Opioid

Fentanyl

Synthetic phenylpiperidine μ-agonist · Sublimaze

Mechanism: μ-opioid receptor agonist; 75–125× more potent than morphine.

Calculate dose for your patient

Enter weight (kg or lb). Always verify before administration.

Patient weight

Computed weight

70.0 kg · 154.3 lb

Induction adjunct

70 mcg – 210 mcg

= 1.40–4.20 mL (50 mcg/mL)

Maintenance 0.5–2 mcg/kg PRN.

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Full dose calculator

Onset

1–2 min

Duration

30–60 min (single dose); context-sensitive half-time grows with infusion.

Metabolism

Hepatic CYP3A4.

Dosing

Adult

Induction adjunct: 1–3 mcg/kg. Maintenance: 0.5–2 mcg/kg PRN. Cardiac dose: 5–20 mcg/kg.

Pediatric

1–2 mcg/kg.

Indications

Intraoperative analgesia
Sedation
Pain control

Contraindications

MAOI use (relative)
Severe respiratory depression

Side Effects

Respiratory depression
Bradycardia
Chest wall rigidity (high doses/fast push)
Pruritus

Clinical Pearls

1Rigidity from rapid bolus → ventilation impossible; treat with NMBA + naloxone.

2Short single-dose action belies long context-sensitive half-time on infusion.

References & Further Reading

1
Textbook
Flood P, Rathmell JP, Shafer S. Stoelting's Pharmacology and Physiology in Anesthetic Practice. 5th ed. Philadelphia: Wolters Kluwer; 2015.
2
Textbook
Gropper MA, Miller RD, Cohen NH, et al., eds. Miller's Anesthesia. 9th ed. Philadelphia: Elsevier; 2020.
3
Textbook
Barash PG, Cullen BF, Stoelting RK, Cahalan MK, Stock MC, Ortega R, Sharar SR, Holt NF. Clinical Anesthesia. 8th ed. Philadelphia: Wolters Kluwer; 2017.
4
Textbook
Adriano A, Morris R, eds. 2021 CA-1 Tutorial Textbook (15th Ed.). Stanford University Medical Center, Department of Anesthesiology.

Citations are provided to direct further study. Always check the most current edition of guidelines and society recommendations — the information in this chapter is a teaching summary, not primary source material.