Limifen (Alfentanil)

• Alfentanil is a µ‑opioid receptor agonist used in anesthesia and peri‑operative pain management.
• Induction of anesthesia: provides rapid onset sedation and analgesia to facilitate endotracheal intubation.
• Intra‑operative analgesia: maintains analgesic depth during surgical procedures.
• Procedural sedation: offers short‑acting sedation for brief diagnostic or therapeutic interventions.

• Alfentanil binds selectively to the µ‑opioid receptors in the central nervous system, activating G‑protein coupled pathways that inhibit adenylate cyclase, reduce calcium influx, and increase potassium efflux. This results in decreased neuronal excitability and suppression of nociceptive transmission, producing potent analgesia and sedation within seconds of intravenous administration. The high lipid solubility of alfentanil facilitates rapid crossing of the blood‑brain barrier, contributing to its quick onset and short duration of action.

Alfentanil may be associated with a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Respiratory depression: reduced breathing rate or depth.
• Hypotension: lowered blood pressure.
• Bradycardia: slowed heart rate.
• Nausea or vomiting: gastrointestinal upset.

Serious or Rare Side Effects

• Chest wall rigidity: severe muscle stiffness affecting ventilation.
• Allergic reaction: rash, itching, or anaphylaxis.
• Seizure activity: rare central nervous system excitation.

When using alfentanil, clinicians should observe specific precautions to minimize risk and ensure safe administration.

• Patient assessment: evaluate respiratory function and opioid tolerance before use.
• Dose titration: adjust dose gradually, especially in the elderly or those with hepatic impairment.
• Monitoring: continuously monitor oxygen saturation, heart rate, and blood pressure during infusion.
• Drug interactions: avoid concurrent use with other central depressants without careful supervision.
• Contraindications: do not use in patients with known hypersensitivity to alfentanil or other opioids.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Alfentanil can interact with several medication classes, affecting its potency or safety profile.

Major Interactions (Avoid)

• Other opioids: additive respiratory depression.
• Benzodiazepines or barbiturates: enhanced central nervous system depression.
• Muscle relaxants: increased risk of chest wall rigidity.

Moderate Interactions (Monitor Closely)

• MAO inhibitors: possible prolonged opioid effect.
• Selective serotonin reuptake inhibitors (SSRIs): monitor for rare serotonin syndrome.
• CYP3A4 inhibitors (e.g., ketoconazole): may increase alfentanil plasma levels.