Class: Mu Opioid Receptor Antagonist FDA Indications: Alcohol Dependence, Blockade Of The Effects Of Exogenously Administered Opioids Off-Label Use: Self-injurious Behaviors, Autism Spectrum Disorder, Impulse Control Disorders, Tobacco Dependence, Trichotillomania
Forms: 25, 50, 100mg tablet; 12 mg/0.6 mL po soln; 380 mg/vial (see Vivitrol) injectable Dose Range: 50 mg/day Starting: 50 mg once daily
Contraindications: Patients receiving opioid analgesics; patients currently dependent on opioids, including those currently maintained on opiate agonists (e.g., methadone) or partial agonists (e.g., buprenorphine); patients in acute opioid withdrawal; anyone who has failed the naloxone challenge test or who has a positive urine screen for opioids Serious Side Effects: Eosinophilic pneumonia, hepatocellular injury (at excessive doses) Side Effects: headache, dizziness, nausea, nervousness, fatigue, insomnia
- Patients taking naltrexone may not benefit from opioid containing medicines, such as cough and cold preparations, antidiarrheal preparations, and opioid analgesics
- patient must be opioid-free for 7-10 days prior to naltrexone administration;
Naloxone Challenge Test
Clinicians are reminded that there is no completely reliable method for determining whether a patient has had an adequate opioid-free period. A naloxone challenge test may be helpful if there is any question of occult opioid dependence. If signs of opioid withdrawal are still observed following naloxone challenge, treatment with REVIA should not be attempted. The naloxone challenge can be repeated in 24 hours.
The naloxone challenge test should not be performed in a patient showing clinical signs or symptoms of opioid withdrawal, or in a patient whose urine contains opioids. The naloxone challenge test may be administered by either the intravenous or subcutaneous routes.
Inject 0.2 mg naloxone.
Observe for 30 seconds for signs or symptoms of withdrawal. If no evidence of withdrawal, inject 0.6 mg of naloxone. Observe for an additional 20 minutes.
Administer 0.8 mg naloxone.
Observe for 20 minutes for signs or symptoms of withdrawal.
Note: Individual patients, especially those with opioid dependence, may respond to lower doses of naloxone. In some cases, 0.1 mg IV naloxone has produced a diagnostic response.
Interpretation of the Challenge
Monitor vital signs and observe the patient for signs and symptoms of opioid withdrawal. These may include, but are not limited to: nausea, vomiting, dysphoria, yawning, sweating, tearing, rhinorrhea, stuffy nose, craving for opioids, poor appetite, abdominal cramps, sense of fear, skin erythema, disrupted sleep patterns, fidgeting, uneasiness, poor ability to focus, mental lapses, muscle aches or cramps, pupillary dilation, piloerection, fever, changes in blood pressure, pulse or temperature, anxiety, depression, irritability, backache, bone or joint pains, tremors, sensations of skin crawling or fasciculations. If signs or symptoms of withdrawal appear, the test is positive and no additional naloxone should be administered.
Warning: If the test is positive, do NOT initiate REVIA therapy. Repeat the challenge in 24 hours. If the test is negative, REVIA therapy may be started if no other contraindications are present. If there is any doubt about the result of the test, hold REVIA and repeat the challenge in 24 hours.
can be given subcutaneously to test for naltrexone tolerability
studies indicate that 50 mg of naltrexone will block the pharmacologic effects of 25 mg of IV administered heroin for periods as long as 24°
μ receptors contribute to the euphoria and "high" of heavy drinking and ∴ μ antagonism ↓'s the enjoyment of heavy drinking & ↑'s abstinence through disruption of reward circuitry
naltrexone not only increases the chances of attaining complete abstinence from alcohol, but also reduces "heavy drinking"
Using a meta-analysis to derive an NNT for naltrexone shows that about 9 to 20 patients would need to be treated for one successful response
Category C—Except for the reports below in which the naltrexone was discontinued very early in gestation, no other references describing the use of the agent during human pregnancy have been located. Although naltrexone did not produce gross structural abnormalities in any of the animal studies, it did alter some opioid receptors in the brain that appeared to have long-lasting consequences. This potential for behavioral alteration in humans cannot be assessed because of the lack of data, but concern is warranted.
Limited Human Data—Probably Compatible
Dose adjustment not generally necessary for mild impairment; not studied in patients with moderate to severe renal impairment
Hepatically metabolized; contraindicated in acute hepatitis or liver failure; dose adjustment not generally necessary for mild impairment; not studied in patients with severe hepatic impairment; has potential to cause hepatocellular injury when given in excessive doses
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Last updated August 16 2023 14:43:53. Disclaimer: This website does not provide medical advice, nor is it a substitute for clinical judgment.
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