Intraoperative use of methadone improves control of postoperative pain in morbidly obese patients: a randomized controlled study

Methadone and Buprenorphine in the Perioperative Setting: A Review of the Literature

PURPOSE OF REVIEW

The purpose of this review is to highlight the most recent literature and guidelines regarding perioperative methadone and buprenorphine use.

RECENT FINDINGS

Surgical patients taking methadone and buprenorphine are being encountered more frequently in the perioperative period, and providers are becoming more familiar with their pharmacologic properties, benefits as well as precautions. Recommendations pertaining to buprenorphine therapy in the perioperative settings have changed in recent years, owing to more clinical and basic science research. In addition to their use in chronic pain and opioid use disorders, they can also be initiated for acute postoperative pain indications, in select patients and situations. Methadone and buprenorphine are being more commonly prescribed for pain management and opioid use disorder, and their continuation during the perioperative period is generally recommended, to reduce the risk of opioid withdrawal, relapse, or inadequately controlled pain. Additionally, both may be initiated safely and effectively for acute pain management during and after the operating room period.

Clinical effectiveness and safety of intraoperative methadone in patients undergoing laparoscopic hysterectomy: a randomised, blinded clinical trial

Background

Laparoscopic hysterectomy is often carried out as day-stay surgery. Minimising postoperative pain is therefore of utmost importance to ensure timely discharge from hospital. Methadone has several desirable pharmacological features, including a long elimination half-life. Therefore, a single intraoperative dose could provide long-lasting pain relief.

Methods

Patients scheduled to undergo laparoscopic hysterectomy were randomly allocated to receive methadone (0.2 mg kg-1) or morphine (0.2 mg kg-1) intraoperatively, 60 min before tracheal extubation. Primary outcomes were opioid consumption (oral morphine equivalents in milligrams) at 6 and 24 h. Secondary outcomes included pain intensity at rest and during coughing, patient satisfaction, postoperative nausea and vomiting, and adverse events up to 72 h after completion of surgery.

Results

The postoperative median opioid consumption was reduced in the methadone group compared with the morphine group at 6 h (35.5 [0-61] mg vs 48 [31-74.5] mg; P=0.01) and 24 h (42 [10-67] mg vs 54.5 [31-83] mg; P=0.03). On arrival at the PACU, pain at rest was significantly lower in patients receiving methadone (numeric rating scale: 3 [2-5] vs 5 [3-6]), whereas pain scores at rest and coughing were not significantly different throughout the rest of the observation period. No differences in other secondary outcomes were found.

Conclusions

In this randomised, blinded, controlled trial, opioid consumption was reduced during the first 24 postoperative hours in patients receiving methadone without causing an increase in adverse events. The difference observed might be considered as small and of limited clinical relevance.

Clinical trial registration

NCT03908060; EudraCT no. 2018-004351-20.

Short-acting versus long-acting opioids for pediatric postoperative pain management

INTRODUCTION

Opioids are potent analgesics commonly used to manage children's moderate to severe perioperative pain in children. A wide range of short and long-acting opioids are used to treat surgical pain and will be reviewed in this article.

AREAS COVERED

Both short- and long-acting opioids contain unique therapeutic benefits and adverse effects; however, due to the side effect profile and safety concerns, lack of familiarity, and evidence with long-acting opioids to treat surgical pain, shorter-acting opioids have traditionally been used in children. Almost all opioids work by binding to the mu receptor. Methadone, a long-acting opioid, is an exception because it also has beneficial N-methyl-D-aspartate antagonist properties. Clinically methadone's properties could translate to improved analgesic outcomes, reduced risk of adverse events, less risk for acute hyperalgesia, tolerance and abuse potential, faster recovery, and reduced risk for chronic persistent surgical pain. This review article summarizes and compares the evidence of commonly used short and long-acting opioids for perioperative pain control in the pediatric population.

EXPERT OPINION

Individualized methadone therapy using pharmacogenomics has the potential to transform opioid use in pain management by improving patient safety and analgesic outcomes, thereby addressing the gaps in current standardized ERAS protocols.

Intravenous Methadone for Perioperative and Chronic Cancer Pain: A Review of the Literature

Intravenous methadone may be useful in acute and chronic pain management compared with other opioids because of its pharmacokinetic and pharmacodynamic characteristics, including the long duration of effect and ability to modulate both pain stimuli propagation and analgesic descending pathways. However, methadone is underused in pain medicine because of several misperceptions. A review of studies was performed to assess data regarding the use of methadone in perioperative pain and chronic cancer pain. The majority of studies have shown that intravenous methadone produces an effective postoperative analgesia and lowers opioid consumption in the postoperative period, without more adverse effects in comparison with other opioid analgesics, and has an interesting potential to prevent persistent postoperative pain. A minority of studies investigated the use of intravenous methadone for cancer pain management. These studies were mostly case series that showed promising activities of intravenous methadone for difficult pain conditions. There is sufficient evidence suggesting that intravenous methadone is effective in perioperative pain, while more studies are needed in patients with cancer pain.

Effect of deuteration on the single dose pharmacokinetic properties and postoperative analgesic activity of methadone

Although methadone is effective in the management of acute pain, the complexity of its absorption-distribution-metabolism-excretion profile limits its use as an opioid of choice for perioperative analgesia. Because deuteration is known to improve the pharmacokinetic, pharmacodynamic and toxicological properties of some drugs, here we characterized the single dose pharmacokinetic properties and post-operative analgesic efficacy of d9-methadone. The pharmacokinetic profiles of d9-methadone and methadone administered intravenously to CD-1 male mice revealed that deuteration leads to a 5.7- and 4.4-fold increase in the area under the time-concentration curve and maximum concentration in plasma, respectively, as well as reduction in clearance (0.9 ± 0.3 L/h/kg vs 4.7 ± 0.8 L/h/kg). The lower brain-to-plasma ratio of d9-methadone compared to that of methadone (0.35 ± 0.12 vs 2.05 ± 0.62) suggested that deuteration decreases the transfer of the drug across the blood-brain barrier. The estimated LD50 value for a single intravenous dose of d9-methadone was 2.1-fold higher than that for methadone. Moreover, d9-methadone outperformed methadone in the efficacy against postoperative pain by primarily activating peripheral opioid receptors. Collectively, these data suggest that the replacement of three hydrogen atoms in three methyl groups of methadone altered its pharmacokinetic properties, improved safety, and enhanced its analgesic efficacy.

Rediscovery of Methadone to Improve Outcomes in Pain Management

Clinically, methadone is most known for its use in the treatment of opioid maintenance therapy. However, methadone's pharmacological profile makes it an excellent analgesic that can enhance acute and chronic pain management. It is a potent μ-receptor agonist with a longer elimination half-life than most clinically used opioids. In addition, methadone inhibits serotonin and norepinephrine uptake, and it is an N-methyl-D-aspartate antagonist. These distinct analgesic pathways mediate hyperalgesic, allodynic, and neuropathic pain. Its unique analgesic properties provide several essential benefits in perioperative use, neuropathic pain, cancer, and noncancer pain. Despite these proven clinical utilities, methadone has not been used widely to treat acute and chronic pain in opioid naïve patients. This article describes the unique pharmacology of methadone and provides emerging evidence to support its application in acute and chronic pain management. Pain management options and guidelines for surgical patients on methadone are discussed as well.

Endogenous opiates and behavior: 2019

This paper is the forty-second consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2019 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Comparison of three intraoperative analgesic strategies in laparoscopic bariatric surgery: a retrospective study of immediate postoperative outcomes

Introduction and objectives

Multimodal Analgesia (MMA) has shown promising results in postoperative outcomes across a broad spectrum of surgeries, including bariatric surgery. We compared the analgesic effect immediately after Laparoscopic Bariatric Surgery (LBS) of the combined effect of MMA and methadone against two techniques that were based mainly on the use of high-potency medium-acting opioids.

Methods

Two hundred seventy-one patients were retrospectively reviewed. The primary outcome was postoperative pain score > 3/10 measured by the Verbal Numeric Scale (VNS) during the Postanesthetic Care Unit (PACU) stay. The three protocols of intraoperative analgesia were: (P1) sufentanil at anesthetic induction followed by remifentanil infusion; (P2) sufentanil at induction followed by dexmedetomidine infusion; and (P3) remifentanil at induction followed by MMA including dexmedetomidine, magnesium, lidocaine, and methadone. Only P1 and P2 patients received morphine toward the end of surgery. Poisson regression was used to adjust confounding factors and calculate Prevalence Ratio (PR).

Results

Postoperative VNS > 3 was recorded in 135 (49.81%) patients, of which 93 (68.89%) were subjected to P1, 25 (18.56%) to P2, and 17 (12.59%) to P3. In the final adjusted model, both anesthetic techniques (P3) (PR = 0.10; 95% CI [0.03–0.28]), and (P2) (PR = 0.42%; 95% CI [0.20–0.90]) were associated with lower occurrence of VNS > 3, whereas age range 20–29 was associated to higher occurrence of VNS > 3 (PR = 3.21; 95% CI [1.22–8.44]) in PACU. Postoperative Nausea and Vomiting (PONV) was distributed as follows: (P1) 20.3%, (P2) 31.25% and (P3) 6.77%; (P3 < P1, P2; p < 0.05). Intraoperative hypotension occurred more often in P3 (39%) compared to P2 (20.31%) and P1 (17.46%) (p < 0.05).

Conclusion

MMA + methadone was associated with higher incidence of intraoperative hypotension and lower incidence of moderate/severe pain in PACU after LBS.

Effect of intraoperative methadone vs other opioids on postoperative outcomes: a meta-analysis of randomized controlled studies

ABSTRACT

Recent randomized controlled trials comparing the efficacy between intraoperative methadone and other opioids on postoperative outcomes have been limited by their small sample sizes and conflicting results. We performed a meta-analysis on randomized controlled trials which investigated outcomes between methadone and an opioid control group. Primary outcome data included postoperative opioid consumption, number of patients who received postoperative opioids, time to first analgesic, and pain scores. Secondary outcomes included time to extubation and incidence of nausea, vomiting, and respiratory depression. Statistical analysis was performed using RevMan. A P < 0.05 was considered statistically significant. Nine studies comprising 632 patients were included. There was no statistically significant reduction in opioid consumption postoperatively between the groups. Forty-seven percentage of patients in the methadone group received a dose of opioid postoperatively compared with 55% in the other opioids control group, which was not statistically significant. (P = 0.25) There was no difference in average time to receiving first postoperative analgesic among the groups. Pain scores within 24 hours were significantly lower in the methadone group when compared with other opioids (8 studies, n = 622, -0.49 [-0.74, -0.23], P = 0.002). However, there was no difference between 24 and 72 hours. There was no difference among the groups with respect to extubation time, nausea, vomiting, or respiratory depression. This meta-analysis concludes that there is currently insufficient evidence for the use of intraoperative methadone, when compared with other opioids. Although there was a decrease in average pain scores with methadone when compared with controls at 24 hours, there was no difference between 24 and 72 hours.

Perioperative Pain Management and Opioid Stewardship: A Practical Guide

Surgical procedures are key drivers of pain development and opioid utilization globally. Various organizations have generated guidance on postoperative pain management, enhanced recovery strategies, multimodal analgesic and anesthetic techniques, and postoperative opioid prescribing. Still, comprehensive integration of these recommendations into standard practice at the institutional level remains elusive, and persistent postoperative pain and opioid use pose significant societal burdens. The multitude of guidance publications, many different healthcare providers involved in executing them, evolution of surgical technique, and complexities of perioperative care transitions all represent challenges to process improvement. This review seeks to summarize and integrate key recommendations into a "roadmap" for institutional adoption of perioperative analgesic and opioid optimization strategies. We present a brief review of applicable statistics and definitions as impetus for prioritizing both analgesia and opioid exposure in surgical quality improvement. We then review recommended modalities at each phase of perioperative care. We showcase the value of interprofessional collaboration in implementing and sustaining perioperative performance measures related to pain management and analgesic exposure, including those from the patient perspective. Surgery centers across the globe should adopt an integrated, collaborative approach to the twin goals of optimal pain management and opioid stewardship across the care continuum.

Impact of Intravenous Methadone Administered Intraoperatively on Postoperative Opioid Utilization

BACKGROUND

Studies have shown that intravenous methadone intraoperatively can reduce opioid usage postoperatively.

OBJECTIVE

This study's purpose was to evaluate the effect of intravenous methadone on postoperative opioid use.

METHODS

A prospective, single-center observational study was conducted to evaluate patients who received intravenous methadone intraoperatively. A control group was identified by matching procedure, gender, and age in a 1:3 ratio of methadone to control. Exclusion criteria included patients less than 18 years old or on methadone maintenance therapy. The primary outcome was morphine milligram equivalents (MME) administered 24h postoperatively. Secondary outcomes included MME administered 48h and 72h postoperatively, discharge prescription MME, daily mean postoperative pain scores, and length of hospital stay. A subgroup analysis was performed comparing opioid-naïve patients.

RESULTS

A total of 240 patients were included in the analysis. At 24h, postoperative MME was increased in the methadone group (142.6 vs 84.5; P = 0.0026). Postoperative MME was also increased in the methadone group at 48h and 72h. Daily pain scores were similar between both groups at all time intervals. Discharge prescription MME was reduced in the methadone group compared with controls, but not statistically significant. A subgroup analysis of opioid-naïve patients showed a significant reduction in MME at 48h (P = 0.0240) and daily pain scores at 24h (P = 0.0366) in the methadone group.

CONCLUSION AND RELEVANCE

Intravenous methadone intraoperatively did not show a significant reduction in postoperative opioid use and discharge prescription MMEs when comparing all patients; however, benefit was seen when examining opioid-naïve patients.

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.

Intra-operative methadone effect on quality of recovery compared with morphine following laparoscopic gastroplasty: a randomised controlled trial

The effect of intra-operative intravenous methadone on quality of postoperative recovery was compared with morphine after laparoscopic gastroplasty. We included 137 adult patients with a body mass index > 35 kg.m^-2 who underwent bariatric surgery. Patients were allocated at random to receive either intra-operative methadone (n = 69) or morphine (n = 68). All patients received the same postoperative care and analgesia. The primary outcome of postoperative quality of recovery was assessed using the Quality of Recovery-40 questionnaire total score 24 h after surgery. Secondary outcomes were assessed in the post-anaesthesia care unit the night of the day of surgery (T1), in the morning after surgery (T2); and at night on the day following surgery (T3). The median (IQR [range]) total Quality of Recovery-40 questionnaire score of 194 (190-197 [165-200]) was higher (p < 0.0001) in the methadone group compared with the score of 181 (174-185.5 [121-200]) in the morphine group. In the post-anaesthesia care unit, the pain burden; incidence of nausea and vomiting; rescue morphine dose; and time to discharge, were significantly lower in the methadone group. On the ward, the methadone group had a lower: incidence of rescue morphine requests at T1 (5.8 vs. 54.4%, p < 0.0001) and T2 (0 vs. 20.1%, p < 0.0001); and incidence of nausea (21.7 vs. 41.2%, p = 0.014), compared with the morphine group. We conclude that intra-operative intravenous methadone improved quality of recovery in patients who underwent laparoscopic gastroplasty, compared with intra-operative morphine. Methadone also reduced postoperative pain, postoperative opioid consumption and the incidence of opioid-related adverse events.

Intraoperative Methadone Reduces Pain and Opioid Consumption in Acute Postoperative Pain: A Systematic Review and Meta-analysis

BACKGROUND

Methadone is a potent opioid exerting an analgesic effect through N-methyl-D-aspartate receptor antagonism and the inhibition of serotonin and noradrenaline reuptake. It has also been used in several procedures to reduce postoperative pain and opioid use. This meta-analysis aimed to determine whether the intraoperative use of methadone lowers postoperative pain scores and opioid consumption in comparison to other opioids.

METHODS

Double-blinded, controlled trials without language restrictions were included from MEDLINE, Embase, LILACS, The Cochrane Central Register of Controlled Trials (CENTRAL), and CINAHL via EBSCOhost. The included studies tracked total opioid consumption, postoperative pain scores, opioid-related side effects, and patient satisfaction until 72 hours postoperatively. Mean difference (MD) was used for effect size.

RESULTS

In total, 476 articles were identified and 13 were considered eligible for inclusion in the meta-analysis. In 486 patients (7 trials), pain at rest (MD, 1.09; 95% confidence interval (CI), 1.47-0.72; P < .00001) and at movement (MD, 2.48; 95% CI, 3.04-1.92; P = .00001) favored methadone 24 hours after surgery. In 374 patients (6 trials), pain at rest (MD, 1.47; 95% CI, 3.04-1.02; P < .00001) and at movement (MD, 2.03; 95% CI, 3.04-1.02; P < .00001) favored methadone 48 hours after surgery. In 320 patients (4 trials), pain at rest (MD, 1.02; 95% CI, 1.65-0.39; P = .001) and at movement (MD, 1.34; 95% CI, 1.82-0.87; P < .00001) favored methadone 72 hours after surgery. A Trial Sequential Analysis was performed and the Z-cumulative curve for methadone crossed the monitoring boundary at all evaluations, additionally crossing Required Information Size at 24 and 48 hours at rest. Methadone group also showed lower postoperative opioid consumption in morphine equivalent dosage (mg) at 24 hours (MD, 8.42; 95% CI, 12.99-3.84 lower; P < .00001), 24-48 hours (MD, 14.33; 95% CI, 26.96-1.91 lower; P < .00001), 48-72 hours (MD, 3.59; 95% CI, 6.18-1.0 lower; P = .007) postoperatively.

CONCLUSIONS

Intraoperative use of methadone reduced postoperative pain scores compared to other opioids, and Trial Sequential Analysis suggested that no more trials are required to confirm pain reduction at rest until 48 hours after surgery. Methadone also reduced postoperative opioid consumption and led to better patient satisfaction scores through 72 hours postoperatively compared to other opioids.