Transdermal Drug Delivery System

Drugs are applied topically using transdermal drug delivery methods. Pharmaceutical preparations called transdermal patches come in different sizes and are designed to be placed to intact skin to transfer active ingredients to the systemic circulation after they have passed through the skin's barriers and prevent first pass effect. A transdermal drug delivery patch offers a controlled release of medication into the patient, which is advantageous over other forms of medication delivery such as oral, topical, intravenous, intramuscular, etc. Usually, this is accomplished by either a porous membrane covering a reservoir of medication or by body heat melting thin layers of medication embedded in the adhesive. The skin acts as a very effective barrier, hence the fundamental drawback of transdermal administration systems is that only drugs whose molecules are tiny enough to pass through the skin may be administered this way. The preparation techniques for several transdermal patch types, including matrix patches, reservoir types, membrane matrix, drug-in-adhesive patches, and tiny reservoir patches, are covered in this book.