Transdermal Patches

Transdermal Patches deliver drugs non-invasively from the surface of skin to the circulatory system (this is Transdermal Drug Delivery System – TDDS).    A transdermal patch is a medicated patch that is placed on the skin to deliver a specific dose of medication through the skin and into the bloodstream.   An advantage of a transdermal drug delivery route over other types of medication delivery such as oral, topical, intravenous, intramuscular, etc. is that the patch provides a controlled absorption, more uniform plasma levels, improved bioavailability, reduced side effects, painless and simple application and flexibility of terminating drug administration by simply removing the patch from the skin. It also reduces the load that the oral route commonly places on the digestive tract and liver. It enhances patient compliance and minimizes harmful side effects of a drug caused from temporary overdose. Another advantage is convenience, especially notable in patches that require only once weekly application. Such a simple dosing regimen can aid in patient adherence to drug therapy. Designing and development of transdermal patches can be described as state of the art.

Basic Components Of TDDS

  • Polymer matrix / Drug reservoir
  • Drug
  • Permeation enhancers
  • Backing laminates
  • Release liner
  • Other excipients like plasticizers and solvents

Most common Types Of Transdermal Patches:

Several system designs have been used in development and fabrication of TDDSs. Two simple and common types of TDDS are followings

The drug and other selected excipients are directly incorporated into the organic solvent adhesive solution, mixed, cast as a thin film and dried to evaporate the solvents, leaving a dried adhesive matrix film containing the drug and excipients. This drug in adhesive matrix is sandwiched between release liner and backing layer.

Pad patches consist of an absorbent material (pad) in the middle of the patch. Pad materials are specifically designed to adsorb either hydrophilic or hydrophobic drug formulations in liquid or semisolid form. After applying on the skin drug is released to the skin from the pad.

Why don’t you call your patches “transdermal” patches?   That’s another post – read more here.   In short, most of our customers are not using drugs in their patches, and because they’re not, we prefer to call those patches “topical”.