Methadone as a First-Line Opioid in Cancer Pain Management: A Systematic Review

Shifting views on cancer pain management: a systematic review and network meta-analysis

CONTEXT

Strong opioids are the cornerstone in the treatment of cancer-related pain.

OBJECTIVES

This study aims to compare analgesic effectiveness of different strong opioids for the treatment of cancer-related pain.

METHODS

PubMed and Embase were searched for RCTs that compared strong opioids for treatment of cancer-related pain against one another. A network meta-analysis was conducted and the related Surface Under the Cumulative RAnking (SUCRA)-based treatment ranks were calculated. Primary outcome was pain intensity (numerical rating scale (NRS)) and/or the percentage of patients with ≥50% pain reduction, after 1 and 2-4 weeks.

RESULTS

Sixteen RCTs (1813 patients) were included. Methadone showed, with a high certainty of evidence, increased ORs for treatment success at 1 week, compared with morphine, buprenorphine, fentanyl, and oxycodone, range 3.230-36.833. Methadone had the highest likelihood to be the treatment of preference (ToP) (SUCRA 0.9720). For fentanyl, ORs were lower, however significant and with high certainty. After 2-4 weeks, methadone again showed the highest likelihood for ToP, however, with moderate certainty and non-significant ORs. The combination of morphine/methadone, compared with morphine, buprenorphine, fentanyl, hydromorphone, methadone, and oxycodone achieved a treatment effect of mean NRS difference after 2-4 weeks between -1.100 and -1.528 and had the highest likelihood for ToP.

CONCLUSION

The results suggest that methadone possibly deserves further promotion as first-line treatment for the treatment of cancer-related pain.

Management of Pain Medication in Patients With a History of Bariatric Surgery: A Systematic Review

CONTEXT

Obesity prevalence is persistently increasing worldwide. Among surgical therapeutic procedures, bypass surgery and sleeve gastrectomy have shown the best results regarding weight loss, prevention, and treatment of secondary complications. However, these surgeries are associated with an increased risk of malabsorption and metabolic changes that could further affect the pharmacokinetics of drugs. On the other hand, patients with a history of such surgeries are more likely to experience pain and request analgesic initiation or adaptation. The question of how to manage pain medication in these patients is challenging due to their narrow therapeutic indexes.

OBJECTIVES

To summarize the current literature on the impact of bariatric surgery on the subsequent pharmacokinetics of analgesics and propose a multidisciplinary therapeutic attitude to optimize pain management in these patients.

METHODS

We conducted a systematic review that included all pharmacological studies published after 2000.

RESULTS

Unexpectedly, these surgeries seem to increase the bioavailability of drugs by long-term improvement of hepatic function. Yet, the medical community drastically lacks robust guidelines for pain management in those patients. This systematic review aims to bring together pharmacological studies related to the use of pain treatments in patients who underwent bypass surgery or sleeve gastrectomy.

CONCLUSIONS

Caution should be exercised regarding the risk of overdose in every circumstance: treatment initiation, change of doses, or change of molecule. More prospective trials comparing the pharmacokinetics of medications in obese patients with and without prior bariatric surgery are needed.

Deletion of arrestin-3 does not improve compulsive drug-seeking behavior in a longitudinal paradigm of oral morphine self-administration

Opioid drugs are potent analgesics that mimic the endogenous opioid peptides, endorphins and enkephalins, by activating the μ-opioid receptor. Opioid use is limited by side effects, including significant risk of opioid use disorder. Improvement of the effect/side effect profile of opioid medications is a key pursuit of opioid research, yet there is no consensus on how to achieve this goal. One hypothesis is that the degree of arrestin-3 recruitment to the μ-opioid receptor impacts therapeutic utility. However, it is not clear whether increased or decreased interaction of the μ-opioid receptor with arrestin-3 would reduce compulsive drug-seeking. To examine this question, we utilized three genotypes of mice with varying abilities to recruit arrestin-3 to the μ-opioid receptor in response to morphine in a novel longitudinal operant self-administration model. We demonstrate that arrestin-3 knockout and wild type mice have highly variable drug-seeking behavior with few genotype differences. In contrast, in mice where the μ-opioid receptor strongly recruits arrestin-3, drug-seeking behavior is much less varied. We created a quantitative method to define compulsivity in drug-seeking and found that mice lacking arrestin-3 were more likely to meet the criteria for compulsivity whereas mice with enhanced arrestin-3 recruitment did not develop a compulsive phenotype. Our data suggest that opioids that engage both G protein and arrestin-3, recapitulating the endogenous signaling pattern, will reduce abuse liability.

A Balancing Act: Learning from the Past to Build a Future-Focused Opioid Strategy

The harmful side effects of opioid drugs such as respiratory depression, tolerance, dependence, and abuse potential have limited the therapeutic utility of opioids for their entire clinical history. However, no previous attempt to develop effective pain drugs that substantially ameliorate these effects has succeeded, and the current opioid epidemic affirms that they are a greater hindrance to the field of pain management than ever. Recent attempts at new opioid development have sought to reduce these side effects by minimizing engagement of the regulatory protein arrestin-3 at the mu-opioid receptor, but there is significant controversy around this approach. Here, we discuss the ongoing effort to develop safer opioids and its relevant historical context. We propose a new model that reconciles results previously assumed to be in direct conflict to explain how different signaling profiles at the mu-opioid receptor contribute to opioid tolerance and dependence. Our goal is for this framework to inform the search for a new generation of lower liability opioid analgesics.

The effects of OPRM1 118A>G on methadone response in pain management in advanced cancer at end of life

Cancer pain is the most feared symptom at end of life. Methadone has advantages over other opioids but is associated with significant variability in clinical response, making dosing challenging in practice. OPRM1 is the most studied pharmacogene associated with the pharmacodynamics of opioids, however reports on the association of the A118G polymorphism on opioid dose requirements are conflicting, with no reports including methadone as the primary intervention. This association study on OPRM1 A118G and response to methadone for pain management, includes a review of this genetic factor's role in inter-patient variability. Fifty-four adult patients with advanced cancer were recruited in a prospective, multi-centre, open label dose individualization study. Patient characteristics were not shown to influence methadone response, and no significant associations were observed for methadone dose or pain score. The findings of our review of association studies for OPRM1 A118G in advanced cancer pain demonstrate the importance of taking ancestry into account. While our sample size was small, our results were consistent with European populations, but in contrast to studies in Chinese patients, where carriers of the A118G polymorphism were associated with higher opioid dose requirements. Pharmacogenetic studies in palliative care are challenging, continued contribution will support future genotype-based drug dosing guidelines.

Exploring the diversity of uncommon oral yeast species and associated risk factors among substance abusers in southwestern Iran

Yeast species are a group of coexistent microorganisms in the oral cavity that can cause opportunistic infections in vulnerable individuals, including addicts. This study aimed to identify the yeast species profile responsible for oral yeast colonization (OYC) and the associated risk factors in patients with substance use disorder (SUD) in Ahvaz, Iran. Oral samples were collected from drug users hospitalized in 12 addiction treatment centers, and the related clinical information was mined. Oral yeast species were identified using 21-plex PCR and sequencing of the internal transcribed spacer region (ITS1-5.8S-ITS2). A total of 244 yeast strains were identified from 245 individuals with substance abuse. Candida albicans was the most common species (37.7%) and non-albicans Candida was responsible for 57.7% of OYC, primarily C. dubliniensis (33.2%) and C. glabrata (11.9%). Moreover, uncommon oral yeasts constituted 5.3% of species, including Saccharomyces cerevisiae, Clavispora lusitaniae, Pichia kluyveri, Geotrichum candidum, Magnusiomyces capitatus, Hanseniospora opuntiae, Wickerhamomyces subpelliculosus, Trichosporon asahii, and Aureobasidium pullulans. Importantly, OYC exhibited associations with such factors as duration of drug use, daily drug consumption rate, opioid utilization, oral drug administration, and the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) score. The present study is the pioneering investigation revealing the prevalence and diversity of oral yeast species, along with associated risk factors, in individuals with SUD in southwestern Iran. Furthermore, it underscores the importance of developing efficient and cost-effective diagnostic methods tailored for resource-constrained settings.

A Side-Effect-Free Interventional Therapy for Precisely Eliminating Unresectable Cancer Pain

Of patients bearing unresectable tumors at advanced stages, most undergo serious pain. For unresectable tumors adjacent to vital organs or nerves, eliminating local cancer pain without adverse effects remains a formidable challenge. Interventional ablative therapies (IATs), such as radio frequency ablation (RFA), microwave ablation, and irreversible electroporation, have been clinically adopted to treat various carcinomas. In this study, we established another palliative interventional therapy to eliminate local cancer pain, instead of relieving nociception temporarily. Here, we developed another interventional ablative therapy (termed nanoparticle-mediated microknife ablation) to locoregionally eliminate cancer pain and tumors. The IAT system was composed of self-assembled nanodrugs, infusion catheters, puncture needles, injection pump, and an empirical tumor ablation formula. Notably, the ablation formula established in the IAT system enables us to predict the essential nanoparticle (NP) numbers used for completely destroying tumors. In a mouse model of cancer pain, tumor-targeted nanodrugs made of Paclitaxel and Hematoporphyrin, which have an extremely high drug-loading efficiency (more than 60%), were infused into tumors through injection pumps under imaging guidance. In conclusion, when compared to classic chemotherapeutic agents, IAT showed significantly higher effectiveness in cancer pain removal. It also presented no damage to the nervous, sensory, and motor capabilities of the treated mice. All of these merits resulted from NPs' long-lasting retention, targeted ablation, and confined diffusion in tumor stroma. Therefore, this safe treatment modality has great potential to eradicate local cancer pain in the clinic.

Methadone dose escalation in patients with opioid use disorder and cancer as a strategy for controlling cancer-related pain: A case series

OBJECTIVES

Opioid use disorder (OUD) and cancer gained attention as co-occurring diseases in the last 2 decades due to the possible relationship between opioid prescriptions for cancer pain and the risk of developing substance use disorder in cancer patients. However, little is known about patients previously diagnosed with OUD who develop cancer and how to manage both OUD symptoms and control pain.

METHODS

The present case series deals with this subpopulation and proposes a dose escalation of methadone to control both the cancer-related pain and drug addiction symptoms.

RESULTS

This approach is peculiar because methadone is not used as a first-line treatment in cancer pain management and is not often used as a second-line treatment as well. Our 4 patients experienced good clinical control of symptoms and no major adverse reactions.

SIGNIFICANCE OF RESULTS

The subgroup of patients with OUD who develop cancer could be the perfect population to reconsider the use of methadone as a first-line treatment for cancer pain. Prospective studies are needed to evaluate the efficacy and safety of increasing doses of methadone in these patients to validate our clinical approach.

Oral Methadone versus Morphine IR for Patients with Cervical Cancer and Neuropathic Pain: A Prospective Randomised Controlled Trial

Objectives

In India, cervical cancer is the most common cancer among women and makes up for up to 29% of all registered cancer in females. Cancer-related pain is one of the major distressing symptoms for all cancer patients. Pain is characterised as somatic or neuropathic, and the total pain experience is often mixed. Conventional opioids are the backbone of analgesic treatment but are most often not sufficient in alleviating neuropathic pain, common in cervical cancer. Accumulating evidence of the advantage of methadone compared to conventional opioids, due to agonist action at both μ and q opioid receptors, N-methyl-D-aspartate (NMDA) antagonist activity and the ability to inhibit the reuptake of monoamines has been demonstrated. We hypothesised that, with these properties', methadone might be a good option for the treatment of neuropathic pain in patients with cervical cancer.

Material and Methods

Patients with cervical cancer stages ll-lll were enrolled in this randomized controlled trial. A comparison was made between methadone versus immediate release morphine (IR morphine), with increasing doses until pain was controlled. Inclusion-period was from October 3rd to December 31st 2020, and the total patient-study period was 12 weeks. Pain intensity was assessed according to the Numeric Rating Scale (NRS) and Douleur Neuropathique (DN4). The primary objective was to determine whether methadone was clinically superior versus noninferior to morphine as an analgesic for the treatment of cancer related neuropathic pain in women with cervical cancer.

Results

A total of 85 women were included; five withdrew and six died during the study period, leaving 74 patients completing the study. All participants showed a reduction in mean values of NRS and DN4 from the time of inclusion and to the end of the study period, for IR morphine and methadone 8.4-2.7 and 8.6-1.5, respectively (P < 0.001). The DN4 score mean reduction for Morphine and Methadone were 6.12-1.37 and 6.05-0, respectively (P < 0.001). Side effects were more common in the group of patients receiving IR morphine compared to the patients treated with methadone.

Conclusion

We found that Methadone had a superior analgesic effect with good overall tolerability compared with morphine as a first-line strong opioid for the management of cancer-related neuropathic pain.

Use of Opioids for Adults With Pain From Cancer or Cancer Treatment: ASCO Guideline

PURPOSE

To provide guidance on the use of opioids to manage pain from cancer or cancer treatment in adults.

METHODS

A systematic review of the literature identified systematic reviews and randomized controlled trials of the efficacy and safety of opioid analgesics in people with cancer, approaches to opioid initiation and titration, and the prevention and management of opioid adverse events. PubMed and the Cochrane Library were searched from January 1, 2010, to February 17, 2022. American Society of Clinical Oncology convened an Expert Panel to review the evidence and formulate recommendations.

RESULTS

The evidence base consisted of 31 systematic reviews and 16 randomized controlled trials. Opioids have primarily been evaluated in patients with moderate-to-severe cancer pain, and they effectively reduce pain in this population, with well-characterized adverse effects. Evidence was limited for several of the questions of interest, and the Expert Panel relied on consensus for these recommendations or noted that no recommendation could be made at this time.

RECOMMENDATIONS

Opioids should be offered to patients with moderate-to-severe pain related to cancer or active cancer treatment unless contraindicated. Opioids should be initiated PRN (as needed) at the lowest possible dose to achieve acceptable analgesia and patient goals, with early assessment and frequent titration. For patients with a substance use disorder, clinicians should collaborate with a palliative care, pain, and/or substance use disorder specialist to determine the optimal approach to pain management. Opioid adverse effects should be monitored, and strategies are provided for prevention and management.Additional information is available at www.asco.org/supportive-care-guidelines.

Association of KCNJ6 rs2070995 and methadone response for pain management in advanced cancer at end-of-life

Opioids are the therapeutic agents of choice to manage moderate to severe pain in patients with advanced cancer, however the unpredictable inter-individual response to opioid therapy remains a challenge for clinicians. While studies are few, the KCNJ6 gene is a promising target for investigating genetic factors that contribute to pain and analgesia response. This is the first association study on polymorphisms in KCNJ6 and response to methadone for pain management in advanced cancer. Fifty-four adult patients with advanced cancer were recruited across two study sites in a prospective, open label, dose individualisation study. Significant associations have been previously shown for rs2070995 and opioid response in opioid substitution therapy for heroin addiction and studies in chronic pain, with mixed results seen in postoperative pain. In this study, no associations were shown for rs2070995 and methadone dose or pain score, consistent with other studies conducted in patients receiving opioids for pain in advanced cancer. There are many challenges in conducting studies in advanced cancer with significant attrition and small sample sizes, however it is hoped that the results of our study will contribute to the evidence base and allow for continued development of gene-drug dosing guidelines for clinicians.

The Use of Low-Dose Methadone as Add-On to Ongoing Opioid Treatment in Palliative Cancer Care—An Underrated Treatment?

The aim of this review is to summarize the current knowledge of low-dose methadone treatment in palliative cancer care. In Sweden, methadone is quite common in specialized palliative care, where almost a tenth of patients are prescribed this drug. Negative attitudes towards methadone do not seem to prevent it from being used for pain management, and by starting with low doses and then increasing slowly and gradually, methadone can apparently be introduced safely. It is still uncertain whether methadone has a better analgesic effect than other opioids. However, for pain relief in cancer patients with severe and complex cancer-related pain, NMDA receptor inhibition with methadone may, in selected cases, be an attractive alternative, especially in the form of low-dose supplements to other ongoing opioids. Due to long half-life and complex metabolism, the use of methadone requires an experienced physician and solid follow-up. Continuous administration of opioids, including low-dose methadone, has been proven effective and safe in reducing pain in dying patients without increasing the risk of confusion, regardless of age.

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.

Association of polymorphisms in ARRB2 and clinical response to methadone for pain in advanced cancer

Background: The prescription of methadone in advanced cancer poses multiple challenges due to the considerable interpatient variation seen in effective dose and toxicity. Previous reports have suggested that ARRB2 influences the response to methadone in opioid substitution therapy. Associations with opioid response for pain management in advanced cancer are conflicting, with no studies including methadone as the primary intervention. Methods: In a prospective, multicenter, open-label dose individualization study, we investigated whether polymorphisms in ARRB2 were associated with methadone dose requirements and pain severity. Results: Significant associations were found for rs3786047, rs1045280, rs2036657 and pain score. Conclusion: While studies are few and the sample size small, ARRB2 genotyping may assist in individualized management of the most feared symptom in advanced cancer.

OUP accepted manuscript

Aim

The aim of this study was to assess the efficacy and adverse effects of methadone when used as first-line therapy in patients that are either receiving low doses of opioids or none.

Methods

Patients with advanced cancer were prospectively assessed. Opioid-naive patients (L-group) were started with methadone at 6 mg/day. Patients receiving weak or other opioids in doses of <60 mg/day of OME (H-group) were started with methadone at 9 mg/day. Methadone doses were changed according to the clinical needs to obtain the most favorable balance between analgesia and adverse effects. Edmonton Symptom Asssement Score (ESAS), Memorial Delirium Assessment Score (MDAS), doses of methadone, and the use of adjuvant drugs were recorded before starting the study treatment (T0), 1 week after (T7), 2 weeks after (T14), 1 month after (T30), and 2 months after (T60). Methadone escalation index percent (MEI%) and in mg (MEImg) were calculated at T30 and T60.

Results

Eighty-two patients were assessed. In both groups H and L, there were significant changes in pain and symptom intensity at the different times during the study. Adverse effects as causes of drop-out were minimal. Mean MEImg was 0.09 (SD 0.28) and 0.02 (SD 0.07) at T30 and T60, respectively. MEI% was 1.01 (SD 3.08) and 0.27 (SD 0.86) at T30 and T60, respectively.

Conclusion

Methadone used as a first-line opioid therapy provided good analgesia with limited adverse effects and a minimal opioid-induced tolerance.

The Introduction and Experiences of Methadone for Treatment of Cancer Pain at a Low-resource Governmental Cancer Center in India

Objectives

This study aimed to describe the clinical experience of the health-care professionals (HCPs) responsible for the introduction of methadone, for the treatment of complex cancer pain, at a low-resource hospital in India in a patient-group, burdened by illiteracy, and low socio-economic status.

Materials and Methods

Ten HCPs: Four medical doctors, four nurses, one pharmacist, and one hospital administrator were interviewed. The interviews are examined using a qualitative conventional content analysis.

Results

The interviews showed a confidence amongst the HCPs, responsible for the safe introduction of methadone in a stressful and low-resource surrounding, to patients with cancer pain and the different aspects of methadone, as initiation, titration, and maintenance of treatment.

Conclusion

Introduction of methadone for cancer pain management is safe and feasible although low resources in a challenging hospital setting and care environment.

Pronounced Regional Disparities in United States Methadone Distribution

BACKGROUND

Methadone is an evidence-based treatment for opioid use disorder (OUD) and pain management. Methadone for OUD may be difficult for some patients to access, particularly those in rural areas.

OBJECTIVE

The purpose of this study was to characterize methadone distribution patterns between 2017 and 2019 across the United States.

METHODS

The US Drug Enforcement Administration's Automated Reports and Consolidated Ordering System was used to acquire the number of opioid treatment programs (OTPs) per state and methadone distribution weight in grams. Methadone distributions by weight, corrected for state population and number of OTPs, were compared from 2017 to 2019 between states, within regions, and nationally.

RESULTS

The national distribution of methadone increased +12.3% for OTPs but decreased -34.6% for pain. Whereas all states saw a decrease in pain distribution, the Northeast showed a significantly smaller decrease than all other regions. Additionally, the majority of states experienced an increase in distribution for OTPs, and most states demonstrated a relatively stable or increasing number of OTPs, with an +11.5% increase nationally. The number of OTPs per 100K state population ranged from 2.1 in Rhode Island to 0.0 in Wyoming.

CONCLUSION AND RELEVANCE

Although methadone distribution for OUD was increasing in the United States, the pronounced regional disparities identified warrant further consideration to improve patient access to this evidence-based pharmacotherapy, particularly in the Midwest and West regions. Greater implementation of telehealth and involvement of primary care into opioid treatment practice offer possible solutions to eliminating geographical treatment barriers.

Antinociceptive synergism upon the joint use of methadone and Phα1β in a model of cancer-related pain in C57BL/6J mice

Opioids are the first-line treatment for cancer pain. Incomplete pain relief and the high rate of adverse effects of these compounds bring a need to combine them with other drugs acting on different targets.

AIMS

We here evaluate the antinociceptive interaction and adverse events of methadone combined with recombinant Phα1β, an analgesic toxin from Phoneutria nigriventer.

MAIN METHODS

Melanoma was produced by intraplantar inoculation of B16-F10 cells into the right paw. von Frey filaments measured the paw-withdrawal threshold after administration of methadone, Phα1β, and their combination. The degree of interaction was evaluated using isobolographic analysis. Spontaneous performance and forced motor performance were assessed with the open-field and rotarod tests, respectively. Intestinal function was evaluated by the distance traveled by charcoal and opioid tolerance was induced by daily morphine injections.

KEY FINDINGS

Co-administration of Phα1β with methadone synergistically reverses the melanoma-induced mechanical hypersensitivity. No motor alterations were observed but mild alterations on intestinal function after treatment with the combination that was also capable of restoring morphine analgesia in the tail-flick test after an opioid-induced tolerance.

SIGNIFICANCE

Combinatorial treatment with Phα1β and methadone produces synergistic analgesic potentiation with potential implications to pain treatment even under opioid tolerance conditions.

First-line methadone for cancer pain: titration time analysis

BACKGROUND

Methadone is a low-cost, strong opioid that is increasingly used as a first-line treatment for pain in palliative care (PC). Its long and unpredictable half-life and slow elimination phase can make titration challenging. Evidence for titration modalities is scarce.

OBJECTIVE

To describe the titration phase of the treatment with low-dose first-line methadone and the use of methadone for breakthrough pain.

METHODS

Prospective study with strong opioid-naïve patients with moderate to severe cancer pain followed at a tertiary PC unit in Argentina. Starting methadone dose was 2.5-5 mg/day every 8, 12, or 24 h. Titration allowed daily dose increases from day 1, and prescription of oral methadone 2.5 mg every 2 h with a maximum of 3 rescue doses/day for breakthrough pain. Pain control, methadone stabilization dose, and adverse effects, among other variables, were daily assessed over the first 7 days (T0-T7).

RESULTS

Sixty-two patients were included. Initial median (IQR) methadone dose was 5 (2.5) mg/day. Pain intensity decreased from a median (IQR) of 8 (2.3) at T0 to 4 (2.3) at T1 and remained ≤ 4 until T7 (all p < 0.0001 compared to T0). Similar results were obtained through the categorical and tolerability scales for pain. Fifty patients (81%) reached pain control, 66% in the first 48 h. Methadone daily doses at T2 and T7 were higher than that at T0: 7.5 (3) and 6.7 (5.5) versus 5 (2.5), respectively (all p < 0.05). The opioid escalation index at T7 was 1.7%. The median (IQR) number of rescues, stabilization dose, and time for stabilization was 0 (1), 5(4.5) mg, and 3(2) days, respectively. Two patients were discontinued due to delirium. All other side effects were mild.

CONCLUSIONS

First-line, low-dose methadone using rescue methadone resulted in a pronounced and rapid decrease in pain, with minimal need for titration and for breakthrough doses, and no evidence of accumulation or sedation by the end of the week.

Effects of Three Consecutive Days of Morphine or Methadone Administration on Analgesia and Open-Field Activity in Mice with Ehrlich Carcinoma

This study assessed the exploratory behavioral responses in BALB/c mice inoculated with Ehrlich ascitic carcinoma after 3 consecutive days of treatment with morphine or methadone. Fifty-three female mice, 60 ± 10 d old, were used. Seven days after intraperitoneal tumor inoculation (2 × 10⁶ cells), the animals were randomized into 7 groups: morphine 5 mg/kg (MO₅), morphine 7.5 mg/kg (MO_7.5), morphine 10 mg/kg (MO₁₀), methadone 2.85 mg/kg (ME_2.85), methadone 4.3 mg/kg (ME_4.3), methadone 5.7 mg/kg (ME_5.7), and 0.9% NaCl (Saline) (n = 7). Drug treatments were administered subcutaneously every 6 h for 3 d. The animals were evaluated for analgesia using the mouse grimace scale (MGS) and for general activity using the open field test. The MGS was performed before tumor inoculation (day 0), on day 7 at 40, 90, 150, 240, and 360 min after drug injection, and on days 8 and 9 at 40, 150, 240, and 360 min after drug injection. The open field test was performed before tumor inoculation (day 0), on day 7 after inoculation at 40, 90, 150, 240, and 360 min after drug injection, and on days 8 and 9 after inoculation at 40, 150, and 360 min after drug injection. MGS results indicated that administration of morphine promoted analgesia for up to 240 min. Conversely, methadone reduced MGS scores only at 40 min. All tested doses promoted a significant dose-dependent increase in the total distance traveled and the average speed, and increase that was markedly pronounced on days 8 and 9 as compared with day 7. The frequencies of rearing and self-grooming decreased significantly after morphine or methadone administration. Despite the difference in analgesia, both drugs increased locomotion and reduced the frequency of rearing and self-grooming as compared with the untreated control animals.

The Use of Methadone in Adult Patients with Cancer Pain at a Governmental Cancer Center in India

Background:

Management of cancer-related pain relies on the access to opioids. When regular opioids as morphine are not tolerated or are insufficient, adjuvant opioids as methadone are an affordable and effective analgesic.

Aim:

The aim of the project was to describe the pattern of use and clinical experiences of methadone in patients with cancer-related pain at a low-resource hospital in Hyderabad, one of few Indian cancer centers with permission to prescribe methadone.

Methods:

Medical records of all patients who had been prescribed methadone, September 9, 2017 and November 19, 2019 were studied retrospectively. Data on analgesic treatment and opioid side effects were analyzed.

Results:

A total of 93 adult cancer patients were included in the study. A majority of patients (79%) were prescribed opioid analgesic, mainly morphine, before methadone introduction. The initial daily dose of methadone ranged between 5 and 22.5 years and in the vast majority of the patients 5 mg, divided in two daily administrations. A good analgesic effect, with decreased pain, was reported in 60% of the patients. No severe side effects were reported.

Conclusions:

In this study, methadone as a primary opioid was used with a good analgesic effect for cancer pain in a low-resource setting. Indication for methadone was mainly uncontrolled pain with a regular opioid treatment. No severe adverse effects were reported. Further research and prospective studies are needed on methadone treatment in low-resource settings to establish the robust guidelines to support prescribing physicians.

The Use of Methadone in Pediatric Cancer Pain - A Retrospective Study from a Governmental Cancer Center in India

Background:

The management of cancer-related pain relies on access to opioids. When regular opioids are not tolerated, or are insufficient, methadone is an affordable and effective analgesic.

Aim:

The aim of the project was to describe the pattern of use and clinical experience of methadone in pediatric cancer pain at a governmental cancer hospital in Hyderabad, one of the four Indian cancer centers with permission to prescribe methadone.

Methods:

This was a retrospective study of medical records of all children, under the age of 18, who had been prescribed methadone from September 9, 2017, to November 19, 2019. Data on analgesic effect, prior and concomitant analgesic treatment, opioid side effects, and the handling of methadone were analyzed.

Results:

A total of 11 children were identified and studied. Methadone was introduced mainly when pain was uncontrolled by regular opioids. Initial daily doses ranged from 1 to 15 mg. The duration of treatment ranged from 7 to 307, with a median of 50 days in the nine patients where treatment exceeded one single dosage. Good analgesic effect was reported in 5/9 children, unchanged from previous analgesic treatment in three patients and without any effect in one child. No severe side effects were reported.

Conclusion:

Low-dose methadone in the treatment of pediatric cancer pain at a low-resource cancer center was safe and well tolerated by the patients, with long treatment durations. It was safely managed, administered with single to double daily dosages, hence easy for patients and family to handle, and an affordable treatment option.

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.

How to Use Methadone in an Era of an Opioid Epidemic

OPINION STATEMENT

The opioid epidemic is one of the most important public health crises as opioid-related deaths have become a leading cause of accidental death in the USA. Various efforts have been made to understand how to safely and appropriately prescribe opioids for patients with chronic pain, including those with cancer-related pain. We find the guidelines proposed by the Expert Consensus White Paper on the use of methadone to be current, comprehensive, and practical. While methadone is a complex medication with unique pharmacokinetics and pharmacodynamics, it remains a superior choice for many patients with cancer pain given its cost and applicability in a variety of situations. Methadone should be prescribed in the context of experienced clinicians as well as an interdisciplinary team. At a critical time when preventing opioid-related deaths is a priority, we recommend implementing additional precautions for monitoring including universal screening for risk of non-medical opioid use, education on proper storage and disposal, as well as discussing a plan with patients and caregivers in the case of serious complications such as opioid overdose.

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.

Recent advances in pain treatment for children with serious illness

Pain is a common distressing symptom in children receiving pediatric palliative care. Both in children with cancer, but especially in children with progressive neurodegenerative and chromosomal conditions with CNS impairment pain is common, and often under-recognized and undertreated. Multimodal analgesia for children with serious illness acts synergistically for more effective pediatric pain and symptom control with fewer side effects than a single analgesic or modality. Successful pain treatment and prevention usually include integrative 'nonpharmacological' therapies, rehabilitation, psychology and spirituality in addition to pharmacology and regional anesthesia. This review article will address these effective components of multimodal pediatric analgesia and present starting doses of basic analgesia, opioids and adjuvants analgesia in infants, children and adolescents with serious illness.

Opioid Rotation to Methadone for Refractory Cancer Pain: A Case Series

Methadone has been increasingly used in the treatment of refractory cancer pain with different conversion methods and ratios described.A retrospective chart review of patients on methadone for cancer pain was conducted to assess its use as the primary opioid, focusing on pain characteristics, opioid rotation indication, previous analgesics, adverse effects and final methadone dose in comparison with the pre-rotation Morphine Equivalent Daily Dose (MEDD).Eight patients were rotated to methadone due to refractory moderate-severe cancer pain and achieved good pain relief. Three developed adverse effects (2 mild, 1 serious). None required withdrawal of methadone. The final methadone dose required varied significantly from predictions made based on equianalgesic conversion tables.Methadone is effective for the treatment of refractory cancer pain. The eventual required methadone doses for these patients were significantly different from predicted doses suggested by equianalgesic conversion tables and guidelines. This highlights the importance of individualized titration and careful clinical assessment during the rotation and in the days after, to prevent serious adverse effects.

Methadone vs. morphine SR for treatment of neuropathic pain: A randomized controlled trial and the challenges in recruitment

Introduction: Accumulating evidence has identified a number of advantages for methadone over other opioids for the treatment of chronic pain including: agonist action at both μ and δ opioid receptors, N-methyl-d-aspartate (NMDA) antagonist activity and the ability to inhibit the reuptake of monoamines. It was hypothesized that with these three mechanisms of action methadone might be a good option for the treatment of neuropathic pain.

Methods: This was a double-blind randomized controlled trial comparing methadone to controlled-release morphine. The primary objective was to determine whether methadone is clinically inferior versus noninferior to morphine as an analgesic.

Results: We attempted recruitment at three academic pain centers over a 3-year period. In the end only 14 participants were able to be recruited; 5 withdrew and only 9 completed the trial. This study was underpowered. All participants showed a mean reduction in pain intensity according to the Numeric Rating Scale for Pain Intensity (morphine 5.86 to 4.38, methadone 6.11 to 4.5) and reported pain relief compared to pretreatment, but the sample size was too small for statistical analysis.

Discussion: Reasons for challenges in recruitment included tight inclusion and exclusion criteria and high participant burden. In addition, there was significant heterogeneity of patients between the three sites, leading to differences in reasons for exclusion. This included seemingly disparate reasons at the different sites, including few participants who were methadone naïve vs. avoidance or fear of opioids. In the end, we were unable to answer the question of the study.

Methadone enhances the effectiveness of 5-aminolevulinic acid-based photodynamic therapy for squamous cell carcinoma and glioblastoma in vitro

Although having shown promising clinical outcomes, the effectiveness of 5-aminolevulinic acid-based photodynamic therapy (ALA-PDT) for squamous cell carcinoma (SCC) and glioblastoma remains to be improved. The analgesic drug methadone is able to sensitize various tumors to chemotherapy. In this in vitro study, the influence of methadone to the effectiveness of ALA-PDT for SCC (FADU) and glioblastoma (A172) was investigated on the protoporphyrin IX (PpIX) fluorescence, survival rates, apoptosis, and cell cycle phase, each with or without the presence of methadone. The production of PpIX was increased by methadone in FADU cells while it was decreased in A172 cells. The survival rates of both cell lines treated by ALA-PDT were significantly reduced by the combination with methadone (P < .05). Methadone also significantly increased the percentage of apoptotic cells and improved the effect of ALA-PDT on the cell cycle phase arrest in the G0/G1 phase (P < .05). This study demonstrates the potential of methadone to influence the cytotoxic effect of ALA-PDT for both SCC and glioblastoma cell lines.

A Systematic Review in Support of the National Consensus Project Clinical Practice Guidelines for Quality Palliative Care, Fourth Edition

CONTEXT

Palliative care continues to be a rapidly growing field aimed at improving quality of life for patients and their caregivers.

OBJECTIVES

The purpose of this review was to provide a synthesis of the evidence in palliative care to inform the fourth edition of the National Consensus Project Clinical Practice Guidelines for Quality Palliative Care.

METHODS

Ten key review questions addressing eight content domains guided a systematic review focused on palliative care interventions. We searched eight databases in February 2018 for systematic reviews published in English from 2013, after the last edition of National Consensus Project guidelines was published, to present. Experienced literature reviewers screened, abstracted, and appraised data per a detailed protocol registered in PROSPERO. The quality of evidence was evaluated using the Grading of Recommendations, Assessment, Development and Evaluations criteria. The review was supported by a technical expert panel.

RESULTS

We identified 139 systematic reviews meeting inclusion criteria. Reviews addressed the structure and process of care (interdisciplinary team care, 13 reviews; care coordination, 18 reviews); physical aspects (48 reviews); psychological aspects (26 reviews); social aspects (two reviews); spiritual, religious, and existential aspects (11 reviews); cultural aspects (three reviews); care of the patient nearing the end of life (grief/bereavement programs, six reviews; final days of life, two reviews); ethical and legal aspects (36 reviews).

CONCLUSION

A substantial body of evidence exists to support clinical practice guidelines for quality palliative care, but the quality of evidence is limited.