Drug information of Alfentanil


A short-acting opioid anesthetic and analgesic derivative of fentanyl. It produces an early peak analgesic effect and fast recovery of consciousness.
Alfentanil is effective as an anesthetic during surgery, for supplementation of analgesia during surgical procedures, and as an analgesic for critically ill patients.

Mechanism of effect

Precise mechanism of action has not been fully elucidated; opiate agonists act at several CNS sites, involving several neurotransmitter systems to produce analgesia.


Opiate agonists act at specific receptor binding sites in the CNS and other tissues; opiate receptors are concentrated in the limbic system, thalamus, striatum, hypothalamus, midbrain, and spinal cord. Agonist activity at the μ-receptor can also result in suppression of opiate withdrawal (and antagonist activity can result in precipitation of withdrawal).


Absorption: For intravenous injection or infusion only.

Volume of distribution: 0.4 to 1 L/kg

Protein binding: 92%

Metabolism: The liver is the major site of biotransformation.

Route of elimination: Only 1.0% of the dose is excreted as unchanged drug; urinary excretion is the major route of elimination of metabolites.

Half life: 90-111 minutes

Drug indications

Analgesic Activity


The dosage of Alfentanil HCl injection should be individualized and titrated to the desired effect in each patient according to body weight, physical status, underlying pathological condition, use of other drugs, and type and duration of surgical procedure and anesthesia. In obese patients (more than 20% above ideal total body weight), the dosage of Alfentanil HCl injection should be determined on the basis of lean body weight. The dose of Alfentanil HCl injection should be reduced in elderly or debilitated patients.

Continuous Infusion: 0.5 to 3 mcg/kg/min administered with nitrous oxide/oxygen in patients undergoing general surgery. Following an anesthetic induction dose of Alfentanil HCl injection , infusion rate requirements are reduced by 30 to 50% for the first hour of maintenance.

Usage in Children: Clinical data to support the use of Alfentanil HCl injection in patients under 12 years of age are not presently available. Therefore, such use is not recommended.

Drug contraindications

hypersensitivity to this drug


  • Hypotension: May cause hypotension; use with caution in patients with hypovolemia, cardiovascular disease (including acute MI), or drugs which may exaggerate hypotensive effects (including phenothiazines or general anesthetics). Monitor for symptoms of hypotension following initiation or dose titration.
  • Hypersensitivity: Anaphylaxis reactions may occur.
  • Respiratory depression: Serious, life-threatening, or fatal respiratory depression, even when used as recommended, may occur. Monitor closely for respiratory depression, especially during initiation or dose escalation. Carbon dioxide retention from opioid-induced respiratory depression can exacerbate the sedating effects of opioids.
  • Serotonin syndrome: Potentially life-threatening serotonin syndrome (SS) has occurred with concomitant use of alfentanil and serotonergic agents (eg, SSRIs, SNRIs, triptans, TCAs, 5-HT3 receptor antagonists, mirtazapine, trazodone, tramadol) and agents that impair metabolism of serotonin (eg, MAO inhibitors). Monitor patients closely for signs of SS such as mental status changes (eg, agitation, hallucinations, delirium, coma); autonomic instability (eg, tachycardia, labile blood pressure, diaphoresis); neuromuscular changes (eg, tremor, rigidity, myoclonus); GI symptoms (eg, nausea, vomiting, diarrhea); and/or seizures. Discontinue alfentanil if serotonin syndrome is suspected
  • Opioid agonist toxicities: Shares the toxic potentials of opioid agonists, and precautions of opioid agonist therapy should be observed.
  • Abuse/misuse/diversion: Alfentanil exposes users to the risks of opioid addiction, abuse, and misuse, which can lead to overdose and death. Assess each patient’s risk prior to prescribing alfentanil and monitor all patients regularly for the development of these behaviors and conditions.
  • Discontinuation of therapy: Discontinue infusion at least 10 to 15 minutes prior to the end of surgery during general anesthesia; during administration for Monitored Anesthesia Care (MAC), infusions may be continued to the end of the procedure.
  • Trained individuals: Alfentanil should be administered health care providers specifically trained in the use of anesthetic agents and should not be used in diagnostic or therapeutic procedures outside the monitored anesthesia setting; opioid antagonist, resuscitative and intubation equipment should be readily available.

Points of recommendation

Consult with your doctor in these cases:  

If you have an allergy to alfentanil or any other part of this medicine.

If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.

If you have any of these health problems: Lung or breathing problems like asthma, trouble breathing, or sleep apnea; high levels of carbon dioxide in the blood; or stomach or bowel block or narrowing.

If you are taking any of these drugs: Buprenorphine, butorphanol, nalbuphine, or pentazocine.

If you have taken certain drugs used for low mood (depression) like isocarboxazid, phenelzine, or tranylcypromine or drugs used for Parkinson's disease like selegiline or rasagiline in the last 14 days. Taking alfentanil within 14 days of those drugs can cause very bad high blood pressure.

If you are taking any of these drugs: Linezolid or methylene blue.

Avoid driving and doing other tasks or actions that call for you to be alert until the effects of alfentanil wear off and you feel fully awake.

To lower the chance of feeling dizzy or passing out, rise slowly if you have been sitting or lying down. Be careful going up and down stairs.

This medicine has an opioid drug in it. The use of opioid drugs along with a benzodiazepine drug or other drugs that may make you drowsy or slow your actions has led to very bad side effects. Side effects that have happened include slowed or trouble breathing and deaths. Benzodiazepine drugs include drugs like alprazolam, diazepam, and lorazepam. Benzodiazepine drugs are used to treat many health problems like anxiety, trouble sleeping, or seizures. Talk with the doctor.

Many drugs interact with this medicine and can raise the chance of side effects like deadly breathing problems. Talk with your doctor and pharmacist to make sure it is safe to use alfentanil with all of your drugs.

Do not take with alcohol or products that have alcohol. Unsafe and sometimes deadly effects may happen.

This medicine may raise the chance of seizures in some people, including people who have had seizures in the past. Talk to your doctor to see if you have a greater chance of seizures while taking this medicine.

If you are 65 or older, use alfentanil with care. You could have more side effects.

This medicine may cause harm to the unborn baby if you take it while you are pregnant. If you are pregnant or you get pregnant while taking this medicine, call your doctor right away.

Using alfentanil for a long time during pregnancy may lead to withdrawal in the newborn baby. This can be life-threatening. Talk with the doctor.

Tell your doctor if you are breast-feeding or plan to breast-feed. This medicine passes into breast milk and may harm your baby.

Pregnancy level


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