Addiction—whether to opioids, amphetamines, or alcohol—damages health, relationships, careers, and can shorten life expectancy. Completing detox is a good first step, but the real challenge lies ahead—most patients relapse within the first year, often with devastating consequences. This cycle strains patients, families, and healthcare systems alike.
Oral medications like naltrexone can reduce cravings and block the pleasurable effects of drugs or alcohol, but they rely on daily adherence. Missed doses, waning motivation, or intentional skipping create windows of vulnerability that often lead to relapse—and in the case of opioids, overdose.
Long-acting naltrexone formulations address this challenge. Monthly depot injections (Vivitrol) and implantable formulations—lasting up to nine months—deliver a continuous dose under the skin. Implants remove the burden of daily decision-making, prevent missed doses, and maintain steady receptor blockade. For patients, this means fewer lapses and more stability during recovery. For clinicians, it provides a reliable foundation to combine with therapy, counseling, and relapse-prevention strategies. The term “depot” refers to a drug formulation that creates a reservoir (or “depot”) of medication at the injection site, allowing it to be released slowly into the body over an extended period. While depot naltrexone is FDA-approved for both alcohol and opioid use, implants are not currently approved in the US.
The problem: relapse after detox is common
After opioid detoxification, relapse rates without ongoing medication can exceed 80% within the first year.[1] Oral naltrexone, approved decades ago, showed some promise but was hampered by poor adherence.[2] Every missed dose represented an open door for relapse.
Long-acting implants remove this obstacle by releasing naltrexone continuously, taking away the daily decision-making that often undermines recovery. Randomized controlled trials (RCTs) confirm that retention in treatment and abstinence are significantly higher with implants than with oral formulations.[3]
What the research says
- Randomized controlled trials: For example, Hulse et al. (2009) conducted an RCT in opioid-dependent patients, finding significantly longer relapse-free survival in the implant group compared to placebo.[4]
- Meta-analyses: A Cochrane review (2014) concluded that long-acting naltrexone (depot or implant) is more effective than oral formulations for maintaining abstinence, though study heterogeneity remains a limitation.[5]
- Real-world evidence: In Western Australia, large cohorts of patients treated with implants demonstrated reduced hospital admissions and overdose events compared to historical controls, suggesting a public health benefit.[6][7]
People with addiction problems need all the help they can get to remain abstinent after detox. My clinical experience with both opiates and alcohol is that naltrexone reduces unwanted cravings by about 50%, improves the sense of control over first and subsequent use, and reduces the pleasurable experiences following use or prevents them completely in the case of opiates. Longer-acting formulations provide people with a sense of psychological stability, helping them feel more settled despite the ups and downs of life.
How naltrexone implants work — pharmacology explained
Naltrexone is essentially a pure opioid antagonist at the μ-opioid receptor. It occupies the receptor without activating it, thereby preventing opioids such as heroin, oxycodone, or fentanyl from producing euphoria or analgesia.[8]
- Implant formulations provide a steady release of naltrexone into the bloodstream, typically lasting 2–6 months depending on the preparation.[9]
- Alcohol use disorder: Naltrexone dampens alcohol-induced stimulation of the endogenous opioid system, reducing craving and the reward effect of heavy drinking episodes.[10]
- Extended-release advantage: Because blood concentrations remain stable, patients cannot forget to take it or “skip a dose” to relapse, which is a common issue with daily oral tablets.[11]
Real-life cases & reports
- “Beating methamphetamines: two men tell their stories of years of addiction to a bright future in recovery” (ABC News, Perth)
- Involves people with long histories of methamphetamine and heroin use who have a rapid detox + naltrexone implants through Dr George O’Neil’s Fresh Start program in Western Australia. They describe how the implant helped reduce cravings, maintain abstinence for months, and rebuild lives. ABC
- Demonstrates how implants help with polydrug / stimulant + opioid addiction, which often overlaps in practice. ABC
- “Woman in naltrexone treatment fix” (The West Australian)
- A woman from Sydney, with a long history of addiction, travels to Western Australia to receive naltrexone implant treatment to stay free of drug use; she reports that this treatment is the only way she can maintain freedom from drug use. The West Australian
- Illustrates personal experience and hardship, followed by travel, sacrifice, and the impact of the implant on quality of life. The West Australian
- “Naltrexone implants a possible solution to Australia’s ice epidemic” (ABC News)
- Johnny Mitchell, age 28, with a long-term addiction to “ice” (crystal meth), lost his home, partner, and child; after deciding to try naltrexone implants, he is interviewed, saying, “I’m getting an implant … to cut craving.” ABC
- A strong human interest story that shows the turning point in addiction. Good for showing what people go through and the hope these treatments can bring. ABC
Who should consider it – indications
Who Can Benefit from Naltrexone Implants
- Patients with repeated relapse: Implants provide continuous receptor blockade, helping those who struggle with daily oral medication achieve sustained abstinence.
- Those avoiding opioid agonists: Offers a drug-free option, blocking opioids without euphoria or dependence.
- Motivated patients seeking a “set-and-forget” approach: Steady medication allows focus on therapy, life rebuilding, and behavioral changes.
- Communities reducing overdose and hospitalizations: When combined with counseling, implants help lower opioid-related harm and support public health initiatives.
Who should avoid it – contraindications and risks
Absolute Contraindications
- Current opioid use: Naltrexone is a strong opioid antagonist. If a person is actively using opioids at the time of implantation, it can trigger precipitated withdrawal, which is often severe and potentially dangerous. In general, patients must be fully detoxified from opioids before receiving an implant.
- Acute hepatitis or severe liver failure: Naltrexone is metabolized in the liver, and impaired liver function can increase the risk of toxicity. Implant therapy is not safe for individuals with significant liver disease. Baseline liver function tests are mandatory before insertion.
- Hypersensitivity to naltrexone or its components: Any known allergy to naltrexone or its components disqualifies a patient from receiving the therapy. Even mild reactions can escalate once the drug is continuously released into the body.
Risks and Considerations
- Reduced opioid tolerance after blockade ends: After the implant wears off, relapse can be dangerous due to lowered tolerance, making post-implant support essential.
- Potential liver enzyme elevation: Mild, usually reversible liver changes can occur; baseline and regular monitoring are recommended.
- Implant-related complications: Minor surgical risks include infection, irritation, pain, or extrusion, which are minimized with proper technique and follow-up.
Comment: While naltrexone implants are generally safe and well-tolerated, understanding these contraindications and risks is critical for both patients and clinicians. Careful patient selection, pre-treatment evaluation, and ongoing monitoring are essential to maximize safety and effectiveness.
The Western Australia experience
Western Australia: Real-World Impact of Naltrexone Implants
Western Australia was among the first regions to implement naltrexone implants for opioid-dependent individuals struggling with oral medications. Clinics in Perth combined implants with detox, counseling, and psychosocial support.
Observed Benefits:
- Reduced overdoses: Hospital and emergency visits for opioid overdose declined, as implants provided consistent protection during high-risk periods.
- Improved treatment retention: Patients were more likely to remain engaged in recovery programs than with oral naltrexone, thanks to the implant’s long-acting properties.
- Community impact: Overall opioid overdose rates fell to some of the lowest levels nationally, suggesting sustained-release naltrexone contributed to population-level improvements.
Commentary:
The Western Australian experience illustrates how pharmacological interventions, such as naltrexone implants, can go beyond individual benefits to influence community health outcomes. By reducing the likelihood of relapse and overdose among high-risk populations, implants help ease the burden on healthcare systems and provide an additional tool for harm reduction. Importantly, these programs work best when paired with structured support services, highlighting that implants are not a stand-alone solution but a critical component of a comprehensive treatment model.
I have visited the Fresh Start Clinic in Western Australia twice and interviewed patients about their experiences with naltrexone implants. I could not fail to be impressed by the stories of their transformed lives, and there is no doubt that it helps many people. Audit data from this clinic showed that abstinence rates at 1 year were 80% for opiates, 69% for amphetamines, and 50% for alcohol (although this included only those who could be contacted). The data on reduced overdose rates in Western Australia is also particularly impressive, and indeed, the Western Australian government provided funding for several years to support the naltrexone implant programme.
Closing thoughts
Long-acting formulations of Naltrexone are not a cure-all, but they represent one of the most powerful tools available today for opioid and alcohol dependence. The longer-acting implants are of particular interest as they reduce the frequency of episodes where the person is vulnerable to relapse. By removing the daily decision to take medication, they give patients the chance to rebuild their lives with fewer relapses. Success is highest when implants are combined with counseling, psychosocial support, and relapse-prevention education.
If you are considering this treatment, consult a physician experienced with naltrexone implants for a full medical assessment.
If you or someone you know experiences mental health issues, it is important to seek help from a qualified professional. Our Mental Health Resource Specialists can assist you in finding expert help and support in your community. Contact us now for more information on this free service.
About the Author: Dr Fergus Law, BSc, MBChB, FRCPsych has degrees in both psychology and medicine, qualified as a doctor in 1985, and became a Consultant Psychiatrist specializing in addiction psychiatry in the British National Health Service in 2001. He was elected a Fellow of the UK Royal College of Psychiatrists for his contribution to psychiatry in 2016. He has a particular interest in promoting recovery from addiction by improving detoxification and abstinence rates, and acts as a Clinical Advisor for DeBinge Ltd.
References
- Smyth BP et al. Relapse following detoxification from opiate dependence: A prospective study. Drug Alcohol Depend. 2010.
- Krupitsky E et al. Naltrexone for opioid dependence. Cochrane Database Syst Rev. 2011.
- Lobmaier P et al. Sustained-release naltrexone for opioid dependence: a clinical review. CNS Drugs. 2011.
- Hulse G et al. Randomized controlled trial of naltrexone implant vs placebo. Arch Gen Psychiatry. 2009.
- Minozzi S et al. Oral naltrexone maintenance treatment for opioid dependence. Cochrane Database. 2014.
- Hulse G, Tait R. Opioid antagonist implants in the treatment of heroin addiction. CNS Drugs. 2003.
- Gibson AE, Degenhardt L. Mortality related to naltrexone in opioid dependence. Aust N Z J Psychiatry. 2007.
- Veverka A et al. Pharmacology of naltrexone. Am J Health Syst Pharm. 2019.
- Waal H, Håseth A. Naltrexone implants: Duration and pharmacokinetics. Eur Addict Res. 2018.
- Anton RF et al. Naltrexone for alcohol dependence: A meta-analysis. JAMA. 2006.
- Krupitsky E et al. Injectable extended-release naltrexone for opioid dependence: A double-blind trial. Lancet. 2011.
- Vivitrol® prescribing information, Alkermes Inc. 2021.
- Kelty E, Hulse G. Fatal opioid overdose risk after naltrexone implant discontinuation. Drug Alcohol Rev. 2017.
- Pettinati HM et al. Naltrexone and liver safety. Am J Addict. 2006.
- Ngo H et al. Complications of naltrexone implants. Drug Alcohol Depend. 2007.
- Lenton S. Trends in overdose in Western Australia and relation to naltrexone implant use. Addiction. 2004.
Photo by cottonbro studio: https://www.pexels.com/photo/a-doctor-talking-the-patient-7579831/
The opinions and views expressed in any guest blog post do not necessarily reflect those of www.rtor.org or its sponsor, Laurel House, Inc. The author and www.rtor.org have no affiliations with any products or services mentioned in the article or linked to therein. Guest Authors may have affiliations to products mentioned or linked to in their author bios.
Recommended for You
- Breaking the Cycle: How Long-Acting Naltrexone Is Changing Addiction Recovery - November 3, 2025
- When ‘Feeling Off’ Means Your Brain Needs Help: A Quick First Step - October 30, 2025
- Your Heart is Listening: The Hidden Impact of Stress and Anxiety on Cardiovascular Health - October 27, 2025
