Administration routes transdermal delivery

Transdermal delivery is a noninvasive intravenous infusion of drug to maintain efficacious drug levels in the body for predictable and extended duration of activity. Diffusion-controlled transdermal systems are designed to deliver the therapeutic agent at a controlled rate from the device to and through the skin into the systemic circulation. This route of administration avoids unwanted presystemic metabolism (first-pass effect) in the GI tract and the liver. Patient satisfaction has been realized through decreased... 

For systemic effect. Transdermal delivery systems (TDS) release drug through a rate-controlling membrane into the skin and so into the systemic circulation. Fluctuations in plasma concentration associated with other routes of administration are largely avoided, as is first-pass elimination in the... 

While the above-mentioned examples cannot be considered an exhaustive representation of all the possible uses of membranes in the delivery field, they serve to give an idea of how many and how variegated the applications can be. The aim of this chapter is to first describe the basic principles mhng mass transport through membranes. Then, in the light of the administration route (oral, transdermal, and implantable), some of the most important applications are presented and discussed. Finally, future applications of membranes in the dehvery field are briefly treated. 

Localized tissue irritation can be seen from the intramuscular (IM) route. This is especially an issue when the formulation pH differs from the pH of the surrounding tissue or when precipitation of poorly soluble drugs occurs. Incorrect administration of IM injections is probably the most important factor that causes local adverse effects. Local skin irritation can also be seen with transdermal delivery systems due to the alcohols, nonionic surfactants, and adhesives. 

Drugs chosen for delivery via a transdermal drug-delivery system must adequately penetrate the skin in such a way that the system determines the delivery rate that should be fairly constant. In addition, the drug must not irritate or sensitize the skin. It is hoped that in the future more drugs will be developed for transdermal delivery. This could become an alternative route for drug delivery to children who have difficulty with oral administration. 

Over the last 20 years, transdermal route of delivery has been considered as a means for systemic drug administration. Over this period, sonophoresis has been attempted to enhance systemic transdermal delivery. Levy et al. ° showed that 3-5 min of ultrasound exposure (IMHz, 1.5W/cm ) increased transdermal permeation of mannitol and physostigmine across hairless rat skin in vivo by up to 15-fold. They also reported that the lag time typically associated with transdermal drug delivery was nearly-completely eliminated after exposure to ultrasound. ° ... 

The success of vaccination depends primarily on the method of presenting the antigen to the host immune system. Antigens have usually been delivered by parenteral (such as intravenous, intramuscular, intraperito-neal, intradermal, and subcutaneous) administration, but recent studies have shown that other routes of delivery such as intranasal, oral, and transdermal delivery have also been effective. In some cases, vaccination through mucosal routes resulted in better responses in IgA production. Because non-parenteral vaccine delivery presents many obvious advantages, numerous attempts have been made on the development of non-parenteral delivery of vaccines. 

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