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Opioid Analgesic (Ultra-Short Acting)

Alfentanil

Brand names: Rapifen

Alfentanil is a short-acting synthetic opioid of the phenylpiperidine class used intravenously to provide analgesia during anaesthesia and to attenuate the response to laryngoscopy and intubation.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It is a potent agonist at mu-opioid receptors, producing rapid-onset analgesia and suppression of nociceptive reflexes through actions in the central nervous system.

Prescribing in practice

  • It causes dose-dependent respiratory depression, so it must only be given where airway support, ventilation and resuscitation facilities are immediately available.
  • It has a rapid onset and short duration relative to other opioids, making it well suited to brief procedures and to attenuating the pressor response to intubation.
  • Concomitant benzodiazepines or other CNS depressants markedly potentiate respiratory depression, hypotension and sedation.

Monitoring

Continuously monitor respiratory rate, oxygen saturation, level of consciousness and haemodynamic status during and after administration.

Counselling the patient

  • Warn the patient that drowsiness and breathing depression can occur and that recovery is monitored closely.
  • Ensure the team has naloxone and airway equipment immediately to hand.

Evidence & guidelines

Use is supported by long-standing anaesthetic practice and product information; opioid prescribing in anaesthesia should follow current MHRA and SPC guidance.

Reference: Stoelting's Pharmacology and Physiology in Anaesthetic Practice; AAGBI Guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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