Very-Low-Dose Methadone To Treat Refractory Neuropathic Pain in Children with Cancer

Methadone versus other opioids for refractory malignant bone pain: a pilot randomised controlled study

PURPOSE

Refractory cancer-induced bone pain (CIBP) affects a patient's functional capacity and quality of life, but there is limited evidence to guide opioid choice. We assessed the feasibility, tolerability and possible efficacy of methadone rotation (MR) compared to other opioid rotations (OOR) in this cohort.

METHODS

Adults with CIBP and worst pain intensity ≥ 4/10 and/or opioid toxicity graded ≥ 2 on the Common Terminology Criteria for Adverse Events were randomised 1:1 to methadone or another opioid rotation. Standardised assessment tools were used at pre-defined study time points up to 14 days.

RESULTS

Of 51 eligible participants, 38 (74.5%) consented, and 29 (76.3%, MR: 14, OOR: 15) completed the fourteen days follow-up post-opioid rotation. Both groups displayed significant reduction in average (MR: d =  - 1.2, p = 0.003, OOR: d =  - 0.8, p = 0.015) and worst pain (MR: d =  - 0.9, p = 0.042, OOR: d =  - 0.6, p = 0.048) and total pain interference score (MR: d =  - 1.1, p = 0.042, OOR: d =  - 0.7, p = 0.007). Oral morphine equivalent daily dose was reduced significantly in MR compared to the OOR group (d =  - 0.8, p = 0.05). The incidence of opioid-related adverse events following MR was unchanged but lower in the OOR group (d = 0.9, 95% CI 0.1,1.7, p = 0.022). There were no within-group or between-group differences in satisfaction with analgesia at the end of the study.

CONCLUSION

This pilot study demonstrated that MR and OOR in patients with refractory CIBP are feasible, safe and acceptable to patients. Appropriately powered multi-centre randomised controlled studies are needed to confirm the efficacy of MR and OOR in this cohort.

TRIAL REGISTRATION

ACTRN12621000141842 registered 11 February 2021.

Methadone for Cancer Pain in Pediatric End-of-Life Care

BACKGROUND

The goal of adequate pain control becomes increasingly salient for children with cancer and their families as the patients approach the end of life. Methadone is one option that is particularly desirable in end-of-life care given its long duration of action and NMDA antagonism that may help in controlling pain refractory to conventional opioids. The purpose of this study was to describe a single institution's experience with methadone for the treatment of cancer pain in pediatric end-of-life care.

METHODS

This retrospective, observational, single-center study included all patients during a 9-year period who died in the inpatient setting and were receiving methadone in their last 30 days of life.

RESULTS

Twenty patients were identified, 18 (90%) of whom received methadone for nociceptive pain. The median duration of methadone use was 32 days (range 2-323 days). Methadone doses ranged from 0.09 to 7.76 mg/kg per day. There were no instances of discontinuing methadone due to an increased QTc interval. No episodes of torsades de pointes were observed.

CONCLUSION

In patients with pediatric cancer who are nearing the end of life, methadone is a valuable adjunctive therapy to treat nociceptive and neuropathic pain and to prevent opioid-induced hyperalgesia and opioid tolerance. An individualized approach to dosage and route should be considered based on specific clinical circumstances.

Prospective randomized trial of interventions for vincristine-related neuropathic pain

BACKGROUND

To evaluate the efficacy of gabapentin at 20 mg/kg per day in the treatment of vincristine-related neuropathic pain.

PROCEDURE

Children aged 1-18 years who developed vincristine-induced neuropathy on a St Jude frontline acute lymphoblastic leukemia trial were prospectively enrolled on a randomized, double-blind, placebo-controlled, phase II trial with two treatment arms: gabapentin plus opioid versus placebo plus opioid. Daily evaluations of morphine dose (mg/kg per day) and pain scores were conducted for up to 21 days; the values of the two arms were compared to assess analgesic efficacy.

RESULTS

Of 51 study participants, 49 were eligible for analyses. Twenty-five participants were treated with gabapentin, with a mean (SD) dose of 17.97 (2.76) mg/kg per day (median 18.26, range 6.82-21.37). The mean (SD) opioid doses taken, expressed as morphine equivalent daily (mg/kg per day), were 0.26 (0.43) in the gabapentin group (25 patients, 432 days) and 0.15 (0.22) in the placebo group (24 patients, 411 days; P = .15). Only the risk classification of acute lymphoblastic leukemia was significantly associated with the daily morphine dosage (P = .0178): patients in the lower risk arm received higher daily morphine dosages. Multivariate analyses revealed a significant difference between the groups' average daily scores for the previous 24 h and "right now."

CONCLUSION

In this population of children with vincristine-related neuropathic pain, opioid consumption and pain scores were higher in the gabapentin group than in the placebo group. Future randomized, double-blind, placebo-controlled studies should test gabapentin given longer or at a higher dose.

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.

Corrected QT Interval Prolongation in Pediatric and Young Adult Patients on Methadone for Cancer-Related Pain

CONTEXT

Methadone has been reported to prolong the corrected QT (QTc) interval and increase the risk of torsades de pointes.

OBJECTIVES

Our study examined the frequency of QTc prolongation among pediatric and young adult patients starting methadone for cancer pain.

METHODS

All patients followed a standardized protocol. Electrocardiograms (ECGs) were obtained at baseline (methadone starting day to 14 days prior), 1-2 weeks, and 4-6 weeks later. QTc values were manually calculated using the Bazett formula. QTc prolongation was defined as ≥460 milliseconds (ms) for prepubertal children, ≥470 ms for pubertal males, and ≥480 ms for pubertal females.

RESULTS

Baseline ECGs were completed in 42 patients. Follow-up ECGs were completed in 38 of 42 (91%) and 31 of 42 (74%) patients at 1-2 weeks and 4-6 weeks, respectively. No patients had prolongation of the QTc at baseline, and 1 of 38 (3%) patients had a prolonged QTc at weeks 1-2. This patient had a history of prolonged QTc that the family did not initially report. No patients had prolongation of the QTc at weeks 4-6. No patients had torsades de pointes or ventricular fibrillation, and none died suddenly. Median (interquartile range [IQR]) baseline QTc was 391 (377-400) ms; median (IQR) 1-2 week follow-up QTc was 399 (374-411) ms (P = .05), and median (IQR) 4-6 week follow-up QTc was 393 (379-423) ms (P = .01).

CONCLUSION

Clinically significant prolongation of the QTc interval occurred only in one patient who had a history of prolonged QTc. Prolonged QTc is rare in this population.

Sovereign Rules and Rearrangements: Banning Methadone in Occupied Crimea

In 2014, Russian authorities in occupied Crimea shut down all medication-assisted treatment (MAT) programs for patients with opioid use disorder. These closures dramatically enacted a new political order. As the sovereign occupiers in Crimea advanced new constellations of citizenship and statehood, so the very concept of "right to health" was re-tooled. Social imaginations of drug use helped single out MAT patients as a population whose "right to health," protected by the state, would be artificially restricted. Here, I argue that such acts of medical disenfranchisement should be understood as contemporary acts of statecraft.

Neuropathic Pain in Pediatric Oncology: A Clinical Decision Algorithm

Neuropathic pain in pediatric oncology can be caused by distinct lesions or disease processes affecting the somatosensory system, including chemotherapy-related neuronal injury, solid tumor-related involvement of neural structures, post-surgical neuropathic pain-including phantom limb pain and pain after limb-sparing surgery-and the complex circumstances of neuropathic pain at the end of life. Treatment algorithms reflect the general treatment principles applied for adult neuropathic pain, but the dose regimens applied in children are modest and rarely escalated to the maximum doses to optimize analgesic efficacy. Pharmacological management of neuropathic pain should be based on a stepwise intervention strategy, as combinations of medications are the most effective approach. Gabapentinoids and tricyclic antidepressants are recommended as first-line therapy. Methadone, ketamine, and lidocaine may be useful adjuvants in selected patients. Prospective studies extended over a substantial length of time are recommended because of the nature of neuropathic pain as persistent, chronic pain and based on the need for sufficient time to escalate medication dose regimens to full analgesic efficacy.

Investigation of Key Genes and Pathways in Inhibition of Oxycodone on Vincristine-Induced Microglia Activation by Using Bioinformatics Analysis

Introduction

The neurobiological mechanisms underlying the chemotherapy-induced neuropathic pain are only partially understood. Among them, microglia activation was identified as the key component of neuropathic pain. The aim of this study was to identify differentially expressed genes (DEGs) and pathways associated with vincristine-induced neuropathic pain by using bioinformatics analysis and observe the effects of oxycodone on these DEG expressions in a vincristine-induced microglia activation model.

Methods

Based on microarray profile GSE53897, we identified DEGs between vincristine-induced neuropathic pain rats and the control group. Using the ToppGene database, the prioritization DEGs were screened and performed by gene ontology (GO) and signaling pathway enrichment. A protein-protein interaction (PPI) network was used to explore the relationship among DEGs. Then, we built the vincristine-induced microglia activation model and detected several DEG expressions by real-time polymerase chain reaction (PCR) and western blotting. Meanwhile, the effects of different concentrations of oxycodone on inflammatory response in primary microglia induced by vincristine were observed.

Results

A total of 38 genes were differentially expressed between normal and vincristine-treated rats. GO and pathway enrichment analysis showed that prioritization DEGs are involved in cAMP metabolic process, inflammatory response, regulation of cell proliferation, and chemokine pathway. The in vitro studies showed that vincristine had dose-dependent cytotoxic effects in microglia. Compared to the control group, vincristine (0.001 μg/ml) could lead to inflammation in primary microglia induced by vincristine and upregulated the CXCL10, CXCL9, SFRP2, and PF4 mRNA and made an obvious reduction in IRF7 mRNA. At protein levels, oxycodone (50, 100 ng/ml) decreased the expression of CXCL10 and CXCL9 in activated microglia.

Conclusion

Our study obtained several DEG expressions and signaling pathways in the vincristine-induced neuropathic pain rat model by bioinformatics analysis. Oxycodone could alleviate the vincristine-induced inflammatory signaling in primary microglia and downregulate some DEGs. Further molecular mechanisms need to be explored in the future.

Attitudes, Beliefs, and Practices of Pediatric Palliative Care Physicians Regarding the Use of Methadone in Children With Advanced Cancer

CONTEXT

Methadone is a long-acting opioid known for its unique pharmacokinetic and pharmacodynamic properties. Most research on methadone in children is limited to its effect on the prolongation of the corrected QT (QTc) interval.

OBJECTIVES

To better understand the attitudes, beliefs, and practices of pediatric palliative care physicians regarding the use of methadone in children with advanced cancer.

METHODS

A survey was sent to the American Academy of Pediatrics Section of Hospice and Palliative Medicine LISTSERV. Information on demographics, dosing of methadone, and the use of electrocardiograms (ECGs) was collected.

RESULTS

One-hundred and five respondents (91%) provide palliative care to children ≥ 50% of the time, and a majority (81, 77%) prescribe methadone. Most (62, 77%) physicians were board certified in Hospice and Palliative Medicine, and most (39, 63%) certified via the direct pathway ("grandfathering"). Most physicians (57, 70%) do not use loading doses of methadone. Board-certified physicians trended toward decreasing methadone dose more (40% ± 19%) than non-board-certified physicians (28%, ±20%) when changing from the oral to intravenous route (P = 0.07). Respondents defined a QTc interval as "prolonged" (mean ± SD) at 444 milliseconds (±68 milliseconds). The percentage of patients receiving a baseline ECG was 65% (±33%). The most common reason for not performing a baseline ECG was that the patient was on hospice (13, 36%).

CONCLUSIONS

There are consistent practices, attitudes, and beliefs of pediatric palliative care providers with regard to methadone. More education is needed on the accurate value of a prolonged QTc interval.

Palliative Care for Children with Central Nervous System Malignancies

Children with central nervous system (CNS) malignancies often suffer from high symptom burden and risk of death. Pediatric palliative care is a medical specialty, provided by an interdisciplinary team, which focuses on enhancing quality of life and minimizing suffering for children with life-threatening or life-limiting disease, and their families. Primary palliative care skills, which include basic symptom management, facilitation of goals-of-care discussions, and transition to hospice, can and should be developed by all providers of neuro-oncology care. This chapter will review the fundamentals of providing primary pediatric palliative care.

Methadone for Pain Management in Children with Cancer

Methadone is a synthetic opioid with unique pharmacodynamic and pharmacokinetic properties. It is effective in treating both nociceptive and neuropathic pain, which commonly co-exist in children with cancer. Upon reviewing the literature describing the use of methadone in pediatric oncology patients, publications are limited in number and low in quality of evidence; nevertheless, there is support for the safety and efficacy of methadone in treating pain in children with cancer, particularly when pain is refractory to conventional treatment. Although the risk of life-threatening arrhythmia is commonly cited as an argument against the use of methadone, our review of the literature did not support this finding in children. Further evaluation with prospective studies is warranted to develop evidence-based recommendations for the use of methadone in pediatric oncology.