Alfentanil

IMPORTANT Confusion between different strengths of alfentanil can lead to severe opioid toxicity or death (See NHS England patient safety insight)

Tables are best viewed in landscape mode on mobile devices

• Third-line injectable opioid for moderate to severe opioid responsive pain in patients unable to tolerate morphine, diamorphine or oxycodone due to persistent side effects (for example sedation, confusion, hallucinations, itch). Refer to Pain management, Choosing and changing opioids guidelines.
• Injectable analgesic for moderate to severe, opioid responsive pain in patients with Stage 4 to 5 chronic kidney disease (eGFR less than 20 ml/minute). Specialists may recommend in less compromised chronic kidney disease, or in severe acute renal impairment.
• Episodic/incident pain is:
• pain often related to a particular event (for example movement, dressing changes); sudden in onset, can be severe, but may not last long
• different from breakthrough pain occurring when the dose of regular analgesic has worn off, and
• assessed and treated independently of the regimen used to manage any continuous/background pain. 

Allergy to alfentanil

• Liver impairment: increased risk of toxicity caused by reduced cytochrome metabolism. Dose reduction of 30 to 50% may be necessary.
• Renal impairment: no dose reduction needed. Not removed by dialysis.

Drug interactions

• Hepatic metabolism is reduced by grapefruit juice and a number of medications, for example fluconazole, QTclarithromycin, QTerythromycin: refer to British National Formulary (BNF).
• Alcohol and central nervous system depressants increase side effects
• Anticonvulsants may reduce its effect. Refer to BNF.

Side effects

Similar to other opioids: nausea, dizziness, sedation, delirium, rarely respiratory depression.

Alfentanil for moderate to severe opioid responsive pain

• • Seek advice from specialist palliative care regarding the starting dose to be used BEFORE prescribing an alfentanil.
  • Administer via continuous subcutaneous infusion in a syringe pump (CSCI) over 24 hours.
  • Check stability and compatibility–refer to syringe pump compatibility tables.
  • Titrate only on the advice of a specialist.

Alfentanil for breakthrough, as required, pain relief

Ideally, alfentanil use as a breakthrough analgesic should be avoided as alfentanil has a very short duration of action. Other opioids with a longer duration of action such as oxycodone are used for breakthrough pain.

• • Seek advice from specialist palliative care regarding the starting dose to be used BEFORE prescribing an alfentanil.
  • Prescribe 1/6th to 1/10th of the equivalent total 24-hour syringe driver dose of alfentanil, up to 1 hourly for breakthrough pain, maximum six doses in 24 hours
  • If three or more doses have been given within four hours with little or no benefit seek urgent advice or review. 
  • If six doses are required in 24 hours seek advice or review.

Alfentanil for episodic/ incident pain

• • Seek advice from specialist palliative care regarding the starting dose to be used BEFORE prescribing an alfentanil.
  • Give a dose five minutes before an event likely to cause pain, for example, a painful dressing change.
  • Seek specialist advice before increasing dose according to response. This dose can be titrated independently of the background dose.

Doses of over 1,000 micrograms should be expressed in milligrams (mg) unless local policy states otherwise–please refer to local prescribing guidance.

Alfentanil is approximately 30 times more potent than oral morphine.

Tables are best viewed in landscape mode on mobile devices

IMPORTANT: Note that any conversions are estimations, and great care is necessary when making any calculation.

Caution when switching from alfentanil CSCI to fentanyl transdermal patch.

A patient whose pain is controlled on a subcutaneous alfentanil infusion can be converted to a fentanyl patch with specialist palliative care oversight.

Seek specialist palliative care advice for dose conversions as cross-titration may be necessary.

• Dose conversions should be conservative and doses rounded down.
• Monitor the patient carefully so that the dose can be adjusted if necessary.
• If the patient has opioid toxicity, reduce dose by approximately a third when changing opioid (refer to choosing and changing opioids guideline).

IMPORTANT: New timing guidance for patch removal during switching period.

Evidence demonstrates a rise in fentanyl levels from 4 hours following patch application, and that this rise has been linked to severe opioid toxicity.

Apply the patch and stop the infusion ideally after 6–8 hours, ensuring the overlap period DOES NOT exceed 12 hours.

• The community pharmacist, GP and community nurse should be informed as preparations may not be readily available.
• The local out of hours/unscheduled care service should be informed that the patient is receiving this third-line opioid.
• Alfentanil can be prescribed by the patient’s GP for the indications listed in liaison with local palliative care specialists.
• Fentanyl patches begin to raise clinically important fentanyl levels from as early as 4 hours following first application.

Professional
Alfentanil. Palliative Care Formulary, MedicinesComplete

NHS England » Confusion between different strength preparations of alfentanil

Dean M. Opioids in renal failure and dialysis patients. J Pain Symptom Manage. 2004;28(5):497-504.

NHS England. NHS England Confusion between different strength preparations of alfentanil 2026 [30 Apr 2026]. Available from: https://www.england.nhs.uk/patient-safety/patient-safety-insight/learning-from-patient-safety-events/how-we-acted-on-patient-safety-issues-you-recorded/confusion-between-different-strength-preparations-of-alfentanil/

Oosten AW, Abrantes JA, Jönsson S, de Bruijn P, Kuip EJ, Falcão A, et al. Treatment with subcutaneous and transdermal fentanyl: results from a population pharmacokinetic study in cancer patients. Eur J Clin Pharmacol. 2016;72(4):459–67.

Urch CE, Carr S, Minton O. A retrospective review of the use of alfentanil in a hospital palliative care setting. Palliat Med. 2004;18(6):516–9.