An innovative transdermal drug delivery device for the treatment of chronic and neurodegenerative diseases

In several chronic and neurodegenerative diseases it is essential to find a drug administration method being effective (low-dose, high effect), personalised and chrono-regulated (according to actual therapeutic window). For example Parkinson's (PD) patients need to be treated several times a day with drugs that compensate the fast depletion of dopaminergic neurons in their brain. Usual pharmaceutical formulations (oral, injection) can hardly achieve those goals at the same time since: the drug often is poorly adsorbed or enzymatic degraded in the gastrointestinal tract or in liver; drug release cannot be controlled interactively and the therapeutic window changes with disease stages [Prausnitz et al 2004]. Transdermal drug delivery (TDD) offers the possibility to maintain an almost constant drug concentration in blood in the treatment of several chronic disease (Parkinson, diabetes, pain relief). Patch-based TDD, however, is still limited by the inability of the drugs to cross skin at therapeutic rates, due to the barrier imposed by the stratum corneum layer (SC) and the impossibility to control the flux across the skin, due to its diffusive nature. We designed and realised a simplified prototype of an innovative biomedical microstructured device for a controlled, painless, transdermal drug delivery based on a matrix of hollow microneedles in order to insert drug just below the upper layers of epidermis (SC, viable epidermis, upper papillary dermis) and let it diffuse into blood vessels. The drug flux rate will be controlled with the help of a tuneable, microstructured, embedded pumping device [Döpper et al 1997]. We performed skin piercing and skin infusion experiments with the device basic prototype on human abdominal skin biopsies (obtained from cosmetic surgery). Microneedle’s piercing and subsequent dye infusion effects are evident on skin surface. Preliminary histological results indicated that SC and viable epidermis are pierced while dermis was undamaged.