DrugindexOnline^{2nd edition}

Pronouncation: (al-FEN-tuh-NILL HIGH-droe-KLOR-ide)
Class: Narcotic agonist analgesic

Trade Names:
Alfenta
- Injection 500 mcg (as hydrochloride)/mL

Mechanism of Action

Pharmacology

Binds opioid receptors in CNS.

Pharmacokinetics

Distribution

Vd is 0.4 to 1 L/kg. Protein binding is about 92%. Sequential distribution t _½ is 1 and 14 min.

Metabolism

Metabolized in the liver.

Elimination

Terminal t _½ is 90 to 111 min. Plasma Cl is about 5 mL/kg/min. One percent is excreted as unchanged drug; urinary excretion is the major route for metabolites.

Special Populations

Hepatic Function Impairment

Reduced plasma Cl and extended terminal elimination may develop.

Elderly

Reduced plasma Cl and extended terminal elimination may develop.

Indications and Usage

Induction of analgesia and anesthesia in specific situations, monitored anesthesia care (MAC).

Contraindications

Hypersensitivity to narcotics; diarrhea caused by poisoning until toxic agent is identified; acute bronchial asthma; upper airway obstruction.

Dosage and Administration

Obese Patients

Calculate dosage on basis of lean body weight.

Spontaneously Breathing/Assisted Ventilation
Adults (initial dose)

IV 8 to 20 mcg/kg.

Adults (maintenance dose)

IV 0.5 to 1 mcg/kg/min.

Incremental Injection
Adults (initial dose)

IV 20 to 50 mcg/kg.

Adults (maintenance dose)

IV 5 to 15 mcg/kg every 5 to 20 min.

Anesthetic Induction
Adults (initial dose)

IV 130 to 245 mcg/kg.

Adults (maintenance dose)

IV 0.5 to 1.5 mcg/kg/min (or use general anesthetic).

Continuous Infusion
Adults (initial dose)

IV 50 to 75 mcg/kg.

Adults (maintenance dose)

IV 0.5 to 3 mcg/kg/min.

MAC
Adults (initial dose)

IV 3 to 8 mcg/kg; total dose, 3 to 40 mcg/kg.

Adults (maintenance dose)

IV 3 to 5 mcg/kg every 5 to 20 min to 1 mcg/kg/min.

Drug Interactions

Cimetidine

Reduces alfentanil Cl.

CNS depressants

May increase CNS and CV effects of alfentanil.

Diazepam

May produce CV depression when given with high doses of alfentanil.

Erythromycin

May increase levels of alfentanil, causing prolonged or delayed respiratory depression.

Protease inhibitors

May increase CNS and respiratory depression.

Laboratory Test Interactions

Amylase or lipase concentration test results may be unreliable for 24 h after administration of alfentanil.

Adverse Reactions

Cardiovascular

Hypotension; hypertension; tachycardia; bradycardia; asystole hypercarbia; arrhythmia.

CNS

Sedation; dizziness.

EENT

Blurred vision.

GI

Nausea; vomiting.

Respiratory

Respiratory depression; bronchospasm; apnea.

Miscellaneous

Muscular rigidity.

Precautions

Pregnancy

Category C .

Lactation

Undetermined.

Children

Hypotension has occurred in newborns receiving alfentanil. Not recommended for children under 12 yr of age.

Elderly

Decreased dosage may be necessary.

Labor and Delivery

Narcotics cross placenta and can affect newborn.

Cardiac effects

Drug may cause bradycardia and hypotension; may aggravate arrhythmias.

CNS depression

Patient may be sensitive to depressive effects of alfentanil.

Head injury

Alfentanil may increase intracranial pressure.

Respiratory effects

Alfentanil may decrease respiratory drive and cause apnea.

Seizures

Alfentanil may cause or aggravate seizure disorder.

Skeletal muscle rigidity

Alfentanil may cause skeletal muscle rigidity, particularly of the truncal muscle.

Overdosage

Symptoms

Respiratory depression, CNS depression, circulatory collapse (usually after rapid IV administration).

Patient Information

• Advise postoperative patient to rise from bed slowly and to call for assistance in ambulation.
• Instruct patient to avoid intake of alcoholic beverages or other CNS depressants for 24 h after outpatient surgery.