Transdermal patch
From Wikipedia, the free encyclopedia
A transdermal patch or skin patch is a medicated adhesive patch that is placed on the skin to deliver a time released dose of medication through the skin and into the bloodstream. Transdermal patches are used to deliver a wide variety of pharmaceuticals. The most common transdermal patch, the nicotine patch, contains nicotine and is used to quit the habit of tobacco smoking. Other skin patches administer scopolamine for motion sickness, estrogen for menopause and to prevent osteoporosis after menopause, nitroglycerin for angina, and lidocaine to relieve the pain of shingles (herpes zoster). Some pharmaceuticals must be combined with substances, such as alcohol, that increase their ability to penetrate the skin in order to be used in a transdermal patch. Molecules of insulin and many other pharmaceuticals, however, are too large to pass through the skin.
Recent developments are their use in the delivery of hormonal contraceptives and antidepressants.
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[edit] Components
The main components to a transdermal patch are:
- Liner - Protects the patch during storage. The liner is removed prior to use.
- Drug - Drug solution in direct contact with release liner
- Adhesive - Serves to adhere the components of the patch together along with adhering the patch to the skin
- Membrane - Controls the release of the drug from the reservoir and multi-layer patches
- Backing - Protects the patch from the outer environment
[edit] Types of Transdermal Patches
There are four main types of transdermal patches listed below. Also the information below was provided by : www.managedcarmag.com
[edit] Single-layer Drug-in-Adhesive
The adhesive layer of this system also contains the drug. In this type of patch the adhesive layer not only serves to adhere the various layers together, along with the entire system to the skin, but is also responsible for the releasing of the drug. The adhesive layer is surrounded by a temporary liner and a backing.
[edit] Multi-layer Drug-in-Adhesive
The multi-layer drug-in adhesive patch is similar to the single-layer system in that both adhesive layers are also responsible for the releasing of the drug. The multi-layer system is different however that it adds another layer of drug-in-adhesive, usually separated by a membrane (but not in all cases). This patch also has a temporary liner-layer and a permanent backing.
[edit] Reservoir
Unlike the Single-layer and Multi-layer Drug-in-adhesive systems the reservoir transdermal system has a separate drug layer. The drug layer is a liquid compartment containing a drug solution or suspension separated by the adhesive layer. This patch is also backed by the backing layer.
[edit] Matrix
The Matrix system has a drug layer of a semisolid matrix containing a drug solution or suspension. The adhesive layer in this patch surrounds the drug layer partially overlaying it.
[edit] Regulatory Aspects
A transdermal patch is classified by the U.S. Food and Drug Administration as a combination product, consisting of a medical device combined with a drug or biological product that the device is designed to deliver. Prior to sale in the United States, any transdermal patch product must apply for and receive approval from the Food and Drug Association, demonstrating safety and efficacy for its intended use.
