Current advances in transdermal delivery of drugs for Alzheimer's disease

Abstract

Alzheimer's disease (AD) is a common, progressive, fatal neurodegenerative disorder, which will play an increasingly important role both socially and financially in the aging populations. Treatments for AD show modest improvements in cognition and global functioning among patients. Furthermore, the oral administration of treating AD has had some drawbacks that decrease the medication adherence and efficacy of the therapy. Transdermal drugs are proposed as an alternative remedy to overcome the disadvantages of current pharmaceutical dosage options for this chronic disorder. They could have different strengths, such as offering a stable diffusion of active substance, avoiding the first pass metabolism, and reducing system adverse reactions. This article reviews the technical principles, novel techniques of transdermal delivery drug, and prospects for future development for the management of cognitive and behavioral dysfunctions in AD patients.

Keywords: Alzheimer's disease; controlled release; patch; permeation flux; transdermal.

Figure 1

Structure of Rivastigmine transdermal patch

Figure 2

Structure of two types of patch for Alzheimer's disease

Figure 3

Illustration of the diffusion of drug from hydrogel microneedles

Figure 4

Schematic depiction of dissolving microneedles in which drug is embedded in the matrix of dissolving microneedles. (a) Hydroscopic lyophilized drug reservoir accelerates uptake of skin interstial fluid into hydrogel-forming microneedles, where drug release into skin from the swell; (b) lyophilized drug reservoir dissolves, maximizing drug release; (c) microneedles are removed completely intact from skin, leaving no polymer behind