Fentanyl Transdermal System
Fentanyl is a Schedule II opioid agonist, a powerful narcotic used in the control of recurring moderate to severe chronic pain. Its chemical name is N-Phenyl-N-(1-(2-phenylethyl)-4-piperidinyl) propanamide.
The fentanyl transdermal system, brand name Duragesic, is a patch that delivers a controlled dose of the drug fentanyl to the patient's skin. The fentanyl is absorbed, then picked up by the systemic circulation beneath the surface of the skin.
The patch comes in different sizes of 5, 10, 20, 30, and 40 cm2 that correspond to a dose delivery rate of 12, 25, 50, 75, and 100 mcg/h respectively (mcg/h stands for micrograms per hour, indicating the drug's release rate). The larger the patch, the more area the drug has to pass through the skin.
The patch is composed of four layers and a protective liner made of plastic film that is rectangular in shape. The bottom layer against the skin has a fentanyl-containing adhesive on it. This is the side that adheres to the outer surface of the skin. Over that layer is an ethylene-vinyl acetate copolymer release membrane that controls the amount of drug passing through it to the skin. Above the release membrane is the drug reservoir containing fentanyl, and alcohol USP gelled with hydroxyethyl cellulose. The fentanyl is mixed with gelled alcohol, and hydroxyethyl cellulose so it can pass through the membrane for delivery to the patient's skin. The outer layer, above the reservoir, is the backing that holds the patch together.
The presence of alcohol in the patch also increases the permeability of the skin, allowing more of the drug to flow through the derma. A minimal amount of alcohol is released into the skin at a rate of 0.2 ml over the 72-hour lifespan of the patch.
Cutting a Fentanyl Patch
When a fentanyl patch is cut or sliced in any way, the drug delivery system is compromised and loses the ability to control the fentanyl release rate. The copolymer membrane in the patch acts like a security gate, allowing only so many molecules of the drug to pass through. When that security gate is damaged, the patch delivers a larger dose of the drug more rapidly.
Delivery of a large dose of fentanyl is potentially fatal. The drug can shut down the breathing centers, causing suffocation if too much is introduced into the body. Under no circumstances should you cut, scrape, slit, scratch or otherwise alter the integrity of a fentanyl patch, because this will cause the entire contents of the system to be delivered at one time causing serious harm, or fatality.
Use extreme caution when taking fentanyl. Nonmedical use of this drug has been fatal due to overdose, or respiratory depression, and it should not be mixed with other drugs unless advised by a physician. The drug should only be used under the supervision of a medical doctor.