Naltrexone is a competitive opioid antagonist medication indicated for the management of alcohol dependence and for the blockade of the effects of exogenously administered opioids. It works by binding to opioid receptors in the brain, blocking the euphoric and sedative effects of opioids and reducing alcohol cravings. Available in oral tablet and extended-release injectable formulations, naltrexone is a cornerstone of medication-assisted treatment (MAT) protocols. Its efficacy is well-supported by clinical evidence, making it a first-line pharmacological option in comprehensive addiction treatment programs.

Features

• Competitive opioid receptor antagonist
• Available as 50 mg oral tablets and 380 mg extended-release intramuscular injection
• Non-addictive with no abuse potential
• Requires initial opioid-free period (typically 7-10 days)
• Compatible with most psychosocial interventions
• FDA-approved for alcohol use disorder and opioid use disorder

Benefits

• Reduces alcohol craving and decreases heavy drinking days
• Blocks euphoric effects of opioids, discouraging relapse
• Non-controlled substance with minimal diversion risk
• Allows patients to focus on counseling and behavioral therapies
• Injectable formulation provides continuous coverage, improving adherence
• Can be used long-term as part of maintenance therapy

Common use

Naltrexone is primarily prescribed for the management of alcohol dependence in patients who have achieved and wish to maintain abstinence. It is equally indicated for the prevention of relapse to opioid dependence following opioid detoxification. The medication is typically incorporated into comprehensive treatment programs that include counseling, psychosocial support, and monitoring. Off-label uses include the treatment of impulse control disorders, though evidence for these applications is less established.

Dosage and direction

Oral formulation: Initiate with 25 mg daily for initial tolerance testing, then increase to 50 mg once daily. May be administered with food to minimize gastrointestinal upset.

Extended-release injection: 380 mg administered intramuscularly in the gluteal muscle every 4 weeks by healthcare professional.

Dosage adjustments may be necessary based on patient response and tolerability. Treatment should not be initiated until the patient is opioid-free for at least 7-10 days to avoid precipitated withdrawal.

Precautions

Patients should be thoroughly screened for current opioid use before initiation. Hepatic function should be assessed at baseline and monitored during treatment. Use with caution in patients with renal impairment. May cause injection site reactions including pain, tenderness, and induration with the extended-release formulation. Patients should carry documentation noting naltrexone use in case emergency opioid analgesia is required.

Contraindications

Absolute contraindications include current opioid dependence, positive urine screen for opioids, acute opioid withdrawal, and failed naloxone challenge test. Additional contraindications include acute hepatitis or liver failure, and hypersensitivity to naltrexone or any component of the formulation.

Possible side effects

Common adverse reactions include nausea (10%), headache (7%), dizziness (4%), nervousness (4%), and fatigue (4%). Injection site reactions occur in approximately 15% of patients receiving the extended-release formulation. Less common but serious side effects may include hepatotoxicity, depression, suicidal ideation, and eosinophilic pneumonia (with injectable form).

Drug interaction

May precipitate acute withdrawal when administered with opioid agonists. Concurrent use with opioid-containing medications (including antitussives and antidiarrheals) is contraindicated. May alter metabolism of drugs hepatically metabolized. Use with caution with other hepatotoxic drugs. Thioridazine may increase somnolence. No significant interactions with disulfiram have been documented.

Missed dose

Oral formulation: Take missed dose as soon as remembered unless close to next scheduled dose. Do not double doses.

Injectable formulation: Administer missed injection as soon as possible. Do not administer two injections simultaneously. Maintain approximately 4-week intervals between doses.

Overdose

No specific antidote exists. Management is supportive and symptomatic. In cases of suspected overdose with the extended-release formulation, surgical removal may be considered. Hemodialysis is not effective due to extensive protein binding. Monitor for hepatotoxicity with significant overdose.

Storage

Store at controlled room temperature (20-25°C/68-77°F). Oral tablets should be kept in original container with tight closure. Extended-release suspension must be stored refrigerated (2-8°C/36-46°F) and administered within 24 hours after preparation. Keep all formulations out of reach of children.

Disclaimer

This information is for educational purposes only and does not constitute medical advice. Naltrexone should only be used under the supervision of a qualified healthcare provider. Patients must undergo comprehensive assessment and monitoring during treatment. Individual results may vary based on patient factors and adherence to comprehensive treatment plan.

Reviews

Clinical studies demonstrate naltrexone’s efficacy in reducing alcohol relapse rates by approximately 36% compared to placebo. The extended-release formulation shows significantly improved adherence rates (89% vs 52% with oral formulation). Patient-reported outcomes indicate improved quality of life measures and reduced craving intensity. Meta-analyses support its position as a first-line pharmacotherapy in alcohol use disorder management.