No

Antidote

Treatment of alcohol dependence; blockade of the effects of exogenously administered opioids

C

Known hypersensitivity to naltrexone; narcotic dependence or current use of opioid analgesics; acute opioid withdrawal; failure to pass Narcan® challenge or positive urine screen for opioids; acute hepatitis or liver failure

Dose-related hepatocellular injury is possible; the margin of separation between the apparent safe and hepatotoxic doses appear to be only fivefold or less. May precipitate withdrawal symptoms in patients addicted to opiates, including pain, hypertension, sweating, agitation, irritability; in neonates: shrill cry, failure to feed. Use with caution in patients with hepatic or renal impairment.

>10%:

Central nervous system: Insomnia, nervousness, headache, low energy

Gastrointestinal: Abdominal cramping, nausea, vomiting

Neuromuscular & skeletal: Arthralgia

1% to 10%:

Central nervous system: Increased energy, feeling down, irritability, dizziness, anxiety, somnolence

Dermatologic: Rash

Endocrine & metabolic: Polydipsia

Gastrointestinal: Diarrhea, constipation

Genitourinary: Delayed ejaculation, impotency

<1%: Increased blood pressure, edema, palpitations, tachycardia, narcotic withdrawal, depression, paranoia, fatigue, restlessness, confusion, disorientation, hallucinations, nightmares, bad dreams, suicide attempts, blurred vision, nasal congestion, itching rhinorrhea, sneezing

Symptoms of overdose include clonic-tonic convulsions, respiratory failure; patients receiving up to 800 mg/day for 1 week have shown no toxicity; seizures and respiratory failure have been seen in animals

Naltrexone decreases effects of opioid-containing products

Lethargy and somnolence have been reported with the combination of naltrexone and thioridazine

Naltrexone (a pure opioid antagonist) is a cyclopropyl derivative of oxymorphone similar in structure to naloxone and nalorphine (a morphine derivative); it acts as a competitive antagonist at opioid receptor sites

Duration of action:

50 mg: 24 hours

100 mg: 48 hours

150 mg: 72 hours

Absorption: Oral: Almost completely

Distribution: V_d: 19 L/kg; distributed widely throughout the body but considerable interindividual variation exists

Protein binding: 21%

Metabolism: Undergoes extensive first-pass metabolism to 6-b-naltrexol

Half-life: 4 hours; 6-b-naltrexol: 13 hours

Time to peak serum concentration: Within 60 minutes

Elimination: Principally in urine as metabolites and unchanged drug

Do not give until patient is opioid-free for 7-10 days as determined by urine analysis

Dosing cautions in renal/hepatic impairment: Caution in patients with renal and hepatic impairment. An increase in naltrexone AUC of approximately 5- and 10-fold in patients with compensated or decompensated liver cirrhosis respectively, compared with normal liver function has been reported.

If there is any question of occult opioid dependence, perform a naloxone challenge test; do not attempt treatment until naloxone challenge is negative

No information available to require special precautions

No effects or complications reported

This medication will help you achieve abstinence from opiates if taken as directed. Do not increase or change dose. Do not use opiates or any medications not approved by your prescriber during naltrexone therapy. You may experience drowsiness, dizziness, or blurred vision (use caution when driving or engaging in tasks requiring alertness until response to drug is known); nausea or vomiting (small frequent meals, frequent mouth care, chewing gum, or sucking lozenges may help); decreased sexual function (reversible when drug is discontinued). Report yellowing of skin or eyes, change in color of stool or urine, increased perspiration or chills, acute headache, palpitations, or unusual joint pain. Pregnancy/breast-feeding precautions: Inform prescriber if you are or intend to be pregnant. Consult prescriber if breast-feeding.

Monitor for narcotic withdrawal

Tablet, as hydrochloride: 50 mg

Kleber HD, "Naltrexone," J Subst Abuse Treat, 1985, 2(2):117-22.

Mitchell JE, "Naltrexone and Hepatotoxicity," Lancet, 1986, 1(8491):1215.

O'Connor PG and Kosten TR, "Rapid and Ultrarapid Opioid Detoxification Techniques," JAMA, 1998, 279(3):229-34.