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Strong Opioid Analgesic — Transdermal Pregnancy: Use only if benefit outweighs risk — neonatal opioid withdrawal; neonatal respiratory depression.

Fentanyl (Transdermal Patch)

Brand names: Durogesic DTrans, Matrifen, Fencino, Mezolar

Adult dose

Dose: Starting patch: 12 micrograms/hour (opioid-naive — low starting dose) or convert from stable oral morphine using equivalence table. Apply to non-irritated, non-hairy skin (upper arm, chest, back). Change every 72 hours (some patients require 48h changes).
Route: Transdermal patch
Frequency: Every 72 hours (change patch)
Max: Multiple patches may be combined — no absolute maximum in cancer pain; titrate to effect
Morphine to fentanyl patch conversion (approximate): 90mg/24h oral morphine = 25 micrograms/hour patch. Takes 12–24h to reach therapeutic level and 12–24h after removal to clear — NOT suitable for titration or unstable/acute pain. Use only when pain is stable and opioid requirement established. Schedule 2 Controlled Drug.

Paediatric dose

Route: Transdermal
Frequency: Every 72 hours
Max: Individualised
BNFc: Licensed from 2 years in children already receiving at least 30mg/day oral morphine equivalent. Seek specialist paediatric pain/palliative care opinion.

Dose adjustments

Renal

Preferred opioid in renal failure — fentanyl metabolites (norfentanyl) are inactive; does not accumulate in CKD. Suitable for eGFR <30 and dialysis patients.

Hepatic

Severe hepatic impairment: use with caution — reduced clearance; may need longer patch change intervals.

Clinical pearls

  • Fever hazard: fever >40°C increases fentanyl absorption from patch by ~30% — risk of overdose; advise patients to seek review if they develop high fever while wearing patch
  • Safe disposal: used patches retain significant fentanyl — fold sticky sides together and dispose in household waste or return to pharmacy; children and pets have died from accidental contact with used patches
  • Antidote: naloxone — but offset of patch effect takes 12–24h after removal; continuous naloxone infusion required (not just bolus) for patch-related overdose
  • Renal failure advantage: fentanyl is the preferred strong opioid in CKD/dialysis — inactive metabolites do not accumulate; monitor for fever-related dose changes

Contraindications

  • Opioid-naive patients (high-strength patches ≥25 micrograms/hour)
  • Acute or post-operative pain (delayed onset/offset makes titration unsafe)
  • Fever >40°C (increases fentanyl release from patch — toxicity risk)
  • Hypersensitivity to fentanyl or patch adhesive

Side effects

  • Constipation
  • Nausea
  • Somnolence
  • Respiratory depression (risk increased by fever)
  • Skin reactions at application site
  • Confusion (particularly elderly)
  • Tolerance and dependence

Interactions

  • Strong CYP3A4 inhibitors (ketoconazole, ritonavir) — increase fentanyl levels; use with caution
  • CNS depressants, benzodiazepines — additive respiratory depression
  • MAOIs — avoid

Monitoring

  • Pain score and breakthrough analgesia use
  • Respiratory rate and sedation (patch initiation and dose change)
  • Temperature (fever increases release)
  • Skin integrity at application site
  • Patch rotation schedule

Reference: BNFc; BNF 90; NICE NG31 (Cancer Pain); PCF6; Murtagh et al. Renal Palliative Care. Verify against your local formulary and the latest BNF before prescribing.

Related

Curated clinical cross-links plus same-class fallbacks.

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