Fentanyl

What is Fentanyl? 12

  • Potent, synthetic opioid with rapid acting analgesic and sedative properties.
  • Can be administered intravenously, intramuscularly, transdermally, transmucosally, or intrathecally.

Mechanism of Action & Pharmacokinetics 123

  • Primarily agonizes mu-opioid receptors, with additional activity on delta and kappa receptors.
    • The mu receptor is predominantly responsible for analgesia, hypoventilation, and euphoria
    • The kappa receptor is involved in analgesia, dysphoria
    • The delta receptor is involved in constipation and urinary retention
  • Fentanyl is highly lipophilic and rapidly redistributes into fat/muscle
  • Peak effect in 3-5 minutes with a duration of 0.5-1 hours.
  • Metabolized via the hepatic system to inactive metabolites which get excreted largely in the urine.
  • Infusions of fentanyl lead to accumulation causing a high context sensitive half-life

Pharmacodynamics

Cardiovascular 2

  • May decrease heart rate and blood pressure as a result of sympathectomy

Respiratory 13

  • With increasing doses, fentanyl can cause respiratory depression, hypoxia, apnea, loss of consciousness, and respiratory arrest without adequate ventilation support.
  • Depresses respiratory centers in the brainstem, leading to decreased respiratory rate and minute ventilation. Often intially compensatory increased tidal volume occurs 3
  • Risk of respiratory depression increases with dose and concomitant use of other CNS depressants.
  • Occasional chest wall rigidity or laryngeal rigidity can make ventilation difficult

Central Nervous System 12

  • Euphoria, drowsiness, delirium, and hallucinations.

Indications 12

  • Preoperative and postoperative Pain ManagementPain Management
    Introduction
    Pain management can be a complex topic in anesthesia. Patient factors, like age, comorbidities, and pre-existing chronic pain can help guide analgesia during the operative period. Surg...
  • Blunts sympathetic response during laryngoscopy
  • Procedural sedation and analgesia
  • Potentiates neuraxial analgesia when given into the CSF during spinal anesthesia

Dosing 13

  • General anesthesia:
    • Induction: 1-2 mcg/kg (variable dosing)
  • Synergizes with other sedative agents

Complications 123

  • Common side effects include nasal pruritus, urinary retention, and constipation.
  • As above, severe respiratory depression and decreased level of consciousness can occur

References

  1. Ramos-Matos, C.F., Bistas, K.G., Lopez-Ojeda, W. (2024). Fentanyl. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK459275/ ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7

  2. UpToDate. (2024). Fentanyl. https://www.uptodate.com/contents/fentanyl-drug-information?search=fentanyl&source=auto_suggest&selectedTitle=1%7E2—1%7E2—fent ↩ ↩2 ↩3 ↩4 ↩5 ↩6

  3. Birdi T, Sullivan P. Ottawa anesthesia primer. Toronto, Ontario: Echo Book Publishing; 2012. ↩ ↩2 ↩3 ↩4 ↩5