Transdermal delivery of treatment for Alzheimer's disease: development, clinical performance and future prospects.

There is increasing interest in the potential of transdermal drug delivery systems for the treatment of neurological disorders, especially in the elderly. In this population, the higher incidence of chronic diseases, such as diabetes mellitus, cardiovascular disease, neurological disease and chronic pain, has dramatically increased the need for long-term medications. Additionally, elderly patients often have a combination of several chronic diseases, meaning drug delivery, drug-drug interactions, absorption/blood concentrations, toxicity and compliance are of concern for patients as well as for their caregivers and physicians. Recent efforts have focused on developing pharmaceutical preparations that overcome these issues. For example, rate-controlled drug delivery systems have been under active development. Transdermal drug delivery systems have been developed to deliver phenserine, rivastigmine, nicotine and estradiol for the management of cognitive and behavioural dysfunctions in patients with Alzheimer's disease because this form of administration has several advantages, including maintenance of sustained therapeutic plasma concentrations of drugs, easy application and reduced systemic adverse effects. Thus, transdermal drug delivery for elderly patients offers promise as the ideal therapeutic approach to treating Alzheimer's disease.This article reviews the technical principles underlying the development of transdermal drug delivery systems, focusing on cholinesterase inhibitors, and the prospects for future development. The clinical performance of transdermal patches, again with emphasis on cholinesterase inhibitors, is also reviewed.