Fentanyl

Fentanyl is a synthetic opioid analgesic in the phenylpiperidine class. It is extremely potent—roughly 50 to 100 times more powerful than morphine—and is used medically for severe pain, during anesthesia, and as an adjunct to surgical procedures. Because of its potency, even very small amounts can cause life‑threatening respiratory depression.

Medical use and formulations include injectable forms for anesthesia and acute pain management, transdermal patches for chronic cancer or breakthrough pain, and lozenges, tablets, or nasal sprays for opioid‑tolerant patients with cancer or procedural pain. Brand names and formulations vary by country, and dosing is carefully tailored to individual tolerance and clinical need.

Fentanyl acts as a mu‑opioid receptor agonist, producing analgesia, sedation, and respiratory depression. Pharmacokinetics vary by formulation: injected fentanyl has a rapid onset with a brief duration, while transdermal patches release drug gradually over days. It is primarily metabolized in the liver to inactive metabolites and is eliminated through the kidneys. Because of its high potency, the margin between therapeutic and dangerous doses is small, and interactions with other central nervous system depressants can markedly increase risk.

Safety concerns include respiratory depression, sedation, constipation, and potential for dependence and addiction with prolonged use. Overdose requires prompt administration of naloxone and supportive care. Caution is advised for opioid‑naive individuals and when combining fentanyl with alcohol or other depressants.

Regulation and illicit use: fentanyl is a controlled substance in most jurisdictions (often Schedule II in the United States). Illegal production and trafficking contribute to overdose deaths, frequently involving counterfeit pills or adulterated street drugs. Fentanyl analogs, such as carfentanil, are extraordinarily potent and carry significant public health risks.

History: fentanyl was synthesized by Paul Janssen in 1960 and quickly adopted for anesthesia and severe pain management, becoming a widely used clinical opioid.