Active Ingredients

Fentanyl – Effect, Application & Risks


Fentanyl was developed by Paul Janssen in 1960 and was the first anilinopiperidine at the time. A few modifications to the molecular formula have since made it possible to develop a number of derivatives from fentanyl that are easier to control.

What is fentanyl?

Fentanyl is a synthetic opioid that is used in anesthesia as a potent analgesic and in the treatment of chronic pain as a transdermal therapeutic system.

It acts as a so-called agonist. In Germany and Switzerland, fentanyl falls under the Narcotics Act, in Austria under the Narcotics Act.

Pharmacological action

Fentanyl has primarily analgesic (strong pain-relieving) and sedative (calming) effects. It is 120 times more potent than morphine , resulting in greater potency and a shorter duration of action.

When administered intravenously, fentanyl takes effect after just two to five minutes, and the so-called half-life is around three to twelve hours. The dose for effective treatment is 0.01 mg per kilogram of body weight, the dose causing death is 3.1 mg per kilogram of body weight, the last figure relating to rats. Even lower doses can therefore lead to death in humans due to respiratory depression .

However, the side effects can generally be compared to those of morphine. Fentanyl dissolves well in fat and can therefore be distributed well in fatty tissue. It is mainly metabolized in the liver , less than ten percent is excreted unchanged via the kidneys. Depending on the patient’s condition and the dose administered, fentanyl may impair cognition, have a sedative effect, cause decreased consciousness or induce a sleep-like state. The latter point is the reason for its use in anesthesia.

Fentanyl is mainly used in operations in conjunction with a sleeping pill as a pain reliever and can also be used as a muscle relaxant. Since fentanyl is stored and released in the adipose tissue in a difficult controlled manner due to its lipophilic nature, the substances remifentanil , alfentanil or sufentanil are often used as alternatives .

Fentanyl has a sedative effect, which can be enhanced by other sedatives and alcohol, or decreased by the use of other opioids. Serious circulatory and respiratory disorders can occur in connection with the intake of so-called monoamine oxidase inhibitors, which is why there should be a period of at least 14 days between the respective intakes.

When using pain plasters, there can also be an interaction with preparations such as omeprazole, furosemide or glibenclamide. Interactions can also occur with preparations that contain St. John’s wort . For smokers, it may be necessary to adjust the dose of fentanyl.

If a drug containing fentanyl is taken together with a drug that has a serotonergic effect, a dangerous serotonin syndrome can occur, the symptoms of which can be blood pressure crises, hallucinations or even a coma.

Medical Application & Use

Fentanyl is used as fentanyl dihydrogen citrate in three forms: as a transdermal therapeutic system, as an intravenous administration in anesthesia and emergency medicine, and as an oral-transmucosal therapeutic system (for breakthrough pain as a lozenge). Nycomed’s Instanyl, the first approved fentanyl nasal spray in the EU, has been approved for breakthrough pain since September 1, 2009.

This drug is suitable for treating breakthrough pain in adult patients who are already on basic therapy with an opioid for chronic cancer pain. Fentanyl has a strong analgesic effect and is therefore usually used perioperatively (before an operation) or also after an operation.

In the case of severe, chronic pain in cancer patients, it is used in the form of a skin plaster as an analgesic. It can also be used in analgesia for chronic pain that is not related to a tumor. The emergency physician may use fentanyl for acute pain in the emergency services.

Risks & side effects

A side effect of fentanyl can be impairment of breathing up to respiratory depression. Side effects such as cramped or stiff muscles, slowed heart rate, euphoria or anxiety , constricted pupils, vomiting , nausea and constipation are also possible. If the injection is made quickly, in rare cases it can also lead to a short-term urge to cough.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.