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Naltrexone
Naltrexone (ReVia)
Naltrexone
(nal-TREX-ohn)
Pregnancy Category: C ReVia (Rx)

Classification: Narcotic antagonist

See Also: See also Narcotic Antagonists.

Action/Kinetics: Competitively binds to opiate receptors, thereby reversing or preventing the effects of narcotics. Peak plasma levels: 1 hr. Duration: 24-72 hr. Metabolized in the liver; a major metabolite--6-beta-naltrexol--is active. Peak serum levels, after 50 mg: naltrexone, 8.6 ng/mL; 6-beta-naltrexol, 99.3 ng/mL. t1/2: naltrexone, approximately 4 hr; 6-beta-naltrexol, 13 hr. Naltrexone and its metabolites are excreted in the urine.

Uses: To prevent narcotic use in former narcotic addicts. Adjunct to the psychosocial treatment for alcoholism. Investigational: To treat eating disorders and postconcussional syndrome not responding to other approaches.

Contraindications: Those taking narcotic analgesics, dependent on narcotics, or in acute withdrawal from narcotics. Liver failure, acute hepatitis.

Special Concerns: Use with caution during lactation. Safety in children under 18 years of age has not been established.

Side Effects: CNS: Headache, anxiety, nervousness, sleep disorders, dizziness, change in energy level, depression, confusion, restlessness, disorientation, hallucinations, nightmares, bad dreams, paranoia, fatigue, drowsiness. GI: N&V;, diarrhea, constipation, anorexia, abdominal pain or cramps, flatulence, ulcers, increased appetite, weight gain or loss, increased thirst, xerostomia, hemorrhoids. CV: Phlebitis, edema, increased BP, changes in ECG, palpitations, epistaxis, tachycardia. GU: Delayed ejaculation, increased urinary frequency or urinary discomfort, increased or decreased interest in sex. Respiratory: Cough, sore throat, nasal congestion, rhinorrhea, sneezing, excess secretions, hoarseness, SOB, heaving breathing, sinus trouble. Dermatologic: Rash, oily skin, itching, pruritus, acne, cold sores, alopecia, athlete's foot. Musculoskeletal: Joint/muscle pain, muscle twitches, tremors, pain in legs, knees, or shoulders. Ophthalmologic: Blurred vision, aching or strained eyes, burning eyes, light-sensitive eyes, swollen eyes. Other: Hepatotoxicity, tinnitus, painful or clogged ears, chills, swollen glands, inguinal pain, cold feet, ``hot'' spells, ``pounding'' head, fever, yawning, side pains.
A severe narcotic withdrawal syndrome may be precipitated if naltrexone is administered to a dependent individual. The syndrome may begin within 5 min and may last for up to 2 days.

How Supplied: Tablet: 50 mg

Dosage
•Tablets To produce blockade of opiate actions.
Initial: 25 mg followed by an additional 25 mg in 1 hr if no withdrawal symptoms occur. Maintenance: 50 mg/day.
Alternate dosing schedule for blockade of opiate actions.
The weekly dose of 350 mg may be given as: (a) 50 mg/day on weekdays and 100 mg on Saturday; (b) 100 mg/48 hr; (c) 100 mg every Monday and Wednesday and 150 mg on Friday; or, (d) 150 mg q 72 hr.
Alcoholism.
50 mg once daily for up to 12 weeks. Treatment for longer than 12 weeks has not been studied.