Management of opioid side effects in cancer-related and chronic noncancer pain: a systematic review

Safe Management of Adverse Effects Associated with Prescription Opioids in the Palliative Care Population: A Narrative Review

In the palliative care population, prescription opioids are often considered viable pain relief options. However, in this complex patient population, the adverse effects of opioid medications should be identified and managed without delay. Common adverse effects can include constipation, nausea, somnolence, dizziness, vomiting, and pruritus. Less common adverse effects can include potentially lethal respiratory depression and cardiovascular effects. Critical aspects of safe opioid prescribing are recognition of side effects and knowledge of effective management strategies; prompt management is necessary for uninterrupted pain relief. Most complications are managed with general approaches such as dose reduction, opioid rotation, alternate routes of administration, and symptomatic management. The only opioid-induced complication for which US Food and Drug Administration-approved treatments currently exist is constipation. Treating laxative-refractory opioid-induced constipation (OIC) with peripherally acting mu-opioid receptor antagonists (PAMORAs), which block gastrointestinal opioid receptors, can restore gastrointestinal motility and fluid secretion. This narrative review discusses key complications of prescription opioid treatment and their management in the palliative care setting.

Safety and Efficacy of Surgical Implantation of Intrathecal Drug Delivery Pumps in Patients With Cancer With Refractory Pain

BACKGROUND AND OBJECTIVES

Pain management in patients with cancer is a critical issue in oncology palliative care as clinicians aim to enhance quality of life and mitigate suffering. Most patients with cancer experience cancer-related pain, and 30%-40% of patients experience intractable pain despite maximal medical therapy. Intrathecal pain pumps (ITPs) have emerged as an option for achieving pain control in patients with cancer. Owing to the potential benefits of ITPs, we sought to study the long-term outcomes of this form of pain management at a cancer center.

METHODS

We retrospectively reviewed medical records of all adult patients with cancer who underwent ITP placement at a tertiary comprehensive cancer center between 2013 and 2021. Baseline characteristics, preoperative and postoperative pain control, and postoperative complication rate data were collected.

RESULTS

A total of 193 patients were included. We found that the average Numerical Rating Scale (NRS) score decreased significantly by 4.08 points (SD = 2.13, P < .01), from an average NRS of 7.38 (SD = 1.64) to an average NRS of 3.27 (SD = 1.66). Of 185 patients with preoperative and follow-up NRS pain scores, all but 9 experienced a decrease in NRS (95.1%). The median overall survival from time of pump placement was 3.62 months (95% CI: 2.73-4.54). A total of 42 adverse events in 33 patients were reported during the study period. The 1-year cumulative incidence of any complication was 15.6% (95% CI: 10.9%-21.1%) and for severe complication was 5.7% (95% CI: 3.0%-9.7%). Eleven patients required reoperation during the study period, with a 1-year cumulative incidence of 4.2% (95% CI: 2.0%-7.7%).

CONCLUSION

Our study demonstrates that ITP implantation for the treatment of cancer-related pain is a safe and effective method of pain palliation with a low complication rate. Future prospective studies are required to determine the optimal timing of ITP implantation.

Managing Severe Cancer Pain with Oxycodone/Naloxone Treatment: A Literature Review Update

Severe cancer pain substantially affects patients' quality of life, increasing the burden of the disease and reducing the disability-adjusted life years. Although opioid analgesics are effective, they may induce opioid-induced bowel dysfunction (OIBD). Oxycodone/naloxone combination therapy has emerged as a promising approach to mitigate opioid-induced constipation (OIC) while providing effective pain relief. This review provides an updated analysis of the literature of the last decade regarding the use of oxycodone/naloxone in the management of severe cancer pain. Through a comprehensive search of databases, studies focusing on the efficacy, safety, and patient experience of oxycodone/naloxone's prolonged release in severe cancer pain management were identified. Furthermore, the literature discusses the mechanism of action of naloxone in mitigating OIC without compromising opioid analgesia. Overall, the evidence suggests that oxycodone/naloxone combination therapy offers a valuable option for effectively managing severe cancer pain while minimizing opioid-induced constipation, thereby improving patients' quality of life. However, further research is needed to optimize dosing regimens, evaluate long-term safety, and assess patient outcomes in diverse cancer populations.

Pain Control Associated With Gabapentinoid Prescription After Elective Total Knee Arthroplasty

BACKGROUND

Gabapentinoid (GABA) prescribing has substantially increased as a nonopioid analgesics for surgical conditions. We examined the effectiveness of GABA use for postoperative pain control among patients receiving total knee arthroplasty (TKA).

METHODS

This retrospective cohort study using 2016 to 2019 data from a 20% national sample of Medicare enrollees included patients aged 66 and over years who received an elective TKA, were discharged to home, received home health care, and had both admission and discharge assessments of pain (n = 35,186). Study outcomes were pain score difference between admission and discharge and less-than-daily pain interfering with activity at discharge. Opioid and GABA prescriptions after surgery and receipt of nerve block within 3 days of surgery were also assessed.

RESULTS

There were 30% of patients who had a pain score decrease of 3 to 4 levels and 55.8% had pain score decreases of 1 to 2 levels. In multivariable analyses, receiving a nerve block was significantly associated with pain score reduction. A GABA prescription increased the magnitude of pain score reduction among those receiving a nerve block. Results from inverse probability weighted analysis with propensity score showed that coprescribing of GABA and low-dose opioid was associated with significantly lower pain scores.

CONCLUSIONS

Post-TKA opioid use was not associated with pain score reduction. Receiving a nerve block was associated with a modest pain score reduction. Co-prescribing GABA with low-dose opioid or receiving a nerve block was associated with increasing magnitudes of pain reduction. Further research should identify alternatives to opioid use for managing postoperative TKA pain.

Dualism, allosteric modulation, and biased signaling of opioid receptors: Future therapeutic potential

Opioids are still the drugs of choice for the treatment of acute post-surgical pain and chronic cancer pain. Overprescribing of these drugs has given rise to an "opioid crisis" in some countries. In this context, attention has been drawn to the therapeutic potential of various ligands that act as allosteric modulators of orthosteric binding sites and modulate the drug's activity, affinity, potency, and even efficacy.

Assessment of Quercetin Antiemetic Properties: In Vivo and In Silico Investigations on Receptor Binding Affinity and Synergistic Effects

Quercetin (QUA), a flavonoid compound, is ubiquitously found in plants and has demonstrated a diverse range of biological activities. The primary objective of the current study is to assess the potential antiemetic properties of QUA using an in vivo and in silico approach. In this experiment, 4-day-old chicks were purchased to induce emesis by orally administering copper sulfate pentahydrate (CuSO4·5H2O) at a dose of 50 mg/kg (orally). Domperidone (DOM) (6 mg/kg), Hyoscine (HYS) (21 mg/kg), and Ondansetron (OND) (5 mg/kg) were treated as positive controls (PCs), and distilled water and a trace amount of Tween 80 mixture was employed as a negative control (NC). QUA was given orally at two distinct doses (25 and 50 mg/kg). Additionally, QUA (50 mg/kg) and PCs were administered separately or in combination to assess their antagonistic or synergistic effects on the chicks. The binding affinity of QUA and referral ligands towards the serotonin receptor (5HT3), dopamine receptors (D2 and D3), and muscarinic acetylcholine receptors (M1-M5) were estimated, and ligand-receptor interactions were visualized through various computational tools. In vivo findings indicate that QUA (25 and 50 mg/kg) has a significant effect on reducing the number of retches (16.50 ± 4.65 and 10.00 ± 4.19 times) and increasing the chick latency period (59.25 ± 4.75 and 94.25 ± 4.01 s), respectively. Additionally, QUA (50 mg/kg) in combination with Domperidone and Ondansetron exhibited superior antiemetic effects, reducing the number of retches and increasing the onset of emesis-inducing time. Furthermore, it is worth noting that QUA exhibited the strongest binding affinity against the D2 receptor with a value of -9.7 kcal/mol through the formation of hydrogen and hydrophobic bonds. In summary, the study found that QUA exhibited antiemetic activity in chicks, potentially by interacting with the D2 receptor pathway.

Nomogram for predicting opioid-induced nausea and vomiting for cancer pain patients

OBJECTIVE

Opioid-induced nausea and vomiting are frequently observed as an adverse effect in the treatment of cancer-related pain. The factors that affect OINV in cancer patients remain unclear. In this study, we developed a nomogram for predicting the occurrence of OINV in this population using retrospective clinical data.

METHODS

We collected data from 416 cancer pain patients, 70% of whom used the training set to analyze demographic and clinical variables. We used multivariate logistic regression to identify significant factors associated with OINV. Then, we construct a prediction nomogram. The validation set comprises the remaining 30%. The reliability of the nomogram is evaluated by bootstrap resampling.

RESULTS

Using multivariate logistic regression, we identified five significant factors associated with OINV. The C-index was 0.835 (95% confidence interval [CI], 0.828-0.842) for the training set and 0.810 (95% CI, 0.793-0.826) for the validation set. The calibrated curves show a good agreement between the predicted and actual occurrence of OINV.

CONCLUSION

In a retrospective study based on five saliency-found variables, we developed and proved a reliable nomogram model to predict OINV in cancer pain patients. Future prospective studies should assess the model's reliability and usefulness in clinical practice.

Opioid-induced Neurotoxicity in Patients with Cancer Pain

OPINION STATEMENT

Opioid-induced neurotoxicity (OINT) is a neuropsychiatric syndrome observed with opioid therapy. The mechanism of OINT is thought to be multifactorial, and many risk factors may facilitate its development. If symptoms of OINT are seen, the prescriber should consider hydration, discontinuation of the offending opioid drug, or switching of opioid medication, or the use of some adjuvants. Multiple factors like inter- and intraindividual differences in opioid pharmacology may influence the accuracy of dose calculations for opioid switching. Experience and clinical judgment in a specialistic palliative care setting should be used and individual patient characteristics considered when applying any conversion table.

Synthesis, In Silico Logp Study, and In Vitro Analgesic Activity of Analogs of Tetrapeptide FELL

BACKGROUND

The inflammatory process represents a specific response of the organism's immune system. More often, it is related to the rising pain in the affected area. Independently of its origin, pain represents a complex and multidimensional acute or chronic subjective unpleasant perception. Currently, medical doctors prescribe various analgesics for pain treatment, but unfortunately, many of them have adverse effects or are not strong enough to suppress the pain. Thus, the search for new pain-relieving medical drugs continues.

METHODS

New tetrapeptide analogs of FELL with a generaanalgesic-Glu-X3-X4-Z, where X = Nle, Ile, or Val and Z = NH2 or COOH, containing different hydrophobic amino acids at positions 3 and 4, were synthesized by means of standard solid-phase peptide synthesis using the Fmoc/OtBu strategy in order to study the influence of structure and hydrophobicity on the analgesic activity. The purity of all compounds was monitored by HPLC, and their structures were proven by ESI-MS. Logp values (partition coefficient in octanol/water) for FELL analogs were calculated. Analgesic activity was examined by the Paw-pressure test (Randall-Selitto test).

RESULTS

The obtained results reveal that Leu is the best choice as a hydrophobic amino acid in the FELL structure.

CONCLUSIONS

The best analgesic activity is found in the parent compound FELL and its C-terminal amide analog.

Improvement in patient-reported pain among patients with metastatic cancer and its association with opioid prescribing

PURPOSE

Opioids are a mainstay of cancer pain management; however, patients with metastatic cancer are often excluded from studies, leading to a lack of evidence on whether increased prescribing (dosage and/or duration) results in improved outcomes for this population. This study aimed to investigate whether increased opioid prescribing is associated with an improvement in patient-reported pain among patients with metastatic cancer.

PATIENTS AND METHODS

A retrospective cohort of all adult patients diagnosed with stage IV cancers, who completed at least two patient-reported outcomes (PROs) within 30 days of each other, was identified from administrative data. Opioid prescriptions were categorized by dosage level and number of prescription days. Multivariable logistic regression was used to investigate the association between opioid prescribing and clinically important improvement in pain score (≥ 1 point change on the Edmonton Symptom Assessment System).

RESULTS

A total of 2169 patients were included, 770 (35.5%) of whom had active opioid prescription between PROs, with an average daily dosage of 86.1 mg of oral morphine equivalent. Active prescription was associated with improvement in pain (OR = 2.17, P < 0.001). However, among patients with active prescription, neither dosage nor number of prescription days was significantly associated with pain improvement.

CONCLUSION

Opioid prescription is important for treating cancer-related pain; however, increased dosage or duration may not be leading to greater improvements in pain. Patients with metastatic cancer who are receiving increased opioid prescribing may have difficult-to-treat pain and may benefit from multidisciplinary pain management strategies to supplement opioid prescription and improve outcomes.

The Top 100 Cited Articles on Acupuncture in the Last 20 Years: A Bibliometric Analysis

BACKGROUND

Acupuncture has gained increasing international attention in recent decades. The act of incorporating acupuncture treatment into the routine treatment of COVID-19 in China drove us to review the 100 most influential articles of the last 20 years to learn about the current status and trends of acupuncture.

METHOD

Articles related to acupuncture from January 1, 2001, to July 4, 2022, were searched in the Clarivate Analytics Web of Science Core Collection database. The top 100 most cited publications were selected, and information was extracted. Software such as VOSviewer, GraphPad Prism, Scimago Graphica, and CiteSpace were used to visualize and analyze the extracted data.

RESULT

The 100 most cited articles were identified, with an average of 218 citations (range: 131-625). The majority of the top 100 articles were from the USA (n = 53). The institution that published the most highly cited papers was Harvard University (n = 16). The most influential team was Klaus Linde's group. Pain was the top-ranked journal in terms of the number of publications. The largest clusters for co-occurrence keyword analysis focused on acupuncture and electroacupuncture analgesia and brain imaging responses to acupuncture stimulation via functional MRI. The two highest strength burst keywords were "randomized controlled trials" and "osteoarthritis," with "randomized controlled trials" being a consistent burst keyword from 2011 to the present.

CONCLUSION

This study provides insight into articles of historical significance in the field of acupuncture through bibliometric analysis. These data should provide clinicians and researchers with insight into future directions related to acupuncture.

Hintergrund

Die Akupunktur hat in den vergangenen Jahrzehnten zunehmend die internationale Aufmerksamkeit auf sich gezogen. Die Einbeziehung der Akupunktur in die Routinebehandlung von COVID-19 in China hat uns dazu veranlasst, die 100 einflussreichsten Artikel der letzten 20 Jahre zu überprüfen, um etwas über den aktuellen Stand und die Trends in der Akupunktur zu erfahren.

Methode

Artikel mit Bezug zu Akupunktur vom 1. Januar 2001 bis 4. Juli 2022 wurden in der Clarivate Analytics Web of Science Core Collection Datenbank gesucht. Die 100 am häufigsten zitierten Veröffentlichungen wurden ausgewählt und die Informationen wurden extrahiert. Visualisierung und Analyse der extrahierten Daten erfolgten mithilfe der Software VOSviewer, GraphPad Prism, Scimago Graphica und CiteSpace.

Ergebnis

Es wurden die 100 am häufigsten zitierten Artikel ermittelt mit durchschnittlich 218 Zitierungen (Spanne: 131 bis 625). Der Großteil der 100 meistzitierten Artikel stammte aus den Vereinigten Staaten (n = 53). Die Institution, die die meisten zitierten Artikel veröffentlichte, war die Harvard-Universität (n = 16). Das einflussreichste Team war die Gruppe von Klaus Linde. Was die Zahl der Veröffentlichungen betrifft, war Pain die am häufigsten zitierte Zeitschrift. Bei der Analyse der Koinzidenz von Schlüsselwörtern lag der Fokus der größten Cluster auf Akupunktur-und Elektroakupunktur-Analgesie sowie auf den Reaktionen auf Akupunkturstimulation in den bildgebenden Untersuchungen des Gehirns mittels funktioneller MRT. Die beiden stärksten Burst-Schlüsselwörter waren “randomisierte kontrollierte Studien” und “Osteoarthritis,” wobei “randomisierte kontrollierte Studien” von 2011 bis heute durchgängig ein Burst-Schlüsselwort ist.

Schlussfolgerung

Diese Studie bietet einen Einblick in historisch bedeutsame Artikel auf dem Gebiet der Akupunktur mittels bibliometrischer analyse. Diese Daten sollen Klinikern und Forschern einen Einblick in zukünftige Richtungen im Zusammenhang mit Akupunktur geben.

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.

Remote local photoactivation of morphine produces analgesia without opioid-related adverse effects

BACKGROUND AND PURPOSE

Opioid-based drugs are the gold standard medicines for pain relief. However, tolerance and several side effects (i.e. constipation and dependence) may occur upon chronic opioid administration. Photopharmacology is a promising approach to improve the benefit/risk profiles of these drugs. Thus, opioids can be locally activated with high spatiotemporal resolution, potentially minimizing systemic-mediated adverse effects. Here, we aimed at developing a morphine photo-derivative (photocaged morphine), which can be activated upon light irradiation both in vitro and in vivo.

EXPERIMENTAL APPROACH

Light-dependent activity of pc-morphine was assessed in cell-based assays (intracellular calcium accumulation and electrophysiology) and in mice (formalin animal model of pain). In addition, tolerance, constipation and dependence were investigated in vivo using experimental paradigms.

KEY RESULTS

In mice, pc-morphine was able to elicit antinociceptive effects, both using external light-irradiation (hind paw) and spinal cord implanted fibre-optics. In addition, remote morphine photoactivation was devoid of common systemic opioid-related undesired effects, namely, constipation, tolerance to the analgesic effects, rewarding effects and naloxone-induced withdrawal.

CONCLUSION AND IMPLICATIONS

Light-dependent opioid-based drugs may allow effective analgesia without the occurrence of tolerance or the associated and severe opioid-related undesired effects.

LINKED ARTICLES

This article is part of a themed issue on Advances in Opioid Pharmacology at the Time of the Opioid Epidemic. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v180.7/issuetoc.

S-ketamine promotes postoperative recovery of gastrointestinal function and reduces postoperative pain in gynecological abdominal surgery patients: a randomized controlled trial

BACKGROUND

This prospective randomized controlled study was designed to evaluate the effect of S-ketamine with sufentanil given intraoperatively and postoperatively on recovery of gastrointestinal (GI) function and postoperative pain in gynecological patients undergoing open abdomen surgery.

METHODS

One hundred gynecological patients undergoing open abdomen surgery were randomized into an S-ketamine group (group S) or placebo group (0.9% saline; group C). Anesthesia was maintained with S-ketamine, sevoflurane, and remifentanil-propofol target-controlled infusion in group S and with sevoflurane and remifentanil-propofol target-controlled infusion in group C. All patients were connected to patient-controlled intravenous analgesia (PCIA) pump at the end of the surgery with sufentanil, ketorolac tromethamine, and tropisetron in group C and additional S-ketamine in group S. The primary outcome was the time of first postoperative flatus, and the secondary outcome was postoperative pain score of patients. Postoperative sufentanil consumption within the first postoperative 24 h and adverse events such as nausea and vomiting were recorded.

RESULTS

The time of first postoperative flatus in group S was significantly shorter (mean ± SD, 50.3 ± 13.5 h) than that in group C (mean ± SD, 56.5 ± 14.3 h, p = 0.042). The patient's visual analog scale (VAS) pain score 24 h after surgery at rest was significantly lower in group S than in group C (p = 0.032). There were no differences in sufentanil consumption within the first postoperative 24 h, postoperative complications related to PCIA between the two groups.

CONCLUSIONS

S-ketamine accelerated postoperative GI recovery and reduced 24 h postoperative pain in patients undergoing open gynecological surgery.

TRIAL REGISTRATION

ChiCTR2200055180. Registered on 02/01/2022. It is a secondary analysis of the same trial.

Optimising psychological treatment for pain after breast cancer: a factorial design study protocol in Denmark

INTRODUCTION

One in five breast cancer (BC) survivors are affected by persistent pain years after completing primary treatment. While the efficacy of psychological interventions for BC-related pain has been documented in several meta-analyses, reported effect sizes are generally modest, pointing to a need for optimisation. Guided by the Multiphase Optimization Strategy, the present study aims to optimise psychological treatment for BC-related pain by identifying active treatment components in a full factorial design.

METHODS AND ANALYSIS

The study uses a 2×3 factorial design, randomising 192 women with BC-related pain (18-75 years) to eight experimental conditions. The eight conditions consist of three contemporary cognitive-behavioural therapy components, namely: (1) mindful attention, (2) decentring, and (3) values and committed action. Each component is delivered in two sessions, and each participant will receive either zero, two, four or six sessions. Participants receiving two or three treatment components will be randomised to receive them in varying order. Assessments will be conducted at baseline (T1), session by session, every day for 6 days following the first session in each treatment component, at post-intervention (T2) and at 12-week follow-up (T3). Primary outcomes are pain intensity (Numerical Rating Scale) and pain interference (Brief Pain Inventory interference subscale) from T1 to T2. Secondary outcomes are pain burden, pain quality, pain frequency, pain catastrophising, psychological distress, well-being and fear of cancer recurrence. Possible mediators include mindful attention, decentring, and pain acceptance and activity engagement. Possible moderators are treatment expectancy, treatment adherence, satisfaction with treatment and therapeutic alliance.

ETHICS AND DISSEMINATION

Ethical approval for the present study was received from the Central Denmark Region Committee on Health Research Ethics (no: 1-10-72-309-40). Findings will be made available to the study funders, care providers, patient organisations and other researchers at international conferences, and published in international, peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov Registry (NCT05444101).

Identifying risk factors for opioid-induced neurotoxicity in cancer patients receiving oxycodone

PURPOSE

The aim of this study was to determine the frequency of opioid-induced neurotoxicity (OIN) in cancer patients receiving oral controlled-release oxycodone and to define risk factors for OIN.

METHODS

This was a single-center, retrospective study of hospitalized adult cancer patients receiving oral controlled-release oxycodone between April 1, 2013, and April, 30, 2020. The onset of OIN within 30 days after oxycodone initiation in the study patients was investigated. OIN was defined as any of the following: delirium, hallucinations (visual or auditory), seizure, myoclonus, hyperesthesia, and excessive somnolence. Multivariate logistic regression analysis was performed to identify risk factors for OIN in patients receiving oxycodone.

RESULTS

In total, 520 patients were included in this study. The number of patients with OIN was 65 (12.5%). The median time until onset of OIN after oxycodone initiation was 7.5 days. Multivariate logistic regression analysis revealed that age ≥ 65 years (OR = 2.74, 95% CI [1.30-5.78], p = 0.008), total bilirubin ≥ 1.3 mg/dL (OR = 4.85, 95% CI [2.13-11.0], p < 0.001), and concomitant use of pregabalin or mirogabalin (OR = 3.11, 95% CI [1.47-6.61], p = 0.003) were significant independent risk factors for OIN.

CONCLUSION

Age ≥ 65 years, liver dysfunction, and concomitant use of pregabalin or mirogabalin were independent risk factors for OIN in patients receiving oxycodone. Patients with these risk factors who are receiving oxycodone should be monitored for OIN, especially early in the administration of oxycodone.

Crosstalk between Mu-Opioid receptors and neuroinflammation: Consequences for drug addiction and pain

Mu-Opioid Receptors (MORs) are well-known for participating in analgesia, sedation, drug addiction, and other physiological functions. Although MORs have been related to neuroinflammation their biological mechanism remains unclear. It is suggested that MORs work alongside Toll-Like Receptors to enhance the release of pro-inflammatory mediators and cytokines during pathological conditions. Some cytokines, including TNF-α, IL-1β and IL-6, have been postulated to regulate MORs levels by both avoiding MOR recycling and enhancing its production. In addition, Neurokinin-1 Receptor, also affected during neuroinflammation, could be regulating MOR trafficking. Therefore, inflammation in the central nervous system seems to be associated with altered/increased MORs expression, which might regulate harmful processes, such as drug addiction and pain. Here, we provide a critical evaluation on MORs' role during neuroinflammation and its implication for these conditions. Understanding MORs' functioning, their regulation and implications on drug addiction and pain may help elucidate their potential therapeutic use against these pathological conditions and associated disorders.

Mechanisms of cancer pain

Personalised and targeted interventions have revolutionised cancer treatment and dramatically improved survival rates in recent decades. Nonetheless, effective pain management remains a problem for patients diagnosed with cancer, who continue to suffer from the painful side effects of cancer itself, as well as treatments for the disease. This problem of cancer pain will continue to grow with an ageing population and the rapid advent of more effective therapeutics to treat the disease. Current pain management guidelines from the World Health Organisation are generalised for different pain severities, but fail to address the heterogeneity of mechanisms in patients with varying cancer types, stages of disease and treatment plans. Pain is the most common complaint leading to emergency unit visits by patients with cancer and over one-third of patients that have been diagnosed with cancer will experience under-treated pain. This review summarises preclinical models of cancer pain states, with a particular focus on cancer-induced bone pain and chemotherapy-associated pain. We provide an overview of how preclinical models can recapitulate aspects of pain and sensory dysfunction that is observed in patients with persistent cancer-induced bone pain or neuropathic pain following chemotherapy. Peripheral and central nervous system mechanisms of cancer pain are discussed, along with key cellular and molecular mediators that have been highlighted in animal models of cancer pain. These include interactions between neuronal cells, cancer cells and non-neuronal cells in the tumour microenvironment. Therapeutic targets beyond opioid-based management are reviewed for the treatment of cancer pain.

Maddalena Opioid Switching Score in patients with cancer pain

ABSTRACT

Evaluation of opioid switching (OS) for cancer pain has not been properly assessed. The aim of this study was to assess an integrated score (Maddalena Opioid Switching Score) as a simple and repeatable tool to evaluate the outcomes of OS, facilitating the interpretation and comparison of studies, and information exchange among researchers. The integrated score took into account pain intensity, intensity of opioid-related symptoms, and cognitive function by using an author's formula. Physical and psychological symptoms were evaluated by the Edmonton Symptom Assessment Scale and Patient Global Impression (PGI) by the minimal clinically important difference. One hundred six patients were analyzed. Ninety-five patients were switched successfully, and 11 patients underwent a further OS and/or an alternative procedure. The Maddalena Opioid Switching Score significantly decreased after OS and was highly correlated to PGI of improvement ( P < 0.0005). In patients with unsuccessful OS, no significant changes in the Maddalena Opioid Switching Score and PGI were observed. A significant reduction in Edmonton Symptom Assessment Scale items intensity was observed after OS. The Maddalena Opioid Switching Score resulted to be a sensitive instrument for measuring the clinical improvement produced by OS.

Ultrasound-Guided Peripheral Nerve Blocks: A Practical Review for Acute Cancer-Related Pain

PURPOSE OF REVIEW

Ultrasound-guided regional techniques, including catheter-based approaches, are a subset of interventional therapies that have gained interest as an option for managing acute cancer-related pain. The authors sought to review the available published evidence and to discuss practical recommendations for expanding access to such therapies.

RECENT FINDINGS

In a MEDLINE/Pubmed search of ultrasound-guided peripheral nerve blocks and peripheral nerve catheters for specific anatomic targets, a total of 28 case reports and case series were identified. Included studies described improved analgesia and reduced opioid requirements with highly variable duration of effect. Current level of evidence remains limited. Pain is a symptom that markedly impacts the quality of life of cancer patients and ultrasound-guided regional techniques are a promising therapeutic option albeit with a limited evidence base. Practical recommendations offered for coordinating access to such therapies in the inpatient, emergency department, and outpatient settings may expand interest and facilitate higher quality research.

A peripheral opioid antagonist for treating urinary retention induced by opioids: A case report

BACKGROUND

Urinary retention is a poorly studied opioid-related adverse effect. There is a paucity of data regarding the treatment of such disturbance in patients with advanced cancer receiving opioids.

ACTUAL CASE

A young man, without comorbidities, was receiving 30 mg/day of oxycodone for abdominal pain due to pancreatic cancer, unsuccessfully. He also complained of severe urinary retention that developed after initiation of opioid therapy. Methadone therapy was effective on pain intensity, but bladder dysfunction persisted.

POSSIBLE COURSES OF ACTION

Only anedoctal experience exists for opioid-induced urinary retention. The options included alpha-receptor blockers and flavoxate, which are symptomatic drugs, not addressed to the possible mechanism.

FORMULATION OF A PLAN

The use of a peripheral opioid antagonist was planned, according to the presumed mechanism of urinary retention. Thus, naldemedine 200 mcg was prescribed for relieving urinary retention.

OUTCOME

The day after starting naldemedine, urinary retention completely reversed and pain was well-controlled.

LESSONS

The rational of using naldemedine was based on the component of opioid-induced urinary retention due to involvement of peripheral receptors in the bladder and sphincter.

VIEW

In this case report, the effect of the peripheral opioid antagonist was prompt and long-lasting. Future studies of this neglected adverse effect of opioids should be performed to confirm this observation.

Long-term opioid treatment and endocrine measures in patients with cancer-related pain: a systematic review

OBJECTIVES

Opioid analgesics are the main stay for cancer pain management; however, long-term opioid treatment (L-TOT) may suppress the endocrine system. This systemic review aimed at investigating effects of L-TOT on the endocrine system in patients with cancer-related pain.

METHODS

A search on MEDLINE, EMBASE and Web of Science databases was performed. Inclusion criteria were clinical studies investigating endocrine measures in adult patients with cancer-related pain in L-TOT (≥4 weeks). Outcomes and quality of evidence were assessed.

RESULTS

A total of 252 abstracts were identified; out of which 247 were excluded and five cross-sectional studies were included and analyzed. L-TOT was associated with lower serum concentration levels of total- and free testosterone in males, follicular stimulating hormone in females, and luteinizing hormone in both sexes. Moreover, higher morphine equivalent daily doses (MEDDs) were correlated with higher levels of cortisol and lower levels of LH in both sexes, and lower levels of total- and free testosterone in males. Sexual dysfunction was associated with low sex hormone levels. Level of evidence was low/very low.

CONCLUSIONS

The studies identified demonstrated that patients with cancer-related pain in L-TOT may have gonadal hypofunction causing sexual dysfunction, which may be correlated with opioid dose level. In addition, high serum concentrations of cortisol were positively correlated with high opioid dose levels. However, the evidence was weak and further research is necessary. PROSPERO, ID-number: CRD42020213059.

Advances in the clinical application of oxycodone in the perioperative period

To review the research progress of pure opioid receptor agonist oxycodone. The research progress of oxycodone in terms of pharmacokinetics, pharmacodynamics, adverse reactions, clinical application, combined medication and new progress in clinical application was summarized by referring to the literature. Oxycodone is a semi-synthetic thebaine derivative of opioid alkaloids, and is a pure opioid μ and κ receptor agonist. The main action sites are the central nervous system and visceral smooth muscle. Due to its advantages of low adverse reactions, good analgesic effects, and a wide range of safe doses, the drug has been widely used in the control of acute and chronic postoperative pain, as well as malignant and non-malignant pain. Since the end of the 20^th century, researchers have begun to formulate antipyretic analgesics, opioid receptor agonists, opioid receptor antagonists, dopamine receptor antagonists and other drugs with oxycodone in different proportions to enhance the analgesic effect. At the same time, it can reduce the dosage of oxycodone and reduce its adverse reactions, so as to achieve the purpose of limiting opioid abuse. With the continuous research on the efficacy and safety of oxycodone in the perioperative period at home and abroad, oxycodone has become the only dual-opioid potent analgesic that can be used in clinical work.

Efficacy and Safety of Transcutaneous Electrical Acupoint Stimulation for Postoperative Pain: A Meta-Analysis of Randomized Controlled Trials

Objective

This meta-analysis aims to evaluate the effectiveness and safety of transcutaneous electrical acupoint stimulation (TEAS) in treating post-operative pain.

Methods

This meta-analysis was registered in PROSPERO (CRD42021286753). We searched PubMed, Embase, and the Cochrane Library for relevant randomized controlled trials (RCTs) about TEAS in treating postoperative pain that were published before November 2021. The primary outcome was visual analogue scale (VAS) within 24 h after surgery. The secondary outcomes included postoperative opioid analgesic drug consumption and the occurrence of adverse reactions within the postoperative 24–72 h. Adverse reactions included dizziness, nausea, and vomiting. Continuous variables were analyzed using mean difference (MDs) or standardized mean difference (SMDs) and 95% CIs. Relative risk (RR) and 95% CI were used for dichotomous data. The data were pooled and analyzed by RevMan 5.4 and STATA15.0 software.

Results

Seventeen trials with 1375 participants were included. The current results suggested that application of TEAS showed obvious superiority in reducing VAS scores (SMD = −1.51, 95% CI = −2.20∼−0.82, I2 = 96%). Subgroup analysis was performed according to open surgery and minimally invasive surgery. VAS scores were decreased after surgery at 24 h (SMD = −0.84, 95% CI = −1.07∼−0.6, I2 = 96%; SMD = −0.88, 95% CI = −1.02∼−0.75, I2 = 96%). The incidence of postoperative dizziness and nausea and vomiting was significantly lower in the TEAS group within postoperative 24–72 h (RR = 0.48, 95% CI = 0.34∼0.68, I2 = 0%; RR = 0.66, 95% CI = 0.44∼1.01, I2 = 69%; and RR = 0.49, 95% CI = 0.24∼1.00, I2 = 51%). Postoperative opioid analgesics were also reduced in the TEAS group within 72 h after surgery (SMD = −2.10, 95% CI = −3.37∼−0.82, I2 = 96%).

Conclusions

TEAS can reduce postoperative pain as well as the incidence of dizziness, nausea, and vomiting and the number of analgesics used after surgery. TEAS is a reasonable modality to incorporate into a multimodal management approach for postoperative pain.

Rational Design, Chemical Syntheses, and Biological Evaluations of Peripherally Selective Mu Opioid Receptor Ligands as Potential Opioid Induced Constipation Treatment

Opioid-induced constipation (OIC) is a common adverse effect of opioid analgesics. Peripherally acting μ opioid receptor antagonists (PAMORAs) can be applied in the treatment of OIC without compromising the analgesic effects. NAP, a 6β-N-4-pyridyl-substituted naltrexamine derivative, was previously identified as a potent and selective MOR antagonist mainly acting peripherally but with some CNS effects. Herein, we introduced a highly polar aromatic moiety, for example, a pyrazolyl or imidazolyl ring to decrease CNS MPO scores in order to reduce passive BBB permeability. Four compounds 2, 5, 17, and 19, when administered orally, were able to increase intestinal motility during morphine-induced constipation in the carmine red dye assays. Among them, compound 19 (p.o.) improved GI tract motility by 75% while orally administered NAP and methylnaltrexone showed no significant effects at the same dose. Thus, this compound seemed a promising agent to be further developed as an oral treatment for OIC.

Design, Synthesis, and Biological Evaluation of NAP Isosteres: A Switch from Peripheral to Central Nervous System Acting Mu-Opioid Receptor Antagonists

The μ opioid receptor (MOR) has been an intrinsic target to develop treatment of opioid use disorders (OUD). Herein, we report our efforts on developing centrally acting MOR antagonists by structural modifications of 17-cyclopropylmethyl-3,14-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl) carboxamido] morphinan (NAP), a peripherally acting MOR-selective antagonist. An isosteric replacement concept was applied and incorporated with physiochemical property predictions in the molecular design. Three analogs, namely, 25, 26, and 31, were identified as potent MOR antagonists in vivo with significantly fewer withdrawal symptoms than naloxone observed at similar doses. Furthermore, brain and plasma drug distribution studies supported the outcomes of our design strategy on these compounds. Taken together, our isosteric replacement of pyridine with pyrrole, furan, and thiophene provided insights into the structure-activity relationships of NAP and aided the understanding of physicochemical requirements of potential CNS acting opioids. These efforts resulted in potent, centrally efficacious MOR antagonists that may be pursued as leads to treat OUD.

Role of Ketamine and Opioid Rotation in the Management of Opioid Induced Hyperalgesia in a Patient With Acute Promyelocytic Leukemia

Introduction

Opioid analgesics are commonly used to manage moderate to severe cancer related pain. However long-term use of opioids has been known to lead to several unintended side effects, including opioid induced hyperalgesia (OIH) which is defined as the paradoxical increase in pain sensitization to pain stimulus following opioid exposure. Currently there are limited reports on the association between patients with cancer and OIH, and this phenomenon is rarely described in patients with leukemia or lymphoma. Here we report a patient with acute promyelocytic leukemia who developed opioid induced hyperalgesia following rapid escalation of opioids.

Case report

A 36-year-old female being treated for acute promyelocytic leukemia presented with rapidly worsening acute on chronic hip pain requiring increasing opioid requriements. Given the rapid escalation of opioid dose with minimal response and physical exam findings consistent with allodynia/hyperalgesia a diagnosis of opioid induced hyperalgesia was made.

Management and outcome

Following recognition of opioid induced hyperalgesia, the patient was managed with opioid rotation and ketamine, which resulted in prompt alleviation of pain.

Discussion

Opioid induced hyperalgesia is likely an underrecognized phenomenon in patients with cancer-related pain. A high index of clinical suspicion are necessary for diagnosis and proper management of this disease entity.

Incidence of Delirium With Different Oral Opioids in Previously Opioid-Naive Patients

Background: Opioids are known to induce delirium, but few studies have closely investigated differences in incidence of delirium among different opioids. Objectives: To determine whether there is a clinically significant difference in the incidence of delirium between oral opioids in previously opioid-naive patients. Methods: Subjects were 259 opioid-naive in-patients with cancer who were started on morphine sulfate, oxycodone hydrochloride, or tapentadol hydrochloride extended-release tablets at our hospital between August 1, 2014, and September 30, 2018. The incidence of delirium during the first week of treatment was compared between the drugs. Results: The incidence of delirium was 4.8% (n = 83) for morphine sulfate, 6.9% (n = 131) for oxycodone hydrochloride, and 6.7% (n = 45) for tapentadol hydrochloride. The incidence did not significantly differ between oxycodone hydrochloride (OR = .69, 95% CI = .20–2.30, P [Fisher’s exact test] = .77) or tapentadol hydrochloride (OR = .71, 95% CI = .15–3.32, P [Fisher’s exact test] = .70) and morphine sulfate (reference group). Moreover, the incidence did not significantly differ between tapentadol hydrochloride (OR = 1.03, 95% CI = .27–3.00, P [Fisher’s exact test] = 1.00) and oxycodone hydrochloride (reference group). Conclusion: The incidence of delirium in previously opioid-naive patients did not differ significantly among morphine sulfate, oxycodone hydrochloride, and tapentadol hydrochloride extended-release tablets, suggesting similar risk of delirium in opioid-naive patients among these oral opioids.

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.

Tapentadol Safety and Patient Characteristics Associated with Treatment Discontinuation in Cancer Therapy: A Retrospective Multicentre Study in Japan

INTRODUCTION

Tapentadol has analgesic effects comparable to those of conventional opioids and is associated with fewer side effects, including gastrointestinal symptoms, drowsiness, and dizziness, than other opioids. However, the safety of tapentadol in the Japanese population remains unclear; the present multicentre study aimed to examine the safety of tapentadol and the characteristics of patients likely to discontinue this treatment owing to adverse events.

METHODS

The safety of tapentadol was assessed retrospectively in patients with any type of cancer treated between August 18, 2014 and October 31, 2019 across nine institutions in Japan. Patients were examined at baseline and at the time of opioid discontinuation. Multivariate analysis was performed to identify factors associated with tapentadol discontinuation owing to adverse events.

RESULTS

A total of 906 patients were included in this study, and 685 (75.6%) cases were followed up until tapentadol cessation for any reason. Among patients who discontinued treatment, 119 (17.4%) did so because of adverse events. Among adverse events associated with difficulty in taking medication, nausea was the most common cause of treatment discontinuation (4.7%), followed by drowsiness (1.8%). Multivariate analysis showed that those who were prescribed tapentadol by a palliative care physician (odds ratio [OR] 2.60, 95% confidence interval [CI] 1.36-4.99, p = 0.004), patients switching to tapentadol due to side effects from previous opioids (OR 2.19, 95% CI 1.05-4.56, p = 0.037), and patients who did not use naldemedine (OR 5.06, 95% CI 2.47-10.37, p < 0.0001) had an increased risk of treatment discontinuation owing to adverse events.

CONCLUSIONS

This study presents the safety profile of tapentadol and the characteristics of patients likely to discontinue this treatment owing to adverse events in the Japanese population. Prospective controlled trials are required to evaluate the safety of tapentadol and validate the present findings.

TRIAL REGISTRATION NUMBER

UMIN 000044282 (University Hospital Medical Information Network).

Randomized Phase 3, Double-blind, Placebo-controlled Study of Prophylactic Gabapentin for the Reduction of Oral Mucositis Pain During the Treatment of Oropharyngeal Squamous Cell Carcinoma

PURPOSE

The purpose of this paper is to determine whether prophylactic gabapentin usage in patients undergoing definitive concurrent chemotherapy and radiation therapy (chemoRT) for oropharyngeal cancer (OPC) improves treatment-related oral mucositis pain, opioid use, and feeding tube (FT) placement.

METHODS AND MATERIALS

This double-blind, randomized phase 3 study for patients with locally advanced OPC undergoing chemoRT randomly allocated patients to prophylactic gabapentin (600 mg thrice daily) or placebo. The primary endpoint was change in Patient-Reported Oral Mucositis Symptom (PROMS) scores over the entire treatment period (baseline to 6 weeks post-radiation therapy [RT] follow-up) with higher scores indicating worse outcomes. Opioid requirements, FT placement, and other patient-reported quality of life (QOL) metrics (Functional Assessment of Cancer Therapy-Head and Neck [FACT-HN] and Patient-Reported Outcomes version of the National Cancer Institute Common Terminology Criteria for Adverse Events [PRO-CTCAE]) were assessed. Lower scores suggested poorer QOL with the FACT-HN questionnaire, and higher scores suggested worse outcomes with the PRO-CTCAE questionnaire. Questionnaires were administered at baseline, weekly during RT, and at 6 weeks post-RT follow-up. Repeated measures analysis of variance was used to detect differences in PROMS scores and change in opioid use from baseline. Wilcoxon rank sum tests were used to compare averages for the other secondary endpoints. A P value less than .05 was considered statistically significant.

RESULTS

Treatment arms were well balanced overall, including T and N staging and dosimetric variables. There were 58 patients analyzed. No significant difference was found in PROMS scores (mean 29.1, standard deviation [SD] 22.5 vs 20.1, SD 16.8 for gabapentin vs placebo, respectively, P = .11). The FACT-HN functional well-being index had a significant decrease in scores from baseline to follow-up in the gabapentin arm (median -6, interquartile range [IQR] -10.0 to -0.5 vs -1, IQR -5.5 to 3.0, P = .03). PRO-CTCAE scores increased significantly at follow-up for gabapentin (median 6.5, IQR 3.5-11.8 vs 1, IQR -2.0 to 6.0, P = .01). There was no significant difference in average or change in opioid use. FT placement was significantly higher in the gabapentin arm (62.1% vs 20.7%, P < .01).

CONCLUSIONS

This study suggests that prophylactic gabapentin is not effective in improving treatment-related oral mucositis symptoms in a select population of patients with OPC undergoing definitive chemoRT.

Prokinetic effects of diatrizoate meglumine (Gastrografin®) in a zebrafish for opioid-induced constipation model

Constipation is a common disease that reduces life quality. Drugs of various mechanisms are being developed to resolve this affliction. Intestinal motility can be easily monitored in zebrafish, and so we selected this organism to develop a constipation model to measure drug-induced prokinetic effects. In this study, intestinal motility was monitored in zebrafish by tracking intestinal transit using fluorescence, after which an opioid-induced constipation model was established using loperamide. We then evaluated the prokinetic effect of diatrizoate meglumine (Gastrografin®), which has been empirically used to treat post-operative ileus or adhesive small bowel obstructions. Diatrizoate meglumine was effective in promoting bowel movements in an opioid-induced zebrafish constipation model and its prokinetic effect was associated with an increased expression of interstitial cells of Cajal (ICC) markers. Therefore, the loperamide-induced zebrafish constipation model developed herein is a promising tool to evaluate novel constipation therapies.

Measurement of the nociceptive flexion reflex threshold in critically ill patients - a randomized observational pilot study

Background

Pain detection and treatment is a major challenge in the care of critically ill patients, rendered more complex by the need to take into consideration the risk of insufficient or excessive analgesia. The nociceptive flexion reflex threshold (NFRT) has become the established basis for measuring the level of analgesia in the perioperative context. However, it remains unclear whether NFRT measurement can be usefully applied to mechanically ventilated, analgosedated critically ill patients who are unable to communicate. Therefore, the aim of the present study was to investigate whether there is an association between the NFRT measurement and the Behavioral Pain Scale (BPS) in critically ill, analgosedated, and mechanically ventilated patients and whether the NFRT measurement can also detect potential excessive analgesia.

Methods

This prospective, observational, randomized single-center pilot study included patients admitted to the surgical Intensive Care Unit of University Hospital Ulm, Germany, all of whom were analgosedated and intubated. Major exclusion criteria were defined as the need for the administration of neuromuscular blocking agents or neurological diseases associated with peripheral nerve conduction restriction. Initial NFRT and BPS measurements were conducted within 12 h after admission. A structured pain assessment was performed at least twice daily until extubation throughout the observation period thereafter (Group A: BPS + NFRT, Group B: BPS).

Results

114 patients were included in the study. NFRT is associated negatively with BPS. NFRT was almost twice as high in patients with a Richmond Agitation Sedation Scale (RASS) score of -5 than in patients with a RASS score ≥ -4 (RASS -5 – NFRT: 59.40 vs. RASS -4 – NFRT: 29.00, p < 0.001).

Conclusions

NFRT measurement is associated negatively with the BPS in critically ill patients. NFRT measurement provides guidance for the evaluation of nociceptive processes in patients with RASS scores ≤ −4, in whom analgesia level is often difficult to assess. However, in order to identify excessive analgesia and derive therapeutic consequences, it is necessary to gradually decrease analgesics and sedatives until a stimulus threshold is reached at which the patient does not feel pain.

Trial Registration

Retrospectively registered in the German Clinical Trials Register, registration number DRKS00021149, date of registration: March 26, 2020. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00021149.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12871-021-01490-8.

Perioperative Multimodal General Anesthesia Focusing on Specific CNS Targets in Patients Undergoing Cardiac Surgeries: The Pathfinder Feasibility Trial

Multimodal general anesthesia (MMGA) is a strategy that utilizes the well-known neuroanatomy and neurophysiology of nociception and arousal control in designing a rational and clinical practical paradigm to regulate the levels of unconsciousness and antinociception during general anesthesia while mitigating side effects of any individual anesthetic. We sought to test the feasibility of implementing MMGA for seniors undergoing cardiac surgery, a high-risk cohort for hemodynamic instability, delirium, and post-operative cognitive dysfunction. Twenty patients aged 60 or older undergoing on-pump coronary artery bypass graft (CABG) surgery or combined CABG/valve surgeries were enrolled in this non-randomized prospective observational feasibility trial, wherein we developed MMGA specifically for cardiac surgeries. Antinociception was achieved by a combination of intravenous remifentanil, ketamine, dexmedetomidine, and magnesium together with bupivacaine administered as a pecto-intercostal fascial block. Unconsciousness was achieved by using electroencephalogram (EEG)-guided administration of propofol along with the sedative effects of the antinociceptive agents. EEG-guided MMGA anesthesia was safe and feasible for cardiac surgeries, and exploratory analyses found hemodynamic stability and vasopressor usage comparable to a previously collected cohort. Intraoperative EEG suppression events and postoperative delirium were found to be rare. We report successful use of a total intravenous anesthesia (TIVA)-based MMGA strategy for cardiac surgery and establish safety and feasibility for studying MMGA in a full clinical trial.

Clinical Trial Number:www.clinicaltrials.gov; identifier NCT04016740 (https://clinicaltrials.gov/ct2/show/NCT04016740).

Acupuncture Relieves Opioid-Induced Constipation in Clinical Cancer Therapy - A Meta-Analysis and Systematic Review

Cancer pain is a common problem in clinical cancer therapy. Opioid analgesia is one of the most effective drugs for pain relief with satisfying performance besides the side effect of opioid-induced constipation (OIC). Acupuncture, as a Chinese traditional non-invasive intervention, has been applied to clinical cancer pain management and functional constipation therapy. However, only a few studies have adopted this treatment for OIC patients. Due to limited numbers of investigated subjects and variability of application methods, including treatment apparatus, acupoints, durations, and sessions, the interpretation of acupuncture’s therapy effects from single-site randomized clinical trials (RCT) is limited. Therefore, we conducted a meta-analysis by collecting published data from Pubmed, Embase, Cochrane library, and Web of Science. Five RCTs focusing on the application of acupuncture with or without medication in OIC patients were included. An overall remission rate of 86.8% in the acupuncture-treated group was achieved, higher than the control group (78.9%; RR, 1.10, 95% CI [1.03, 1.18]). The symptom scores, reporting on defecation frequency, defecation straining, abdominal pain, defection time, and stool property, in acupuncture groups were lower than control groups with a standardized mean difference (SMD) of −2.21 [−4.15, −0.27]. The quality of life (QOL) for patients in the acupuncture treated group increased compared to the control group with reduced PAC-QOL scores (SMD, −1.02 [−1.78, −0.26]). Referring to the effects from pure acupuncture treatment (SMD, −0.43 [−0.83, −0.03]), the co-intervention of acupuncture and drugs (SMD, −1.77 [−2.51, −1.02]) improved the life quality of patients more remarkably (P < 0.05). Overall, our data confirmed the therapeutic effects of acupuncture in the treatment of OIC. The co-intervention of acupuncture with drugs improves the outcomes of OIC patients better than a single strategy. Combined therapy with both medicine and acupuncture has insightful potential for future clinical cancer patient management on constipation problems.

An Audio-Recorded Hypnosis Intervention for Chronic Pain Management in Cancer Survivors: A Randomized Controlled Pilot Study

This pilot study evaluated the feasibility, acceptability, and potential efficacy of a 4-week hypnosis audio-recording intervention in cancer survivors with chronic pain. Forty participants were randomly assigned to treatment (n = 21) or wait-list (n = 19) conditions. Pain intensity ratings were lower at Week 4 for both groups. The effect size for pain reduction in the treatment group was d = 0.25 from baseline to 4 weeks, and the interaction effect (Time x Group) was F = .024; η²_p = .001. The small interaction effect may be due to the availability of only one recording and large variability in dose. Qualitative data indicated that the intervention's benefits included participation in self-care, improved relaxation, and an opportunity to focus on oneself in a positive way. Further efficacy testing of an audio-recording intervention in a fully powered clinical trial is warranted.

Biological Effects on μ-Receptors Affinity and Selectivity of Arylpropenyl Chain Structural Modification on Diazatricyclodecane Derivatives

Opioid analgesics are clinically used to relieve severe pain in acute postoperative and cancer pain, and also in the long term in chronic pain. The analgesic action is mediated by μ-, δ-, and κ-receptors, but currently, with few exceptions for k-agonists, μ-agonists are the only ones used in therapy. Previously synthesized compounds with diazotricyclodecane cores (DTDs) have shown their effectiveness in binding opioid receptors. Fourteen novel diazatricyclodecanes belonging to the 9-propionyl-10-substituted-9,10-diazatricyclo[4.2.1.12,5]decane (compounds 20-23, 53, 57 and 59) and 2-propionyl-7-substituted-2,7-diazatricyclo[4.4.0.03,8]decane (compounds 24-27, 54, 58 and 60) series, respectively, have been synthesized and their ability to bind to the opioid μ-, δ- and κ-receptors was evaluated. Five of these derivatives, compounds 20, 21, 24, 26 and 53, showed μ-affinity in the nanomolar range with a negligible affinity towards δ- and κ-receptors and high μ-receptor selectivity. The synthesized compounds showed μ-receptor selectivity higher than those of previously reported methylarylcinnamyl analogs.

Behavioral phenotyping of cancer pain in domesticated cats with naturally occurring squamous cell carcinoma of the tongue: initial validation studies provide evidence for regional and widespread algoplasticity

Feline oral squamous cell carcinoma (FOSCC) is a common and naturally occurring condition that recapitulates many features of human head and neck cancer (HNC). In both species, there is need for improved strategies to reduce pain caused by HNC and its treatment. Research to benefit both species could be conducted using pet cats as a comparative model, but this prospect is limited by lack of validated methods for quantifying FOSCC-associated pain. A prospective non-randomized pilot study was performed for initial validation of: (1) a pet owner administered quality of life questionnaire and visual assessment scoring tool (FORQ/CLIENT); (2) a clinician assessment questionnaire (UFEPS/VET); (3) electronic von Frey testing [EVF]; and (4) Cochet-Bonnet (COBO) aesthesiometry. To assess intra-rater reliability, discriminatory ability, and responsiveness of each assay, 6 cats with sublingual SCC and 16 healthy control cats were enrolled. The intra-rater reliability was moderate-to-good for the clinical metrology instruments and EVF (intraclass correlation coefficient [ICC] ≥ 0.68), but poor for COBO (ICC = 0.21). FORQ/CLIENT scores were higher (worse quality of life) in FOSCC cats vs healthy controls. The internal reliability of FORQ/CLIENT scoring was high (Cronbach α = 0.92); sensitivity and specificity were excellent (100% when using cut-offs determined using receiver operating characteristic [ROC] curves). For the FORQ/CLIENT, there was strong and inverse correlation between scores from the questions and visual assessment (r =  − 0.77, r² = 0.6, P < 0.0001). For the UFEPS/VET, Cronbach’s α was 0.74 (high reliability). Sensitivity and specificity were 100% and 94%, respectively, when using a cut-off score (3.5) based on ROC curves (Youden index of 0.94). Total UFEPS/VET scores were positively correlated with FORQ/CLIENT scores (r² = 0.72, P < 0.0001). Sensitivity of EVF and COBO ranged from 83 to 100% and specificity ranged from 56 to 94%. Cats with cancer were more sensitive around the face (lower response thresholds) and on the cornea (longer filament lengths) than control animals (P < 0.03). Reduced pressure response thresholds were also observed at a distant site (P = 0.0002) in cancer cats. After giving buprenorphine, EVF pressure response thresholds increased (P = 0.04) near the mandible of cats with OSCC; the length of filament required to elicit a response in the COBO assay also improved (shortened; P = 0.017). Based on these preliminary assessments, the assays described herein had reasonable inter-rater reliability, and they were able to both discriminate between cats with and without oral cancer, and respond in a predictable manner to analgesic therapy. In cats with tongue cancer, there was evidence for regional peripheral sensitization, and widespread somatosensory sensitization. These results provide a basis for multi-dimensional assessments of pain and sensitivity in cats with oral SCC.

Anxiety, Depression, and Opioid Misuse Among Adults With Chronic Pain: The Role of Anxiety Sensitivity

OBJECTIVES

The opioid epidemic is a significant public health problem largely driven by opioid prescriptions for chronic pain. Among those with chronic pain, anxiety and depressive symptoms have been linked to opioid misuse, and individual differences in anxiety and depressive symptoms among adults with chronic pain may be important for better understanding pain. Yet, little work has examined mechanisms that may link anxiety and depressive symptoms to opioid misuse among adults with chronic pain. Anxiety sensitivity (AS), or the fear of anxiety-related physical sensations, may be one candidate construct that has been linked independently to anxiety and depressive symptoms as well as opioid misuse.

METHODS

The current survey-based study examined the indirect association of AS in the relation between anxiety and depressive symptoms and opioid misuse among 429 adults with chronic pain currently using prescription opioid medication (73.9% female, Mage=38.32 y, SD=11.07).

RESULTS

Using structural equation modeling, it appears that AS is a potential construct in the interrelation between anxiety and depressive symptoms and opioid misuse. However, an alternative model found equally strong empirical support, as mental health symptoms may serve as an explanatory factor between AS and opioid misuse.

DISCUSSION

Bi-directional effects are apt to be involved among the studied variables. Prospective research is needed to replicate the study results and isolate the temporal patterning between the studied constructs. Nonetheless, the data overall highlight the importance of both AS and anxiety and depressive symptoms in terms of understanding opioid misuse among adults with chronic pain.

Irradiation of the Normal Murine Tongue Causes Upregulation and Activation of Transient Receptor Potential (TRP) Ion Channels

Signal transduction at sensory neurons occurs via transmembrane flux of cations, which is largely governed by the transient receptor potential (TRP) family of ion channels. It is unknown whether TRP channel activation contributes to the pain that accompanies radiation-induced oral mucositis. This study sought to characterize changes in TRP channel expression and function that occur in the locally irradiated tissues and afferent neurons of mice. Female CD-1 mice received singe high-dose (27 Gy) tongue irradiation, or sham irradiation. Animals were euthanized either before overt glossitis developed (days 1 and 5 postirradiation), when glossitis was severe (day 11), or after mice had recovered (days 21 and 45). Tongue irradiation caused upregulation of the Trpv1 gene in trigeminal ganglia (TG) neurons. Other TRP genes (Trpv2, Trpv4, Trpa1, Trpm8) and Gfrα3 (which acts upstream of several TRP channels) were also upregulated in TGs and/or tongue tissue, in response to radiation. Ex vivo calcium imaging experiments demonstrated that the proportions of TG neurons responding to histamine (an activator of TRPV1, TRPV4 and TRPA1), TNF-α (an activator of TRPV1, TRPV2 and TRPV4), and capsaicin (a TRPV1 agonist), were increased as early as one day after tongue irradiation; these changes persisted for at least 21 days. In a subsequent experiment, we found that genetic deletion of TRPV1 mitigated weight loss (a surrogate marker of pain severity) in mice with severe glossitis. The results intimate that various TRP channels, and TRPV1 in particular, should be explored as analgesic targets for patients experiencing pain after oral irradiation.

Molecular mechanisms of opioid tolerance: From opioid receptors to inflammatory mediators (Review)

Opioids are considered the most effective analgesics for the treatment of both acute and chronic pain. However, prolonged opioid use can induce a certain level of tolerance to its analgesic effects, leading to a reduction in its effectiveness, addiction and abuse. A better understanding of the mechanisms underlying opioid tolerance may provide insights into this phenomenon and aid in the development of novel methods to combat the side effects of opioid tolerance. The present review focused on two major contributors to tolerance, opioid receptors and inflammatory mediators. The molecular mechanisms involved in the desensitization of the opioid receptors were briefly described, including their phosphorylation, internalisation and recycling. Subsequently, the effects of Toll like receptor 4/NOD-like receptor family pyrin domain containing 3-mediated proinflammatory responses in opioid tolerance were discussed, aiming in supporting the identification of novel therapeutic targets.

Experimental considerations for the assessment of in vivo and in vitro opioid pharmacology

Morphine and other mu-opioid receptor (MOR) agonists remain the mainstay treatment of acute and prolonged pain states worldwide. The major limiting factor for continued use of these current opioids is the high incidence of side effects that result in loss of life and loss of quality of life. The development of novel opioids bereft, or much less potent, at inducing these side effects remains an intensive area of research, with multiple pharmacological strategies being explored. However, as with many G protein-coupled receptors (GPCRs), translation of promising candidates from in vitro characterisation to successful clinical candidates still represents a major challenge and attrition point. This review summarises the preclinical animal models used to evaluate the key opioid-induced behaviours of antinociception, respiratory depression, constipation and opioid-induced hyperalgesia and tolerance. We highlight the influence of distinct variables in the experimental protocols, as well as the potential implications for differences in receptor reserve in each system. Finally, we discuss how methods to assess opioid action in vivo and in vitro relate to each other in the context of bridging the translational gap in opioid drug discovery.

Impact of opioid-free anaesthesia on postoperative nausea, vomiting and pain after gynaecological laparoscopy - A randomised controlled trial

STUDY OBJECTIVE

Opioid-free anaesthesia may enhance postoperative recovery by reducing opioid-related side effects such as nausea, hyperalgesia or tolerance. The objective was to investigate the impact of multimodal opioid-free general anaesthesia on postoperative nausea, vomiting, pain and morphine consumption compared to the traditional opioid-based approach.

DESIGN

This study was conducted as a prospective parallel-group randomised controlled trial.

SETTING

Perioperative Care.

PATIENTS

152 adult women undergoing elective inpatient gynaecological laparoscopy.

INTERVENTIONS

Patients were randomly assigned for opioid-free anaesthesia (Group OF) with dexmedetomidine, esketamine and sevoflurane or to have opioid-based anaesthesia (Group C) with sufentanil and sevoflurane.

MEASUREMENTS

Primary outcome was the occurrence of nausea within 24 h after surgery. Patients were assessed for the incidence and severity of PONV, postoperative pain and morphine consumption and recovery characteristics.

MAIN RESULTS

Patients in both groups had comparable clinical and surgical data. 69.7% of patients in the control group and 68.4% of patients in the opioid-free group met the primary endpoint (OR 1.06, 95% Confidence Interval (CI) (0.53; 2.12) p = 0.86). The incidence of clinically important PONV defined by the PONV impact scale was 8.1% (Group C) vs 10.5% (OF); p = 0.57). Antiemetic requirements, pain scores and morphine consumption were equivalent in both groups. Postoperative sedation was significantly increased in group OF (p < 0.001), and the median length of stay at the post-anaesthesia care unit was 69.0 min (46.5-113.0) vs 50.0 (35.3-77.0) minutes in the control group (p < 0.001).

CONCLUSIONS

Opioid-free multimodal general anaesthesia is feasible but did not decrease the incidence of PONV, or reduce pain scores and morphine consumption compared to an opioid-containing anaesthetic regimen.

Evaluation of Therapies for Peripheral and Neuraxial Opioid-induced Pruritus based on Molecular and Cellular Discoveries

Opioids are a mainstay of treatment for pain worldwide. Pruritus, a common side effect of opioids, is a patient dissatisfier that limits their use in many clinical settings. Both parenteral and neuraxial administration of opioids frequently evoke pruritus. The ability of opioids to suppress pain while causing itch continues to perplex clinicians and researchers alike. Several mechanisms have been proposed to explain how opioids can give rise to pruritus, but specific knowledge gaps perpetuate debate. This review summarizes the clinical burden of opioid-induced pruritus and emphasizes recent discoveries of peripheral and central mechanisms for opioid-induced pruritus, particularly with respect to scientific and conceptual advances in spinal cord circuitry and mast cell biology. The mechanisms and effectiveness of existing medications used for clinical management of pruritus will be evaluated, and we will highlight the emerging preclinical utility of selective κ-opioid receptor agonists, such as nalfurafine, for the management of opioid-induced pruritus.

Characterization and Associated Costs of Constipation Relating to Exposure to Strong Opioids in England: An Observational Study

PURPOSE

Opioid use is associated with gastrointestinal adverse events, including nausea and constipation. We used a real-world dataset to characterize the health care burden associated with opioid-induced constipation (OIC) with particular emphasis on strong opioids.

METHODS

This retrospective cohort study was conducted using the Clinical Practice Research Datalink, a large UK primary care dataset linked to hospital data. Patients prescribed opioids during 2016 were selected and episodes of opioid therapy constructed. Episodes with ≥84 days of exposure were classified as chronic, with date of first prescription as the index date. The main analysis focused on patients prescribed strong opioids who were laxative naive. Constipation was defined by ≥2 laxative prescriptions during the opioid episode. Patients for whom initial laxative therapy escalated by switch, augmentation, or dose were defined as OIC unstable, and the first 3 lines of OIC escalation were classified. Health care costs accrued in the first 12 months of the opioid episode were aggregated and compared.

FINDINGS

A total of 27,629 opioid episodes were identified; 5916 (21.4%) involved a strong opioid for patients who were previously laxative naive. Of these patients, 2886 (48.8%) were defined as the OIC population; 941 (33.26%) were classified as stable. Of the 1945 (67.4%) episodes classified as unstable, 849 (43.7%), 360 (18.5%), and 736 (37.8%) had 1, 2, and ≥3 changes of laxative prescription, respectively. Patients without OIC had lower costs per patient year (£3822 [US$5160/€4242]) compared with OIC (£4786 [US$6461/€5312]). Costs increased as patients had multiple changes in therapy: £4696 (US$6340/€5213), £4749 (US$6411/€5271), and £4981 (US$6724/€5529) for 1, 2, and ≥3 changes, respectively. The adjusted cost ratio relative to non-OIC was 1.14 (95% CI, 1.09-1.32) for those classified as stable and 1.19 (95% CI, 1.09-1.32) for those with ≥3 laxative changes. Similar patterns were observed for patients taking anyopioid, with costs increased for those classified as having OIC (£3727 [US$5031/€4137] vs £2379 [US$3212 /€2641),and for those patients classified as unstable versus stable (£3931 [US$5307/€4363] vs £3432 [US$4633/€3810). Costs increased with each additional line of therapy from £3701 (US$4996/€4108), £3916 (US$5287/€4347), and £4318 (US$5829/€4793).

IMPLICATIONS

OIC was a common adverse event of opioid treatment and was poorly controlled for a large number of patients. Poor control was associated with increased health care costs. The impact of OIC should be considered when prescribing opioids. These results should be interpreted with consideration of the caveats associated with the analysis of routine data.

Cost comparison of osteopathic manipulative treatment for patients with chronic low back pain

CONTEXT

Chronic low back pain (cLBP) is the second leading cause of disability in the United States, with significant physical and financial implications. Development of a multifaceted treatment plan that is cost effective and optimizes patients' ability to function on a daily basis is critical. To date, there have been no published prospective studies comparing the cost of osteopathic manipulative treatment to that of standard care for patients with cLBP.

OBJECTIVES

To contrast the cost for standard of care treatment (SCT) for cLBP with standard of care plus osteopathic manipulative treatment (SCT + OMT).

METHODS

This prospective, observational study was conducted over the course of 4 months with two groups of patients with a diagnosis of cLBP. Once consent was obtained, patients were assigned to the SCT or the SCT + OMT group based on the specialty practice of their physician. At enrollment and after 4 months of treatment, all patients in both groups completed two questionnaires: the 11 point pain intensity numerical scale (PI-NRS) and the Roland Morris Disability Questionnaire (RMDQ). Cost data was collected from the electronic medical record of each patient enrolled in the study. Chi-square (χ ² _Yates) tests for independence using Yates' correction for continuity were performed to compare the results for each group.

RESULTS

There was a total of 146 patients: 71 (48.6%) in the SCT + OMT group and 75 (51.4%) in the SCT group. The results showed no significant differences between the mean total costs for the SCT + OMT ($831.48 ± $553.59) and SCT ($997.90 ± $1,053.22) groups. However, the utilization of interventional therapies (2; 2.8%) and radiology (4; 5.6%) services were significantly less for the SCT + OMT group than the utilization of interventional (31; 41.3%) and radiology (17; 22.7%) therapies were for the SCT group (p<0.001). Additionally, the patients in the SCT + OMT group were prescribed fewer opioid medications (15; 21.1) than the SCT (37; 49.3%) patients (p.001). Patients in the SCT group were approximately 14.7 times more likely to have received interventional therapies than patients in the SCT + OMT group. Likewise, the patients in the SCT group were approximately four times more likely to have received radiological services. Paired t tests comparing the mean pre- and 4 month self reported pain severity scores on the RMDQ for 68 SCT + OMT patients (9.91 ± 5.88 vs. 6.40 ± 5.24) and 66 SCT patients (11.44 ± 6.10 vs. 8.52 ± 6.14) found highly significant decreases in pain for both group (<0.001).

CONCLUSIONS

The mean total costs for the SCT and SCT + OMT patients were statistically comparable across 4 months of treatment. SCT + OMT was comparable to SCT alone in reducing pain and improving function in patients with chronic low back pain; however, there was less utilization of opioid analgesics, physical therapy, interventional therapies, radiologic, and diagnostic services for patients in the SCT + OMT group.

Analgesic effects of indomethacin spray on drug-induced oral mucositis pain in patients with cancer: A single-arm cross-sectional study

Aims

Symptomatic treatment is insufficient for chemotherapy‐ or targeted therapy‐induced oral mucositis (OM) pain, and benzydamine mouthwash is not commercially available in Japan. We evaluated the analgesic effects of an in‐hospital preparation of 0.25% indomethacin spray (IMS) on anticancer drug‐induced OM pain.

Methods

This single‐arm prospective trial enrolled 20 patients (median age 62.0 years) with OM and numerical rating scale scores of ≥5 who were undergoing chemotherapy or targeted therapy in our hospital. Pain scores were recorded using a visual analog scale (VAS) before and 30 min after IMS administration. Pain relief (PR) scores were recorded at 15, 30, and 60 min after IMS administration; total PR after 60 min (TOTPAR₆₀) was calculated, and the mean PR score after 3 days (PR_3days) was determined.

Results

The median (interquartile range) OM grade of the participants was 2.0 (2.0–2.3). The VAS score decreased significantly at 30 min after IMS administration (p = .001). The median (interquartile range) TOTPAR₆₀ and PR_3days were 6.0 (3.8–7.3) and 2.0 (2.0–3.0), respectively.

Conclusions

IMS helped improve patients’ quality of life. The risk of systemic adverse effects was low because of the low dose administered. IMS effectively relieved anticancer drug‐induced OM pain and may be useful for immediate self‐medication.

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.