Naltrexone in the treatment of heroin dependence: relationship with depression and risk of overdose

Spatial proximity and access to buprenorphine or methadone treatment for opioid use disorder in a sample of people misusing opioids in Southern California

BACKGROUND

In response to the opioid crisis, over the last 10 years substantial strides have been made to increase the availability of evidence-based treatments for opioid use disorder, in particular buprenorphine maintenance, in the United States. Despite these worthwhile efforts, uptake rates of evidence-based treatment remain relatively low. As part of a broader study of opioid misuse, we examined proximity to evidence-based treatment as a potential barrier to treatment access.

METHODS

In 2017-2018, we surveyed 218 individuals misusing prescription opioids or using street opioids in three Southern Californian counties. The study calculated driving distance from place of residence to the closest treatment provider offering buprenorphine or methadone treatment for opioid use disorders.

RESULTS

Median distance to providers was 3.8 km (2.4 miles). Seventy one (33%) participants had received some form of treatment in the last 3 months; however, only 26 (40%) of these had received buprenorphine or methadone maintenance treatment. Participants receiving treatment at the time of their interview were traveling an average 16.8 km (10.4 miles) to reach treatment, indicating that as a group this population was both willing and able to seek and engage with treatment.

CONCLUSIONS

In the suburban and exurban communities in which our study was based, our findings suggest that simple physical proximity to providers of evidence-based treatment for opioid use disorder is no longer a critical barrier. Other barriers to uptake of buprenorphine or methadone maintenance treatment clearly remain and need to be addressed.

DISCLAIMER

Findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Novel Targets to Treat Depression: Opioid-Based Therapeutics

After participating in this activity, learners should be better able to:• Identify the effects of dysregulated opioid signalling in depression• Evaluate the use of opioid compounds and ketamine in patients with depression ABSTRACT: Major depressive disorder (MDD) remains one of the leading causes of disability and functional impairment worldwide. Current antidepressant therapeutics require weeks to months of treatment prior to the onset of clinical efficacy on depressed mood but remain ineffective in treating suicidal ideation and cognitive impairment. Moreover, 30%-40% of individuals fail to respond to currently available antidepressant medications. MDD is a heterogeneous disorder with an unknown etiology; novel strategies must be developed to treat MDD more effectively. Emerging evidence suggests that targeting one or more of the four opioid receptors-mu (MOR), kappa (KOR), delta (DOR), and the nociceptin/orphanin FQ receptor (NOP)-may yield effective therapeutics for stress-related psychiatric disorders. Furthermore, the effects of the rapidly acting antidepressant ketamine may involve opioid receptors. This review highlights dysregulated opioid signaling in depression, evaluates clinical trials with opioid compounds, and considers the role of opioid mechanisms in rapidly acting antidepressants.

Solving the Opioid Crisis Isn't Just a Public Health Challenge-It's a Bioethics Challenge

Among those who discuss America's opioid crisis, it is popular to claim that we know what we, as a society, ought to do to solve the problem-we simply don't want it badly enough. We don't lack knowledge; we lack the will to act and to fund the right policies. In fact, I've heard two versions of this. Among those who focus on prescription opioids, it is clear that we ought to stop prescribing so many powerful opioid painkillers. And among my public health colleagues focusing on illicit drug use, it is clear that we ought to expand addiction treatment and harm-reduction services. The problem, however, is that the second claim is not obvious (and, indeed, is denied by many Americans), and the first claim probably isn't even true (at least, not in so crude a form). In short, the opioid crisis presents not only a problem of political will but also one of ethics. It will take work to discover or justify our normative claims in this arena.

Systematic Structure-Based Virtual Screening Approach to Antibody Selection and Design of a Humanized Antibody against Multiple Addictive Opioids without Affecting Treatment Agents Naloxone and Naltrexone

Opioid drug use, especially heroin, is known as a growing national crisis in America. Heroin itself is a prodrug and is converted to the most active metabolite 6-monoacetylmorphine (6-MAM) responsible for the acute toxicity of heroin and then to a relatively less-active metabolite morphine responsible for the long-term toxicity of heroin. Monoclonal antibodies (mAbs) are recognized as a potentially promising therapeutic approach in the treatment of opioid use disorders (OUDs). Due to the intrinsic challenges of discovering an mAb against multiple ligands, here we describe a general, systematic structure-based virtual screening and design approach which has been used to identify a known anti-morphine antibody 9B1 and a humanized antibody h9B1 capable of binding to multiple addictive opioids (including 6-MAM, morphine, heroin, and hydrocodone) without significant binding with currently available OUD treatment agents naloxone, naltrexone, and buprenorphine. The humanized antibody may serve as a promising candidate for the treatment of OUDs. The experimental binding affinities reasonably correlate with the computationally predicted binding free energies. The experimental activity data strongly support the computational predictions, suggesting that the systematic structure-based virtual screening and humanization design protocol is reliable. The general, systematic structure-based virtual screening and design approach will be useful for many other antibody selection and design efforts in the future.

Depression and substance use disorders: Clinical comorbidity and shared neurobiology

Mood disorders, including major depressive disorder (MDD), are the most prevalent psychiatric illnesses, and pose an incredible burden to society, both in terms of disability and in terms of costs associated with medical care and lost work time. MDD has extremely high rates of comorbidity with substance use disorders (SUD) as many of the same neurobiological circuits and molecular mechanisms regulate the reward pathways disrupted in both conditions. MDD may induce SUDs, SUD may contribute to MDD development, or underlying vulnerabilities and common life experience may confer risk to developing both conditions. In this chapter we explore theories of MDD and SUD comorbidity, the neurobiological underpinnings of depression, overlapping cellular and molecular pathways for both conditions, and current treatment approaches for these comorbid conditions.

Kappa Opioid Receptor Antagonists as Potential Therapeutics for Stress-Related Disorders

Exposure to stressful stimuli activates kappa opioid receptor (KOR) signaling, a process known to produce aversion and dysphoria in humans and other species. This endogenous opioid system is dysregulated in stress-related disorders, specifically in major depressive disorder (MDD). These findings serve as the foundation for a growing interest in the therapeutic potential of KOR antagonists as novel antidepressants. In this review, data supporting the hypothesis of dysregulated KOR function in MDD are considered. The clinical data demonstrating the therapeutic efficacy and safety of selective and mixed opioid antagonists are then presented. Finally, the preclinical evidence illustrating the induction of behaviors relevant to the endophenotypes of MDD and KOR antagonist activity in stress-naïve and stress-exposed animals is evaluated. Overall, this review highlights the emergent literature supporting the pursuit of KOR antagonists as novel therapeutics for MDD and other stress-related disorders.

Pharmacological characterization of 17-cyclopropylmethyl-3,14-dihydroxy-4,5-epoxy-6-[(3'-fluoro-4'-pyridyl)acetamido]morphinan (NFP) as a dual selective MOR/KOR ligand with potential applications in treating opioid use disorder

For thousands of years opioids have been the first-line treatment option for pain management. However, the tolerance and addiction potential of opioids limit their applications in clinic. NFP, a MOR/KOR dual-selective opioid antagonist, was identified as a ligand that significantly antagonized the antinociceptive effects of morphine with lesser withdrawal effects than naloxone at similar doses. To validate the potential application of NFP in opioid addiction treatment, a series of in vitro and in vivo assays were conducted to further characterize its pharmacological profile. In calcium mobilization assays and MOR internalization studies, NFP showed the apparent capacity to antagonize DAMGO-induced calcium flux and etorphine-induced MOR internalization. In contrast to the opioid agonists DAMGO and morphine, cells pretreated with NFP did not show apparent desensitization and down regulation of the MOR. Though in vitro bidirectional transport studies showed that NFP might be a P-gp substrate, in warm-water tail-withdrawal assays it was able to antagonize the antinociceptive effects of morphine indicating its potential central nervous system activity. Overall these results suggest that NFP is a promising dual selective opioid antagonist that may have the potential to be used therapeutically in opioid use disorder treatment.

Characterization of 17-Cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(indole-7-carboxamido)morphinan (NAN) as a Novel Opioid Receptor Modulator for Opioid Use Disorder Treatment

The opioid crisis is a significant public health issue with more than 115 people dying from opioid overdose per day in the United States. The aim of the present study was to characterize the in vitro and in vivo pharmacological effects of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(indole-7-carboxamido)morphinan (NAN), a μ opioid receptor (MOR) ligand that may be a potential candidate for opioid use disorder treatment that produces less withdrawal signs than naltrexone. The efficacy of NAN was compared to varying efficacy ligands at the MOR, and determined at the δ opioid receptor (DOR) and κ opioid receptor (KOR). NAN was identified as a low efficacy partial agonist for G-protein activation at the MOR and DOR, but had relatively high efficacy at the KOR. In contrast to high efficacy MOR agonists, NAN did not induce MOR internalization, downregulation, or desensitization, but it antagonized agonist-induced MOR internalization and stimulation of intracellular Ca2+ release. Opioid withdrawal studies conducted using morphine-pelleted mice demonstrated that NAN precipitated significantly less withdrawal signs than naltrexone at similar doses. Furthermore, NAN failed to produce fentanyl-like discriminative stimulus effects in rats up to doses that produced dose- and time-dependent antagonism of fentanyl. Overall, these results provide converging lines of evidence that NAN functions mainly as a MOR antagonist and support further consideration of NAN as a candidate medication for opioid use disorder treatment.

Blocking drug activation as a therapeutic strategy to attenuate acute toxicity and physiological effects of heroin

Heroin is a growing national crisis in America. There is an increasing frequency of heroin overdoses. All of the currently used therapeutic approaches to treatment of heroin abuse and other opioid drugs of abuse focus on antagonizing a brain receptor (particularly µ-opiate receptors). However, it has been known that the therapeutic use of certain µ-opiate receptor antagonist may actually increase heroin overdose. Once overdosed, heroin addicts may continue to get overdosed again and again until fatal. Here we report our design and validation of a novel therapeutic strategy targeting heroin activation based on our analysis of the chemical transformation and functional change of heroin in the body. An effective blocker of heroin activation, such as ethopropazine tested in this study, may be used as a standalone therapy or in combination with a currently available, traditional medications targeting µ-opiate receptors (e.g. naltrexone or its extended-release formulation Vivitrol). The combination therapy would be ideal for heroin abuse treatment as the effects of two therapeutic agents targeting two independent mechanisms are cooperative.

Medications for Alcohol and Opioid Use Disorders and Risk of Suicidal Behavior, Accidental Overdoses, and Crime

OBJECTIVE

The authors examined associations between medications for alcohol and opioid use disorders (acamprosate, naltrexone, methadone, and buprenorphine) and suicidal behavior, accidental overdoses, and crime.

METHOD

In this total population cohort study, 21,281 individuals who received treatment with at least one of the four medications between 2005 and 2013 were identified. Data on medication use and outcomes were collected from Swedish population-based registers. A within-individual design (using stratified Cox proportional hazards regression models) was used to compare rates of suicidal behavior, accidental overdoses, and crime for the same individuals during the period when they were receiving the medication compared with the period when they were not.

RESULTS

No significant associations with any of the primary outcomes were found for acamprosate. For naltrexone, there was a reduction in the hazard ratio for accidental overdoses during periods when individuals received treatment compared with periods when they did not (hazard ratio=0.82, 95% CI=0.70, 0.96). Buprenorphine was associated with reduced arrest rates for all crime categories (i.e., violent, nonviolent, and substance-related) as well as reduction in accidental overdoses (hazard ratio=0.75, 95% CI=0.60, 0.93). For methadone, there were significant reductions in the rate of suicidal behaviors (hazard ratio=0.60, 95% CI=0.40-0.88) as well as reductions in all crime categories. However, there was an increased risk for accidental overdoses among individuals taking methadone (hazard ratio=1.25, 95% CI=1.13, 1.38).

CONCLUSIONS

Medications currently used to treat alcohol and opioid use disorders also appear to reduce suicidality and crime during treatment.

We Can't Go Cold Turkey: Why Suppressing Drug Markets Endangers Society

This essay argues that policies aimed at suppressing drug use exacerbate the nation's opioid problem. It neither endorses drug use nor advocates legalizing the consumption and sale of all substances in all circumstances. Instead, it contends that trying to suppress drug markets is the wrong goal, and in the midst of an addiction crisis it can be deadly. There is no single, correct drug policy; the right approach depends crucially on the substance at issue, the patterns of use and supply, and the jurisdiction's culture, institutions, and material resources. Decriminalization is no panacea for a nation's drug problems. Nevertheless, either de jure or de facto decriminalization of personal drug possession is a necessary condition for mitigating this crisis.

In vitro and in vivo functional profile characterization of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(isoquinoline-3-carboxamido)morphinan (NAQ) as a low efficacy mu opioid receptor modulator

Evidence has shown that downstream signaling by mu opioid receptor (MOR) agonists that recruit β-arrestin2 may lead to the development of tolerance. Also, it has been suggested that opioid receptor desensitization and cyclic AMP overshoot contributes to the development of tolerance and occurrence of withdrawal, respectively. Therefore, studies were conducted with 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(isoquinoline-3-carboxamido)morphinan (NAQ), a MOR selective partial agonist discovered in our laboratory, to characterize its effect on β-arrestin2 recruitment and precipitation of a cyclic AMP overshoot. DAMGO, a MOR full agonist dose-dependently increased β-arrestin2 association with the MOR, whereas NAQ did not. Moreover, NAQ displayed significant, concentration-dependent antagonism of DAMGO-induced β-arrestin2 recruitment. After prolonged morphine treatment of mMOR-CHO cells, there was a significant overshoot of cAMP upon exposure to naloxone, but not NAQ. Moreover, prolonged incubation of mMOR-CHO cells with NAQ did not result in desensitization nor downregulation of the MOR. In functional studies comparing NAQ with nalbuphine in the cAMP inhibition, Ca2+ flux and [35S]GTPγS binding assays, NAQ did not show agonism in the Ca2+ flux assay but showed partial agonism in the cAMP and [35S]GTPγS assays. Also, NAQ significantly antagonized DAMGO-induced intracellular Ca2+ increase. In conclusion, NAQ is a low efficacy MOR modulator that lacks β-arrestin2 recruitment function and does not induce cellular hallmarks of MOR adaptation and fails to precipitate a cellular manifestation of withdrawal in cells pretreated with morphine. These characteristics are desirable if NAQ is pursued for opioid abuse treatment development.

Impairment of opiate-mediated behaviors by the selective TRPV1 antagonist SB366791

Transient receptor potential vanilloid type 1 (TRPV1), the archetypal member of the vanilloid TRP family, was initially identified as the receptor for capsaicin, the pungent ingredient in hot chili peppers. We previously demonstrated that TRPV1 in the dorsal striatum significantly contributes to morphine reward by using the conditioned place preference paradigm in mice; however, it is unknown whether TRPV1 has the same effect in other reward models. In this study, we investigated the role of TRPV1 in morphine reward by using a self-administration paradigm in rats. We found that treatment with a selective TRPV1 antagonist, SB366791, significantly decreased morphine self-administration on a fixed-ratio 1 schedule or a progressive ratio schedule of reinforcement. In addition, treatment with another selective TRPV1 antagonist, AMG9810, not only significantly prevented morphine self-administration but also prevented morphine-induced c-fos expression in the nucleus accumbens. Furthermore, administration of SB366791 decreased an anxiolytic-like effect during the morphine abstinence period. Moreover, treatment with SB366791 significantly decreased morphine-priming reinstatement. Taken together, our findings suggest that blockade of TRPV1 receptors could provide an approach to limiting morphine addiction.

Binding mode analyses of NAP derivatives as mu opioid receptor selective ligands through docking studies and molecular dynamics simulation

Mu opioid receptor selective antagonists are highly desirable because of their utility as pharmacological probes for receptor characterization and functional studies. Furthermore, the mu opioid receptors act as an important target in drug abuse and addiction treatment. Previously, we reported NAP as a novel lead compound with high selectivity and affinity towards the mu opioid receptor. Based on NAP, we have synthesized its derivatives and further characterized their binding affinities and selectivity towards the receptor. NMP and NGP were identified as the two most selective MOR ligands among NAP derivatives. In the present study, molecular modeling methods were applied to assess the dual binding modes of NAP derivatives, particularly on NMP and NGP, in three opioid receptors, in order to analyze the effects of structural modifications on the pyridyl ring of NAP on the binding affinity and selectivity. The results indicated that the steric hindrance, electrostatic, and hydrophobic effects caused by the substituents on the pyridyl ring of NAP contributed complimentarily on the binding affinity and selectivity of NAP derivatives to three opioid receptors. Analyses of these contributions provided insights on future design of more potent and selective mu opioid receptor ligands.

Medication-assisted treatment of opioid use disorder: review of the evidence and future directions

Medication-assisted treatment of opioid use disorder with physiological dependence at least doubles rates of opioid-abstinence outcomes in randomized, controlled trials comparing psychosocial treatment of opioid use disorder with medication versus with placebo or no medication. This article reviews the current evidence for medication-assisted treatment of opioid use disorder and also presents clinical practice imperatives for preventing opioid overdose and the transmission of infectious disease. The evidence strongly supports the use of agonist therapies to reduce opioid use and to retain patients in treatment, with methadone maintenance remaining the gold standard of care. Combined buprenorphine/naloxone, however, also demonstrates significant efficacy and favorable safety and tolerability in multiple populations, including youth and prescription opioid-dependent individuals, as does buprenorphine monotherapy in pregnant women. The evidence for antagonist therapies is weak. Oral naltrexone demonstrates poor adherence and increased mortality rates, although the early evidence looks more favorable for extended-release naltrexone, which has the advantages that it is not subject to misuse or diversion and that it does not present a risk of overdose on its own. Two perspectives-individualized treatment and population management-are presented for selecting among the three available Food and Drug Administration-approved maintenance therapies for opioid use disorder. The currently unmet challenges in treating opioid use disorder are discussed, as are the directions for future research.

A conjugate vaccine attenuates morphine- and heroin-induced behavior in rats

BACKGROUND

Currently approved medications for opioid addiction have shown clinical efficacy, but undesired side effects, dependence induced by the medications themselves, and low treatment compliance necessitate the need for novel therapies.

METHODS

A novel morphine-keyhole limpet hemocyanin conjugate vaccine was synthesized with 6-glutarylmorphine as the hapten and a lengthened linker of 6 carbon atoms. The titer and specificity of the triggered antibody were assessed by enzyme-linked immunosorbent assay. The effects of the vaccine on the morphine-induced elevation of dopamine levels in the nucleus accumbens were determined by high-performance liquid chromatography. The effects of the vaccine on morphine-induced locomotor sensitization and heroin-primed reinstatement of heroin self-administration were also assessed.

RESULTS

After subcutaneous administration in rats, the vaccine triggered a high antibody titer, with comparable specificity for morphine, 6-acetylmorphine, and heroin, but no interaction with dissimilar therapeutic opioid compounds, including buprenorphine, naloxone, and nalorphine, was observed. The vaccine significantly prevented the elevation of dopamine levels in the nucleus accumbens induced by a single morphine challenge. Moreover, the vaccine prevented the expression of morphine-induced locomotor sensitization and heroin-primed reinstatement of heroin seeking, suggesting its potential for preventing relapse.

CONCLUSION

These results demonstrate that active immunization with the present vaccine induces a robust morphine/heroin-specific antibody response in rats and attenuates the behavioral effects of morphine and heroin.

Behavioral and cellular pharmacology characterization of 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-(isoquinoline-3'-carboxamido)morphinan (NAQ) as a mu opioid receptor selective ligand

Mu opioid receptor (MOR) selective antagonists and partial agonists have been used for the treatment of opioid abuse and addiction. Our recent efforts on the identification of MOR antagonists have provided several novel leads displaying interesting pharmacological profiles. Among them, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6α-[(3'-isoquinolyl)acetamido]morphinan (NAQ) showed sub-nanomolar binding affinity to the MOR with significant selectivity over the delta opioid receptor (DOR) and the kappa opioid receptor (KOR). Its central nervous system penetration capacity together with marginal agonism in the MOR-GTPγS binding assay made it a very interesting molecule for developing novel opioid abuse and addiction therapeutic agents. Therefore, further pharmacological characterization was conducted to fully understand its biological profile. At the molecular and cellular level, NAQ not only induced no translocation of β-arrestin2 to the MOR, but also efficaciously antagonized the effect of DAMGO in MOR-βarr2eGFP-U2OS cells in the β-arrestin2 recruitment assay. At the in vivo level, NAQ displayed a potent inhibition of the analgesic effect of morphine in the tail-flick assay (ID50=1.19 mg/kg). NAQ (10 mg/kg) also significantly decreased the hyper-locomotion induced by acute morphine without inducing any vertical jumps. Meanwhile NAQ precipitated lesser withdrawal symptoms in morphine dependent mice than naloxone. In conclusion, NAQ may represent a new chemical entity for opioid abuse and addiction treatment.

Extended release naltrexone injection is performed in the majority of opioid dependent patients receiving outpatient induction: a very low dose naltrexone and buprenorphine open label trial

BACKGROUND

The approval of extended release injectable naltrexone (XR-NTX; Vivitrol(®)) has introduced a new option for treating opioid addiction, but studies are needed to identify its place within the spectrum of available therapies. The absence of physiological opioid dependence is a necessary and challenging first step for starting XR-NTX. Outpatient detoxification gives poor results and inpatient detoxification is either unavailable or too brief for the physiological effects of opioids to resolve. Here we present findings from an open label study that tested whether the transition from opioid addiction to XR-NTX can be safely and effectively performed in an outpatient setting using very low dose naltrexone and buprenorphine.

METHODS

Twenty treatment seeking opioid addicted individuals were given increasing doses of naltrexone starting at 0.25mg with decreasing doses of buprenorphine starting at 4 mg during a 7-day outpatient XR-NTX induction procedure. Withdrawal discomfort, craving, drug use, and adverse events were assessed daily until the XR-NTX injection, then weekly over the next month.

RESULTS

Fourteen of the 20 participants received XR-NTX and 13 completed weekly assessments. Withdrawal, craving, and opioid or other drug use were significantly lower during induction and after XR-NTX administration compared with baseline, and no serious adverse events were recorded.

CONCLUSIONS

Outpatient transition to XR-NTX combining upward titration of very low dose naltrexone with downward titration of low dose buprenorphine was safe, well tolerated, and completed by most participants. Further studies with larger numbers of subjects are needed to see if this approach is useful for naltrexone induction.

'Miracle cure' or 'liquid handcuffs': reporting on naltrexone and methadone in the Australian print media

INTRODUCTION AND AIMS

The news media is an important source of information regarding new developments in medicine and public health interventions. Previous research has indicated that in many cases, reporting on new treatments can be inaccurate or sensationalist. This paper presents analysis of Australian print media reporting on two treatment options for heroin dependence (naltrexone and methadone). The aim of this study was to quantitatively compare the volume and content of Australian print media reporting on these two treatments, one of which had a long history of use in Australia, and the other which was comparatively newer.

DESIGN AND METHODS

The study constituted a quantitative content analysis of a sample of 859 Australian newspaper articles, published over a 10-year period (1997-2007). Each article paragraph was coded for positive outcomes/benefits of treatment, as well as negative outcomes associated with treatment.

RESULTS

The analysis revealed that during this period, the Australian print media was significantly more likely to report the potential positive outcomes of naltrexone treatment, compared with the negative outcomes. In contrast, reporting on methadone focused more on the negative outcomes and side effects.

DISCUSSION AND CONCLUSIONS

The relative frequency by which the benefits of naltrexone were mentioned in this sample of news content is somewhat at odds with the extant efficacy and effectiveness research evidence. The findings suggest that reporting on these treatments in the Australian print media has not been balanced. This type of reporting has potential implications for public attitudes, as well as policy decisions.

Improving clinical outcomes for naltrexone as a management of problem alcohol use

Despite being a relatively effective and safe treatment, the clinical management of alcohol abuse/dependence by oral naltrexone can be compromised due to the patient's non-compliance with daily use of this medication. Over the past decade an increasing body of research has suggested that the use of sustained release depot naltrexone preparations can overcome this issue and deliver improved clinical outcomes. However, at the same time, research findings from diverse areas of pharmacogenetics, neurobiology and behavioural psychology have also been converging to identify variables including genetic markers, patient psychosocial characteristics and drug use history differences, or clusters of these variables that play a major role in mediating the response of alcohol abuse/dependent persons to treatment by naltrexone. While this article does not attempt to review all available data pertaining to an individual alcohol dependent patient's response to treatment by naltrexone, it does identify relevant research areas and highlights the importance of data arising from them. The characterization of clinical markers, to identify those patients who are most likely to benefit from naltrexone and to tailor a more individual naltrexone treatment, will ultimately provide significant benefit to both patients and clinicians by optimizing treatment outcome.

Health promotion and prevention strategies

Opiate dependency is a medical disorder that requires treatment intervention. Primary health care not only entails treatment of illness but also involves disease prevention and health promotion. Based on Pender's revised Health Promotion Model, a descriptive study comparing the health promoting behaviors/practices in abusing and recovering opiate-dependent drug users is analyzed. Using the Health Promoting Lifestyle Profile II, a comparative descriptive, exploratory, nonexperimental design study was conducted to identify key health-promoting behaviors in recovering opiate-dependent drug users. Prevention strategy recommendations are discussed, along with future research recommendations.

Binding mode characterization of 6α- and 6β-N-heterocyclic substituted naltrexamine derivatives via docking in opioid receptor crystal structures and site-directed mutagenesis studies: application of the 'message-address' concept in development of mu opioid receptor selective antagonists

Highly selective opioid receptor antagonists are essential pharmacological probes in opioid receptor structural characterization and opioid agonist functional studies. Currently, there is no highly selective, nonpeptidyl and reversible mu opioid receptor antagonist available. Among a series of naltrexamine derivatives that have been designed and synthesized, two compounds, NAP and NAQ, were previously identified as novel leads for this purpose based on their in vitro and in vivo pharmacological profiles. Both compounds displayed high binding affinity and selectivity to the mu opioid receptor. To further study the interaction of these two ligands with the three opioid receptors, the recently released opioid receptor crystal structures were employed in docking studies to further test our original hypothesis that the ligands recognize a unique 'address' domain in the mu opioid receptor involving Trp318 that facilitates their selectivity. These modeling results were supported by site-directed mutagenesis studies on the mu opioid receptor, where the mutants Y210A and W318A confirmed the role of the latter in binding. Such work not only enriched the 'message-address' concept, also facilitated our next generation ligand design and development.

Opioid receptor selectivity profile change via isosterism for 14-O-substituted naltrexone derivatives

Isosterism is commonly used in drug discovery and development to address stability, selectivity, toxicity, pharmacokinetics, and efficacy issues. A series of 14-O-substituted naltrexone derivatives were identified as potent mu opioid receptor (MOR) antagonists with improved selectivity over the kappa opioid receptor (KOR) and the delta opioid receptor (DOR), compared to naltrexone. Since esters are not metabolically very stable under typical physiological conditions, their corresponding amide analogs were thus synthesized and biologically evaluated. Unlike their isosteres, most of these novel ligands seem to be dually selective for the MOR and the KOR over the DOR. The restricted flexibility of the amide bond linkage might be responsible for their altered selectivity profile. However, the majority of the 14-N-substituted naltrexone derivatives produced marginal or no MOR stimulation in the (35)S-GTP[γS] assay, which resembled their ester analogs. The current study thus indicated that the 14-substituted naltrexone isosteres are not bioisosteres since they have distinctive pharmacological profile with the regard to their opioid receptor binding affinity and selectivity.

Dynamic vaccine blocks relapse to compulsive intake of heroin

Heroin addiction, a chronic relapsing disorder characterized by excessive drug taking and seeking, requires constant psychotherapeutic and pharmacotherapeutic interventions to minimize the potential for further abuse. Vaccine strategies against many drugs of abuse are being developed that generate antibodies that bind drug in the bloodstream, preventing entry into the brain and nullifying psychoactivity. However, this strategy is complicated by heroin's rapid metabolism to 6-acetylmorphine and morphine. We recently developed a "dynamic" vaccine that creates antibodies against heroin and its psychoactive metabolites by presenting multihaptenic structures to the immune system that match heroin's metabolism. The current study presents evidence of effective and continuous sequestration of brain-permeable constituents of heroin in the bloodstream following vaccination. The result is efficient blockade of heroin activity in treated rats, preventing various features of drugs of abuse: heroin reward, drug-induced reinstatement of drug seeking, and reescalation of compulsive heroin self-administration following abstinence in dependent rats. The dynamic vaccine shows the capability to significantly devalue the reinforcing and motivating properties of heroin, even in subjects with a history of dependence. In addition, targeting a less brain-permeable downstream metabolite, morphine, is insufficient to prevent heroin-induced activity in these models, suggesting that heroin and 6-acetylmorphine are critical players in heroin's psychoactivity. Because the heroin vaccine does not target opioid receptors or common opioid pharmacotherapeutics, it can be used in conjunction with available treatment options. Thus, our vaccine represents a promising adjunct therapy for heroin addiction, providing continuous heroin antagonism, requiring minimal medical monitoring and patient compliance.

Examination of mortality rates in a retrospective cohort of patients treated with oral or implant naltrexone for problematic opiate use

AIMS

To examine and compare mortality rates in patients treated with oral and implant naltrexone.

DESIGN

A retrospective cohort study.

SETTING

A community not-for-profit drug treatment clinic.

PARTICIPANTS

Patients treated with oral naltrexone (n = 2155, 17 207 patient-years) and implant naltrexone (n = 2389, 11 678 patient-years) for problematic opiate use between August 1997 and December 2009.

MEASUREMENTS

Crude gender, age, treatment period and cause-specific mortality rates were calculated using data obtained from the National Death Index.

FINDINGS

Crude mortality rates for patients treated with oral naltrexone [8.78 deaths per 1000 patient-years (ptpy), 95% confidence interval (CI): 7.38-10.17] were significantly different to those treated with implant naltrexone (6.59 ptpy, 95% CI: 5.13-8.06) (P = 0.0339). During the first 4 months following treatment, differences in the two groups were particularly apparent, with a mortality rate of 26.28 ptpy in patients treated with oral naltrexone compared to 7.34 ptpy in patients treated with implant naltrexone (P = 0.0003). Differences in initial mortality rates following treatment were associated predominantly with high rates of opiate overdoses in oral naltrexone patients during the first 4 months following treatment (17.22 ptpy compared with 0.67 ptpy in implant naltrexone patients) (P < 0.0001).

CONCLUSIONS

The use of implant naltrexone can reduce all-cause mortality and opiate overdose during the first 4 months following treatment compared with patients treated with oral naltrexone.

Agonist treatment in opioid use: advances and controversy

Opioid dependence is a chronic relapsing condition which requires comprehensive care; pharmacological agents form the mainstay of its long term treatment. The two most popular approaches are the harm reduction method using agonists and the complete abstinence method using antagonists. Currently, particularly from the harm minimization perspective and the low feasibility of an abstinence based approach, there is an increasing trend toward agonist treatment. The use of buprenorphine has gained popularity in view of its safety profile and the availability of the buprenorphine-naloxone combination has made it popular as a take-home treatment. This review outlines the pharmacological advances and controversies in this area.

Naltrexone depot formulations for opioid and alcohol dependence: a systematic review

Naltrexone is an opioid receptor antagonist that blocks the reinforcing effects of opioids and reduces alcohol consumption and craving. It has no abuse potential, mild and transient side effects, and thus appears an ideal pharmacotherapy for opioid dependence. Its effectiveness in alcohol dependence is less evident, but compliance with naltrexone combined with psychosocial support has been repeatedly shown to improve drinking outcomes. Limited compliance with oral naltrexone treatment is a known drawback. Several naltrexone implant and injectable depot formulations are being investigated and provide naltrexone release for at least 1 month. Studies among opioid-dependent patients indicate significant reductions in heroin use, but sample sizes are usually small. In alcohol dependence, two large multicenter trials report alcohol and craving reductions for naltrexone and placebo groups, indicating a significant but moderate effect. The pharmacokinetic profile of the injectable formulation indicates reliable naltrexone release over 1 month at therapeutic levels. Implant formulations releasing naltrexone up to 7 months are reported. Findings on safety and tolerability confirm the generally mild adverse effects described for naltrexone tablets. However, further research on therapeutic levels (i.e., opioid blocking) is warranted. The majority of naltrexone implants lacks approval for regular clinical use and larger longitudinal studies are needed. The available naltrexone depot formulations have the potential to significantly improve medication compliance in opioid and alcohol dependence. In certain circumstances, they may constitute a promising new treatment option.

Naltrexone extended-release injection: an option for the management of opioid abuse

The United States Food and Drug Administration (FDA) approved naltrexone, a synthetic competitive antagonist at opioid receptors, in oral form in 1984 for use in the management of opioid abuse and addiction. Because naltrexone and its major metabolite, 6-β-naltrexone, are both competitive antagonists at opioid receptors - and thereby inhibit opioid agonist-induced effects including those desired by abusers - it was hypothesized that once maintained on naltrex-one, opioid-induced desirable effects would be diminished to the point that relapse to illicit use would decline because it was no longer rewarding. However, good medication compliance is a requisite for such a strategy to be effective and a systematic review of oral naltrexone concluded that this method of treatment was not superior for any outcomes measured (ie, retention, abstinence, or side effects) to placebo, psychotherapy, benzodiazepines, or buprenorphine treatment. In addition, the retention rate on oral naltrexone was very low (less than 30%). Recently, the FDA approved an extended-release formulation (intramuscular depot injection) of naltrexone for prevention of relapse to opioid dependence following opioid detoxification and to be used along with counseling and social support. Since it needs to be administered only monthly, as opposed to the daily administration required for the oral formulation, naltrexone injection has the potential for increasing adherence and retention rates. Concerns include liver damage at high doses (oral formulation) and possible opioid overdose if an attempt is made to surmount receptor antagonism by taking higher doses of an opioid agonist or if opioid receptors become "sensitized" under long-term antagonism. The focus of the present review is the current information regarding the safety and efficacy of naltrexone extended-release therapy.

Selective review and commentary on emerging pharmacotherapies for opioid addiction

Pharmacotherapies for opioid addiction under active development in the US include lofexidine (primarily for managing withdrawal symptoms) and Probuphine®, a distinctive mode of delivering buprenorphine for six months, thus relieving patients, clinicians, and regulatory personnel from most concerns about diversion, misuse, and unintended exposure in children. In addition, two recently approved formulations of previously proven medications are in early phases of implementation. The sublingual film form of buprenorphine + naloxone (Suboxone®) provides a less divertible, more quickly administered, more child-proof version than the buprenorphine + naloxone sublingual tablet. The injectable depot form of naltrexone (Vivitrol®) ensures consistent opioid receptor blockade for one month between administrations, removing concerns about medication compliance. The clinical implications of these developments have attracted increasing attention from clinicians and policymakers in the US and around the world, especially given that human immunodeficiency virus/acquired immunodeficiency syndrome and other infectious diseases are recognized as companions to opioid addiction, commanding more efforts to reduce opioid addiction. While research and practice improvement efforts continue, reluctance to adopt new medications and procedures can be expected, especially considerations in the regulatory process and in the course of implementation. Best practices and improved outcomes will ultimately emerge from continued development efforts that reflect input from many quarters.

Behavioral Therapy to Augment Oral Naltrexone for Opioid Dependence: A Ceiling on Effectiveness?

The effectiveness of antagonist maintenance with oral naltrexone for opioid dependence has been limited by high dropout rates. Behavioral Naltrexone Therapy (BNT) was developed to improve retention on oral naltrexone by integrating voucher incentives, Motivational and Cognitive Behavioral therapies, and a significant other for monitoring medication adherence. In a 6-month, randomized, controlled trial in heroin dependent patients, BNT (N = 36) improved retention in treatment compared to a standard treatment control (Compliance Enhancement (CE); N = 33) (log rank = 4.28; p = .04). Most patients retained beyond 3 months achieved abstinence from opioids, but retention at 6 months was only 22% on BNT and 9% on CE. A systematic review of related controlled trials revealed similar effect sizes in the small to medium range, and substantial dropout. There may be a limit on the extent to which behavioral therapy can overcome poor adherence to oral naltrexone. Future research should consider combinations of behavioral methods with new long-acting injectable or implantable naltrexone formulations.

The effects of maternally administered methadone, buprenorphine and naltrexone on offspring: review of human and animal data

Most women using heroin are of reproductive age with major risks for their infants. We review clinical and experimental data on fetal, neonatal and postnatal complications associated with methadone, the current "gold standard", and compare these with more recent, but limited, data on developmental effects of buprenorphine, and naltrexone. Methadone is a micro-opioid receptor agonist and is commonly recommended for treatment of opioid dependence during pregnancy. However, it has undesired outcomes including neonatal abstinence syndrome (NAS). Animal studies also indicate detrimental effects on growth, behaviour, neuroanatomy and biochemistry, and increased perinatal mortality. Buprenorphine is a partial micro-opioid receptor agonist and a kappa-opioid receptor antagonist. Clinical observations suggest that buprenorphine during pregnancy is similar to methadone on developmental measures but is potentially superior in reducing the incidence and prognosis of NAS. However, small animal studies demonstrate that low doses of buprenorphine during pregnancy and lactation lead to changes in offspring behaviour, neuroanatomy and biochemistry. Naltrexone is a non-selective opioid receptor antagonist. Although data are limited, humans treated with oral or sustained-release implantable naltrexone suggest outcomes potentially superior to those with methadone or buprenorphine. However, animal studies using oral or injectable naltrexone have shown developmental changes following exposure during pregnancy and lactation, raising concerns about its use in humans. Animal studies using chronic exposure, equivalent to clinical depot formulations, are required to evaluate safety. While each treatment is likely to have maternal advantages and disadvantages, studies are urgently required to determine which is optimal for offspring in the short and long term.

Management of relapse in naltrexone maintenance for heroin dependence

Opioid dependence is a growing public health problem. Maintenance on the antagonist naltrexone for clinic- or office-based treatment of opioid dependence is plagued by high rates of relapse. This paper identifies critical determinants of lapses to opioid use during naltrexone maintenance. Time retained in treatment was examined as a function of whether lapses to opioid use occurred while adherent to naltrexone (blocked use), or after having missed naltrexone doses (unblocked).

METHOD

Participants (N=83) met DSM-IV criteria for opioid dependence and identified a significant other willing to participate in their treatment. Following inpatient detoxification, participants were enrolled in a 26-week outpatient course of therapy and naltrexone maintenance.

RESULTS

Patients with unblocked use had a very high rate of dropout (10% retained at 6 months), dropout usually occurring within 2 weeks after unblocked use. Patients with only blocked use had less dropout (33% retained at 6 months). However, episodes of blocked use were often followed by unblocked use and dropout.

CONCLUSIONS

During naltrexone maintenance for opioid dependence unblocked opioid use calls for immediate intervention, such as detoxification or switching to the partial agonist buprenorphine. Episodes of blocked use warrant increased clinical attention, such as direct observation of naltrexone ingestion, increased dose, or increased intensity of treatment contact. Maintenance on oral naltrexone is a fragile treatment because it is so easily undermined by episodes of opioid use while non-compliant. New long-acting injectable or implantable formulations of naltrexone may address this limitation and should be investigated for treatment of opioid dependence.

Risk of fatal overdose during and after specialist drug treatment: the VEdeTTE study, a national multi-site prospective cohort study

BACKGROUND

Specialist drug treatment is critical to overdose prevention; methadone maintenance is effective, but we lack evidence for other modalities. We evaluate the impact of a range of treatments for opiate dependence on overdose mortality.

METHODS

Prospective cohort study of 10,454 heroin users entering treatment 1998-2001 in Italy followed-up for 10,208 person-years in treatment and 2,914 person-years out of treatment. Standardized overall mortality ratios (SMR) estimate excess mortality risk for heroin users in and out of treatment compared to the general population. Cox models compare the hazard ratio (HR) of overdose between heroin users in treatment and out of treatment.

RESULTS

There were 41 overdose deaths, 10 during treatment and 31 out of treatment, generating annual mortality rates of 0.1% and 1.1% and SMRs of 3.9 [95% confidence interval (CI) 2.8-5.4] and 21.4 (16.7-27.4), respectively. Retention in any treatment was protective against overdose mortality (HR 0.09 95% CI 0.04-0.19) compared to the risk of mortality out of treatment, independent of treatment type and potential confounders. The risk of a fatal overdose was 2.3% in the month immediately after treatment and 0.77% in the subsequent period; compared to the risk of overdose during treatment the HR was 26.6 (95% CI 11.6-61.1) in the month immediately following treatment and 7.3 (3.3-16.2) in the subsequent period.

CONCLUSIONS

We demonstrate that a range of treatments for heroin dependence reduces overdose mortality risk. However, the considerable excess mortality risk in the month following treatment indicates the need for greater health education of drug users and implementation of relapse and overdose death prevention programmes. Further investigation is needed to measure and weigh the potential benefits and harms of short-term therapies for opiate use.

Mortality related to pharmacotherapies for opioid dependence: a comparative analysis of coronial records

INTRODUCTION AND AIMS

The aim of this study was to compare the mortality associated with oral naltrexone, methadone and buprenorphine in opioid dependence treatment, employing a retrospective data analysis using coronial and prescription data.

DESIGN AND METHODS

The number of deaths were identified through national coronial data and number of treatment recipients were estimated from 2000 to 2003 prescriptions and restricted medications data. Mortality rates were expressed as deaths per number of treatment episodes and per person-years at high and low risk of fatal opioid overdose.

RESULTS

Thirty-two oral naltrexone, one buprenorphine and 282 methadone-related deaths were identified. Mortality rates in the highest risk period in deaths per 100 person-years were 22.1 (14.6 - 32.2) for oral naltrexone following treatment cessation and 3.0 (2.3 - 3.9) for methadone during treatment induction. Rates in the lowest risk period in deaths per 100 person-years were 1.0 (0.3 - 2.2) during oral naltrexone treatment and 0.34 (0.3 - 0.4) during post-induction methadone treatment. The relative risk of death for oral naltrexone subjects was 7.4 times (high-risk period, p < 0.0001) or 2.8 times (low-risk period, p = 0.055) that of methadone subjects.

DISCUSSION AND CONCLUSIONS

This is the first comparison of mortality associated with these three pharmacotherapies for opioid dependence. The risk of death related to oral naltrexone appears higher than that related to methadone treatment.

Mortality in heroin users 3 years after naltrexone implant or methadone maintenance treatment

Concerns that treatment for heroin dependence using naltrexone may increase suicide rates during treatment and fatal overdoses posttreatment have been expressed. There is also disquiet about mortality during induction onto methadone. We assessed mortality during specific periods following treatment with naltrexone implants or methadone. Data were assembled using the Western Australian Data Linkage System. The methadone cohort comprised all those who started methadone in Western Australia during 2001-2002: The naltrexone cohort comprised all Western Australian heroin-dependent persons who received their first implant in 2001-2002. There were 15 (2.7%) deaths in the methadone cohort (n = 553) and 6 (1.8%) deaths in the naltrexone cohort (n = 341). Mortality rates for the "initial 14-day period," "stable treatment," and "overall" were 94.47, 0.0, and 5.83 deaths/1,000 person-years for the methadone group. In the naltrexone group, the rates "during first treatment (0-6 months)," "post first treatment," and overall were 0.0, 4.21, and 3.76 deaths/1,000 person-years. The age-standardized mortality rate ratio for naltrexone compared to methadone was 0.645 (95% confidence interval = 0.123-1.17). Increased mortality during induction onto methadone was confirmed. Evidence relating naltrexone to either increased suicide or overdose was not found. Overall mortality rates for naltrexone implant were similar to those for methadone, but increased mortality during methadone induction was avoided.

Sustained-release naltrexone: novel treatment for opioid dependence

The devastating costs of opioid abuse and dependence underscore the need for effective treatments for these disorders. At present, several different maintenance medications exist for treating opioid dependence, including methadone, buprenorphine and naltrexone. Of these, naltrexone is the only one that possesses no opioid agonist effects. Instead, naltrexone occupies opioid receptors and prevents or reverses the effects produced by opioid agonists. Despite its clear pharmacologic effectiveness, its clinical effectiveness in treating opioid dependence has been disappointing, primarily due to non-compliance with taking the medication. However, the recent availability of sustained-release formulations of naltrexone has renewed interest in this medication. The present paper describes the development of sustained-release naltrexone formulations and discusses the clinical issues associated with their use in treating opioid dependence.

Mental health outcomes following naltrexone implant treatment for heroin-dependence

BACKGROUND

Oral naltrexone is an approved treatment for opioid dependence. However, the impact of sustained release naltrexone on the mental health of treated opioid users has not been studied.

AIMS

To assess if naltrexone via implant treatment was associated with any change in (i) risk, (ii) rate, and (iii) duration for hospital morbidity related to several categories of mental disorders among treated heroin users.

METHOD

A cohort of 359 heroin users treated with sustained release naltrexone via implants in Western Australia was retrospectively followed up for mental health related outcomes via a health record linkage system over an average period of 1.78 years post-treatment.

RESULTS

Individual patient's risk for hospital mental diagnoses was not altered after naltrexone implant. On a population cohort level, hospital admission rates related to all mental health problems, except mood disorders, declined significantly post-treatment; however, length of hospital stay did not improve. Overall, young, female patients or those with pre-existing mental illness were more likely than other patients to require hospital care for mental health issues following treatment. Longer period of heroin use was associated with poorer mood outcomes.

CONCLUSIONS

Naltrexone implants were not associated with an increased risk for hospitalisation due to mental illness, and in most cases, were associated with a decrease in mental related hospital admission rate.

Prescribing naloxone to actively injecting heroin users: a program to reduce heroin overdose deaths

Heroin overdose deaths have increased alarmingly in Chicago over the past decade. Naloxone, an opioid antagonist with no abuse potential, has been used to reverse opiate overdose in emergency medical settings for decades. We describe here a program to educate opiate users in the prevention of opiate overdose and its reversal with intramuscular naloxone. Participant education and naloxone prescription are accomplished within a large comprehensive harm reduction program network. Since institution of the program in January 2001, more than 3,500 10 ml (0.4 mg/ml) vials of naloxone have been prescribed and 319 reports of peer reversals received. The Medical Examiner of Cook County reported a steady increase in heroin overdose deaths since 1991, with a four-fold increase between 1996 and 2000. This trend reversed in 2001, with a 20% decrease in 2001 and 10% decreases in 2002 and 2003.

Evidenced-based treatment of opioid-dependent patients

OBJECTIVE

To provide an overview of treatment options for opioid-dependent patients.

METHOD

We screened all published studies on the treatment of opioid dependence, with a special focus on systematic literature reviews, formal metaanalyses, and recent trials.

RESULTS

Both clinical experience and neurobiological evidence indicate that opioid dependence is a chronic relapsing disorder. Treatment objectives depend on the pursued goals: crisis intervention, abstinence-oriented treatment (detoxification and relapse prevention), or agonist maintenance treatment. The high quality of solid evidence in the literature demonstrates that there are numerous effective interventions available for the treatment of opioid dependence. Crisis intervention, frequently necessary owing to the high overdose rate, can be effectively handled with naloxone. Abstinence-oriented interventions are effective for only a few motivated patients with stable living conditions and adequate social support. Agonist maintenance treatment is considered the first line of treatment for opioid dependence. Numerous studies have shown efficacy for methadone and buprenorphine treatment, while maintenance with other agonists is also becoming available to a greater extent. Maintenance treatment with diamorphine should be made available for the small group of treatment-resistant, severely dependent addicts. Other harm-reduction measures can serve to engage individuals with opioid addiction who are not in treatment.

CONCLUSION

Opioid dependence is a chronic relapsing disease that is difficult to cure, but effective treatments are available to stabilize patients and reduce harm, thereby increasing life expectancy and quality of life.

A systematic review of the effectiveness of naltrexone in the maintenance treatment of opioid and alcohol dependence

This systematic review summarises evidence of the effectiveness of naltrexone (NTX) and the added value of psychosocial treatment in the maintenance treatment of opioid and alcohol dependence. Studies were selected through a literature search conducted in March 2004. Seven opioid and seventeen alcohol studies were identified. When possible, meta-(regression) analyses were performed. There is lack of evidence about the effectiveness of NTX in the maintenance treatment of opioid dependence. There is evidence for the effectiveness and applicability of NTX in the management of alcohol dependence. The opioid studies combined NTX with a variety of psychosocial interventions, which plagued the evaluation of their value. Concomitant psychosocial interventions used in the alcohol studies were mainly cognitive behavioural, which seems to be more effective than NTX combined with supportive therapy. Available data do not allow firm conclusions regarding the added effect of psychosocial interventions. However, the data suggest that a combination of naltrexone with cognitive behavioural relapse prevention therapy is beneficial in alcohol dependent patients.

Injectable, sustained-release naltrexone for the treatment of opioid dependence: a randomized, placebo-controlled trial

CONTEXT

Oral naltrexone can completely antagonize the effects produced by opioid agonists. However, poor compliance with naltrexone has been a major obstacle to the effective treatment of opioid dependence.

OBJECTIVE

To evaluate the safety and efficacy of a sustained-release depot formulation of naltrexone in treating opioid dependence.

DESIGN AND SETTING

Randomized, double-blind, placebo-controlled, 8-week trial conducted at 2 medical centers.

PARTICIPANTS

Sixty heroin-dependent adults.

INTERVENTIONS

Participants were stratified by sex and years of heroin use (> or = 5 vs < 5) and then were randomized to receive placebo or 192 or 384 mg of depot naltrexone. Doses were administered at the beginning of weeks 1 and 5. All participants received twice-weekly relapse prevention therapy, provided observed urine samples, and completed other assessments at each visit.

MAIN OUTCOME MEASURES

Retention in treatment and percentage of opioid-negative urine samples.

RESULTS

Retention in treatment was dose related, with 39%, 60%, and 68% of patients in the placebo, 192 mg of naltrexone, and 384 mg of naltrexone groups, respectively, remaining in treatment at the end of 2 months. Time to dropout had a significant main effect of dose, with mean time to dropout of 27, 36, and 48 days for the placebo, 192 mg of naltrexone, and 384 mg of naltrexone groups, respectively. The percentage of urine samples negative for opioids, methadone, cocaine, benzodiazepines, and amphetamine varied significantly as a function of dose. When the data were recalculated without the assumption that missing urine samples were positive, a main effect of group was not found for any drugs tested except cocaine, where the percentage of cocaine-negative urine samples was lower in the placebo group. Adverse events were minimal and generally mild. This formulation of naltrexone was well tolerated and produced a robust, dose-related increase in treatment retention.

CONCLUSION

These data provide new evidence of the feasibility, efficacy, and tolerability of long-lasting antagonist treatments for opioid dependence.

Naltrexone implants -- duration, tolerability and clinical usefulness. A pilot study

Naltrexone blocks opioid effects effectively, but poor compliance limits the clinical usefulness in the treatment of opioid dependence. Long-acting implanted formulations might increase the clinical feasibility. Several implants have been produced, but few clinical reports have been published. This paper describes an open trial with an Australian implant. This implant is claimed to have duration of up to six months with double implants and acceptable levels of side effects. This was explored in the present pilot study with 13 opioid-dependent patients. By single implant of 1.8 g naltrexone the duration judged by naltrexone plasma levels above 1 ng/ml naltrexone was between 2 and 4 months. Double implants maintained such plasma levels for 5-6.5 months. Clinically, the implants appeared promising. Side effects were minimal. During the period with adequate plasma levels of naltrexone, use of opioids was absent and use of other psychoactive drugs reduced. At 1-year follow-up, the patients rated the implants highly positively.

The role of depression symptoms in predicting drug abstinence in outpatient substance abuse treatment

OBJECTIVE

This study examined the role of depressive symptoms in the context of specific demographic and individual treatment characteristics in predicting drug abstinence at discharge from outpatient substance abuse treatment.

METHODS

Data from 827 clients entering a large public funded outpatient substance abuse treatment program were analyzed using logistic regression to assess the effects of depressive symptoms on drug abstinence status at discharge. Analyses on the effects of gender, race, age, education level, frequency of drug use, insurance status, referral source, and length of stay in treatment on drug abstinence status at discharge were also conducted.

RESULTS

Higher depressive symptom scores significantly predicted a decreased likelihood of clients' abstinence at discharge even after accounting for other significant demographic and treatment variables such as insurance status, race, age, primary drug of choice, frequency of drug use at admission and length of stay in treatment.

CONCLUSION

The findings suggest that depression symptoms are an important factor affecting successful substance abuse treatment outcomes. Treatment approaches that address depressive symptoms are likely to enhance substance abuse treatment outcomes in real world clinical settings.

Serious adverse events in the Australian National Evaluation of Pharmacotherapies for Opioid Dependence (NEPOD)

AIMS

The study estimated serious adverse event (SAE) rates among entrants to pharmacotherapies for opioid dependence, during treatment and after leaving treatment.

DESIGN

A longitudinal study based on data from 12 trials included in the Australian National Evaluation of Pharmacotherapies for Opioid Dependence (NEPOD).

PARTICIPANTS AND SETTINGS

A total of 1244 heroin users and methadone patients treated in hospital, community and GP settings. Intervention Six trials included detoxification; all included treatment with methadone, buprenorphine, levo-alpha-acetyl-methadol (LAAM) or naltrexone.

FINDINGS

During 394 person-years of observation, 79 SAEs of 28 types were recorded. Naltrexone participants experienced 39 overdoses per 100 person-years after leaving treatment (44% occurred within 2 weeks after stopping naltrexone). This was eight times the rate recorded among participants who left agonist treatment. Rates of all other SAEs were similar during treatment versus out of treatment, for both naltrexone-treated and agonist-treated participants. Five deaths occurred, all among participants who had left treatment, at a rate of six per 100 person-years. Total SAE rates during naltrexone and agonist treatments were similar (20, 14 per 100 person-years, respectively). Total SAE and death rates observed among participants who had left treatment were three and 19 times the corresponding rates during treatment.

CONCLUSIONS

Individuals who leave pharmacotherapies for opioid dependence experience higher overdose and death rates compared with those in treatment. This may be due partly to a participant self-selection effect rather than entirely to pharmacotherapy being protective. Clinicians should alert naltrexone treatment patients in particular about heroin overdose risks. Duty of care may extend beyond cessation of dosing.