Fentanyl

Strong Opioid·Analgesia - Opioids

Intra-operative analgesia, severe trauma, palliative cancer pain, chronic intractable pain

S8Authority requiredPBSOPIOIDDurogesic (Patch), Sublimaze (IV)+2

Potency

100x MORPHINE

Half-life

Minutes (IV)

Heat Tox

HIGH RISK

Renal Safe

YES

Rapid Summary

Overview

Synthetic, ultra-potent, ultra-lipophilic pure mu-opioid agonist. 100 times stronger than Morphine. Used IV for instant procedural analgesia or via transdermal patch for severe chronic/cancer pain.

Maximum Dose

Titrated to effect.

Clinical Focus

Transdermal patches must NEVER be used in opioid-naive patients. They are strictly for patients already tolerant to high-dose daily opioids.

Bottom Line

Fentanyl is the most potent synthetic opioid for severe pain and anaesthesia, but has an extremely narrow margin between therapeutic and lethal doses and is the leading cause of opioid overdose deaths.

Formulation & Access

Brand Names

Durogesic (Patch), Sublimaze (IV)

Parenteral

Ampoules (100 mcg/2 mL or 500 mcg/10 mL) for IV use. Lozenges/Lollipops (Actiq).

Topical

Transdermal Patches (12, 25, 50, 75, 100 mcg/hour).

Prescribing & PBS

Highly Restricted (S8). Authority Required (PBS).

Indications & Use

Primary

PBSTGA

Intra-operative analgesia, severe trauma, palliative cancer pain, chronic intractable pain.

Clinical Place

The gold standard in ICU/Anaesthetics due to instant onset/offset and cardiovascular stability.

Quick reference

Class & Role

Strong Opioid — Synthetic, ultra-potent, ultra-lipophilic pure mu-opioid agonist.

Route / Formulation

Ampoules (100 mcg/2 mL or 500 mcg/10 mL) for IV use. Lozenges/Lollipops (Actiq). (Durogesic (Patch), Sublimaze (IV))

Usual Dose & Max

IV 10-50 mcg (micrograms!) STAT. Titrate every 5 mins. Titrated to effect.

Key Indication Doses

Procedural / Acute Severe Pain: IV 10-50 mcg (micrograms!) STAT. Titrate every 5 mins. Chronic / Cancer Pain: Topical Patch applied every 72 HOURS. Start at 12 mcg/hr. Rotate sites. Renal Impairment: No active metabolites. The safest IV opioid (alongside Hydromorphone) for severe renal failure.

Best Uses

Avoid / Cautions

Patch use in opioid-naive patients or for acute/post-op pain (Fatal overdose risk). Pregnancy Category C.

Key Risks

Respiratory: Sudden, profound apnoea (especially if pushed rapidly IV). Cardiovascular: Very stable. Does NOT release histamine (unlike morphine), so it maintains blood pressure perfectly in trauma/shock. Neuromuscular: Chest Wall Rigidity ('Wooden Chest Syndrome'). If pushed IV too fast, the diaphragm paralyzes, preventing ventilation.

Key Interactions

CYP3A4 inhibitors (Clarithromycin, Ketoconazole) block hepatic clearance, spiking blood levels and risking fatal apnoea. Benzodiazepines (Synergistic respiratory arrest).

Monitoring

For patches: No heat packs or hot baths. Heat massively accelerates absorption, causing lethal overdose. Ensure old patch is removed before placing a new one. Continuous SpO2, RR, and BP when giving IV.

Clinical Pearl

A fentanyl patch takes 12-24 hours to reach therapeutic blood levels. Do NOT place a patch on a patient in agony and expect it to work today. You must bridge them with regular IV/PO opioids until the patch kicks in tomorrow.

Access

Authority requiredDurogesic (Patch), Sublimaze (IV)

Brand: Durogesic (Patch), Sublimaze (IV)
PBS status: Authority required