sedative

Fentanyl

Sublimaze (IV) / Duragesic (patch) / Actiq (lozenge)

Route: IV · transdermal patch · transmucosal · IN · epidural/IT
Onset: 1–2 minutes (IV)
Duration: 30–60 minutes (single dose); prolonged with infusion

Mechanism of action

Synthetic opioid. Binds mu-opioid receptors in CNS and periphery → analgesia via decreased pain signal transmission, altered pain perception. Also produces sedation, euphoria, respiratory depression, and GI effects.

Dosing

Adult: ICU analgesia: 25–200 mcg/hr continuous infusion. Bolus: 25–100 mcg IV PRN. Procedural: 1–2 mcg/kg IV
Pediatric: 0.5–2 mcg/kg IV bolus; 1–5 mcg/kg/hr infusion

Indications

Analgesia in mechanically ventilated patients
Procedural pain management
Adjunct to sedation in ICU (analgesia-first approach)
Acute pain management

Contraindications

Hypersensitivity to fentanyl
MAOIs within 14 days (risk of serotonin syndrome)
Severe respiratory depression in non-monitored setting

Side effects

Respiratory depression (most critical)
Chest wall rigidity ('wooden chest') — rapid IV boluses at high doses
Constipation (prolonged use)
Hypotension (less than morphine)
Urinary retention
Pruritis (less than morphine)
Tolerance and dependence (prolonged use)

Monitoring parameters

Respiratory rate and SpO2
CPOT or NRS pain scale
Level of sedation (RASS)
GI motility (constipation)
Signs of withdrawal with abrupt discontinuation

Drug interactions

CNS depressants (potentiated respiratory depression)
MAOIs (serotonin syndrome)
CYP3A4 inhibitors (increased fentanyl levels)
Benzodiazepines (FDA black box — additive respiratory depression)
Naloxone (reversal agent)

NBRC high-yield

100× more potent than morphine
Preferred ICU opioid — minimal histamine, less hemodynamic instability
Chest wall rigidity with rapid high-dose boluses
Reversal: naloxone
Analgesia-first approach in ICU: treat pain before adding sedation
SpO2 and respiratory rate monitoring mandatory

Clinical pearls

100× more potent than morphine
Preferred opioid in ICU due to minimal histamine release (vs. morphine) and less hemodynamic compromise
Chest wall rigidity: use NMB or naloxone; prevent with slow administration
Analgesia-First sedation: treat pain before adding sedative (fentanyl first, then propofol/midazolam)
Reversal: naloxone 0.04–0.4 mg IV (titrate to respiratory effect, not full reversal to avoid pain crisis)
Context-sensitive half-life increases significantly with prolonged infusion

Mnemonic

Fentanyl: Fast (1–2 min IV), Fifty... no, 100× morphine potency

All Drugs

Clinical pearls

100× more potent than morphine

Preferred opioid in ICU due to minimal histamine release (vs. morphine) and less hemodynamic compromise

Chest wall rigidity: use NMB or naloxone; prevent with slow administration

Analgesia-First sedation: treat pain before adding sedative (fentanyl first, then propofol/midazolam)

Reversal: naloxone 0.04–0.4 mg IV (titrate to respiratory effect, not full reversal to avoid pain crisis)

Context-sensitive half-life increases significantly with prolonged infusion