetrants across excised human epidermis.

The effect of short-term current application (0.4mA for 10min) on the epidermal transport of two model penetrants (butyl paraben, BP; caffeine, CF) of differing lipohilicity was investigated and compared to that produced by employing an established method of skin penetration enhancement (delipidisation). The aim was to investigate the mechanism of enhancement and route of skin permeation associated with each penetrant and mode of treatment.

Transdermal drug delivery systems: skin perturbation devices.

Human skin serves a protective function by imposing physicochemical limitations to the type of permeant that can traverse the barrier. For a drug to be delivered passively via the skin it needs to have a suitable lipophilicity and a molecular weight < 500 Da. The number of commercially available products based on transdermal or dermal delivery has been limited by these requirements.

Effect of abrasion induced by a rotating brush on the skin permeation of solutes with varying physicochemical properties.

A transient reduction in the barrier nature of the skin can be a pre-requisite for successful (trans)dermal delivery of some drugs. The aim of this present study was to investigate and effect of a dermal abrading "rotating brush" device on percutaneous absorption and skin integrity. In vitro experiments were conducted using excised human epidermal membrane.

Variability in human skin permeability in vitro: comparing penetrants with different physicochemical properties.

Appreciating and compensating for the inherent variability associated with percutaneous absorption is essential in optimizing (trans)dermal therapy. In this study, the variability in human skin permeability associated with model penetrants of differing lipophilicity (caffeine (CF), methyl paraben (MP), and butyl paraben (BP)) was examined in a standardized intra-laboratory study (Franz cell experiments) using epidermal tissue from various donors. Experimentally derived permeability coefficients (K(P)) were also compared to that derived from two skin permeation models namely, Potts & Guy and Robinson (revised) models in order to further validate the Franz diffusion method employed and also elucidate the potential permeation pathway(s) employed by the model penetrants.

Dermal and transdermal drug delivery systems: current and future prospects.

The protective function of human skin imposes physicochemical limitations to the type of permeant that can traverse the barrier. For a drug to be delivered passively via the skin it needs to have adequate lipophilicity and also a molecular weight <500 Da. These requirements have limited the number of commercially available products based on transdermal or dermal delivery.