Clinical pharmacology of methadone for pain

Opioid use disorder in pediatric populations: considerations for perioperative pain management and precision opioid analgesia

INTRODUCTION

Opioids are commonly used for perioperative analgesia, yet children still suffer high rates of severe post-surgical pain and opioid-related adverse effects. Persistent and severe acute surgical pain greatly increases the child's chances of chronic surgical pain, long-term opioid use, and opioid use disorder.

AREAS COVERED

Enhanced recovery after surgery (ERAS) protocols are often inadequate in treating a child's severe surgical pain. Research suggests that 'older' and longer-acting opioids such as methadone are providing better methods to treat acute post-surgical pain. Studies indicate that lower repetitive methadone doses can decrease the incidence of chronic persistent surgical pain (CPSP). Ongoing research explores genetic components influencing severe surgical pain, inadequate opioid analgesia, and opioid use disorder. This new genetic research coupled with better utilization of opioids in the perioperative setting provides hope in personalizing surgical pain management, reducing pain, opioid use, adverse effects, and helping the fight against the opioid pandemic.

EXPERT OPINION

The opioid and analgesic pharmacogenomics approach can proactively 'tailor' a perioperative analgesic plan to each patient based on underlying polygenic risks. This transition from population-based knowledge of pain medicine to individual patient knowledge can transform acute pain medicine and greatly reduce the opioid epidemic's socioeconomic, personal, and psychological strains globally.

A new coaxial flow-through probe for electromembrane extraction of methadone from clinical samples on-line coupled to capillary electrophoresis

BACKGROUND

A new design of a flow-through coaxial electromembrane extraction (EME) probe that can be on-line coupled with CE instrument is described and tested. The supporting base of the probe is a PDMS microchip with T-shaped channels into which two coaxially arranged capillaries for inlet and outlet solutions are inserted. The extraction part of the probe is a porous polypropylene hollow fiber, sealed at one end and modified with nitrophenyloctyl ether (NPOE) extraction fluid. The internal volume of the extraction probe is 1.1 μL.

RESULTS

The EME probe was tested on laboratory samples and methadone was extracted into 3.0 M AcOH as acceptor. The concentration dependence was linear in the range of 0.1-1.0 μg mL-1 at EME 300 s/150 V and in the range of 0.5-10.0 μg mL-1 at EME 100 s/150 V. The enrichment factor was greater than 30 and the LOD was 0.21 μg mL-1. The EME of methadone in clinical samples showed a linear concentration dependence in human urine and a nonlinear concentration dependence in serum. The distribution of methadone in each phase of the extraction system and the effect of extraction membrane thickness on the enrichment factor were studied. The EME probe can be applied repeatedly.

SIGNIFICANCE

The supporting base of EME probe and flow gating interface (FGI) are realized by a microfluidic PDMS microchips cast in the laboratory without the use of lithography. A supporting PDMS chip with coaxially arranged capillaries and extraction membrane forms a compact analytical instrument. The entire EME/CE analysis process is performed on a laboratory-made instrument and automated by LabView.

Methadone Requires the Co-Activation of μ-Opioid and Toll-Like-4 Receptors to Produce Extracellular DNA Traps in Bone-Marrow-Derived Mast Cells

Methadone is an effective and long-lasting analgesic drug that is also used in medication-assisted treatment for people with opioid use disorders. Although there is evidence that methadone activates μ-opioid and Toll-like-4 receptors (TLR-4s), its effects on distinct immune cells, including mast cells (MCs), are not well characterized. MCs express μ-opioid and Toll-like receptors (TLRs) and constitute an important cell lineage involved in allergy and effective innate immunity responses. In the present study, murine bone-marrow-derived mast cells (BMMCs) were treated with methadone to evaluate cell viability by flow cytometry, cell morphology with immunofluorescence and scanning electron microscopy, reactive oxygen species (ROS) production, and intracellular calcium concentration ([Ca2+]i) increase. We found that exposure of BMMCs to 0.5 mM or 1 mM methadone rapidly induced cell death by forming extracellular DNA traps (ETosis). Methadone-induced cell death depended on ROS formation and [Ca2+]i. Using pharmacological approaches and TLR4-defective BMMC cultures, we found that µ-opioid receptors were necessary for both methadone-induced ROS production and intracellular calcium increase. Remarkably, TLR4 receptors were also involved in methadone-induced ROS production as it did not occur in BMMCs obtained from TLR4-deficient mice. Finally, confocal microscopy images showed a significant co-localization of μ-opioid and TLR4 receptors that increased after methadone treatment. Our results suggest that methadone produces MCETosis by a mechanism requiring a novel crosstalk pathway between μ-opioid and TLR4 receptors.

Switching to Intravenous Methadone in Advanced Cancer Patients: A Retrospective Analysis

CONTEXT

Information about opioid switching to intravenous methadone is lacking.

OBJECTIVES

The aim of this study was to assess the outcome of opioid switching to intravenous methadone (IV-ME) in patients admitted to an acute supportive/palliative care unit (ASPCU). The secondary outcome was to assess the conversion ratio from IV-ME to oral methadone at time of hospital discharge.

METHODS

We retrieved from the pharmacy registry the list of patients who were prescribed IV-ME during their ASPCU admission for a period of 47 months. Poor analgesia with previous opioids and/or adverse effects were the main indications for opioid switching. IV-ME was titrated until acceptable analgesia was achieved. The effective dose was multiplied by three to establish the intravenous daily dose, given as a continuous infusion. Doses were then changed according to the clinical needs. Once the patient was stabilized, IV-ME dose was converted to oral methadone, by using an initial ratio of 1:1.2. Further dose changes were made according to clinical needs until stabilization, before patients' discharge. Information about patients' characteristics, pain scores on the Edmonton Symptom Assessment Scale (ESAS), Memorial Delirium Assessment Scale (MDAS), Cut-down, Annoyed, Guilty, Eye-opener (CAGE) questionnaire, previous opioids and their doses, expressed as oral morphine equivalents (OME), were recorded. The effective bolus of IV-ME, initial daily infusion rate, and oral methadone doses were assessed, and conversion ratios calculated.

RESULTS

Forty-one patients were taken into consideration for the study. The mean effective bolus of IV-ME titrated for achieving acceptable analgesia was 9 mg (range 5-15 mg). The mean daily continuous infusion rate of IV-ME was 27.6 mg/day (SD 21). The mean daily dose of oral methadone at time of discharge was 46.8 mg/day (SD 43). Discharge occurred within a median of seven days (range 6-9) after admission. Previous opioid (OME)/IV-ME, oral-IV-ME, and previous opioid (OME)/oral methadone were 6.25, 1.7, and 3.7, respectively.

CONCLUSION

IV-ME dose titration followed by intravenous infusion allowed a rapid pain control in few minutes in patients with severe pain intensity, not responsive to previous opioids. Conversion to oral route was successful and facilitated home discharge. Further studies should be performed to confirm these preliminary results.

Central sensitization in opioid use disorder: a novel application of the American College of Rheumatology Fibromyalgia Survey Criteria

Central sensitization may be an underlying mechanism linking chronic pain and opioid use disorder associated with opioid use disorder onset, maintenance, escalation, treatment delay, and relapse.

Introduction:

Central sensitization (CS) involves dysfunctional central nervous system pain modulation resulting in heightened pain perception. Central sensitization is not commonly assessed among patients with opioid use disorder (OUD), despite the fact that pain has been implicated in the development, maintenance, and relapse of OUD and chronic opioid use may produce opioid-induced hyperalgesia. Central sensitization is a plausibly important mechanism underlying the complex relationship between OUD and chronic pain. However, this premise is largely untested.

Methods:

Participants with OUD (n = 141) were recruited from an academic addiction treatment center in Columbus, Ohio. An established surrogate measure of CS, the American College of Rheumatology 2011 Fibromyalgia Survey Criteria, was administered using electronic survey. Participants also responded to questions about pain interference (Brief Pain Inventory), quality of life (RAND-36), and items regarding pain beliefs and expectations of pain and addiction treatment. Descriptive analyses, Spearman rho correlations, and Mann–Whitney U tests were performed.

Results:

Hypothesized relationships were confirmed between degree of CS, pain interference, and health-related quality of life. Degree of CS was also positively correlated with greater endorsement of pain as a reason for the onset, maintenance, and escalation of OUD; treatment delay; and OUD relapse. Participants with the American College of Rheumatology 2011 Fibromyalgia Survey Criteria ≥13 had significantly greater endorsement of pain as a reason for delaying OUD treatment, continuing and increasing opioid use, and precipitating OUD relapse.

Conclusions:

This study provides early evidence CS may underlie previously observed connections between clinically salient features of chronic pain and OUD, potentially informing future mechanistic research and precision treatment.

Viral vector-mediated gene therapy for opioid use disorders

Chronic exposure to opioids typically results in adverse consequences. Opioid use disorder (OUD) is a disease of the CNS with behavioral, psychological, neurobiological, and medical manifestations. OUD induces a variety of changes of neurotransmitters/neuropeptides in the nervous system. Existing pharmacotherapy, such as opioid maintenance therapy (OMT) is the mainstay for the treatment of OUD, however, current opioid replacement therapy is far from effective for the majority of patients. Pharmacological therapy for OUD has been challenging for many reasons including debilitating side-effects. Therefore, developing an effective, non-pharmacological approach would be a critical advancement in improving and expanding treatment for OUD. Viral vector mediated gene therapy provides a potential new approach for treating opioid abused patients. Gene therapy can supply targeting gene products directly linked to the mechanisms of OUD to restore neurotransmitter and/or neuropeptides imbalance, and avoid the off-target effects of systemic administration of drugs. The most commonly used viral vectors in rodent studies of treatment of opioid-used disorder are based on recombinant adenovirus (AV), adeno-associated virus (AAV), lentiviral (LV) vectors, and herpes simplex virus (HSV) vectors. In this review, we will focus on the recent progress of viral vector mediated gene therapy in OUD, especially morphine tolerance and withdrawal.

Methadone bioavailability and dose conversion implications with intravenous and enteral administration: A scoping review

PURPOSE

Despite its availability for more than 70 years, many details concerning methadone remain contentious, such as the dosing equivalents for intravenous and enteral administration. A scoping review was performed to evaluate whether existing literature on methadone bioavailability in human subjects support the current recommendation that an equivalent enteral dose is twice the intravenous dose.

METHODS

A librarian-assisted search of the PubMed and EMBASE databases identified all English-language articles with the terms methadone and bioavailability and/or conversion in the title or abstract published from inception though December 2019. A manual search of references was also performed to identify any additional articles. Studies were included in a scoping review if they were published in English and evaluated methadone bioavailability in human subjects.

RESULTS

Among 65 publications initially identified, 6 studies involving a total of 50 patients were included in the review. Bioavailability data for healthy volunteers and patients with opioid use disorder, metastatic cancer, chronic pain from malignant or nonmalignant disease were available for analysis. The pooled mean (95% confidence interval) bioavailability (F) was 85.4% (75.2%-95.6%), with heterogeneity (I2) of 0. In the 4 studies that provided individual patient-level data, F was >50% in 40 of 42 patient measurements (95.2%) and ≥75% in 33 of 42 patient measurements (78.6%).

CONCLUSION

Available evidence suggests the bioavailability of methadone is generally more than 75%, there is limited evidence for the currently recommended 1:2 ratio (intravenous:enteral), and a more appropriate dosing ratio may be 1:1.3. This scoping review underscores the need for further research to establish an effective and safe ratio when converting between intravenous and enteral dosing formulations of methadone.

Occurrence, distribution, and potential health risks of psychoactive substances in Chinese surface waters

Ten psychoactive substances (PSs) and metabolites were identified and quantified in 217 surface water samples collected across China to reveal the occurrence, distribution, and potential health risks in Chinese surface waters. The results showed the ubiquitous occurrence of caffeine (CFI), paraxanthine (PXT) and cotinine (CTN) at all the monitored sites, the concentrations of which ranged from not detected to 3460 ng L^-1, while the remaining PSs were detected at trace levels (<50 ng L^-1). High concentrations of diet-related PSs (CTN, CFI, and PXT) typically occurred in areas with high population densities. Traditional drugs tended to occur in megacities and the illegal manufacturing bases of the illicit drugs. Emerging drugs were found to be very popular across the whole country, with no significant differences among the samples. The risk assessment results suggest that drinking water containing these PS residues posed no potential human health risk in any life stage. However, the age-dependent risk quotients (RQs) of the 5 assessed PSs for the 12 age intervals ranged from < 1.0 × 10^-7 to 0.005. In terms of the evaluated life stages, the RQs for early stages (from birth to <2 years) were significantly higher than the RQs for other stages.

D,L-Methadone causes leukemic cell apoptosis via an OPRM1-triggered increase in IP3R-mediated ER Ca2+ release and decrease in Ca2+ efflux, elevating [Ca2+]i

The search continues for improved therapy for acute lymphoblastic leukemia (aLL), the most common malignancy in children. Recently, d,l-methadone was put forth as sensitizer for aLL chemotherapy. However, the specific target of d,l-methadone in leukemic cells and the mechanism by which it induces leukemic cell apoptosis remain to be defined. Here, we demonstrate that d,l-methadone induces leukemic cell apoptosis through activation of the mu1 subtype of opioid receptors (OPRM1). d,l-Methadone evokes IP3R-mediated ER Ca²⁺ release that is inhibited by OPRM1 loss. In addition, the rate of Ca²⁺ extrusion following d,l-methadone treatment is reduced, but is accelerated by loss of OPRM1. These d,l-methadone effects cause a lethal rise in [Ca²⁺]_i that is again inhibited by OPRM1 loss, which then prevents d,l-methadone-induced apoptosis that is associated with activation of calpain-1, truncation of Bid, cytochrome C release, and proteolysis of caspase-3/12. Chelating intracellular Ca²⁺ with BAPTA-AM reverses d,l-methadone-induced apoptosis, establishing a link between the rise in [Ca²⁺]_i and d,l-methadone-induced apoptosis. Altogether, our findings point to OPRM1 as a specific target of d,l-methadone in leukemic cells, and that OPRM1 activation by d,l-methadone disrupts IP3R-mediated ER Ca²⁺ release and rate of Ca²⁺ efflux, causing a rise in [Ca²⁺]_i that upregulates the calpain-1-Bid-cytochrome C-caspase-3/12 apoptotic pathway.

Cancer, the Media and Dealing with Knowledge

Among the primary function of the media are conveying personal understanding and expanding the subjective knowledge of the recipient citizen. A particular challenge arising during this process is the mediation of medical knowledge. In addition to pure factual knowledge, it often involves subjective experiences, hopes and wishes. One example of this is media reports about cancer therapies. As a result of widespread media coverage since 2017, the public is under the impression that methadone is a promising treatment for cancer. This chapter analyzes the part played by the media and the ethical debate. The ethical issues that arise concern good scientific practice, patient autonomy and the media coverage of methadone. We conclude that, according to the current state of research, the promotion of methadone as a cure for cancer is ethically unacceptable. In this case the media are not fulfilling their task of imparting knowledge, because they are not communicating the current state of research or the associated ethical questions.

Analgesic opioid use disorders in patients with chronic non-cancer pain: A holistic approach for tailored management

Chronic pain is a major public health issue that frequently leads to analgesic opioid prescriptions. These prescriptions could cause addiction issues in high-risk patients with associated comorbidities, especially those of a psychiatric, addictive, and social nature. Pain management in dependent patients is complex and is yet to be established. By combining the views of professionals from various specialties, we conducted an integrative review on this scope. This methodology synthesizes knowledge and results of significant practical studies to provide a narrative overview of the literature. The main results consisted in first proposing definitions that could allow shared vocabulary among health professionals regardless of their specialties. Next, a discussion was conducted around the main strategies for managing prescription opioid dependence, as well as pain in the context of opioid dependence and associated comorbidities. As a conclusion, we proposed to define the contours of holistic management by outlining the main guidelines for creating a multidisciplinary care framework for multi-comorbid patients with chronic pathologies.

Opioids in the Management of Acute Pediatric Pain: An Update in a Time of Crisis

Management of acute pain in children is fundamental to our practice. Its myriad benefits include reduced suffering, improved patient satisfaction, more rapid recovery, and a reduced risk of developing postsurgical chronic pain. Although a multimodal analgesic approach is now routinely used, informed and judicious use of opioid receptor agonists remains crucial in this treatment paradigm, as long as the benefits and risks are fully understood. Further, an ongoing public health response to the current opioid crisis is required to help prevent new cases of opioid addiction, identify opioid-addicted individuals, and ensure access to effective opioid addiction treatment, while at the same time continuing to safely meet the needs of patients experiencing pain.

Methadone for Pain Management: A Pharmacotherapeutic Review

Methadone is increasingly being used for its analgesic properties. Despite the increasing popularity, many healthcare providers are not familiar with methadone's complex pharmacology and best practices surrounding its use. The purpose of this narrative review article is to discuss the pharmacology of methadone, the evidence surrounding methadone's use in acute pain management and both chronic cancer and non-cancer pain settings, as well as highlight pertinent safety, monitoring, and opioid rotation considerations. Methadone has a unique mechanism of action when compared with all other opioids and for this reason methadone has come to hold a niche role in the management of opioid-induced hyperalgesia and central sensitization. Understanding of the mechanisms of variability in methadone disposition and drug interactions has evolved over the years, with the latest evidence revealing that CYP 2B6 is the major determinant of methadone elimination and plays a key role in methadone-related drug interactions. From an acute pain perspective, most studies evaluating the use of intraoperative intravenous methadone have reported lower pain scores and post-operative opioid requirements. Oral methadone is predominantly used as a second-line opioid treatment for select chronic pain conditions. As a result, several oral morphine to oral methadone conversion ratios have been proposed, as have methods in which to rotate to methadone. From an efficacy standpoint, limited literature exists regarding the effectiveness of methadone in the chronic pain setting with most of the available efficacy data pertaining to methadone's use in the treatment of cancer pain. Many of the prospective studies that exist feature low participant numbers. Few clinical trials investigating the role of methadone as an analgesic treatment are currently underway. The complicated pharmacokinetic properties of methadone and risks of harm associated with this drug highlight how critically important it is that healthcare providers understand these features before prescribing/dispensing methadone. Particular caution is required when converting patients from other opioids to methadone and for this reason only experienced healthcare providers should undertake such a task. Further randomized trials with larger sample sizes are needed to better define the effective and safe use of methadone for pain management.

Low-dose methadone for refractory chronic migraine accompanied by medication-overuse headache: a prospective cohort study

Objectives

A refractory chronic migraine (RCM) accompanied by medication-overuse headache (MOH) is an extremely disabling disease. Evidence suggests that in selected patients, chronic opioids may be a valuable therapeutic option for RCM. The aim of the present study was to evaluate the effectiveness and safety of prophylaxis with low-dose methadone (LDM) in patients affected by RCM with continuous headache and MOH.

Methods

A prospective cohort study was performed between May 2012 and November 2015 at the Headache Center and Toxicology Unit of the Careggi University Hospital. Eligible patients were treated with prophylactic LDM and followed up for 12 months. Headache exacerbations, pain intensity, use of rescue medications, and occurrence of adverse drug reactions (ADRs) were recorded.

Results

Thirty patients (24 females, median age 48 years) were enrolled. Nineteen (63%) patients dropped out, mainly because of early ADRs (n = 10), including nausea, vomiting, and constipation. At last available follow-up, LDM was associated with a significant decrease in the number of headache attacks/month (from a median of 45 (interquartile range 30–150) to 16 (5–30), p < 0.001), in pain intensity (from 8.5 (8–9) to 5 (3–6), p < 0.001), and in the number of rescue medications consumed per month (from 95 (34–240) to 15 (3–28), p < 0.001). No misuse or diversion cases were observed.

Conclusion

LDM could represent a valuable and effective option in selected patients affected by RCM with continuous headache and MOH, although the frequency of early ADRs poses major safety concerns. Randomized controlled trials are needed to confirm the efficacy and safety of LDM prophylaxis.

Methadone in Cancer Pain

Methadone has been an unique, versatile, cost effective, synthetic opioid utilized in nociceptive as well as neuropathic pain. Pain and palliative care physicians started accepting methadone in treatment of complex pain associated with advanced cancer and neuropathic pain syndromes in which conventional opioids were no longer effective. The challenge is in accepting methadone as a main stream first line opioid, from being considered as a second line replacement/substitution drug all these years. Methadone has a significant role as opioid rotation in refractory cancer pain, especially when started early leading to successful conversion. Advantages of methadone in paediatric patients with advanced cancer were its safety and efficacy as a first-choice opioid, availability as a liquid formulation and its infrequent dose requirements. Methadone is neither recommended nor justified to be used as an anti-cancer drug and its role as an anti-cancer agent is a misconception. Many guidelines were proposed after 2008 to address methadone safety. Most of them emphasized on prevention of cardiac arrhythmia and association of methadone with QTc prolongation rather than address the real issue. Methadone has been established to be safe when used in opioid naïve patients with careful titration instituted in an ambulatory setting and has equal success in opioid rotation in outpatient setup. Methadone prescription should be carried out by experienced pain and palliative care providers with careful dose titration and clinical monitoring.

[Pain therapy in intensive care patients]

After intensive care unit (ICU) treatment, the recollection of experienced pain is one of the most burdensome aftermaths. In addition, pain has several negative physiological consequences. The majority of patients report moderate to severe pain while being treated on an ICU, often caused by diagnostic or therapeutic procedures. Pain and its functional consequences during ICU treatment should therefore be systematically recorded and treated. Due to their high analgesic potency, pharmacological pain therapy focuses on opioids; however, gastrointestinal motility disturbance and development of tolerance are disadvantages. When applying non-opioids, such as non-steroidal anti-inflammatory drugs (NSAID) and paracetamol, attention should be paid to their possible organ toxicity. Ketamine and α₂-antagonists can complement the analgesic concept. Analogous to its perioperative administration, intravenous lidocaine in intensive care seems acceptable because of a favorable impact on opioid requirements and gastrointestinal motility. When using regional anesthesia the positive therapeutic effect and the possible complications need to be carefully weighed. Non-pharmaceutical procedures, especially transcutaneous electrical nerve stimulation (TENS), have proven successful in postoperative pain management. Even if only limited data from intensive care are available, a therapeutic attempt seems justifiable because of the low risk of complications.

Methadone and buprenorphine pharmacokinetics and pharmacodynamics when coadministered with fostemsavir to opioid-dependent, human immunodeficiency virus seronegative participants

AIMS

Regional human immunodeficiency virus (HIV) prevalence rates are high in people with history of injection drug use, including those managed with maintenance opioids. Fostemsavir (FTR) is an oral prodrug of temsavir, a first-in-class attachment inhibitor that binds HIV-1 gp120, preventing initial HIV attachment and entry into host immune cells. Here we determine the impact of FTR on the pharmacokinetics of opioids methadone (MET: R-, S- and total) or buprenorphine and norbuprenorphine (BUP and norBUP) when coadministered.

METHODS

Study 206216 (NCT02666001) was a Phase I, open-label study, assessing the effect of FTR 600 mg (extended-release formulation) twice daily on pharmacokinetics of MET or BUP and norBUP, in non-HIV-infected participants on stable maintenance therapy with MET (40-120 mg; n = 16) or BUP plus naloxone (8-24 mg plus 2-6 mg; n = 16); pharmacodynamic response was assessed using standard opioid rating scales.

RESULTS

Following coadministration with FTR, dose-normalized MET (R-, S- and total) exposures (maximum concentration in plasma, area under the plasma concentration-time curve over the dosing interval and concentration in plasma at 24 hours) increased 9-15% and BUP and norBUP exposures increased 24-39%. The 90% confidence interval ranges for MET (1.01-1.21) and BUP and norBUP (1.03-1.69) were within respective no-effect ranges (0.7-1.43 and 0.5-2.0). Opioid pharmacodynamic scores were similar with and without MET/BUP with no symptoms of withdrawal/overdose; no new safety signal for FTR when combined with a stable opioid regimen.

CONCLUSIONS

FTR did not impact MET and had no clinically significant impact on BUP pharmacokinetics. Standardized assessments of opioid pharmacodynamics were unchanged throughout FTR administration with MET or BUP. FTR can be administered with MET or BUP without dose adjustment.

Medications for management of opioid use disorder

Purpose

The use of buprenorphine, methadone, and long-acting naltrexone for treatment of opioid use disorder (OUD) is discussed, including a review of current literature detailing treatment approaches and action steps to optimize treatment in acute care and office-based settings.

Summary

The U.S. epidemic of opioid-related deaths has been driven by misuse of prescription opioids and, increasingly, illicit drugs such as heroin, fentanyl, and fentanyl analogs, necessitating a refocusing of treatment efforts on expanding access to life-saving, evidence-based OUD pharmacotherapy. Inpatient treatment of opioid withdrawal includes acute symptom control through a combination of nonopioid medications and long-term pharmacotherapy to lessen opioid craving and facilitate stabilization and recovery. Methadone and buprenorphine reduce opioid craving, increase treatment retention, reduce illicit opioid use, and increase overall survival. Buprenorphine has logistical advantages over methadone, such as greater flexibility of treatment setting and less risk of adverse effects. Studies have shown the efficacy of long-acting injectable naltrexone to be comparable to that of buprenorphine if patients are detoxified prior to initiation of therapy; however, patients with active OUD are often not able to complete the week-long period of opioid abstinence needed prior to initiation of naltrexone injections. Although buprenorphine is preferred by many patients and can be prescribed in office-based settings, there remains a paucity of physicians certified to prescribe it.

Conclusion

Buprenorphine has become the medication of choice for many patients with OUD, but its use is limited by the low number of physicians certified to prescribe the agent. Other agents studied for treatment of OUD include methadone and naltrexone.

Preoperative oral methadone for postoperative pain in patients undergoing cardiac surgery: A randomized double-blind placebo-controlled pilot

Background: Inadequately controlled sternotomy pain after cardiac surgery can lead to delayed recovery and patient suffering. Preoperative intravenous methadone is effective for reducing both postoperative pain and opioid consumption. Despite ease of administration, the effects of preoperative oral methadone are not well described in the literature.

Aims: This pilot study investigated the effect of preoperative oral methadone on pain scores, analgesia requirements, and opioid-induced side effects.

Methods: A randomized double-blind placebo-controlled model was used with sampling of patients undergoing sternotomy for isolated coronary artery bypass graft (CABG) surgery (ClinicalTrials.gov registration no. NCT02774499). Participants were randomized to receive oral methadone (0.3 mg/kg) or oral placebo prior to entering the operating room. The primary outcome was pain scores on a 0–10 Verbal Rating Scale. Secondary outcomes included morphine requirements using patient-controlled analgesia (PCA), time to extubation, level of sedation, and side effects such as nausea, vomiting, pruritus, hypoventilation, and hypoxia over a 72-h monitoring time.

Results: Twenty-one patients completed the study. Oral methadone did not reduce pain scores in the methadone group (P = 0.08). However, postoperative morphine requirement during the first 24 h was reduced by a mean of 23 mg in the methadone group (mean difference, −23; 99% confidence interval [CI], 37–13 mg; P < 0.005). No reduction in pain scores or PCA morphine was observed beyond 24 h postoperatively. There was no difference in incidence of opioid-related side effects between groups throughout the postoperative period.

Conclusions: Though preoperative oral methadone did not reduce pain scores, morphine requirements were reduced in the first 24 h post-CABG.

Pharmacologic Treatment of Opioid Use Disorder: a Review of Pharmacotherapy, Adjuncts, and Toxicity

Opioid use disorder continues to be a significant source of morbidity and mortality in the USA and the world. Pharmacologic treatment with methadone and buprenorphine has been shown to be effective at retaining people in treatment programs, decreasing illicit opioid use, decreasing rates of hepatitis B, and reducing all cause and overdose mortality. Unfortunately, barriers exist in accessing these lifesaving medications: users wishing to start buprenorphine therapy require a waivered provider to prescribe the medication, while some states have no methadone clinics. As such, users looking to wean themselves from opioids or treat their opioid dependence will turn to alternative agents. These agents include using prescription medications, like clonidine or gabapentin, off-label, or over the counter drugs, like loperamide, in supratherapeutic doses. This review provides information on the pharmacology and the toxic effects of pharmacologic agents that are used to treat opioid use disorder. The xenobiotics reviewed in depth include buprenorphine, clonidine, kratom, loperamide, and methadone, with additional information provided on lofexidine, akuamma seeds, kava, and gabapentin.

The Association between Patient Characteristics and Opioid Treatment Response in Neuropathic and Nociceptive Pain due to Cancer

BACKGROUND

Cancer pain remains a difficult problem, for which opioids are often necessary. At present it is difficult to predict the effectiveness of opioid therapy.

OBJECTIVES

We aim to assess the association between patient characteristics and opioid treatment response in cancer patients, and develop a model to predict probability of response.

SUBJECTS

We used data from two previously published randomized clinical trials, in which patients with head and neck cancer were treated with fentanyl or methadone (total N = 134).

MEASUREMENTS

Treatment success was defined as ≥50% pain reduction at one and five weeks. We analyzed patient characteristics (age, sex, depression, and anxiety), treatment characteristics (having had chemotherapy, radiotherapy, surgery, methadone, or fentanyl) and pain characteristics (neuropathic and nociceptive).

DESIGN

Based on univariable and multivariable regression analyses determinants of therapy success were assessed. Based on these analyses a prediction model was developed.

RESULTS

Our analyses show that one-week therapy success was associated with methadone (odds ratio [OR] = 5.21), duration of pain in months (OR = 1.12), neuropathic pain (OR = 3.36), and age of the patient in years (OR = 0.95). Inclusion of these four characteristics into our prediction model resulted in an area under the curve of 81.6%.

CONCLUSIONS

Careful analyses of patient attributes, treatment, and pain type of patients with head and neck cancer resulted in a prediction model that allowed to predict short-term pain relief and the opioid treatment response in neuropathic and nociceptive pain owing to cancer.

Catalytic Alkyne Arylation Using Traceless Directing Groups

By using Pd0 /Mandyphos, we achieved a three-component aminoarylation of alkynes to generate enamines, which are then hydrolyzed to either α-arylphenones or α,α-diarylketones. This Pd-catalyzed method overcomes established known pathways to enable the use of amines as traceless directing groups for C-C bond formation.

Analgesic and sedative agents used in the intensive care unit: A review

Pain is a common experience for most patients in the intensive care unit (ICU). In the current study, the advantages and disadvantages of analgesic and sedative drugs used in the ICU are reviewed. An ideal sedative and analgesic agent should have features such as rapid onset of action, rapid recovery after discontinuation, predictability, minimal accumulation of the agent and metabolites in the body, and lack of toxicity. None of the sedative and analgesic agents have all of these desired characteristics; nevertheless, clinicians must be familiar with these classes of drugs to optimize pharmacotherapy and ensure as few side-effects as possible for ICU patients.

Comparison of sedation in dogs: methadone or butorphanol in combination with dexmedetomidine intravenously

OBJECTIVE

Opioids can be combined with alpha-2-adrenoreceptor agonists to sedate dogs for radiography. The study investigated the sedative effects of methadone or butorphanol in combination with dexmedetomidine in dogs undergoing stifle radiography.

STUDY DESIGN

Prospective, blinded, randomized, clinical trial.

ANIMALS

A total of 52 healthy dogs requiring sedation for stifle radiography were enrolled.

METHODS

Dogs were assessed for body condition [body condition score (BCS)], temperament and pain using the short-form composite measure pain scale (CMPS-SF). Dogs were randomized to be administered methadone 0.2 mg kg^-1 (group M) or butorphanol 0.2 mg kg^-1 (group B) in combination with dexmedetomidine 2 μg kg^-1 intravenously (IV). Sedation was assessed using a numerical descriptive score, from 0 (no sedation) to 11 (greatest sedation), before administration and at 5, 10, 15 and 20 minutes by one blinded assessor. Onset signs of sedation, pulse rate and respiratory rates were recorded. Positioning for radiography was attempted at 5 minutes. If positioning was not possible at 10 minutes, dexmedetomidine 2 μg kg^-1 was administered IV, with the dog recorded as failed sedation and withdrawn from further analysis. Following normality testing, data were assessed using Student t test, Mann-Whitney test, two-way analysis of variance and Fisher's exact test for failed sedations. Results are reported as mean ± standard deviation. Statistical significance was set at p < 0.05.

RESULTS

Groups were similar for sex, age, weight, BCS, temperament and CMPS-SF. The onset of sedation was faster in group B than in group M (p = 0.048). Sedation scores were higher in group B at 10 minutes compared to group M (p = 0.003). Failed sedation occurred in 12 dogs in group M and two in group B (p = 0.002). Pulse rates were lower in group B at 5 and 10 minutes (p = 0.002).

CONCLUSION AND CLINICAL RELEVANCE

IV butorphanol provides more effective sedation at 10 minutes than methadone, in combination with dexmedetomidine.

Effects of cytochrome P450 single nucleotide polymorphisms on methadone metabolism and pharmacodynamics

Methadone is a synthetic, long-acting opioid with a single chiral center forming two enantiomers, (R)-methadone and (S)-methadone, each having specific pharmacological actions. Concentrations of (R)- and (S)-methadone above therapeutic levels have the ability to cause serious, life-threatening, and fatal side effects. This toxicity can be due in part to the pharmacogenetics of an individual, which influences the pharmacokinetic and pharmacodynamic properties of the drug. Methadone is primarily metabolized in the liver by cytochrome P450 (CYP) enzymes, predominately by CYP2B6, followed by CYP3A4, 2C19, 2D6, and to a lesser extent, CYP2C18, 3A7, 2C8, 2C9, 3A5, and 1A2. Single nucleotide polymorphisms (SNPs) located within CYPs have the potential to play an important role in altering methadone metabolism and pharmacodynamics. Several SNPs in the CYP2B6, 3A4, 2C19, 2D6, and 3A5 genes result in increases in methadone plasma concentrations, decreased N-demethylation, and decreased methadone clearance. In particular, carriers of CYP2B6*6/*6 may have a greater risk for detrimental adverse effects, as methadone metabolism and clearance are diminished in these individuals. CYP2B6*4, on the other hand, has been observed to decrease plasma concentrations of methadone due to increased methadone clearance. The involvement, contribution, and understanding the role of SNPs in CYP2B6, and other CYP genes, in methadone metabolism can improve the therapeutic uses of methadone in patient outcome and the development of personalized medicine.

Challenges of Using Methadone in the Indian Pain and Palliative Care Practice

Palliative care providers across India lobbied to gain access to methadone for pain relief and this has finally been achieved. Palliative care activists will count on the numerous strengths for introducing methadone in India, including the various national and state government initiatives that have been introduced recognizing the importance of palliative care as a specialty in addition to improving opioid accessibility and training. Adding to the support are the Non-Governmental Organizations (NGOs), the medical fraternity and the international interactive and innovative programs such as the Project Extension for Community Health Outcome. As compelling as the need for methadone is, many challenges await. This article outlines the challenges of procuring methadone and also discusses the challenges specific to methadone. Balancing the availability and diversion in a setting of opioid phobia, implementing the amended laws to improve availability and accessibility in a country with diverse health-care practices are the major challenges in implementing methadone for relief of pain. The unique pharmacology of the drug requires meticulous patient selection, vigilant monitoring, and excellent communication and collaboration with a multidisciplinary team and caregivers. The psychological acceptance of the patient, the professional training of the team and the place where care is provided are also challenges which need to be overcome. These challenges could well be the catalyst for a more diligent and vigilant approach to opioid prescribing practices. Start low, go slow could well be the way forward with caregiver education to prescribe methadone safely in the Indian palliative care setting.

No Clinically Relevant Drug-Drug Interactions between Methadone or Buprenorphine-Naloxone and Antiviral Combination Glecaprevir and Pibrentasvir

The combination of glecaprevir (formerly ABT-493), a nonstructural protein 3/4A (NS3/4A) protease inhibitor, and pibrentasvir (formerly ABT-530), an NS5A protein inhibitor, is being developed as treatment for HCV genotype 1 to 6 infection. The pharmacokinetics, pharmacodynamics, safety, and tolerability of methadone or buprenorphine-naloxone when coadministered with the glecaprevir-pibrentasvir combination in HCV-negative subjects on stable opioid maintenance therapy were investigated in a phase 1, single-center, two-arm, multiple-dose, open-label sequential study. Subjects received methadone (arm 1) or buprenorphine-naloxone (arm 2) once daily (QD) per their existing individual prescriptions alone (days 1 to 9) and then in combination with glecaprevir at 300 mg QD and pibrentasvir at 120 mg QD (days 10 to 16) each morning. Dose-normalized exposures were similar with and without glecaprevir and pibrentasvir for (R)- and (S)-methadone (≤5% difference) and for buprenorphine and naloxone (≤24% difference); the norbuprenorphine area under the curve was 30% higher with glecaprevir and pibrentasvir, consistent with maximum and trough plasma concentrations that increased by 21% to 25%. No changes in pupil response, short opiate withdrawal scale score, or desire for drugs questionnaire were observed when glecaprevir and pibrentasvir were added to methadone or buprenorphine-naloxone therapy. No dose adjustment is required when glecaprevir and pibrentasvir are coadministered with methadone or buprenorphine-naloxone.

Methadone versus Fentanyl in Patients with Radiation-Induced Nociceptive Pain with Head and Neck Cancer: A Randomized Controlled Noninferiority Trial

BACKGROUND

Pain is still a burden for many patients with cancer. A recent trial showed the superiority of methadone over fentanyl in neuropathic pain, and we expect that this finding could influence the number of patients treated with methadone.

METHODS

We performed a randomized controlled noninferiority trial in patients with nociceptive pain. Eighty-two strong-opioid-naïve patients with head and neck cancer with substantial pain (pain numeric rating scale [NRS] score ≥ 4) due to radiation therapy were included. Forty-two patients were treated with methadone, and 40 with fentanyl. Patients were evaluated at 1, 3, and 5 weeks. The primary outcomes were reduction in average pain and clinical success (50% pain decrease). We set the predefined noninferiority margin at 1 on the NRS and 10% clinical success. Secondary outcomes were pain interference, global perceived effect (GPE), side effects, and opioid escalation index.

RESULTS

Noninferiority was shown for decrease in NRS for maximum and mean pain scores at 1 and 3 weeks. Noninferiority was shown for clinical success at 1 week only. The opioid escalation index was lower in the methadone group at 3 and 5 weeks as compared to fentanyl (1.44 vs. 1.99, P = 0.004; and 1.50 vs. 2.32, P = 0.013). The pain interference in the methadone group was significantly decreased at 3 weeks only. GPE and side effects were not different.

CONCLUSION

This is the first study to show noninferiority of methadone compared to fentanyl at 1 and 3 weeks in the treatment of radiation-induced nociceptive pain in patients with head and neck cancer.

A case report of methadone-associated hypoglycemia in an 11-month-old male

BACKGROUND

Methadone is a synthetic μ-opioid receptor agonist that is used in the management of pain, neonatal abstinence withdrawal syndrome, and opioid dependence. Overdose can cause miosis, respiratory depression, and central nervous system depression. Rarely, hypoglycemia has been reported. We present the case of an 11-month-old male who developed hypoketotic, hyperinsulinemic, hypoglycemia after an acute, unintentional methadone exposure.

CASE DETAILS

The patient was a previously healthy 11-month-old male who presented in respiratory failure. He was intubated and transferred to a large tertiary care center where his physical exam was notable for miosis. His labs were notable for a blood glucose of 17 mg/dL, an elevated insulin level, and suppressed serum beta-hydroxybutyrate. The patient was given a dextrose bolus with improvement in blood glucose. Administration of IV naloxone improved his miosis and mental status. A quantitative methadone level was sent upon arrival and was 123 ng/mL. Testing for ethanol, salicylates, sulfonylureas, and metabolic causes of hypoglycemia was negative. A fasting study showed euglycemia with suppression of insulin and appropriate ketosis. Case discussion: We present the case of an 11-month-old male who developed hypoketotic, hyperinsulinemic, hypoglycemia after an acute, unintentional methadone exposure. Alternative explanations for hypoketotic hypoglycemia were rule out. Methadone-induced hypoglycemia has been reported in cancer patients receiving methadone for pain, but a mechanism has not been identified. Based on this case, we believe that the patient's hypoglycemia was the result of methadone-induced insulin secretion.

CONCLUSIONS

This case proposes that hyperinsulinism is the mechanism responsible for methadone-associated hypoglycemia. Methadone exposure should be included in the differential diagnosis of new onset hypoglycemia.

Modulation of NMDA Receptor Activity in Fibromyalgia

Activation of the N-methyl-d-aspartate receptor (NMDAR) results in increased sensitivity of spinal cord and brain pathways that process sensory information, particularly those which relate to pain. The NMDAR shows increased activity in fibromyalgia and hence modulation of the NMDAR is a target for therapeutic intervention. A literature review of interventions impacting on the NMDAR shows a number of drugs to be active on the NMDAR mechanism in fibromyalgia patients, with variable clinical effects. Low-dose intravenous ketamine and oral memantine both show clinically useful benefit in fibromyalgia. However, consideration of side-effects, logistics and cost need to be factored into management decisions regarding use of these drugs in this clinical setting. Overall benefits with current NMDAR antagonists appear modest and there is a need for better strategy trials to clarify optimal dose schedules and to delineate potential longer–term adverse events. Further investigation of the role of the NMDAR in fibromyalgia and the effect of other molecules that modulate this receptor appear important to enhance treatment targets in fibromyalgia.

Determination of illicit drugs in aqueous environmental samples by online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry

In this study, a fully automated analytical method, based on online solid phase extraction coupled to liquid chromatography-triple quadrupole tandem mass spectrometry (online SPE-LC-MS/MS), has been developed and optimized for the quantification of 10 illicit drugs and metabolites in environmentally aqueous samples collected from China. The particular attention was devoted to minimize the matrix effects through a washing step, which washed out the interferences effectively and helped to reduce the matrix effect significantly. The key advantages of the method are high sensitivity, selectivity and reliability of results, smaller sample manipulation, full automation, and fairly high throughput. The whole procedure was then successfully applied in the analysis of various surface water and wastewater effluents samples. Pseudoephedrine have been detected at trace levels (several tens ng L(-1) or less), while MDA, MDMA, benzoylecgonine and methadone were below the LOQ in all samples. Caffeine, cotinine and paraxanthine, which may be derived from medicines and foods, were detected with the highest frequencies and concentrations.

Methadone analgesia in the critically ill

PURPOSE

Methadone is increasingly used as an analgesic or a bridge to weaning other analgesics and sedatives in critically ill patients. This review discusses the pharmacology of methadone, summarizes available evidence for its use in the intensive care unit setting, and makes suggestions for appropriate use and monitoring.

MATERIALS/METHODS

Articles evaluating the efficacy, safety, and pharmacology of methadone were identified from a PubMed search through June 2015. References from selected articles were reviewed for additional material. Experimental and observational English-language studies that focused on the efficacy, safety, and pharmacology of methadone in critically-ill adults and children were selected.

RESULTS

Methadone is a synthetic opioid analgesic with potential advantages over other commonly used opioids. Limited evidence from critically ill pediatric, adult, and burn populations suggests that methadone protocols may expedite weaning opiate infusions, decrease the length of mechanical ventilation, and reduce the incidence of negative outcomes such as opiate withdrawal, delirium, and over-sedation.

CONCLUSIONS

Data from current literature supports a role for methadone analgesia in weaning opiates and potentially reducing the duration of mechanical ventilation in critically ill patients. More studies are needed to confirm these benefits and determine criteria for patient selection.

Genome-Wide Pharmacogenomic Study on Methadone Maintenance Treatment Identifies SNP rs17180299 and Multiple Haplotypes on CYP2B6, SPON1, and GSG1L Associated with Plasma Concentrations of Methadone R- and S-enantiomers in Heroin-Dependent Patients

Methadone maintenance treatment (MMT) is commonly used for controlling opioid dependence, preventing withdrawal symptoms, and improving the quality of life of heroin-dependent patients. A steady-state plasma concentration of methadone enantiomers, a measure of methadone metabolism, is an index of treatment response and efficacy of MMT. Although the methadone metabolism pathway has been partially revealed, no genome-wide pharmacogenomic study has been performed to identify genetic determinants and characterize genetic mechanisms for the plasma concentrations of methadone R- and S-enantiomers. This study was the first genome-wide pharmacogenomic study to identify genes associated with the plasma concentrations of methadone R- and S-enantiomers and their respective metabolites in a methadone maintenance cohort. After data quality control was ensured, a dataset of 344 heroin-dependent patients in the Han Chinese population of Taiwan who underwent MMT was analyzed. Genome-wide single-locus and haplotype-based association tests were performed to analyze four quantitative traits: the plasma concentrations of methadone R- and S-enantiomers and their respective metabolites. A significant single nucleotide polymorphism (SNP), rs17180299 (raw p = 2.24 × 10⁻⁸), was identified, accounting for 9.541% of the variation in the plasma concentration of the methadone R-enantiomer. In addition, 17 haplotypes were identified on SPON1, GSG1L, and CYP450 genes associated with the plasma concentration of methadone S-enantiomer. These haplotypes accounted for approximately one-fourth of the variation of the overall S-methadone plasma concentration. The association between the S-methadone plasma concentration and CYP2B6, SPON1, and GSG1L were replicated in another independent study. A gene expression experiment revealed that CYP2B6, SPON1, and GSG1L can be activated concomitantly through a constitutive androstane receptor (CAR) activation pathway. In conclusion, this study revealed new genes associated with the plasma concentration of methadone, providing insight into the genetic foundation of methadone metabolism. The results can be applied to predict treatment responses and methadone-related deaths for individualized MMTs.

Methadone maintenance treatment (MMT), among the most effective therapies for heroin-dependent patients, reduces craving and withdrawal symptoms, increases treatment compliance, and improves the quality of life of patients. The plasma concentration of methadone is a primary index for quantifying and determining therapy responses to MMT. This study was the first whole-genome pharmacogenomic study on MMT to locate genomic regions associated with the plasma concentration of methadone. The analysis identified a single nucleotide polymorphism (SNP) marker (rs17180299) and 17 haplotypes on the SPON1, GSG1L, and CYP450 genes, including CYP2B6 significantly associated with the plasma concentrations of methadone enantiomers. The identified genetic variations accounted for approximately 10% and 25% of the variations in plasma concentrations of methadone R- and S-enantiomers, respectively. The identified genetic variations have afforded insight into the genetic mechanism of the metabolism of MMT, and have potential to pave the way towards individualized MMTs for heroin-dependent patients.

Pharmacokinetics of Oral Methadone in the Treatment of Neonatal Abstinence Syndrome: A Pilot Study

OBJECTIVE

To characterize the population pharmacokinetics of oral methadone in neonates requiring pharmacologic treatment of neonatal abstinence syndrome and to develop a pharmacokinetic (PK) model toward an evidence-based treatment protocol.

STUDY DESIGN

Based on a methadone dosing protocol, serum concentrations of methadone and its metabolites were assessed by high performance liquid chromatography-tandem mass spectrometry from dried blood spots. Population PK analysis was performed to determine the volume of distribution and clearance of oral methadone. Methadone plasma concentration-time profiles were simulated from the deduced PK model to optimize the dosing regimen.

RESULTS

There was substantial interindividual variability in methadone concentrations. Blood concentrations of methadone were best described by a 1-compartment model with first-order absorption. The population mean estimates (coefficient of variation percentage) for oral clearance and volume of distribution were 8.94 (103%) L/h/70 kg and 177 (133%) L/70 kg, respectively. Optimized dosing strategies were developed based on the simulated PK profiles. We suggest a starting dose of 0.1 mg/kg per dose every 6 hours for most patients requiring pharmacologic treatment of neonatal abstinence syndrome followed by an expedited weaning phase.

CONCLUSIONS

The proposed dosing regimen may reduce the cumulative dose of opioid and shorten the length of hospitalization. Future studies should aim to validate the simulated dosing schemes with clinical data and expand our understanding of the between-patient PK variability.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01754324.

Impact of hepatitis C status on 20-year mortality of patients with substance use disorders

Background

The magnitude of the effect of hepatitis C viral infection on survival is still not fully understood. The objective of this study was to determine whether the presence of hepatitis C viral antibodies in 1991 was associated with increased mortality 20 years later within a cohort of patients with substance use disorders. Secondary objectives were to determine other factors that were associated with increased mortality in the cohort.

Methods

A subset of a 1991 study cohort of patients who had presented for detoxification was reexamined 20 years later. The Social Security Death Index was queried to identify which of the original patients had died. Attributes of survivors and non-survivors were compared, with special attention to their hepatitis C status in 1991. The original study and this analysis were conducted in the chemical detoxification unit at Johns Hopkins Bayview (previously Francis Scott Key Hospital), an academic urban hospital. All participants met the criteria for alcohol or opioid dependence at the time of admission in 1991. The primary study outcome was 20-year mortality after initial admission in 1991, with a planned analysis of hepatitis C status.

Results

Twenty years after admission, 362 patients survived and 82 had died. Of the 284 patients who were hepatitis C positive, 228 survived (80 %). Of the 160 patients who were hepatitis C negative, 134 survived (84 %). This absolute risk increase of 4 % was not statistically significant (p = 0.37). Factors associated with increased mortality included male sex, white race, older age, and reported use of alcohol, cocaine, and illicit methadone. Binary logistic regression including hepatitis C status and these other variables yielded an adjusted odds ratio of 0.87 (95 % CI 0.49–1.55); (p = 0.64) for hepatitis C positive 20-year survival.

Conclusions

Hepatitis C positivity was not associated with a statistically significant difference in 20-year survival. The effect of the virus on mortality, if present, is small, relative to the effect of substance use disorders alone.

Tapering Long-term Opioid Therapy in Chronic Noncancer Pain: Evidence and Recommendations for Everyday Practice

Increasing concern about the risks and limited evidence supporting the therapeutic benefit of long-term opioid therapy for chronic noncancer pain are leading prescribers to consider discontinuing the use of opioids. In addition to overt addiction or diversion, the presence of adverse effects, diminishing analgesia, reduced function and quality of life, or the absence of progress toward functional goals can justify an attempt at weaning patients from long-term opioid therapy. However, discontinuing opioid therapy is often hindered by patients' psychiatric comorbidities and poor coping skills, as well as the lack of formal guidelines for the prescribers. The aim of this article is to review the existing literature and formulate recommendations for practitioners aiming to discontinue long-term opioid therapy. Specifically, this review aims to answer the following questions: What is an optimal opioid tapering regimen? How can the risks involved in a taper be managed? What are the alternatives to an opioid taper? A PubMed literature search was conducted using the keywords chronic pain combined with opioid withdrawal, taper, wean and detoxification. Six hundred ninety-five documents were identified and screened; 117 were deemed directly relevant and are included. On the base of this literature review, this article proposes evidence-based recommendations and expert-based suggestions for clinical practice. Furthermore, areas of lack of evidence are identified, providing opportunities for further research.

Demographic and clinical factors predicting retention in methadone maintenance: results from an Irish cohort

BACKGROUND

Retention in Methadone Maintenance Treatment (MMT) is superior to that of other therapies for opioid addiction, but with international retention rates around 50 % after 1 year of treatment, there remains a need for improved retention rates.

AIMS

This study aimed to explore the demographic and clinical factors predicting retention in MMT.

METHODS

Face-to-face surveys with MMT patients in a Dublin methadone clinic were conducted. Retention was assessed by the presence and duration of breaks in treatment at any stage.

RESULTS

189 patients participated in the study. 46 % (n = 87) reported having at least one break in treatment, and the median duration of a break was 3 months. Age, current methadone dose and prescription of antipsychotic medication were significant predictors of retention. Patients who were older, single, living in their own home, on a higher dose of methadone, or taking antipsychotic medications had fewer breaks in treatment. Males tended to have significantly longer breaks. Patients reported that the main reasons for breaks were relapse into drug use (21.8 %, n = 19), incarceration (11.4 %, n = 10), weary of MMT (13.7 %, n = 12) or problems at the clinic (10.3 %, n = 9). Factors enabling regular attendance included wanting to get or stay clean (37.5 %, n = 51), avoidance of withdrawal symptoms (16.1 %, n = 22), methadone dependence (13.9 %, n = 19) and services provided (10.2 %, n = 14).

CONCLUSION

Patients who were older, single, living in their own home, on a higher dose of methadone, or taking antipsychotic medications had fewer breaks in treatment.