Transdermal donepezil on the treatment of Alzheimer’s disease

Figures & data

Figure 1 Structure of ChEIs.

Abbreviation: ChEIs, cholinesterase inhibitors.

Table 1 Advantages of the transdermal drug delivery route

Reduced dosing frequency due to longer duration of action Improved bioavailability Uniform plasma levels, resulting in reduced side effects Possibility of terminating the drug administration by simple removal of the patch Improved patient compliance via non-invasive, painless, and simple application

Table 2 Factors influencing transdermal drug administration

Body site of application Thickness, composition, integrity, and hydration of the stratum corneum epidermis Drug properties, such as molecular weight, lipid or water solubility, membrane permeability, metabolism melting point, and degree of partitioning Alteration of blood flow in the skin by additives and body temperature

Table 3 Patch components

Component	Function
Backing	Protects the patch from the outer environment, is impermeable to the transdermal patch components, and provides the patch with its flexibility. It is made of elastomers (polyolefin oils, polyester, polyethylene, polyvinylidene chloride and polyurethane) and is preferably nonbreathable (by adding aluminum foil).^Citation30
Membrane	Controls the release of the drug. It is made of natural or synthetic polymer or synthetic elastomers, and its thickness ranges from about 2 mm to about 7 mm.
Adhesive	It binds the components of the patch together and the patch to the skin. It is composed by silicone, rubber, polyvinylacetate, or polyisobutylene, depending on the skin–adhesion properties desired. It may contain permeation enhancers (solvents, surfactants or miscellaneous chemicals) to promote skin permeability by altering its structure.^Citation34
Liner	Protects the patch during storage and is peeled off before use.

Figure 2 Representation of different types of patches.

ValiaKHRamarajuVSCore Tech Solutions, assigneeTransdermal methods and systems for treating Alzheimer’s diseaseUnited States patentUS 20080044461A12212008

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Chanukya KumarGA review on transdermal therapeutics systemIJPT20113313671381

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