Pharmacotherapy in the treatment of addiction: methadone

Pharmacotherapy for opioid use disorder in pregnancy

PURPOSE OF REVIEW

Opioid use disorder (OUD) in pregnancy has significantly increased in the last decade, impacting 8.2 per 1000 deliveries. OUD carries significant risk of morbidity and mortality for both the birthing person and neonate, but outcomes for both are improved with opioid agonist treatment (OAT). Here, we describe the recommended forms of OAT in pregnancy, updates to the literature, and alternate OAT strategies, and share practical peripartum considerations for patients on OAT.

RECENT FINDINGS

Recent studies comparing buprenorphine and methadone have reaffirmed previous findings that buprenorphine is associated with superior outcomes for the neonate, without clear differences in morbidity or mortality for the birthing person. Optimal initiation and dosing of OAT remains unclear, with several recent studies evaluating methods of initiation, as well as a potential role for higher and more rapid dosing in the fentanyl era. Alternative products such as buprenorphine-naloxone and extended-release buprenorphine are of significant research interest, though randomized prospective data are not yet available.

SUMMARY

Buprenorphine and methadone are standard of care for treatment of OUD during pregnancy, and multiple patient factors impact the optimal choice. Insufficient data exist to recommend alternative agents as a primary strategy currently. All patients with OUD in pregnancy should be counseled regarding OAT.

VIDEO

http://links.lww.com/COOG/A94.

Methadone pharmacokinetics in opioid agonist treatment: Influencing factors and clinical implications

BACKGROUND

A considerable inter-individual variability has been reported in the relationship between methadone doses applied and serum concentrations achieved in methadone maintenance treatment. However, the underlying causes for this variability are not fully understood.

OBJECTIVES

We investigated the influence of genetic, pathophysiological and pharmacological factors on serum methadone concentration-to-dose ratio (CDR) and discussed the clinical implications of the findings.

METHODS

We used data from two retrospective laboratory databases and a prospective cohort study to investigate the impact on methadone CDR of hepatic cytochrome P450 enzyme system (CYP) genetic polymorphisms, age, sex, concomitant medication, liver fibrosis and body mass index through linear mixed model analyses.

FINDINGS

A positive association was found between CDR and the homozygous CYP2B6*6 genotype, concurrent treatment with CYP3A4 inhibitors and body mass index. CDR was lower among women and during concomitant use of CYP inducers. CDR was not associated with age or the degree of liver fibrosis in our investigations.

CONCLUSIONS

This research work supports the need for individually tailored dosage considering the various factors that influence methadone CDR. The gained knowledge can contribute to reducing the risks associated with the treatment and optimizing the desired outcomes.

Main targets of ibogaine and noribogaine associated with its putative anti-addictive effects: A mechanistic overview

BACKGROUND

There is a growing interest in studying ibogaine (IBO) as a potential treatment for substance use disorders (SUDs). However, its clinical use has been hindered for mainly two reasons: First, the lack of randomized, controlled studies informing about its safety and efficacy. And second, IBO's mechanisms of action remain obscure. It has been challenging to elucidate a predominant mechanism of action responsible for its anti-addictive effects.

OBJECTIVE

To describe the main targets of IBO and its main metabolite, noribogaine (NOR), in relation to their putative anti-addictive effects, reviewing the updated literature available.

METHODS

A comprehensive search involving MEDLINE and Google Scholar was undertaken, selecting papers published until July 2022. The inclusion criteria were both theoretical and experimental studies about the pharmacology of IBO. Additional publications were identified in the references of the initial papers.

RESULTS

IBO and its main metabolite, NOR, can modulate several targets associated with SUDs. Instead of identifying key targets, the action of IBO should be understood as a complex modulation of multiple receptor systems, leading to potential synergies. The elucidation of IBO's pharmacology could be enhanced through the application of methodologies rooted in the polypharmacology paradigm. Such approaches possess the capability to describe multifaceted patterns within multi-target drugs.

CONCLUSION

IBO displays complex effects through multiple targets. The information detailed here should guide future research on both mechanistic and therapeutic studies.

Drug Permeability: From the Blood-Brain Barrier to the Peripheral Nerve Barriers

Drug delivery into the peripheral nerves and nerve roots has important implications for effective local anesthesia and treatment of peripheral neuropathies and chronic neuropathic pain. Similar to drugs that need to cross the blood-brain barrier (BBB) and blood-spinal cord barrier (BSCB) to gain access to the central nervous system (CNS), drugs must cross the peripheral nerve barriers (PNB), formed by the perineurium and blood-nerve barrier (BNB) to modulate peripheral axons. Despite significant progress made to develop effective strategies to enhance BBB permeability in therapeutic drug design, efforts to enhance drug permeability and retention in peripheral nerves and nerve roots are relatively understudied. Guided by knowledge describing structural, molecular and functional similarities between restrictive neural barriers in the CNS and peripheral nervous system (PNS), we hypothesize that certain CNS drug delivery strategies are adaptable for peripheral nerve drug delivery. In this review, we describe the molecular, structural and functional similarities and differences between the BBB and PNB, summarize and compare existing CNS and peripheral nerve drug delivery strategies, and discuss the potential application of selected CNS delivery strategies to improve efficacious drug entry for peripheral nerve disorders.

Impact of liver fibrosis and clinical characteristics on dose-adjusted serum methadone concentrations

BACKGROUND

There is limited knowledge on the causes of large variations in serum methadone concentrations and dose requirements.

OBJECTIVES

We investigated the impact of the degree of liver fibrosis on dose-adjusted steady-state serum methadone concentrations.

METHODS

We assessed the clinical and laboratory data of 155 Norwegian patients with opioid use disorder undergoing methadone maintenance treatment in outpatient clinics in the period 2016-2020. A possible association between the degree of liver fibrosis and dose-adjusted serum methadone concentration was explored using a linear mixed-model analysis.

RESULTS

When adjusted for age, gender, body mass index, and genotypes of CYP2B6 and CYP3A5, the concentration-to-dose ratio of methadone did not increase among the participants with liver fibrosis (Coefficient: 0.70; 95% CI: -2.16, 3.57; P: 0.631), even among those with advanced cirrhosis (-0.50; -4.59, 3.59; 0.810).

CONCLUSIONS

Although no correlation was found between the degree of liver stiffness and dose-adjusted serum methadone concentration, close clinical monitoring should be considered, especially among patients with advanced cirrhosis. Still, serum methadone measurements can be considered a supplement to clinical assessments, taking into account intra-individual variations.

Effect of TRV130 and methadone on fentanyl-vs.-food choice and somatic withdrawal signs in opioid-dependent and post-opioid-dependent rats

The high efficacy mu-opioid receptor (MOR) agonist methadone is an effective opioid use disorder (OUD) medication used exclusively in opioid-dependent patients. However, methadone has undesirable effects that limit its clinical efficacy. Intermediate efficacy MOR agonists may treat OUD with fewer undesirable effects. We compared the effects of methadone with the intermediate efficacy MOR agonist TRV130 (oliceridine) on fentanyl-vs.-food choice and somatic withdrawal signs in opioid-dependent and post-opioid-dependent rats. Male rats (n = 20) were trained under a fentanyl-vs.-food choice procedure. Rats were then provided extended fentanyl (3.2 µg/kg/infusion) access (6 p.m.-6 a.m.) for 10 days to produce opioid dependence/withdrawal. Rats were treated with vehicle (n = 7), TRV130 (3.2 mg/kg; n = 8), or methadone (3.2 mg/kg; n = 5) three times per day after each extended-access session (8:30 a.m., 11 a.m., 1:30 p.m.). Withdrawal sign scoring (1:55 p.m.) and choice tests (2-4 p.m.) were conducted daily. Vehicle, TRV130, and methadone effects on fentanyl choice were redetermined in post-opioid-dependent rats. Vehicle-, TRV130-, and methadone-treated rats had similar fentanyl intakes during extended access. Vehicle-treated rats exhibited increased withdrawal signs and decreased bodyweights. Both methadone and TRV130 decreased these withdrawal signs. TRV130 was less effective than methadone to decrease fentanyl choice and increase food choice in opioid-dependent rats. Neither methadone nor TRV130 decreased fentanyl choice in post-opioid-dependent rats. Results suggest that higher MOR activation is required to reduce fentanyl choice than withdrawal signs in fentanyl-dependent rats. Additionally, given that TRV130 did not precipitate withdrawal in opioid-dependent rats, intermediate efficacy MOR agonists like TRV130 may facilitate the transition of patients with OUD from methadone to lower efficacy treatments like buprenorphine.

Association between rs1799971 in the mu opioid receptor gene and methadone maintenance treatment response

OBJECTIVE

Genetic variations can affect individual response to methadone maintenance treatment (MMT) for heroin addiction. The A118G variant (rs1799971) in the mu opioid receptor gene (OPRM1) is a potential candidate single nucleotide polymorphism (SNP) for personalized MMT. This study determined whether rs1799971 is related to MMT response or dose.

METHODS

We recruited 286 MMT patients from a Han Chinese population. The rs1799971 genotype was determined via TaqMan genotyping assay. The genetic effect of this SNP on MMT response or dose was evaluated using logistic regression. A meta-analysis was performed to merge all available data to evaluate the role of rs1799971 in MMT using RevMan 5.3 software.

RESULTS

No statistical significance was observed in the association between the OPRM1 rs1799971 and MMT response or dose in our Chinese cohort. Meta-analysis indicated that the OPRM1 A118G variation was not significantly associated with MMT response or dose requirement.

CONCLUSION

The results suggest that rs1799971 in OPRM1 might not play a critical role alone in influencing MMT response or dose.

Endogenous opioid systems alterations in pain and opioid use disorder

Decades of research advances have established a central role for endogenous opioid systems in regulating reward processing, mood, motivation, learning and memory, gastrointestinal function, and pain relief. Endogenous opioid systems are present ubiquitously throughout the central and peripheral nervous system. They are composed of four families, namely the μ (MOPR), κ (KOPR), δ (DOPR), and nociceptin/orphanin FQ (NOPR) opioid receptors systems. These receptors signal through the action of their endogenous opioid peptides β-endorphins, dynorphins, enkephalins, and nociceptins, respectfully, to maintain homeostasis under normal physiological states. Due to their prominent role in pain regulation, exogenous opioids-primarily targeting the MOPR, have been historically used in medicine as analgesics, but their ability to produce euphoric effects also present high risks for abuse. The ability of pain and opioid use to perturb endogenous opioid system function, particularly within the central nervous system, may increase the likelihood of developing opioid use disorder (OUD). Today, the opioid crisis represents a major social, economic, and public health concern. In this review, we summarize the current state of the literature on the function, expression, pharmacology, and regulation of endogenous opioid systems in pain. Additionally, we discuss the adaptations in the endogenous opioid systems upon use of exogenous opioids which contribute to the development of OUD. Finally, we describe the intricate relationship between pain, endogenous opioid systems, and the proclivity for opioid misuse, as well as potential advances in generating safer and more efficient pain therapies.

Naturalistic follow-up after a trial of medications for opioid use disorder: Medication status, opioid use, and relapse

AIM

This report examined naturalistic opioid use outcomes and utilization of medications for opioid use disorder (MOUD) 36 weeks post-randomization in the National Drug Abuse Treatment Clinical Trials Network (CTN) Extended-Release Naltrexone (XR-NTX) versus Buprenorphine-Naloxone (BUP-NX) for Opioid Treatment trial (CTN-0051, X:BOT).

DESIGN

X:BOT was a multisite, randomized, 24-week comparative effectiveness trial of BUP-NX (N = 287) and XR-NTX (N = 283). Study medications were discontinued following treatment completion, relapse, or dropout. Participants were encouraged to continue MOUD. This report examined opioid use outcomes in 428 (75%) of the 570 participants who attended the 36-week follow-up visit.

SETTING AND PARTICIPANTS

Adults with opioid use disorder recruited from 8 community treatment programs across the United States.

MEASUREMENTS

Outcomes included medication status (on/off MOUD), type of MOUD (BUP-NX, XR-NTX, or methadone), abstinence from non-prescribed opioids, opioid use days, relapse, and other substance use 30 days prior to the 36-week visit. Relapse was defined as opioid use for 4 consecutive weeks or 7 consecutive days in the past month. Baseline and clinical variables included opioid use severity, intravenous drug use, study medication assignment, and induction status.

FINDINGS

Of the 428 participants who completed the 36-week visit, 225 (53%) of participants were receiving MOUD and 203 (47%) were not. Compared to those off medication, participants on medication had fewer opioid use days (4.4 days (SD 9.0) versus 9.8 days (SD 12.1)), fewer met relapse criteria (37 (16.4%) versus 79 (38.9%)), and reported less stimulant use (34 (15.2%) versus 56 (27.7%)) and sedative use (14 (6.3%) versus 31 (15.3%)). There was no difference in abstinence rates between those on or off MOUD. A greater proportion of participants on XR-NTX (47 (53.4%) of 88 participants) were abstinent from non-prescribed opioids compared to those on buprenorphine (28 (23.3%) of 120 participants).

CONCLUSIONS

Naturalistic outcomes data showed that despite potential barriers to continuing treatment in the community, about half of individuals were on opioid use disorder pharmacotherapy at follow-up and those on medication generally had better outcomes. Future research should explore barriers and facilitators to treatment retention in community settings; and developing interventions tailored to improve treatment engagement and adherence.

Synergistic immune and antinociceptive effects induced from the combination of two different vaccines against morphine/heroin in mouse

Animal studies have reported the use of different opioid-vaccine formulations with relative success These studies have suggested that new opioid-vaccine formulations are required, which are capable of triggering a robust humoral response. One strategy that has been used is the co-administration of two or more vaccines with different but complementary properties, which are capable of generating a robust immune response. We have developed two formulations of opioid-vaccine, the M6-TT, and M3-TT, which generate a robust immune response capable of recognizing heroin and morphine. In this work, we evaluate the combination of two vaccine formulations, which we call the M3/6-TT vaccine, to elicit a robust immune response and protection against heroin and morphine. Balb/c mice were immunized simultaneously with M6-TT vaccine and with M3-TT vaccine. A solid-phase antibody-capture ELISA was used for monitoring antibody titer responses after each booster dose in vaccinated animals. The study used tail-flick and hot-plate testing to evaluate the antinociceptive effects induced by heroin or morphine. Immunization with M3-TT and M6-TT vaccine elicits a robust immune response with an antibody titer of 1: 590 000 able to recognize heroin and morphine. These antibodies are capable of reducing the antinociceptive effects induced by doses of up to 40 mg/Kg. of morphine or 10 mg/kg of heroin. This suggests that the combination of two vaccine formulations that generate antibodies with different but complementary characteristics would be a new therapeutic strategy aimed at reducing drug relapses.

Kratom Alkaloids, Natural and Semi-Synthetic, Show Less Physical Dependence and Ameliorate Opioid Withdrawal

Chronic administration of opioids produces physical dependence and opioid-induced hyperalgesia. Users claim the Thai traditional tea "kratom" and component alkaloid mitragynine ameliorate opioid withdrawal without increased sensitivity to pain. Testing these claims, we assessed the combined kratom alkaloid extract (KAE) and two individual alkaloids, mitragynine (MG) and the analog mitragynine pseudoindoxyl (MP), evaluating their ability to produce physical dependence and induce hyperalgesia after chronic administration, and as treatments for withdrawal in morphine-dependent subjects. C57BL/6J mice (n = 10/drug) were administered repeated saline, or graded, escalating doses of morphine (intraperitoneal; i.p.), kratom alkaloid extract (orally, p.o.), mitragynine (p.o.), or MP (subcutaneously, s.c.) for 5 days. Mice treated chronically with morphine, KAE, or mitragynine demonstrated significant drug-induced hyperalgesia by day 5 in a 48 °C warm-water tail-withdrawal test. Mice were then administered naloxone (10 mg/kg, s.c.) and tested for opioid withdrawal signs. Kratom alkaloid extract and the two individual alkaloids demonstrated significantly fewer naloxone-precipitated withdrawal signs than morphine-treated mice. Additional C57BL/6J mice made physically dependent on morphine were then used to test the therapeutic potential of combined KAE, mitragynine, or MP given twice daily over the next 3 days at either a fixed dose or in graded, tapering descending doses. When administered naloxone, mice treated with KAE, mitragynine, or MP under either regimen demonstrated significantly fewer signs of precipitated withdrawal than control mice that continued to receive morphine. In conclusion, while retaining some liabilities, kratom, mitragynine, and mitragynine pseudoindoxyl produced significantly less physical dependence and ameliorated precipitated withdrawal in morphine-dependent animals, suggesting some clinical value.

Association study of genetic polymorphisms in GABRD with treatment response and dose in methadone maintenance treatment

Aim: This study determined if gene variants in the GABA receptor delta subunit (GABRD) are associated with treatment response and dose in methadone maintenance treatment (MMT) for heroin addiction. Materials & methods: A total of 286 MMT patients were recruited and divided into response and nonresponse groups based on retention time in therapy. A total of 177 responders were classified into low dose and high dose subgroups according to the stabilized methadone dose. Four (single nucleotide polymorphisms) SNPs (rs13303344, rs4481796, rs2376805 and rs2229110) in GABRD were genotyped using the TaqMan SNP assay. Logistic regression was used to assess the genetic effects of the SNPs in MMT. Results: No significant associations were observed between the SNPs and treatment response or dose, except the frequency of haplotype ACGC at the four SNPs significantly differed between responders and nonresponders. Conclusion: The results indicated that GABRD variants may play a small role in modulating methadone treatment response.

Precision dosing of methadone during pregnancy: A pharmacokinetics virtual clinical trials study

BACKGROUND

Methadone use for the management of opioid dependency during pregnancy is commonplace. Methadone levels are altered during pregnancy due to changes in maternal physiology. Despite this, a paucity of data exist regarding the most appropriate optimal dosing regimens during pregnancy.

METHODS

This study applied a pharmacokinetic modeling approach to examine gestational changes in R- and S-methadone concentrations in maternal plasma and fetal (cord) blood. This study did so to derive a theoretical optimal dosing regimen during pregnancy, and to identify the impact of Cytochromes P450 (CYP) 2B6 and 2C19 polymorphisms on methadone maternal and fetal pharmacokinetics.

RESULTS

The study noted significant decreases in maternal R- and S-methadone plasma concentrations during gestation, with concomitant increases in fetal levels. At a dose of 90 mg once daily, 75% (R-) and 94% (S-) of maternal methadone trough levels were below the lower therapeutic window at term (week 40). The developed optimal dosing regimen escalated doses to 110 mg by week 5, followed by 10 mg increments every 5 weeks up to a maximum of 180 mg once daily near term. This increase resulted in 27% (R-) and 11% (S-) of subjects with trough levels below the lower therapeutic window at term. CYP2B6 poor metabolizers (PM) and either CYP2C19 extensive metabolizers (EM), PM, or ultra-rapid (UM) metabolizer phenotypes demonstrated statistically significant increases in concentrations when compared to their matched CYP2B6 EM counterparts.

CONCLUSIONS

Specific and gestation-dependent dose titrations are required during pregnancy to reduce the risks associated with illicit drug use and to maintain fetal safety.

Subjective symptoms and serum methadone concentrations: what should guide dose adjustments in methadone maintenance treatment? A naturalistic cohort study from Norway

BACKGROUND

There is little evidence-based guidance on how to optimize methadone dosages among patients with opioid addiction undergoing methadone maintenance treatment (MMT). This study aims to investigate whether self-perceived opioid withdrawal symptoms, adverse effects, and self-reported substance use in patients on MMT are related to serum methadone concentrations and the role that these variables could play in clinical decisions on dose adjustments.

METHODS

This naturalistic prospective cohort study included clinical and laboratory measurements from 83 patients undergoing MMT in outpatient clinics in Bergen, Norway, from May 2017 to January 2020. Information on age, gender, methadone daily doses and serum concentrations, subjective opioid withdrawal symptoms using 16 items Subjective Opioid Withdrawal Scale (SOWS) questionnaire, self-reported adverse effects, and substance use was obtained. Linear mixed modelling was used for analyzing the data.

RESULTS

The mean age of the participants was 45 years, and 33% were women. Almost half reported mild to moderate subjective opioid withdrawal symptoms, and all had experienced at least one subjective adverse effect. The use of at least one substance was reported by 88% of the participants. Serum concentration-to-dose ratios were lower among those who had reported subjective opioid withdrawal symptoms (p) = 0.039). The total SOWS score (p < 0.001); the specific subjective withdrawal symptoms of anxiety (p = 0.004), bone and muscle aches (p = 0.003), restlessness (p = 0.017), and (slightly) shaking (p = 0.046), also use of heroin (p = 0.015) and alcohol (p = 0.011) were associated with lower methadone concentrations. Cannabis use was slightly related to higher methadone concentrations (p = 0.049).

CONCLUSIONS

The findings suggest that the patient's self-perceived symptoms and current clinical condition are related to the serum concentrations of methadone. This interpretation supports dose adjustments based on patient-reported symptoms. In some aberrant cases, measurement of serum concentrations together with other individual assessments may be considered to support the clinical decision.

Association between methadone or buprenorphine use during medically supervised opioid withdrawal and extended-release injectable naltrexone induction failure

BACKGROUND

Extended-release naltrexone (XR-NTX) is an effective maintenance treatment for opioid use disorder, but induction from active opioid use is a challenge as individuals must complete detoxification before induction. We aimed to determine whether use of methadone or buprenorphine, long acting agonist opioids commonly used for detoxification, were associated with decreased likelihood of induction onto XR-NTX.

METHODS

We performed a secondary analysis of a large open-label randomized trial of buprenorphine versus XR-NTX for treatment of individuals with opioid use disorder recruited from eight short term residential (detoxification) units. This analysis only included individuals randomized to the XR-NTX arm of the trial (N = 283). The method of detoxification varied according to usual practices at each inpatient program. Logistic regression models estimating the log-odds of induction onto XR-NTX were fit, with detoxification regimen received as the predictor.

RESULTS

In the unadjusted logistic regression model, detoxification drug received (either methadone or buprenorphine) was significantly associated with decreased likelihood of induction onto XR-NTX compared to receiving non-opioid detoxification (Overall: P < 0.001); buprenorphine vs non-opioid detoxification: OR (95% CI) = 0.32 (0.15-0.67); methadone vs non-opioid detoxification: OR (95% CI) = 0.23 (0.11-0.46). After controlling for site as a random effect, the association of detoxification drug with induction success lost statistical significance.

CONCLUSIONS

Use of agonist medication during detoxification was associated with XR-NTX induction failure. Medication choice was determined by each site's clinical practice and therefore this association could not be separated from other site level variables.

CLINICAL TRIAL REGISTRATION

NCT02032433.

Clinical pharmacology and dosing regimen optimization of neonatal opioid withdrawal syndrome treatments

In this paper, we review the management of neonatal opioid withdrawal syndrome (NOWS) and clinical pharmacology of primary treatment agents in NOWS, including morphine, methadone, buprenorphine, clonidine, and phenobarbital. Pharmacologic treatment strategies in NOWS have been mostly empirical, and heterogeneity in dosing regimens adds to the difficulty of extrapolating study results to broader patient populations. As population pharmacokinetics (PKs) of pharmacologic agents in NOWS become more well‐defined and knowledge of patient‐specific factors affecting treatment outcomes continue to accumulate, PK/pharmacodynamic modeling and simulation will be powerful tools to aid the design of optimal dosing regimens at the patient level. Although there is an increasing number of clinical trials on the comparative efficacy of treatment agents in NOWS, here, we also draw attention to the importance of optimizing the dosing regimen, which can be arguably equally important at identifying the optimal treatment agent.

Gender Differences in Patterns and Correlates of Continued Substance Use among Patients in Methadone Maintenance Treatment

BACKGROUND

Continued substance use is common during opioid use disorder (OUD) treatment. There are still inconsistencies in how continued substance use and concurrent patterns of substance use among patients with OUD varies by gender. There is still more to learn regarding how factors associated with continued and concurrent use might differ for men and women in methadone maintenance treatment (MMT). Methods: This cross-sectional study examined predictors of concurrent substance use subgroups among patients receiving MMT. The sample included 341 (n = 161 women) MMT patients aged 18 and older from opioid treatment programs in Southern New England and the Pacific Northwest. Patients completed a survey assessing sociodemographic and clinical characteristics including past-month substance use. Latent class analyses were conducted by gender to identify groups based on substance use and determine predictors of those classes. Results: Three-class solutions were the optimal fit for both men and women. For both genders, the first subgroup was characterized as Unlikely Users (59.8% women, 52.8% men). Classes 2 and 3 among women were Cannabis/Opioid Users (23.7%) and Stimulant/Opioid Users (13.0%). Among men, Classes 2 and 3 consisted of Alcohol/Cannabis Users (21.9%) and Cannabis/Stimulant/Opioid Users (25.3%). Ever using Suboxone (buprenorphine/naloxone) and depression/anxiety symptoms were significantly linked to substance use group among women, whereas homelessness and employment status were significantly associated with substance use group among men. Conclusions: This study furthers understanding of gender differences in factors associated with continued substance use and distinctive patterns of concurrent substance use that may guide tailored treatments among patients MMT.

Medications Development for Treatment of Opioid Use Disorder

This review describes methods for preclinical evaluation of candidate medications to treat opioid use disorder (OUD). The review is founded on the propositions that (1) drug self-administration procedures provide the most direct method for assessment of medication effectiveness, (2) procedures that assess choice between opioid and nondrug reinforcers are especially useful, and (3) states of opioid dependence and withdrawal profoundly influence both opioid reinforcement and effects of candidate medications. Effects of opioid medications and vaccines on opioid choice in nondependent and opioid-dependent subjects are reviewed. Various nonopioid medications have also been examined, but none yet have been identified that safely and reliably reduce opioid choice. Future research will focus on (1) strategies for increasing safety and/or effectiveness of opioid medications (e.g., G-protein-biased μ-opioid agonists), and (2) continued development of nonopioid medications (e.g., clonidine) that might serve as adjunctive agents to current opioid medications.

New directions in the treatment of opioid withdrawal

The treatment of opioid withdrawal is an important area of clinical concern when treating patients with chronic, non-cancer pain, patients with active opioid use disorder, and patients receiving medication for opioid use disorder. Current standards of care for medically supervised withdrawal include treatment with μ-opioid receptor agonists, (eg, methadone), partial agonists (eg, buprenorphine), and α2-adrenergic receptor agonists (eg, clonidine and lofexidine). Newer agents likewise exploit these pharmacological mechanisms, including tramadol (μ-opioid receptor agonism) and tizanidine (α2 agonism). Areas for future research include managing withdrawal in the context of stabilising patients with opioid use disorder to extended-release naltrexone, transitioning patients with opioid use disorder from methadone to buprenorphine, and tapering opioids in patients with chronic, non-cancer pain.

All about pain pharmacology: what pain physicians should know

From the perspective of the definition of pain, pain can be divided into emotional and sensory components, which originate from potential and actual tissue damage, respectively. The pharmacologic treatment of the emotional pain component includes antianxiety drugs, antidepressants, and antipsychotics. The anti-anxiety drugs have anti-anxious, sedative, and somnolent effects. The antipsychotics are effective in patients with positive symptoms of psychosis. On the other hand, the sensory pain component can be divided into nociceptive and neuropathic pain. Non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are usually applied for somatic and visceral nociceptive pain, respectively; anticonvulsants and antidepressants are administered for the treatment of neuropathic pain with positive and negative symptoms, respectively. The NSAIDs, which inhibit the cyclo-oxygenase pathway, exhibit anti-inflammatory, antipyretic, and analgesic effects; however, they have a therapeutic ceiling. The adverse reactions (ADRs) of the NSAIDs include gastrointestinal problems, generalized edema, and increased bleeding tendency. The opioids, which bind to the opioid receptors, present an analgesic effect only, without anti-inflammatory, antipyretic, or ceiling effects. The ADRs of the opioids start from itching and nausea/vomiting to cardiovascular and respiratory depression, as well as constipation. The anticonvulsants include carbamazepine, related to sodium channel blockade, and gabapentin and pregabalin, related to calcium blockade. The antidepressants show their analgesic actions mainly through inhibiting the reuptake of serotonin or norepinephrine. Most drugs, except NSAIDs, need an up-dose titration period. The principle of polypharmacy for analgesia in case of mixed components of pain is increasing therapeutic effects while reducing ADRs, based on the origin of the pain.

Optimisation of methadone treatment in a group of patients on a mephedrone binge and dependent on many psychoactive substances

Objectives: In recent years, an increase in the frequency of hospitalisations of patients on a mephedrone binge has been observed. The literature lacks data on the optimisation of methadone treatment in this group of people.Methods: The study included 601 patients who took mephedrone on a regular basis between 2010 and 2018. Based on the pharmacological database created, it was verified which methadone interaction contributed to subsequent hospitalisations in the group of people studied and which of them had the best therapeutic effect.Results: During the study, 62.4% of patients received methadone (p < .001). The higher the number of drugs taken together with methadone, the higher the frequency of hospitalisations (p < .001). The highest frequency of re-hospitalisations was recorded in patients who combined mephedrone with at least two other psychoactive substances, as well as those who used methadone with chlorprothixene (p < .001). The most optimal therapeutic effect is characteristic for the intake of methadone with thiazolidine carboxylic acid, namely 95% of people using this type of treatment were hospitalised once (p < .001).Conclusions: Therapy with methadone and thiazolidine carboxylic acid seems to be the most optimal therapy for patients taking mephedrone.Key pointsThe number of hospitalisations of patients receiving mephedrone on a regular basis grows from year to year.The multiple use of poly-pharmacotherapy increased in a group of patients on a mephedrone binge.There is a statistically significant correlation between the number of hospitalisations of patients on a mephedrone binge and the total number of drugs taken together with methadone.Administration of methadone with thiazolidine carboxylic acid was the most effective therapy for patients regularly combining mephedrone with at least two other psychoactive substances.

Divergent behavioral responses in protracted opioid withdrawal in male and female C57BL/6J mice

Persons suffering from opioid use disorder (OUD) experience long-lasting dysphoric symptoms well into extended periods of withdrawal. This protracted withdrawal syndrome is notably characterized by heightened anxiety and hyperkatifeia. Here, we investigated if an exacerbated withdrawal model of acute morphine dependence results in lasting behavioral adaptation 6 weeks into forced abstinence in C57BL/6J mice. We found that our exacerbated morphine withdrawal paradigm produced distinct alterations in behavior in elevated plus maze (EPM), open field, and social interaction tests in male and female mice. Following protracted withdrawal male mice showed enhanced exploration of the open arms of the EPM, reduced latency to enter the corner of the OF, and a social interaction deficit. In contrast, female mice showed enhanced thigmotaxis in the OF. In both sexes, protracted withdrawal enhanced locomotor behavior in response to subsequent morphine challenge, albeit at different doses. These findings will be relevant for future investigation examining the neural mechanisms underlying these behaviors and will aid in uncovering physiological sex differences in response to opioid withdrawal.

Sociodemographic Profiles and Clinical Outcomes for Clients on Methadone Maintenance Treatment in a Western Canadian Clinic: Implications for Practice

INTRODUCTION

Clients on methadone maintenance treatment (MMT) have high attrition rates that are attributed to personal and system-related factors. To develop supportive interventions for these clients, it is imperative to understand social demographic characteristics and challenges that clients in the MMT program face.

OBJECTIVES

This article aims to describe (a) the sociodemographic characteristics and clinical profiles of clients in a MMT program, (b) factors that impact their positive clinical outcomes, and (c) the study's implications for practice.

METHODS

A retrospective review of 101 randomly selected electronic medical records representing one third of all the records were examined for sociodemographic characteristics, clinical profiles, and outcomes. Descriptive statistics were used to analyze these variables. Interviews with 18 healthcare providers focusing on their experiences of caring for clients in the MMT program were analyzed thematically.

RESULTS

The average age of clients on MMT is 35.5 years. Clients had early exposure to alcohol and drugs, and at the time of enrollment to the program, they presented with complex healthcare needs, borne from chronic use, and exposure to adverse traumatic events. Personal and systemic factors impact clients' recovery. These include poverty, homelessness, and inadequate healthcare services. Understanding sociodemographic characteristics, clinical profiles, and clients' challenges is central to the development of supportive interventions that enhance retention to care and recovery.

Methadone serum concentrations and influencing factors: A naturalistic observational study

RATIONALE

Although methadone maintenance treatment (MMT) has long been used for opioid addiction, our knowledge on its pharmacokinetics is still limited.

OBJECTIVES

We aimed to investigate effects of age, gender, and various co-medications on methadone serum concentration-to-dose ratio (CDR) in a naturalistic setting.

METHODS

In total, 4425 routine serum methadone concentrations obtained from 1691 MMT patients in the period October 1999 to July 2017 were included. Information about doses, age, gender, and concurrent medications was available in the laboratory database at the Department of Clinical Pharmacology at St. Olav University Hospital in Trondheim, Norway. A log-linear mixed model was used when analyzing the data.

RESULTS

Mean age was 38.4 (range, 21-78) years and 70% were men. Mean CDR was 332 (range, 7-1776) (ng/mL)/(100 mg/d). Concomitant medication with at least one out of totally 170 drugs was recorded in 26% of the samples. CDRs were significantly lower in women (- 9%; confidence interval (CI), - 13%, - 4%; p = 0.001) and with concurrent use of CYP inducers (- 36%; CI, - 44%, - 28%; p < 0.001), but higher using CYP3A4 inhibitors as co-medications (+ 36%; CI, + 10%, + 68%; p = 0.005).

CONCLUSIONS

Our results warrant taking into consideration gender differences in methadone metabolism as well as the impact of potential drug-drug interactions to obtain an optimal therapeutic effect and avoid adverse effects in MMT. Although the clinical implications of the altered drug levels require further study, our results call for close clinical monitoring of all patients undergoing MMT, preferably along with laboratory measurements of methadone serum concentrations.

The optimization of methadone dosing whilst treating with rifampicin: A pharmacokinetic modeling study

BACKGROUND

The use of oral methadone in opioid substitution treatment (OST) for the management of opioid use disorder is established clinical practice. Confounding treatment is the increased risks of contracting Mycobacterium tuberculosis, the mainstay treatment of which incorporates the potent CYP 2B6 inducer rifampicin.

METHODS

This study applied pharmacokinetic modelling using virtual clinical trials, to pharmacokinetically quantify the extent and impact of rifampicin-mediated drug-drug interactions (DDI) on methadone plasma concentrations. An R-methadone model was developed and validated against 11 retrospective clinical studies prior to use in all subsequent studies. The aims were to investigate: (i) the impact of the DDI on daily methadone doses of 60 mg, 90 mg and 120 mg; (ii) dose escalation during rifampicin and (iii) dose reduction following rifampicin cessation.

RESULTS

A dose increase to 160 mg daily during rifampicin treatment phases was required to maintain peak methadone plasma concentrations within a derived therapeutic window of 80-700 ng/mL. Dose escalation prior to rifampicin initiation was not required and resulted in an increase in subjects with supra-therapeutic concentrations. However, during rifampicin cessation, a dose reduction of 10 mg every 2 days commencing prior to rifampicin cessation, ensured that most patients possessed a peak methadone plasma concentration within an optimal therapeutic window.

IMPLICATIONS

Rifampicin significantly alters methadone plasma concentrations and necessitates dose adjustments. Daily doses of almost double those used perhaps more commonly in clinical practice are required for optimal plasma concentration and careful consideration of dose reduction strategies would be required during the deinduction phase.

An Interdisciplinary Approach to Reducing Opioid Prescriptions to Patients with Chronic Pain in a Spinal Cord Injury Center

BACKGROUND

The increasing use of prescription opioids has contributed to the epidemic of opioid abuse in the United States. Efforts to reduce opioid prescriptions and offer alternatives for pain management are needed.

OBJECTIVE

To determine the success of a multidisciplinary project to manage chronic pain while reducing reliance on opioids in a population of patients with spinal cord injury (SCI).

DESIGN

Retrospective analysis.

SETTING

This study was conducted in an SCI system of care in northeast Ohio.

PARTICIPANTS

Individuals with SCI receiving outpatient care were included.

INTERVENTIONS

Clinicians in SCI and pain management specialties developed a plan to manage individuals with SCI, particularly for individuals using opioids, including physical, occupational, recreational, and vocational therapy. These services worked closely with the SCI physicians when chronic pain was identified to help better medically manage their pathology and support efforts to decrease opioid use in a multipronged approach.

MAIN OUTCOMES

The primary outcome measures from opioid prescription data from 2008 to 2016 were the percent of outpatients receiving opioids, opioid prescription rates, and opioid prescription doses over time.

RESULTS

The percentage of outpatients receiving opioids and the number of opioid prescriptions through the outpatient service significantly decreased, from 39% to 16% and from 2.5 to 1.5 prescriptions per patient per quarter, respectively, correlating with the introduction of the multidisciplinary interventions. The total morphine equivalent quantities of prescription medications, particularly nonmethadone opioids, also decreased significantly.

CONCLUSIONS

The multidisciplinary interventional approach was associated with marked decreases in the percentage of patients receiving opioids and the amounts of opioids being prescribed. This reduction could have a significant impact on the opioid crisis.

LEVEL OF EVIDENCE

IV.

Medications for Treatment of Opioid Use Disorder among Persons Living with HIV

PURPOSE OF REVIEW

Recent HIV outbreaks have occurred as a result of the current US opioid epidemic. Providing medications for opioid use disorder (MOUD) with methadone, buprenorphine, and extended-release naltrexone is essential to achieving optimal HIV treatment outcomes including viral suppression and retention in treatment. This review describes the pharmacology of MOUD with specific attention to interactions with antiretroviral therapy, and to the effect of MOUD on HIV treatment outcomes.

RECENT FINDINGS

Methadone and buprenorphine both improve HIV viral suppression, adherence to antiretroviral therapy, and overall mortality for persons with opioid use disorder (OUD). Extended-release naltrexone has been most extensively studied in persons with HIV leaving incarcerated settings, and improves HIV viral suppression in that context. Strategies that integrate MOUD and HIV treatment are crucial to optimize viral suppression. The differing pharmacokinetic and delivery characteristics of these MOUD offer diverse options. Given the chronic and relapsing nature of both HIV and OUD, long-term approaches are required.

Can Tramadol be Used for Maintenance Treatment of Opioid Dependence?

BACKGROUND

Certain limitations of the existing opioid substitution therapies necessitate exploration of other options for maintenance of patients with opioid dependence. This study aimed to present the experience of use of tramadol for long-term treatment of patients with opioid dependence.

METHODS

This was a cross-sectional interview-based observational study conducted in Uttar Pradesh state in India. Patients with opioid dependence who received oral tramadol treatment for a period of more than 6 months were recruited. Outcome was assessed in terms of self-reported abstinence on tramadol.

RESULTS

A total of 102 participants were recruited in the study, with a mean age of 41.3 years. All the participants were males. Abstinence to extraneous opioids was reported by 58.8% of the sample, and the median dose of tramadol at which abstinence was achieved was 350 mg/d. Those who reported to be taking natural opioids (raw opium or poppy husk) at the time of seeking treatment had higher rates of achieving abstinence.

CONCLUSIONS

Tramadol may be a possible option for the maintenance treatment among some opioid-dependent individuals. Further studies are required to establish its efficacy vis-à-vis other medications used in opioid substitution treatment.

Alcohol Drinking in Chinese Methadone-maintained Clients: A Self-medication for Depression and Anxiety?

OBJECTIVES

Unhealthy alcohol use is associated with negative health outcomes in clients attending methadone maintenance therapy (MMT) programs. However, debates exist regarding the methadone dose of drinkers, and little is known about the health outcomes of drinkers with other types of alcohol use. This study examined the drinking pattern and its association with methadone dose, and depressive and anxiety symptoms in Chinese clients undergoing MMT.

METHODS

A secondary data analysis was conducted with data from a large-scale cross-sectional survey of 549 clients of 3 MMT clinics in Wuhan, China. Depression, anxiety, and alcohol dependence were measured with Zung Self-rating Depression Scale, Zung Self-rating Anxiety Scale, and Alcohol Dependence Scale, respectively. Drinking pattern was assessed using 3 indicators: weekly amount of alcohol consumed, weekly frequency of alcohol consumed, and severity of alcohol dependence.

RESULTS

The prevalence of current drinking, hazardous drinking, regular drinking, and alcohol abuse/dependence was 29.0%, 10.4%, 14.2%, and 8.7%, respectively. In adjustment analyses, relative to nondrinkers, drinkers had significantly lower weight-based methadone dose (β = -0.136, P = 0.008); hazardous drinkers, irregular drinkers, and drinkers without alcohol abuse/dependence had less severe depression (β = -3.67, P = 0.004; β = -2.37, P = 0.034; β = -3.20, P = 0.001) and anxiety (β = -4.90, P < 0.001; β = -3.24, P = 0.006; β = -4.52, P < 0.001), but drinkers with alcohol abuse/dependence had more severe depression (β = 5.55, P < 0.001) and anxiety (β = 4.31, P = 0.005).

CONCLUSION

In Chinese MMT clinics, drinkers may use alcohol to compensate for inadequate MMT and self-medicate negative emotions. Compared with nondrinkers, the severities of depression and anxiety were lower among drinkers without alcohol abuse/dependence, but higher among those with alcohol abuse/dependence.

Sex differences in opioid use and medical issues during buprenorphine/naloxone treatment

BACKGROUND

There are sex differences in buprenorphine/naloxone clinical trials for opioid use. While women have fewer opioid-positive urine samples, relative to men, a significant decrease in opioid-positive samples was found during treatment for men, but not women. In order to inform sex-based approaches to improve treatment outcomes, research is needed to determine if opioid use, and predictors of opioid use, differs between men and women during treatment.

OBJECTIVES

To test for sex differences in opioid use during a buprenorphine/naloxone clinical trial and determine if sex differences exist in the associations between addiction-related problem areas and opioid use over the course of the trial.

METHOD

This secondary data analysis of the National Drug Abuse Treatment Clinical Trials Network (CTN) 0003 examined sex differences (men = 347, women = 169) in opioid-positive samples in a randomized clinical trial comparing 7-day vs. 28-day buprenorphine/naloxone tapering strategies. Addiction-related problem areas were defined by Addiction Severity-Lite (ASI-L) domain composite scores.

RESULTS

Women were more likely than men to use opioids during the course of the buprenorphine/naloxone clinical trial (B = .33, p = .01) and medical issues were positively related to submitting an opioid-positive sample during treatment for women (B = 1.67, p = .01). No ASI-L domain composite score was associated with opioid-positive samples during treatment for men.

CONCLUSION

Women were more likely than men to use opioids during the course of the buprenorphine/naloxone clinical trial, and medical issues predicted opioid use during treatment for women but not men. Complementary treatment for medical problems during opioid replacement therapy may benefit women.

Associations between pharmacotherapy for opioid dependence and clinical and criminal justice outcomes among adults with co-occurring serious mental illness

Adults suffering from a serious mental illness (SMI) and a substance use disorder are at especially high risk for poor clinical outcomes and also arrest and incarceration. Pharmacotherapies for treating opioid dependence could be a particularly important mode of treatment for opioid-dependent adults with SMI to lower their risk for overdose, high-cost hospitalizations, repeated emergency department visits, and incarceration, given relapse rates are very high following detoxification in the absence of one of the three FDA-approved pharmacotherapies. This study estimates the effects of methadone, buprenorphine, and oral naltrexone on clinical and justice-related outcomes in a sample of justice-involved adults with SMI, opioid dependence, and criminal justice involvement. Administrative data were merged from several public agencies in Connecticut for 8736 adults 18years of age or older with schizophrenia spectrum disorder, bipolar disorder, or major depression; co-occurring moderate to severe opioid dependence; and who also had at least one night in jail during 2002-2009. Longitudinal multivariable regression models estimated the effect of opioid-dependence pharmacotherapy as compared to outpatient substance abuse treatment without opioid-dependence pharmacotherapy on inpatient substance abuse or mental health treatment, emergency department visits, criminal convictions, and incarcerations, analyzing instances of each outcome 12months before and after an index treatment episode. Several baseline differences between the study groups (opioid-dependence pharmacotherapy group versus outpatient treatment without opioid-dependence pharmacotherapy) were adjusted for in the regression models. All three opioid-dependence pharmacotherapies were associated with reductions in inpatient substance abuse treatment, and among the oral naltrexone subgroup, also reductions in inpatient mental health treatment, as well as improved adherence to SMI medications. Overall, the opioid-dependence pharmacotherapy group had higher rates of arrest and incarceration in the follow-up period than the comparison group; but those using oral naltrexone had lower rates of arrest (including felonies). The analysis of observational administrative data provides useful population-level estimates but also has important limitations that preclude conclusive causal inferences. Large reductions in crisis-driven service utilization associated with opioid-dependence pharmacotherapy in this study suggest that evidence-based medications for treating opioid dependence can be used successfully in adults with SMI and should be considered more systematically during assessments of treatment needs for this population.

Nitric oxide-heat shock protein axis in menopausal hot flushes: neglected metabolic issues of chronic inflammatory diseases associated with deranged heat shock response

BACKGROUND

Although some unequivocal underlying mechanisms of menopausal hot flushes have been demonstrated in animal models, the paucity of similar approaches in humans impedes further mechanistic outcomes. Human studies might show some as yet unexpected physiological mechanisms of metabolic adaptation that permeate the phase of decreased oestrogen levels in both symptomatic and asymptomatic women. This is particularly relevant because both the severity and time span of hot flushes are associated with increased risk of chronic inflammatory disease. On the other hand, oestrogen induces the expression of heat shock proteins of the 70 kDa family (HSP70), which are anti-inflammatory and cytoprotective protein chaperones, whose expression is modulated by different types of physiologically stressful situations, including heat stress and exercise. Therefore, lower HSP70 expression secondary to oestrogen deficiency increases cardiovascular risk and predisposes the patient to senescence-associated secretory phenotype (SASP) that culminates in chronic inflammatory diseases, such as obesities, type 2 diabetes, neuromuscular and neurodegenerative diseases.

OBJECTIVE AND RATIONALE

This review focuses on HSP70 and its accompanying heat shock response (HSR), which is an anti-inflammatory and antisenescent pathway whose intracellular triggering is also oestrogen-dependent via nitric oxide (NO) production. The main goal of the manuscript was to show that the vasomotor symptoms that accompany hot flushes may be a disguised clue for important neuroendocrine alterations linking oestrogen deficiency to the anti-inflammatory HSR.

SEARCH METHODS

Results from our own group and recent evidence on hypothalamic control of central temperature guided a search on PubMed and Google Scholar websites.

OUTCOMES

Oestrogen elicits rapid production of the vasodilatory gas NO, a powerful activator of HSP70 expression. Whence, part of the protective effects of oestrogen over cardiovascular and neuroendocrine systems is tied to its capacity of inducing the NO-elicited HSR. The hypothalamic areas involved in thermoregulation (infundibular nucleus in humans and arcuate nucleus in other mammals) and whose neurons are known to have their function altered after long-term oestrogen ablation, particularly kisspeptin-neurokinin B-dynorphin neurons, (KNDy) are the same that drive neuroprotective expression of HSP70 and, in many cases, this response is via NO even in the absence of oestrogen. From thence, it is not illogical that hot flushes might be related to an evolutionary adaptation to re-equip the NO-HSP70 axis during the downfall of circulating oestrogen.

WIDER IMPLICATIONS

Understanding of HSR could shed light on yet uncovered mechanisms of menopause-associated diseases as well as on possible manipulation of HSR in menopausal women through physiological, pharmacological, nutraceutical and prebiotic interventions. Moreover, decreased HSR indices (that can be clinically determined with ease) in perimenopause could be of prognostic value in predicting the moment and appropriateness of starting a HRT.

Missense mutation at CLDN8 associated with a high plasma interferon gamma-inducible protein 10 level in methadone-maintained patients with urine test positive for morphine

We previously reported a high plasma chemokine interferon gamma-inducible protein 10 (IP-10) level and prolonged electrocardiography QT-interval in methadone maintenance treatment (MMT) patients with HIV or HCV infection. The purpose of this study was to evaluate the genetic association of high plasma IP-10 level in the MMT patients. The gene-based and pathway-based association analyses were conducted using a genome-wide association study dataset in 344 MMT patients for identifying genes and pathways associated with plasma IP-10 level. We found that plasma IP-10 level was significantly associated with a pathway in the tight junction (P = 1.01x10-5), where the claudin 8 (CLDN8) gene had the most significant association (P = 6.8x10-5). A functional single nucleotide polymorphism (SNP) rs686364 at exon 1 of CLDN8 showed strong association with plasma IP-10 levels, in the MMT subjects with positive urine test for morphine (dominant model, P = 0.00004). The minor allele type carriers had higher plasma IP-10 levels than the major allele type carriers. Our data support that the tight junction protein claudin 8 exon 1 is a predictor for the plasma levels of IP-10 in MMT patients with urine test positive for morphine.

Why People Who Inject Drugs Voluntarily Transition Off Methadone in Ukraine

Methadone maintenance therapy (MMT) treats opioid use disorder among people who inject drugs (PWID). To understand why PWID may voluntarily discontinue MMT, we analyzed data from 25 focus groups conducted in five Ukrainian cities from February to April 2013 with 199 participants who were currently, previously, or never on MMT. Using constant comparison method, we uncovered three themes explaining why PWID transition off MMT: (a) purposeful resistance to rigid social control associated with how MMT is delivered and to power asymmetries in provider-patient relationships, (b) self-management of a PWID's "wounded identity" that is common in socially stigmatized and physically sick persons-MMT serves as a reminder of their illness, and (c) the quest for a "normal life" uninterrupted by daily MMT site visits, harassment, and time inefficiencies, resources, and social capital. Focusing on holistic principles of recovery would improve addiction treatment and HIV prevention in Ukraine and globally.

Pharmacoepigenomics of opiates and methadone maintenance treatment: current data and perspectives

Current treatments of opioid addiction include primarily maintenance medications such as methadone. Chronic exposure to opiate and/or long-lasting maintenance treatment induce modulations of gene expression in brain and peripheral tissues. There is increasing evidence that epigenetic modifications underlie these modulations. This review summarizes published results on opioid-induced epigenetic changes in animal models and in patients. The epigenetic modifications observed with other drugs of abuse often used by opiate abusers are also outlined. Specific methadone maintenance treatment induced epigenetic modifications at different treatment stages may be combined with the ones resulting from patients’ substance use history. Therefore, research comparing groups of addicts with similar history and substances use disorders but contrasting for well-characterized treatment phenotypes should be encouraged.

Opioids and Opioid Maintenance Therapies: Their Impact on Monocyte-Mediated HIV Neuropathogenesis

BACKGROUND

HIV-1 enters the CNS within two weeks after peripheral infection and results in chronic neuroinflammation that leads to HIV associated neurocognitive disorders (HAND) in more than 50% of infected people. HIV enters the CNS by transmigration of infected monocytes across the blood brain barrier. Intravenous drug abuse is a major risk factor for HIV-1 infection, and opioids have been shown to alter the progression and severity of HAND. Methadone and buprenorphine are opioid derivates that are used as opioid maintenance therapies. They are commonly used to treat opioid dependency in HIV infected substance abusers, but their effects on monocyte migration relevant to the development of cognitive impairment are not well characterized.

CONCLUSION

Here, we will discuss the effects of opioids and opioid maintenance therapies on the inflammatory functions of monocytes and macrophages that are related to the development of neuroinflammation in the context of HIV infection.

Methadone for neuropathic pain in adults

BACKGROUND

This review replaces an earlier review, "Methadone for chronic non-cancer pain in adults". This review serves to update the original and includes only studies of neuropathic pain. Methadone belongs to a class of analgesics known as opioids, that are considered the cornerstone of therapy for moderate-to-severe postsurgical pain and pain due to life-threatening illnesses; however, their use in neuropathic pain is controversial. Methadone has many characteristics that differentiate it from other opioids, which suggests that it may have a different efficacy and safety profile.

OBJECTIVES

To assess the analgesic efficacy and adverse events of methadone for chronic neuropathic pain in adults.

SEARCH METHODS

We searched the following databases: CENTRAL (CRSO), MEDLINE (Ovid), and Embase (Ovid), and two clinical trial registries. We also searched the reference lists of retrieved articles. The date of the most recent search was 30 November 2016.

SELECTION CRITERIA

We included randomised, double-blind studies of two weeks' duration or longer, comparing methadone (in any dose, administered by any route, and in any formulation) with placebo or another active treatment in chronic neuropathic pain.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Two review authors independently considered trials for inclusion in the review, assessed risk of bias, and extracted data. There were insufficient data to perform pooled analyses. We assessed the overall quality of the evidence for each outcome using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We included three studies, involving 105 participants. All were cross-over studies, one involving 19 participants with diverse neuropathic pain syndromes, the other two involving 86 participants with postherpetic neuralgia. Study phases ranged from 20 days to approximately eight weeks. All administered methadone orally, in doses ranging from 10 mg to 80 mg daily. Comparators were primarily placebo, but one study also included morphine and tricyclic antidepressants.The included studies had several limitations related to risk of bias, particularly incomplete reporting, selective outcome reporting, and small sample sizes.There were very limited data for our primary outcomes of participants with at least 30% or at least 50% pain relief. Two studies reported that 11/29 participants receiving methadone achieved 30% pain relief versus 7/29 participants receiving placebo. Only one study presented data in a manner that allowed us to calculate the number of participants with at least 50% pain relief. None of the 19 participants achieved a 50% reduction in pain intensity, either when receiving methadone or when receiving placebo. No study provided data for our other primary outcomes of Patient Global Impression of Change scale (PGIC) much or very much improved (equivalent to at least 30% pain relief) and PGIC very much improved (equivalent to at least 50% pain relief).For secondary efficacy outcomes, one study reported maximum and mean pain intensity and pain relief, and reported statistically significant improvements versus placebo for all outcomes with 20 mg daily doses of methadone, but not with 10 mg daily doses. The second study reported differences in pain reduction between methadone (n = 26) and morphine (n = 38) and found morphine to be statistically superior. The third study reported the number of responders (variously defined) for several pain and functional outcomes and found methadone to be statistically superior to placebo for the outcomes of categorical pain intensity and evoked pain. In the two studies that reported data, 0/29 participants withdrew due to lack of efficacy, whereas 4/29 participants withdrew due to adverse events while taking methadone versus 3/29 while taking placebo.One study reported incidences for several individual adverse events, but found a statistically significant increased incidence for methadone over placebo for only one event, dizziness. The other studies did not report data in a manner that enabled us to analyze adverse events. There were no serious adverse events or deaths reported.We assessed the quality of the evidence as very low for all efficacy and safety outcomes using GRADE, primarily because of the heterogeneity of study designs and populations, short durations, cross-over methodology, and few participants and events.

AUTHORS' CONCLUSIONS

The three studies provide very limited, very low quality evidence of the efficacy and safety of methadone for chronic neuropathic pain, and there were too few data for pooled analysis of efficacy or harm, or to have confidence in the results of the individual studies. No conclusions can be made regarding differences in efficacy or safety between methadone and placebo, other opioids, or other treatments.

The association between age of onset of opioid use and comorbidity among opioid dependent patients receiving methadone maintenance therapy

Background

Opioid use disorder (OUD) affects approximately 21.9 million people worldwide. This study aims to determine the association between age of onset of opioid use and comorbid disorders, both physical and psychiatric, in patients receiving methadone maintenance treatment (MMT) for OUD. Understanding this association may inform clinical practice about important prognostic factors of patients on MMT, enabling clinicians to identify high-risk patients.

Methods

This study includes data collected between June 2011 and August 2016 for the Genetics of Opioid Addiction research collaborative between McMaster University and the Canadian Addiction Treatment Centers. All patients were interviewed by trained health professionals using the Mini-International Neuropsychiatric Interview and case report forms. Physical comorbidities were verified using patients’ electronic medical records. A multi-variable logistic regression model was constructed to determine the strength of the association between age of onset of opioid use and the presence of physical or psychiatric comorbidity while adjusting for current age, sex, body mass index, methadone dose and smoking status.

Results

Data from 627 MMT patients with a mean age of 38.8 years (SD = 11.07) were analyzed. Individuals with an age of onset of opioid use younger than 18 years were found to be at higher odds for having a physical or psychiatric comorbid disorder compared to individuals with an age of onset of opioid use of 31 years or older (odds ratio 2.94, 95% confidence interval 1.20, 7.19, p = 0.02). A significant association was not found between the risk of having a comorbidity and an age of onset of opioid use between 18 and 25 years or 26 and 30 years, compared to an age of onset of opioid use of 31 years or older.

Conclusion

Our study demonstrates that the younger one begins to use opioids, the greater their chance of having a physical or psychiatric co-morbidity. Understanding the risk posed by an earlier onset of opioid use for the later development of comorbid disorders informs clinical practice about important prognostic predictors and aids in the identification of high-risk patients.

NIDA Clinical Trials Network CTN-0051, Extended-Release Naltrexone vs. Buprenorphine for Opioid Treatment (X:BOT): Study design and rationale

INTRODUCTION

For opioid-dependent patients in the US and elsewhere, detoxification and counseling-only aftercare are treatment mainstays. Long-term abstinence is rarely achieved; many patients relapse and overdose after detoxification. Methadone, buprenorphine-naloxone (BUP-NX) and extended-release naltrexone (XR-NTX) can prevent opioid relapse but are underutilized. This study is intended to develop an evidence-base to help patients and providers make informed choices and to foster wider adoption of relapse-prevention pharmacotherapies.

METHODS

The National Institute on Drug Abuse's Clinical Trials Network (CTN) study CTN-0051, X:BOT, is a comparative effectiveness study of treatment for 24weeks with XR-NTX, an opioid antagonist, versus BUP-NX, a high affinity partial opioid agonist, for opioid dependent patients initiating treatment at 8 short-term residential (detoxification) units and continuing care as outpatients. Up to 600 participants are randomized (1:1) to XR-NTX or BUP-NX.

RESULTS

The primary outcome is time to opioid relapse (i.e., loss of persistent abstinence) across the 24-week treatment phase. Differences between arms in the distribution of time-to-relapse will be compared (construction of the asymptotic 95% CI for the hazard ratio of the difference between arms). Secondary outcomes include proportions retained in treatment, rates of opioid abstinence, adverse events, cigarette, alcohol, and other drug use, and HIV risk behaviors; opioid cravings, quality of life, cognitive function, genetic moderators, and cost effectiveness.

CONCLUSIONS

XR-NTX and BUP-NX differ considerably in their characteristics and clinical management; no studies to date have compared XR-NTX with buprenorphine maintenance. Study design choices and compromises inherent to a comparative effectiveness trial of distinct treatment regimens are reviewed.

CLINICAL TRIAL REGISTRATION

NCT02032433.

Animal Models and the Development of Vaccines to Treat Substance Use Disorders

The development of pharmacotherapies for substance use disorders (SUDs) is a high priority in addiction research. At present, there are no approved pharmacotherapies for cocaine and methamphetamine use disorders, while treatments for nicotine and opioid use are moderately effective. Indeed, many of these treatments can cause adverse drug side effects and have poor medication compliance, which often results in increased drug relapse rates. An alternative to these traditional pharmacological interventions is immunotherapy or vaccines that can target substances associated with SUDs. In this chapter, we discuss the current knowledge on the efficacy of preclinical vaccines, particularly immunogens that target methamphetamine, cocaine, nicotine, or opioids to attenuate drug-induced behaviors in animal models of SUDs. We also review vaccines (and antibodies) against cocaine, nicotine, and methamphetamine that have been assessed in human clinical trials. While preclinical studies indicate that several vaccines show promise, these findings have not necessarily translated to the clinical population. Thus, continued effort to design more effective vaccine immunogens using SUD animal models is necessary in order to support the use of immunotherapy as a viable option for individuals with SUDs.

Methadone dose in heroin-dependent patients: role of clinical factors, comedications, genetic polymorphisms and enzyme activity

AIMS

Methadone is characterized by wide intersubject variability regarding the dose needed to obtain full therapeutic response. We assessed the influence of sociodemographic, ethnic, clinical, metabolic and genotypic variables on methadone maintenance dose requirement in opioid-dependent responder patients.

METHODS

Eighty-one stable patients (60 men and 21 women, 43.7 ± 8.1 years old, 63.1 ± 50.9 mg day(-1) methadone), divided into quartiles with respect to the median daily dose, were enrolled and underwent clinical examination, treatment history and determination of liver/intestinal cytochrome P450 (CYP) 3A4 activity measured by the midazolam test, R,S-methadone trough concentration and clinically significant polymorphisms of the OPRM1, DRD2, COMT, ABCB1, CYP2B6, CYP3A5, CYP2C19 and CYP2D6 genes.

RESULTS

Methadone maintenance dose was correlated to the highest dose ever used (r(2) = 0.57, P < 0.0001). Fractioned methadone intake (odds ratio 4.87, 95% confidence interval 1.27-18.6, P = 0.02), bodyweight (odds ratio 1.57, 95% confidence interval 1.01-2.44, P = 0.04), history of cocaine dependence (80 vs. 44 mg day(-1) in never-addict patients, P = 0.005) and ethnicity (Asian > Caucasian > African, P = 0.04) were independently associated with high-dose methadone in multiple regression analysis. A modest correlation was observed between liver/intestinal CYP3A4 activity and methadone dose at steady state (Spearman rank correlation coefficient [rs ] = 0.21, P = 0.06) but not with highest dose ever used (rs = 0.15, P = 0.18) or dose-normalized R,S-methadone trough concentrations (rs = -0.05, P = 0.64). Concomitant CYP3A4 inhibitors only affected the relationship between methadone dose and R,S-methadone trough concentration. None of the genetic polymorphisms explored was predictive of the methadone maintenance dose.

CONCLUSIONS

Methadone maintenance dose was predicted by sociodemographic and clinical variables rather than genetic polymorphisms or liver/intestinal CYP3A4 activity in stable patients.