Alfentanil


Generic Medicine Info
Indications and Dosage
Intravenous
Induction of anaesthesia
Adult: Assisted ventilation (undergoing procedures of at least 45 min): Initially, 130-245 mcg/kg, followed by maintenance doses of 0.5-1.5 mcg/kg per minute or by an inhalation anaesth. Assisted ventilation (intensive care): Initially, a loading dose of 5 mg in divided doses over 10 min (slower if hypotension/bradycardia occur); or via infusion at a rate of 2 mg/hr. Therapy should not exceed 4 days.
Child: ≥12 yr Initially, 10-20 mcg/kg as bolus, w/ supplements of 5-10 mcg/kg.
Elderly: Dose or frequency reduction may be necessary.

Intravenous
Analgesia in patients with spontaneous respiration
Adult: Patient receiving monitored anaesthesia care (MAC): Initially, 3-8 mcg/kg, followed by supplements of 3-5 mcg/kg every 5-20 min; or an infusion of 0.25-1 mcg/kg per min.
Child: ≥12 yr Same as adult dose.
Elderly: Dose or frequency reduction may be necessary.

Intravenous
Adjunct in maintenance of general anaesthesia
Adult: Spontaneous respiration: Initially, up to 500 mcg given slowly over 30 seconds w/ supplements of 250 mcg. Assisted ventilation: Initially, 30-50 mcg/kg w/ supplements of 15 mcg/kg; alternatively, an initial loading dose of 50-100 mcg/kg as a bolus or via infusion over 10 min, followed by infusion at 0.5-1 mcg/kg per min. Maintenance infusion should be stopped 10-30 min the anticipated end of surgery.
Child: Maintenance: 0.5-2 mcg/kg per min infusion rate (1 mcg/kg per min when given with IV anaesth), titrated according to response.
Elderly: Dose or frequency reduction may be necessary.
Special Patient Group
Debilitated patient: Dose or frequency reduction may be necessary.
Reconstitution
Dilute w/ IV NaCl 0.9%, dextrose 5% in water, or compound Na lactate (Hartmann’s soln) infusions, and use w/in 24 hr of preparation.
Incompatibility
Y-site admin: Incompatible w/ ampothericin B cholesteryl sulfate complex, thiopental.
Contraindications
Obstructive airway disease, resp depression. Admin in labour or before clamping of cord during caesarean section. Concomitant use during or w/in 14 days of MAOI therapy.
Special Precautions
Patient w/ hypovolaemia, CV disease (e.g. acute MI), bradyarrhythmias, history of drug abuse or acute alcoholism, head injury, intracranial lesions, increased intracranial pressure, pulmonary disease, decreased resp reserve, compromised respiration, COPD or other obstructive pulmonary disease, kyphoscoliosis or other skeletal disorder, and compromised intracerebral compliance, hypothyroidism. Hepatic and renal impairment. Elderly and debilitated patients. Childn. Pregnancy and lactation.
Adverse Reactions
Significant: Hypotension, bradycardia, drug dependency, exaggerated elevation of intracranial pressure, skeletal muscle rigidity, fatigue, agitation.
Nervous: Euphoric mood, disorientation; movement disorder, dizziness, sedation, dyskinesia, headache, somnolence, unresponsive to stimuli, loss of consciousness, convulsion, myoclonus, apnoea.
CV: Tachycardia, arrhythmia, decreased heart rate, cardiac arrest, HTN.
GI: Nausea, vomiting.
Resp: Hiccups, laryngospasm, cough, hypercapnia.
Ophthalmologic: Visual disturbance, miosis.
Dermatologic: Dermatitis, hyperhidrosis, erythema, rash.
Others: Chills, inj site pain, pyrexia.
Potentially Fatal: Resp depression.
Patient Counseling Information
This drug may cause impaired cognitive function, if affected, do not drive or operate machinery.
Monitoring Parameters
Continuously monitor vital signs, oxygen saturation, BP, and heart rate. Monitor the patient well after surgery for delayed effects.
Overdosage
Symptoms: Bradycardia, hypoventilation/apnoea, muscle rigidity, hypovolaemia, resp depression. Management: Treat bradycardia w/ anticholinergics (e.g. atropine, glycopyrrolate). Treat hypoventilation/apnoea w/ admin of oxygen, and establishment of patient airway and assisted/controlled ventilation. Treat muscle rigidity w/ IV neuromuscular blocker. Treat resp depression w/ an opioid antagonist (e.g. naloxone). IV fluids and vasoactive agents may be beneficial to manage haemodynamic instability.
Drug Interactions
Increased risk of prolonged/delayed resp depression w/ CYP3A4 isoenzyme inhibitors (e.g. ketoconazole, itraconazole, fluconazole, voriconazole, ritonavir, erythromycin, diltiazem, cimetidine). Enhanced resp depressant effect w/ barbiturates, benzodiazepines, neuroleptics, halogenic gases, and non-selective CNS depressants (e.g. alcohol). May increase blood concentration of propofol by 17%. May predispose to bradycardia or hypotension w/ drugs that depress the heart or increase vagal tone (e.g. β-blockers, anaesth agents). May cause bradycardia and cardiac arrest w/ non-vagolytic muscle relaxants.
Potentially Fatal: Rarely, may cause severe and unpredictable potentiation of MAOIs.
Action
Description: Alfentanil is a short-acting opioid analgesic related to fentanyl. It binds w/ stereospecific receptors w/in the CNS, thereby altering pain perception, increasing pain threshold, and inhibiting ascending pain pathways.
Onset: W/in 5 min.
Duration: 30-60 min (dose-dependent).
Pharmacokinetics:
Distribution: Crosses the placenta and blood-brain barrier. Detected in colostrum. Volume of distribution: 0.4-1 L/kg. Plasma protein binding: 88-92%, mainly to α1-acid glycoprotein.
Metabolism: Metabolised in the liver by CYP3A4 enzyme via oxidative N- and O-dealkylation into inactive metabolites.
Excretion: Via urine (1% as unchanged). Terminal elimination half-life: 90-111 min.
Chemical Structure

Chemical Structure Image
Alfentanil

Source: National Center for Biotechnology Information. PubChem Database. Alfentanil, CID=51263, https://pubchem.ncbi.nlm.nih.gov/compound/Alfentanil (accessed on Jan. 20, 2020)

Storage
Store between 20-25°C. Protect from light.
ATC Classification
N01AH02 - alfentanil ; Belongs to the class of opioid anesthetics. Used as general anesthetics.
References
Alfentanil Hydrochloride Injection (Akorn, Inc.). DailyMed. Source: U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/. Accessed 18/08/2016.

Anon. Alfentanil. Lexicomp Online. Hudson, Ohio. Wolters Kluwer Clinical Drug Information, Inc. https://online.lexi.com. Accessed 18/08/2016.

Buckingham R (ed). Alfentanil Hydrochloride. Martindale: The Complete Drug Reference [online]. London. Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 18/08/2016.

Joint Formulary Committee. Alfentanil. British National Formulary [online]. London. BMJ Group and Pharmaceutical Press. https://www.medicinescomplete.com. Accessed 18/08/2016.

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