Classifications: narcotic (opiate agonist) analgesic; general anesthetic;
Therapeutic: narcotic analgesic
; general anesthetic
Prototype: Morphine
Pregnancy Category: C
Controlled Substance: Schedule II


500 mcg/mL injection


Alfentanil is a narcotic agonist analgesic with rapid onset and short duration of action. CNS effects appear to be related to interaction of drug with opiate receptors.

Therapeutic Effect

Analgesia is mediated through changes in the perception of pain at the spinal cord and at higher levels in the CNS. Brief duration of action is advantageous for short surgical procedures, but necessitates incremental injections or continuous infusion for long operations.


Major component of balanced anesthesia; analgesic, analgesic supplement, and primary anesthetic for induction of anesthesia when endotracheal and mechanical ventilation are required.


Coagulation disorders, bacteremia, infection at injection site; pregnancy (category C); lactation. Safety in children <12 y is not established.

Cautious Use

Older adults, history of pulmonary disease.

Route & Dosage

Induction of MAC
Adult: IV 3–8 mcg/kg; maintenance of MAC: 3–5 mcg/kg q5–20 min or 0.25–1 mcg/kg/min; total dose: 3–40 mcg/kg.

Dose based on IBW.

Hepatic Impairment
Maintenance doasge adjustment recommended.



PREPARE: Direct or Continuous: ??Alfentanil is available in concentrations of 500 mcg/mL. Small volumes may be given direct IV undiluted or diluted in 5 mL of NS.??Add 20 mL of alfentanil to 230 mL of compatible IV solution to yield 40 mcg/mL. Compatible IV solutions include NS, D5/NS, D5W, and RL.?? Note: Alfentanil may be diluted to concentrations of 25–80 mcg/mL.  

ADMINISTER: Direct: Administer over at least 3 min. Do not administer more rapidly.  Continuous: Administer at a rate of 0.5–1 mcg/kg/min. Note: Dose may be individualized.  

INCOMPATIBILITIES Y-site: Amphotericin B, lansoprazole, thiopental.

  • Store at 15°–30° C (59°–86° F). Avoid freezing.

Adverse Effects (≥1%)

Body as a Whole: Thoracic muscle rigidity, flushing, diaphoresis; extremities feel heavy and warm. CNS: Dizziness, euphoria, drowsiness. CV: Hypotension, hypertension, tachycardia, bradycardia. GI: Nausea, vomiting, anorexia, constipation, cramps. Respiratory: Apnea, respiratory depression, dyspnea.


Drug: beta-adrenergic blockers increase incidence of bradycardia; cns depressants such as barbiturates, tranquilizers, neuromuscular blocking agents, opiates, and inhalation general anesthetics may enhance the cardiovascular and CNS effects of alfentanil in both magnitude and duration; enhancement or prolongation of postoperative respiratory depression also may result from concomitant administration of any of these agents with alfentanil.


Onset: 2 min. Duration: Injection 30 min; continuous infusion 45 min. Distribution: Crosses placenta. Metabolism: In liver by CYP3A4. Elimination: Excreted in breast milk. Half-Life: 46–111 min.

Nursing Implications

Assessment & Drug Effects

  • Monitor for S&S of increased sympathetic stimulation (arrhythmias) and evidence of depressed postoperative analgesia (tachycardia, pain, pupillary dilation, spontaneous muscle movement) if a narcotic antagonist has been administered to overcome residual effects of alfentanil.
  • Evaluate adequacy of spontaneous ventilation carefully during postoperative period.
  • Monitor vital signs carefully during postoperative period; check for bradycardia, especially if patient is also taking a beta blocker.
  • Note: Narcotic effects wear off quickly with negligible residual effects.
  • Note: Dizziness, sedation, nausea, and vomiting are common when drug is used as a postoperative analgesic.

Patient & Family Education

  • Report unpleasant adverse effects when drug is used for patient-controlled analgesia.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

© 2006-2022 Last Updated On: 11/26/2022 (0)
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