Transdermal Patches: How Do They Work?

Transdermal patches are becoming more popular and are being developed for everything from contraception to Parkinson's disease. How do they work? Are they effective in getting the medication into you skin? Transdermal patches are considered to be a combination product, which is one that uses a drug as well as a delivery system. The delivery system being the parts of the patch (backing, adhesive etc.) are all important in the transdermal process.

Transdermal patches are available to help quit smoking, to ease motion sickness, to provide oral contraception or to infuse hormones into the blood stream to alleviate symptoms of menopause. Transdermal patches are considered to be parenteral and are diffused through intact skin structures.

The patch adheres to the skin and delivers the medication through the blood stream. Some pharmaceuticals must be combined with substances, such as alcohol within the patch to increase their ability to penetrate the skin in order to be used in a transdermal patch. The molecules of the medication must be small enough to pass through the skin.

There are five crucial parts to the transdermal patch which enable the success of the medication to be distributed into the bloodstream. There is the liner, the drug, the adhesive, the membrane and the backing. The liner is removed prior to use and protects the patch while it is not in use. Drug comes in contact with the liner and is the solution which is exposed to the skin. The adhesive binds the components of the patch together while keeping it adhered to the skin. The membrane controls the release time for the drug and is often used in many different layers to release a certain amount at a time. The backing is the part that is exposed to the air, and protects the drug at all times. All of these parts work as the sum of the whole to infuse the medication into the bloodstream, through the skin.

This is a non invasive way to treat many diseases and disorders. In addition to the aspects of each patch - there are four types of transdermal patches. These four types are: Single layer drug in adhesive, multi layer drug in adhesive, reservoir and matrix.

"Drugs can be delivered across the skin to have an effect on the tissues adjacent to the site of application (topical delivery) or to have an effect after distribution through the circulatory system (systemic delivery). While there are many advantages to delivering drugs through the skin the barrier properties of the skin provide a significant challenge. By understanding the mechanisms by which compounds cross the skin it will be possible to devise means for improving drug delivery"

Since 1979 transdermal patches have been in use and are available in a wide variety of treatments. Since many oral medications harm the liver, transdermal medications have proven to be less harsh on the effects of the liver and effective in transmission and treatment.