Quick summary: Sustained-release naltrexone occupies opioid receptors for months, so using again is less likely to produce the expected high, and a 2025 Cochrane review of 22 randomised studies found it reduced illicit opioid use compared with usual care and with daily oral naltrexone. In one trial of 306 patients, 52.9% of those given an implant stayed in treatment without relapse at six months, against 15.7% on oral naltrexone and 10.8% on placebo, though it is not shown to be better than methadone or buprenorphine for every person. That longer block can give counselling, work, sleep, and family repair a real chance to take hold, which is the practical point for mental health care rather than detox alone.
For someone recovering from opioid addiction, deciding to stop is often only the beginning of the treatment. The harder questions are how will I handle withdrawal and what happens three weeks later, three months later, or on the unexpectedly difficult evening when stress takes over or triggers will start creeping in, memory and opportunity collide and the desire to use returns.
This is one reason addiction treatment increasingly looks beyond detoxification alone. Getting a drug out of the body is important, but maintaining recovery requires something more difficult: giving a person enough stability and time to change what happens after the drug is gone.
Cravings are central to that problem.
A person can be completely committed to recovery and still be hit by powerful urges to use. Those urges may be triggered by stress, a familiar place, a certain person, a difficult memory or simply the expectation that opioids will bring fast relief. For example, someone may have been drug-free for several weeks, but after an argument or a stressful day at work, the brain can quickly reconnect that discomfort with the memory of how opioids once numbed it. If the person uses again and experiences that relief, the association between distress and opioid use can become even stronger, making the next craving harder to resist.
What if part of that cycle could be interrupted for months rather than hours or days? A longer period of stability may give someone the chance to return to work, rebuild damaged relationships, become more present for their children and regain control over everyday responsibilities. It can also create space to develop healthier routines, improve sleep and physical health, manage finances more reliably and rediscover interests or goals that addiction had pushed aside. For some people, having sustained distance from repeated relapse may be the period in which recovery begins to feel less like constant survival and more like rebuilding a normal life; this is possible with Naltrexone treatment by Dr George O’Neill.
Naltrexone changes the reward equation
Naltrexone is an opioid antagonist. Unlike methadone and buprenorphine, it is not an opioid agonist and does not produce an opioid high. Instead, it occupies opioid receptors and reduces or prevents other opioids from producing their expected effects. This changes an important part of the psychological calculation behind relapse.
When a person knows that taking an opioid is unlikely to produce the anticipated reward, the connection between craving, drug-seeking and reward is weakened. Naltrexone is not a substitute for counselling, social support or behavioural change, but pharmacological protection can create a period up to a year, during which those other parts of recovery have more opportunity to work.
The difficulty has historically been adherence.
Oral naltrexone can be effective when it is taken consistently, but daily adherence can be a major weakness. Some people simply forget doses, especially when routines are unstable, while others may stop taking the medication deliberately because they are thinking about using opioids again and want the blockade to wear off. That creates a vulnerable gap in protection at exactly the point when relapse risk may be increasing. In practice, the effectiveness of a daily medication therefore depends not only on the drug itself, but also on whether the person continues taking it every single day.
That problem led researchers to investigate longer-acting formulations.
Why duration may matter
Sustained-release naltrexone is designed to remove the daily decision about whether to take medication.
A major 2025 Cochrane review examined 22 randomised studies involving 3,416 participants. Its conclusions were appropriately cautious, but important. Compared with treatment as usual, sustained-release naltrexone reduced illicit opioid use. Compared with oral naltrexone, it also reduces opioid use significantly. The same review found that comparisons with opioid agonist treatments such as methadone and buprenorphine are more complicated. Sustained-release naltrexone should therefore not be presented as universally superior. Different patients have different clinical circumstances, and medication choice should be individualised.
Earlier implant studies nevertheless provide an interesting insight into the potential value of prolonged treatment.
A randomised study involving 306 opioid-dependent patients compared a sustained-release naltrexone implant with oral naltrexone and placebo. After six months, 52.9% of the implant group remained in treatment without relapse, compared with 15.7% receiving oral naltrexone and 10.8% receiving placebo.
Another randomised study found that patients receiving a six-month naltrexone implant used heroin on substantially fewer days during the following 180 days than patients receiving usual aftercare. These studies do not establish that every implant, programme or patient will achieve the same result. Implant formulations differ, and systematic reviews have repeatedly called for larger and higher-quality studies. They do, however, raise an important recovery question: what becomes possible when relapse-prevention medication remains present for months without requiring a new decision every morning?
From resisting drugs to rebuilding life
Recovery consumes mental energy.
Someone in early recovery may be attempting to repair a relationship, return to employment, manage debt, deal with anxiety, reconnect with children and learn to respond differently to stress; while simultaneously trying not to use opioids. Reducing one of those pressures can matter.
Longer-term craving and relapse control should therefore perhaps be viewed not as the recovery itself, but as a protected period in which recovery can be built. Counselling during that period can focus on triggers, emotional regulation, relationships, routines, employment, physical health and the reasons substance use became important in the person’s life. Months of greater stability may allow new behaviours to become normal rather than temporary.
This is also why medication without continuing care is an incomplete answer. The objective is not simply to prevent someone from experiencing an opioid effect. It is to use that period to help the person create a life they are less desperate to escape from.
A technology with a longer history than many realise
Australian physician Dr George O’Neil began developing long-acting naltrexone technology more than two decades ago. His sustained-release technology was the subject of patent protection, and the implant was subsequently used clinically at the Fresh Start Recovery Programme in Western Australia.
In 2012, O’Neil told ABC News that he had implanted approximately 6,000 patients during the preceding 12 years. That scale of clinical use is notable, although real-world experience should not be confused with controlled evidence.
Likewise, a patent demonstrates that an invention has met the relevant legal criteria for patentability; it does establish that a medical treatment is clinically effective. Clinical claims must still be judged through more trials to be allowed in the US, now it is available in Australia. Pharmacokinetic research, systematic reviews and continuing safety evaluation.
That distinction is particularly important in addiction medicine, where vulnerable patients and families deserve accuracy rather than exaggerated promises.
Today, O’Neil’s long-acting implant approach is also used by DeBinge in The Bahamas as one component of a wider recovery programme combining medical management, sustained-release naltrexone and continuing counselling. The implant formulation is not FDA-approved for routine clinical use in the US, and patients considering treatment outside their home country should understand the regulatory status, evidence, risks and available alternatives before making a decision.
The aim is not simply more months of medication
The most interesting question about longer-acting treatment may ultimately have little to do with the implant itself. It is what the person does with the time this treatment creates. Nine months or twelve months cannot erase trauma, repair a family or construct a new identity automatically. Medication cannot attend counselling for someone, change their friendships or give them a purpose.
But reducing craving, blocking opioid reinforcement and removing the daily medication decision may create something enormously valuable: breathing room. No cravings, prevention from relapse and overdose gives a lot of space for recovery. For some people, the repeated craving–relapse cycle has lasted for years. Breaking that cycle long enough for different habits, relationships and expectations to develop may be one of the ways pharmacology can support psychological recovery.
The goal is not merely to stop someone taking an opioid today. It is to give recovery enough time to become a life they can continue tomorrow.
Fergus Law, MD works with DeBinge in The Bahamas, where he is involved in the clinical management of patients undergoing addiction treatment, including long-acting naltrexone-based care.
