Opioid Analgesic (Short-Acting)

Fentanyl (IV — Anaesthesia/ICU)

Brand names: Sublimaze

Fentanyl is a potent synthetic opioid used intravenously in anaesthesia and intensive care and, as transdermal patches, for stable chronic severe pain; it is a controlled drug.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

• Fentanyl Citrate Injection should be administered only by persons specifically trained in the use of intravenous anesthetics and management of the respiratory effects of potent opioids. • Ensure that an opioid antagonist, resuscitative and intubation equipment, and oxygen are readily available ( 2.1 ). • Individualize dosing based on the factors such as age, body weight, physical status, underlying pathological condition, use of other drugs, type of anesthesia to be used, and the surgical procedure involved. ( 2.1 ) • Initiate treatment in adults with 50 mcg to 100 mcg. ( 2.2 ) • Initiate treatment in children 2 to 12 years of age, with a reduced dose as low as 2 mcg/kg to 3 mcg/kg. ( 2.2 …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-09-24. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It is a potent mu-opioid receptor agonist with rapid onset given intravenously.

Prescribing in practice

It is many times more potent than morphine, so dosing errors are dangerous; transdermal patches are only for opioid-tolerant patients with stable pain, not for acute or opioid-naive use.
Heat increases absorption from patches (fever or external heat) and can cause overdose.
Respiratory depression is the main risk; it causes less histamine release and is often preferred in haemodynamic instability or renal impairment.

Monitoring

Monitor respiratory rate, sedation and pain; with patches review at each change.

Counselling the patient

With a patch, avoid heat (hot baths, heat pads) over it and follow the change schedule.
Report excessive drowsiness or slow breathing.
Dispose of used patches safely — they still contain drug.

Evidence & guidelines

A potent opioid for anaesthesia and intensive care and, as patches, for stable chronic severe pain in opioid-tolerant patients.

Reference: FICM Guidelines on Analgesia/Sedation in ICU; Stoelting's Pharmacology; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways