Ethics and evidence on naltrexone treatment of offenders
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Ethics and evidence on naltrexone treatment of offenders

‘Hot topics’ offer background and analysis on important issues which sometimes generate heated debate. Opinion is sharply divided on the ethics and effectiveness of pressuring opioid-dependent offenders to take the opiate-blocker naltrexone. Especially sharp is the controversy over long-acting products not approved for medical practice in the UK. Do they constitute an unacceptable infringement of autonomy, or is forcing them on some offenders as caring as holding back someone about to (by choice or not) walk off a cliff?

Referring to long-acting naltrexone implants and injections, another hot topic explored the “curious possibility that precisely because a technology is (relatively) effortlessly effective, it is to that degree under suspicion”. That was in relation to opioid use treatment in general; here we focus on convicted offenders, and ask: Are we missing a trick by not pressuring opioid-dependent offenders under supervision to take the pills or be implanted/injected with naltrexone?

Particularly for offenders, naltrexone seems the perfect medication for promoting abstinence from heroin and allied drugs – a pill taken daily or just twice a week which makes heroin use a disappointment rather than a ‘high’. Free itself of psychoactive effects, naltrexone commandeers and blocks the neural receptors targeted by opiate-type (‘opioid’) drugs. A chemical instead of a physical shackle, it seems in tune with the deprivation of liberty imposed on offenders because it deprives them of opioid experiences rather than providing these in the form of substitute opioids. At its most optimistic, the hope and expectation is that long-acting naltrexone implants will result in patients “learning to abstain successfully”, likened to learning to speak a foreign language fluently in that “It is not enough simply to know the foreign words, or the social and psychological techniques for resisting temptation. What matters is practice and the ability to use those words or techniques not just correctly and appropriately but automatically”. However, lasting effects are not necessarily critical to treatment linked to a probation or parole order. Judges just need to be persuaded that treatment is likely to do as good a crime-prevention job as prison – that it will prevent or keep offending to a minimum for as long as the offender would have been locked up, rarely more than a year for non-violent drug-related offences.

Yet compared to substitute medications like methadone, naltrexone is rarely used inside or outside the criminal justice system. One reason is a limitation applicable to any medication which deprives patients of valued experiences: the more effective it is, the more patients simply refuse it or quickly abandon the treatment. Again this seems to make the treatment suitable for sentenced offenders, by definition already coerced into doing things they would not otherwise do. Let’s examine this apparently suitable marriage between treatment and patient, and ask ourselves if by under-using it, we are missing what could be the most effective way yet to break opioid-dependent offenders of a crime-generating habit.

Overcoming resistance

There are at least three ways to overcome reluctance to start or continue with naltrexone. For convicted offenders, these could coalesce into a powerful treatment. The first way is technical – the availability of long-acting naltrexone products which once inserted in the body more or less consign the patient to a period when opiate effects are blocked; they cannot (or not easily) stop the medication, even if they want to. An implant inserted under the skin blocks opiates usually for two to six months; an intramuscular depot injection approved for medical use in the USA and Russia lasts about a month. From cell A3 we know that among treatment populations willing to try these products, they are more effective in preventing illegal opiate use than naltrexone pills which patients can simply stop taking, and also more effective than placebo versions of the implant or injection. In other words, at least while active they certainly can work for patients motivated to return to a life free of dependence on opiate-type drugs.

A major (but not absolute) impediment to using these products in the UK is that they have not been licensed for medical use. They can still be and have been prescribed (1 2 3 4), but patient and doctor have to accept the added responsibility of using a product which has not yet been certified as meeting the safety and efficacy requirements involved in licensing.

The second way to overcome non-compliance is psychological – to engender the motivation to take naltrexone by making it worth the patient’s while in order to gain valued rewards or avoid aversive punishments. Third are social influences – the availability and commitment of someone with influence over the patient who is in a position to encourage them take the pills and monitor whether they do.

All three ways to prevent naltrexone being neutralised by non-compliance can in theory be marshalled for opioid-dependent offenders under criminal justice supervision. Long-acting implants or injections should be as available to them as to other patients, the prospect of early release from prison or avoidance of a more unpalatable sentence might be a powerful motivation-generator, while criminal justice staff – or treatment personnel reporting to them – can insist on frequent contact to bolster motivation and supervise administration of the pills or renewal of implants/injections.

But is it ethical?

However, because something can be done does not mean that it should be. With naltrexone ethical misgivings about pressuring people into treatment – ultimately aimed at benefiting not them but society at large – are sharpened by its potential danger. If it does not also succeed in preventing relapse, any procedure which erodes opioid-dependent patients’ capacity to tolerate high doses by successfully interrupting use of the drugs leaves those patients at heightened risk of fatal overdose. Naltrexone may further aggravate the risk. Experts convened by the World Health Organization have warned that patients who stop naltrexone in order to resume heroin use can find that same ineffective dose they took hours before is later fatal as naltrexone levels fall and the blockade weakens. Some of the highest drug user death rates ever seen were recorded in Australia among patients who completed detoxification and tried to avoid relapse by taking oral naltrexone, findings explored in Effectiveness Bank analyses (1 2).

Post-detoxification overdose risk is one reason why UK national guidelines caution careful selection of patients fully committed to abstinence and with supportive and stable social environments available after discharge, among which may be seamless entry to residential rehabilitation. The preparation phase and the detoxification interlude itself should, said the guidelines, be used to bolster psychological resilience and social supports.

The problem is that heroin-dependent patients in general lack these kinds of supports, and convicted offenders may lack them even more, raising concerns about leveraging their restricted freedom to persuade them to accept naltrexone-based treatment. So prominent had this question become that in 2006 an issue of the Journal of Substance Abuse Treatment devoted a special section to “Mandating Naltrexone Among Court-Referred Patients: Is It Ethical?”

Naltrexone inserts tie the patient’s hands, preventing them terminating the treatment

Summarised here, the supplementary text (click to unfold Unfold supplementary text) explores these and other commentaries on the ethics of naltrexone treatment of offenders. You will see that there is generally agreement that given safeguards, it is ethically defensible to offer the choice of naltrexone-based treatment if this qualifies an offender for a more lenient sentence than would otherwise be imposed, such as early parole from prison or probation instead of imprisonment. This option has even been lauded as extending the offender’s choices rather than restricting their autonomy. Still there are concerns that when treatment takes the form of a long-acting insert in the body which can be active for several months, it ties the patient’s hands, preventing them terminating the treatment even if they want to, and that treatment has been subverted to criminal justice objectives rather than the good of the patient. Safeguards considered mandatory include what in societies with treatment systems like those of the UK would be a make-or-break condition – that naltrexone be just one of a menu of options which would include methadone or other substitutes for illegally obtained opioids. Since the great majority of opioid users would either choose no medication at all or methadone-type treatment rather than naltrexone, this is almost certain to scupper naltrexone’s chances with all but a few offenders.

In contrast to the Hobson’s choice considered above, usually rejected as unethical is forced treatment over which the patient has no choice – not even of the usual sentence instead. But again there are dissenting voices, arguing that this might be acceptable as long as by restricting the patient’s freedom to experience opioid effects, naltrexone extends their autonomy by freeing them from the cravings that constrict and dominate their life; “Infringing autonomy to create autonomy”. Also, the case was made that forced intervention is a more caring response than leaving the helplessly addicted to generate their own destruction and that of others: “Leaving … addicted people to their own destiny is not a ‘no-fault’ exercise for peers and for society at large. The self-destruction, incarceration, or disability of a family member does affect others.” Counter-arguments are that the ‘addict’ retains their freedom to choose, and not having lost this, does not need it ‘restored’ by naltrexone, that the medication has not been shown to dampen cravings which lead to relapse when the treatment ends, and that this line of thinking would justify ignoring patients’ wishes and forcing treatment on the over-eater or those exhibiting obsessive-compulsive tendencies – a slippery slope to state control via medicine displacing the (in Western cultures) valued autonomy of the individual.

Check out these powerful arguments by unfolding Unfold supplementary text the supplementary text, preparatory to answering our final questions on where you stand on these controversial issues.

Does it work?

Given ethical concerns, the fact that the long-acting products have not been licensed for medical use in the UK, and the treatment’s lack of appeal to many prospective patients, it is no surprise that both in the USA and the UK naltrexone is very much a minority option, even for offenders. In 2004, Dr Colin Brewer, whose private clinic provided long-acting naltrexone, recorded that despite “considerable benefits from probation-linked naltrexone,” researchers evaluating court-ordered drug treatment in England found that only one offender in their sample had received naltrexone.

Another sign of how rarely this option has been used is that in 2006 a thorough search for randomised trials among offenders found just one dating from 1997 (it is listed above). A fresh search ending in 2014 found just three randomised trials. Even then the 1997 trial remained the most important test of naltrexone added to ‘treatment as usual,’ though it had been supplemented by a another US trial published in 2010.

These two trials are critical because they sampled offenders living in the community under criminal justice supervision, the main use envisaged for naltrexone. Both recorded marginally significant reductions in the proportions of offenders who violated parole attributable to adding an oral naltrexone programme to usual procedures. The later review found these results amalgamated to a clearly significant reduction. Parole violation was the only measure of criminality which could be amalgamated, but in the 2010 study there were others which gave a different picture – notably records rather than self-reports of parole violations (not significantly reduced) and the non-significantly but considerably more (32% v. 10%) naltrexone offenders charged with drug offences during the six-month follow-up.

These and other studies are analysed below unfold Unfold supplementary text supplementary text. As a whole, they show how few (previously) opioid-dependent offenders opt for naltrexone, even when opiate substitutes like methadone are not on offer, but also that when naltrexone administration is supervised, when offenders want it, have strong incentives to comply, and the treatment is active, it helps suppress opioid use and prevent parole or probation violations, affording offenders opportunities for learning to live opioid-free in the community which may otherwise be denied them. Without these conditions, rejection and drop-out from the programmes becomes the norm. Even with them, there seems no evidence that the substance use and parole/probation violation gains made while naltrexone is active persist after treatment ends, or (perhaps related) that they automatically extend to the stabilisation and improvement of other aspects of the patients’ lives.

As with the ethical considerations outlined above, check out these findings in greater detail by unfolding Unfold supplementary text the supplementary text, preparatory to answering our final questions on where you stand on naltrexone treatment for offenders.


Efficacy and ethical considerations should come together in guidance for practitioners and service planners, but in the UK there is no guidance specific to offenders. Last published in 2017, the so-called ‘Orange guidelines’ for clinicians involved in treating problem drug use said of naltrexone:
• Among highly motivated patients provided with adequate supervision, naltrexone can help to maintain abstinence.
• Naltrexone should usually be used only after a patient is opioid-free (verified by testing for the presence of opioids).
• The impact of naltrexone may be enhanced by additional support from a keyworker or group, allowing service users to discuss any issues related to sustaining abstinence.
• Its effectiveness should be reviewed regularly and if opioid use becomes apparent, discontinuation of naltrexone should be considered.

In this the guidelines echo recommendations from Britain’s National Institute for Health and Care Excellence (NICE) that the drug is suitable for detoxified patients who are highly motivated to remain in an abstinence programme, and should be administered under adequate supervision as part of a programme of supportive care to people who have been fully informed of the risks. Despite an unpromising record among the generally randomly allocated patients in clinical trials, NICE’s experts were convinced that among selected individuals and in the recommended circumstances, naltrexone can greatly aid abstinence from opiate-type drugs with associated improvements in the patient’s quality of life. The World Health Organization is clear that the post-treatment overdose risk means naltrexone is best reserved for patients who have a reasonable chance of remaining abstinent, and that those severely dependent should be cautious about embarking on the treatment.

Specifically in relation to long-acting products, an Effectiveness Bank hot topic concluded that the clearest candidates for naltrexone implants and injections are patients motivated to return to a life without opiate-type drugs, who have the resources, stability and support to sustain this, are unlikely simply to use other drugs instead, but who when free to experience opiates, cannot resist them. Long-acting formulations may also be considered for unstable patients at very high risk of overdose, but who will not accept or do poorly in substitute prescribing programmes. Other candidates might include those unwilling or unable to accept daily supervised consumption if this is a requirement of being prescribed substitute medications.

Unresolved questions

This introduction to the ethics and effectiveness of naltrexone treatment for offenders has raised but not resolved questions for you to ponder, including: Is it OK to force this treatment on the unwilling in their own interests and that of their families and the broader society, because once freed of their addiction, this will extend the patient’s autonomy rather than restrict it? Or only OK if the offender can choose naltrexone as part of a less onerous sentence than they would otherwise have been given? Do we have enough evidence that naltrexone-based treatment works to feel comfortable about pressurising anyone to accept it? Should we also offer better established alternatives like methadone maintenance, even if this means naltrexone will rarely be chosen, and even if methadone-maintained patients commonly break the law by taking heroin once in a while? Like holding back someone about to walk off the edge of a cliff – even if that is what they choose to do Are we missing a trick by not more widely forcing or pressuring opioid-dependent offenders to take naltrexone under supervision or to be fitted with long-acting implanted or injected naltrexone products? These products, after all, force an interruption in regular opioid use which may not be achievable by any other feasible means, and which could be used to embed opioid-free ways of coping. Or is this an ethically and perhaps also physically dangerous subversion of treatment to criminal justice ends when medicine is supposed to prioritise the patient’s welfare? But perhaps this is – despite their contrary wishes – the best way to safeguard some patients’ welfare, rather than leaving them (and those around them) to descend deeper into a destructive addiction – like forcibly holding back someone about to walk off the edge of a cliff, even if that is what they choose to do?

Thanks for their comments on this entry to Colin Brewer, a psychiatrist based in England. Commentators bear no responsibility for the text including the interpretations and any remaining errors.

Last revised 15 August 2018. First uploaded 15 August 2018

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