Monolithic transdermal drug delivery

Figure 2.8 Schematic of a monolithic transdermal drug-delivery system (A) and the drug-release rate obtained (B).

Because of the large surface area of the skin and its bypass of the liver as a first pass step in metabolism, many drug delivery systems have been developed that control the rate of drug delivery to the skin for subsequent absorption. Effective transdermal drug delivery systems of this type deliver uniform quantities of drug to the skin over a period of time. Technically, transdermal drug delivery systems may be classified into monolithic and membrane-controlled systems (9). 

Transdermal drug-delivery systems offer several important adventages over more traditional approaches, in addition to the benefits of avoiding the hepatic first-pass effect. Transdermal drug delivery systems (TDDS) are usually in the form of patches incorporating pressure sensitive adhesives. There are two basic designs for transdermal patches matrix or reservoir type. Matrix-type patches include monolithic adhesive and polymer matrices, whereas reservoir-type patches include liquid and solid-state reservoirs [71-73]. For various types of transdermal delivery systems, medical grade adhesive silicones are used as [73,74] ... 

Transbuccal drug delivery systems are a new technology and spinoff of transdermal/topical drug delivery systems. Similar to monolithic adhesive matrix—type skin patches, transbuccal systems are designed to adhere to mucosal tissue in the oral cavity. A number of compounds are being evaluated in clinical studies.88... 

---