Clinical beta

FMBM is currently in clinical beta. Content is for professional review/testing and must not replace local protocols, senior clinical judgment, or official prescribing references.

Drug Monograph

Fentanyl

USE IF: Severe acute pain, ICU sedation, procedural analgesia, renal failure opioid

AVOID IF: Opioid-naive (patch), respiratory depression, MAOI use

Fentanyl

Synthetic opioid (mu-opioid receptor agonist)

OpioidICU analgesiaRapid onsetHigh potencyPatch

Indication

Severe acute pain, ICU sedation, procedural analgesia, renal failure opioid

At a glance

INDICATION -> ICU/procedural opioid with rapid onset

ADULT DOSE -> 25–50 mcg IV bolus

MAX DOSE -> No ceiling (titrate); typical max 100 mcg IV bolus opioid-naive

CONTRA -> Patch in opioid-naive, respiratory depression, MAOI use

ANTIDOTE -> Naloxone (higher/repeated doses often needed)

Quick facts

Onset

30–60 sec (IV)

Duration

Peak 1–5 min; duration 30–60 min (IV), 48–72 h (patch). Half-life 2–4 h IV, 17–27 h patch.

Routes

IV, IM, transdermal, transmucosal, intranasal, epidural

Pregnancy

Use if needed short-term

Renal

Preferred opioid in CKD

Hepatic

Reduce dose

Do not miss

Time to action: 30—60 sec IV

Max dose

  • No ceiling; titrate carefully.

Critical risks

  • Respiratory depression.
  • Chest wall rigidity (WCS).
  • Apnea.

Antidote

  • Naloxone often requires higher/repeated dosing.
  • Infusion may be needed for re-narcotization.

High-risk scenarios

  • Rapid IV push.
  • CYP3A4 inhibitors.
  • Opioid-naive patch use.

Key interactions

  • Benzodiazepines.
  • CYP3A4 inhibitors.
  • MAOI.

Indications

Primary

  • Procedural analgesia
  • ICU sedation
  • Perioperative analgesia

Secondary

  • Cancer pain (patch)
  • Breakthrough pain (transmucosal)
  • Trauma

Other

  • Intranasal pediatric analgesia
  • Opioid rotation in renal failure

Dosing

Opioid-naive: 25 mcg IV slow

Opioid-tolerant: 25—50 mcg IV titrated

Max daily dose

  • No fixed ceiling in monitored settings; titrate to response and safety.

Adult - PO

  • Not applicable.

Adult - IV

  • Opioid-naive: 25 mcg IV slow.
  • Opioid-tolerant: 25–50 mcg IV titrated.
  • Infusion: 0.5–1.5 mcg/kg/h.

Pediatric

  • IV: 1–2 mcg/kg.
  • IN: 1.5 mcg/kg.

Renal adjustment

  • Preferred in renal impairment.
  • Reduce dose in severe renal disease.

Hepatic adjustment

  • Reduce 25–50%.

Warnings

Clinical warnings

  • Respiratory depression (black box).
  • Chest wall rigidity (WCS).
  • CYP3A4 interaction risk (black box context).
  • Addiction and misuse.
  • Neonatal withdrawal.
  • Accidental patch exposure can be fatal.

Adverse effects

  • Common: sedation, nausea, constipation, pruritus.
  • Serious: apnea, chest wall rigidity, severe respiratory depression.

Contraindications / caution

Do not use

  • Transdermal patch use in opioid-naive patients (absolute contraindication).
  • Respiratory depression.
  • MAOI use.
  • Paralytic ileus.

Use caution / avoid high doses

  • Elderly.
  • Liver disease.
  • COPD/OSA.
  • CYP3A4 inhibitors.
  • Fever (patch ↑ absorption).

Drug interactions

  • Benzodiazepines -> respiratory depression/death.
  • CYP3A4 inhibitors (ritonavir, fluconazole) -> ↑ fentanyl levels.
  • CYP3A4 inducers -> ↓ efficacy.
  • MAOI -> contraindicated.
  • Alcohol -> additive CNS depression.

Special populations

Pediatrics

Weight-based IV/IN dosing with close respiratory monitoring.

Pregnancy

Short-term use acceptable; avoid prolonged use (NOWS).

Breastfeeding

Low transfer; monitor infant.

Elderly

Start low (12.5–25 mcg IV).

Liver disease

Reduce dose.

Renal impairment

Preferred opioid in CKD; still titrate carefully.

Administration

  • IV preferred in acute care.
  • Avoid rapid IV push (WCS risk).
  • Patch: apply to upper body and avoid heat exposure.

Infusion / dilution

  • Dilute to ~10–50 mcg/mL.
  • IV must be given slowly over >=3–5 minutes to reduce chest wall rigidity risk.

Monitoring

  • Renal function and LFTs.
  • Respiratory rate.
  • SpO2.
  • Use capnography (EtCO2) when available, especially in procedural sedation and ICU.
  • Sedation score.
  • Pain score.
  • Peak airway pressure in ICU (WCS clue).

Overdose / toxicity

IF SUSPECTED FENTANYL OVERDOSE: ABC first

Recognition

  • Variable toxic dose due to high potency.
  • Miosis + respiratory depression + coma; may include chest rigidity (WCS).

Immediate actions

  • Naloxone with higher/repeated dosing as needed.
  • Repeat naloxone every 2–3 minutes as needed based on response.
  • Escalate naloxone doses up to 2 mg IV and repeat as needed in high-potency opioid toxicity.
  • Airway and ventilatory support.
  • Consider NMBA (e.g., rocuronium) for severe WCS with ventilation difficulty.

Antidote

  • Naloxone with repeat dosing based on response.

Decontamination

  • Per local toxicology protocol when appropriate.

Escalation

  • Naloxone infusion for re-narcotization risk.

Clinical pearls

Common mistakes, resistance logic, and bedside traps

Renal choice

  • Preferred opioid in renal failure.

Patch safety

  • Patch is NEVER for opioid-naive patients.
  • Patch effect persists 18–24 h after removal.

WCS risk

  • Rapid IV push can cause life-threatening chest wall rigidity.

Naloxone

  • Fentanyl toxicity often requires higher naloxone doses.

CYP3A4

  • CYP3A4 interactions are critical.

Potency conversion

  • 100 mcg fentanyl ≈ 10 mg IV morphine.

Pediatric IN

  • Intranasal fentanyl is excellent for pediatric analgesia in selected settings.

Pharmacokinetics

  • Highly lipophilic.
  • Hepatic metabolism (CYP3A4).
  • No active metabolites.
  • Tissue redistribution can prolong effect despite short plasma profile.

Mechanism of action

  • Full mu-opioid receptor agonist.
  • Decreased cAMP and neurotransmitter release.
  • Rapid CNS penetration due to high lipophilicity.

Common brand names

Saudi Arabia

Fentanyl (generic) · Duragesic · Durogesic DTrans · Sublimaze

Global

Actiq · Fentora · Abstral · Subsys · Lazanda · Instanyl

Common trade names are curated examples only — formulations and availability vary. Verify the exact product name with your local pharmacy and national regulator before prescribing or dispensing.

Country practice notes

  • Strictly controlled opioid across Gulf (special narcotic permits required).
  • Widely used in ICU/anesthesia (often preferred over morphine in CKD).
  • Transdermal patches are restricted to opioid-tolerant patients.
  • Limited outpatient access in some MENA countries.
  • Regulatory oversight via SFDA/GCC narcotics frameworks.

Saudi Arabia — confirm with local formulary.