What is Fentanyl?

Fentanyl is a synthetic opioid drug that is used as a potent analgesic or anesthetic adjuvant. The agent is available under various brand names including Duragesic, Sublimaze, Actiq, Onsolis, Instanyl and Fentora.

Fentanyl has a rapid onset of action, which lasts only for a short time. The drug is widely used in the management of breakthrough pain as well as an anesthetic. Fentanyl is also used in the form of a transdermal patch to manage chronic pain. The drug is released by the patch into the body fats, from where it slowly moves into the bloodstream over two or three days, therefore providing long-term pain relief.

Mechanism of action

Fentanyl is an μ-opioid agonist that binds to μ-opioid G-protein-coupled receptors. This prevents the release of pain neurotransmitters by decreasing the cellular calcium level. Fentanyl is around one hundred times as potent as morphine, partly owing to its lipophilicity, meaning it can penetrate the central nervous system more easily than morphine can.


Fentanyl was first developed by Dr. Paul Janssen in 1959, after which it was used as an anesthetic under the brand name Sublimaze. Its popularity triggered the advent of other fentanyl analogues such as Sufentanil, Alfentanil, Lofentanil and Remifentanil.

In the mid-1990s, clinical trials were performed to test the Duragesic patch as a way of administering slow-release fentanyl to relieve pain over long-term periods. After a series of successful trials, the Duragesic patch was introduced and it became prescribed as part of normal medical practice. This was followed by the introduction of a fentanyl lollipop called Actiq, which provided fast acting relief of breakthrough pain. Further fentanyl products included an effervescent lozenge and a buccal spray.

Further Reading

Last Updated: Feb 26, 2019

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


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  1. Susan Moses Susan Moses United States says:

    What can cause a false positive for Fentanyl? I just read that they would have to do a Specific test for the Fentanyl. Why would my Dr of 7 years do that? I take Morphine  300 mg 3x daily and Oxycodone 15 mg 4x daily and have for years. I get tested at least 10x per year and live in Terrible Pain so I would Never take anything not prescribed to me. I had a horrible car accident two weeks ago and they gave me a script of Vicodin and I never filled it. Can you help? The test was on 11/5/14. Can I get a Blood Test to disprove this??  Thank you very much.

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