Opioid switching in cancer pain: From the beginning to nowadays

Opioid analgesic dose and route conversion ratio studies: a scoping review to inform an eDelphi guideline

BACKGROUND

Clinicians regularly prescribe opioids to manage acute and chronic cancer pain, frequently to address acute postoperative pain, and occasionally to manage chronic non-cancer pain. Clinical efficacy may be suboptimal in some patients due to side effects and/or poor response, and opioid rotation/switching (conversions) is frequently necessary. Despite the widespread practice, opioid conversion ratios are inconsistent between clinicians, practices, and countries. Therefore, we performed a scoping systematic review of opioid conversion studies to inform an international eDelphi guideline.

METHODS

To ensure a comprehensive review, we conducted a systematic search across multiple databases (OVID Medline, PsycINFO, Embase, EBM-Cochrane Database of Systematic Reviews and Registered Trials, LILACS, IMEMR, AIM, WPRIM) using studies published up to June 2022. Additionally, we performed hand and Google Scholar searches to verify the completeness of our findings. Our inclusion criteria encompassed randomized and non-randomized studies with no age limit, with only a few pediatric studies identified. We included studies on cancer, non-cancer, acute, and chronic pain. The level and grade of evidence were determined based on the Multinational Supportive Care in Cancer (MASCC) criteria.

RESULTS

Our search yielded 21,118 abstracts, including 140 randomized (RCT) and 68 non-randomized (NRCT) clinical trials. We compared these results with recently published conversion ratios. Modest correlations were noted between published reviews and the present scoping systematic review.

CONCLUSION

The present scoping systematic review found low-quality evidence to support an opioid conversion guideline. We will use these data, including conversion ratios and type and route of administration, to inform an eDelphi guideline.

Opioid analgesics for nociceptive cancer pain: A comprehensive review

Pain is one of the most burdensome symptoms in people with cancer, and opioid analgesics are considered the mainstay of cancer pain management. For this review, the authors evaluated the efficacy and toxicities of opioid analgesics compared with placebo, other opioids, nonopioid analgesics, and nonpharmacologic treatments for background cancer pain (continuous and relatively constant pain present at rest), and breakthrough cancer pain (transient exacerbation of pain despite stable and adequately controlled background pain). They found a paucity of placebo-controlled trials for background cancer pain, although tapentadol or codeine may be more efficacious than placebo (moderate-certainty to low-certainty evidence). Nonsteroidal anti-inflammatory drugs including aspirin, piroxicam, diclofenac, ketorolac, and the antidepressant medicine imipramine, may be at least as efficacious as opioids for moderate-to-severe background cancer pain. For breakthrough cancer pain, oral transmucosal, buccal, sublingual, or intranasal fentanyl preparations were identified as more efficacious than placebo but were more commonly associated with toxicities, including constipation and nausea. Despite being recommended worldwide for the treatment of cancer pain, morphine was generally not superior to other opioids, nor did it have a more favorable toxicity profile. The interpretation of study results, however, was complicated by the heterogeneity in the study populations evaluated. Given the limited quality and quantity of research, there is a need to reappraise the clinical utility of opioids in people with cancer pain, particularly those who are not at the end of life, and to further explore the effects of opioids on immune system function and quality of life in these individuals.

Opioid dose titration for cancer pain

BACKGROUND

Opioid dose titration is a fundamental process of opioid therapy in cancer pain.

AIMS

To assess data opioid dose titration.

METHODS

The principal opioid dose titration methods, outcomes, and modalities of administration regarding the different opioid preparations were examined in different clinical contexts.

RESULTS

Most studies suggested that opioid-naive patients should be started at doses of 15-30 mg/day of oral morphine equivalents. Opioid-tolerant patients may receive low or higher doses of oral morphine equivalents, depending on the level of opioid tolerance. Generally, dose increments of 30%-50% seem to be indicated to start dose titration. Some patients with severe excruciating cancer pain may present as an emergency requiring a rapid application of powerful analgesic strategies. The intravenous use of opioids may circumvent this problem providing a faster pain relief, due to the large availability and rapid achievement of effective plasma concentrations.

DISCUSSION

Opioid dose titration is a delicate passage in patients with cancer pain. This approach may be different according to different clinical conditions. Opioid dose titration requires expertise to optimize cancer pain management while minimizing the development of adverse effects.

CONCLUSION

While most approaches are meaningful and partially supported by existing literature, more studies are necessary to establish advantages and disadvantages in different clinical conditions. Optimization of opioid dose titration is of paramount importance.

SIGNIFICANCE

This review provides the most recent insights on the different modalities of opioid dose titration in cancer pain management.

Opioid Switch Dosing in Chronic Cancer Pain: A Prospective Longitudinal Study

Background: Opioid switching is common, however, conversion tables have limitations. Guidelines suggest postswitch dose reduction, yet, observations show opioid doses may increase postswitch. Objectives: To document the opioid conversion factor postswitch in cancer, and whether pain and adverse effect outcomes differ between switched opioid groups. Design/Setting: This multicenter prospective longitudinal study included people with advanced cancer in Australia. Clinical data (demographics, opioids) and validated instruments (pain, adverse effects) were collected twice, seven days apart. Results: Opioid switch resulted in dose increase (median oral morphine equivalent daily dose 90 mg [interquartile range {IQR} 45-184] to 150 mg [IQR 79-270]), reduced average pain (5.1 [standard deviation {SD} 1.7] to 3.8 [SD 1.6]), and reduced adverse effects. Hydromorphone dose increased 2.5 times (IQR 1.0-3.6) above the original conversion factor used. Conclusions: Opioid switching resulted in overall dose increase, particularly when switching to hydromorphone. Higher preswitch dosing may require higher dose conversion ratios. Dose reduction postswitch risks undertreatment and may not be always appropriate.

Cancer survivors: long-term opioid therapy - the challenge

The use of opioids in cancer survivors with chronic pain raises concerns as it occurs with chronic non-malignant pain .Thus, in some circumstances advanced therapeuthic strategies should be performed to allow pain control for prolonged periods of time We describe a case of a long-survivor patient receiving prolonged opioid therapy. She received multiple opioid rotations or some more complex treatments, including burst of ketamine and midazolam, which allowed to maintain an acceptable pain control for 12 years, despite her poor compliance. Different opioids in different phases were given. A high level of knowledge, experience, and assessment is mandatory to implement of pain management among survivors.

An overview of the current drug treatment strategies for moderate to severe, chronic malignant tumor-related pain

INTRODUCTION

The pharmacological management of cancer pain is a complex issue that requires knowledge and experience in the use of analgesics. The aim of this expert review is to provide a panorama of the pharmacological strategies in cancer pain management.

AREAS COVERED

Opioid dose titration is a delicate process regarding the start of opioid treatment in different clinical conditions. How to improve the opioid response is a fundamental step, which includes different strategies when an initial treatment with opioids fails. The use of adjuvants is another relevant issue that should be considered in some specific circumstances to optimize the management of cancer pain management. Some clinical conditions, such as neuropathic pain and breakthrough pain, deserve a special attention. Relevant literature was selected to provide an overview of cancer pain management strategies.

EXPERT OPINION

Opioid therapy still remains the cornerstone of pharmacological management of cancer pain. Opioids should be used according to the level of tolerance, also personalizing the treatment (route, drug, and dosing). Adjuvant drugs may help in specific conditions, although their use should be balanced with the adverse effects. Breakthrough pain requires expertise in tailoring a treatment according to patient's profile and characteristics of episodes.

Methadone for Cancer Pain Management in Children: A Review of Literature

Pain associated with cancer is a common feature among children and adolescents. Among opioids, methadone is a unique drug for its multiple mechanisms of action. Methadone is currently underutilized in children. The use of methadone for cancer pain management in children was assessed in a systematic review. Altogether, 141 children receiving methadone were examined, and another 126 children were assessed for QT prolongation. In the clinical studies, modalities of use, dosing, and duration of assessment were highly variable. In general, methadone was effective and well tolerated with a limited tendency for dose increases. QT prolongation was reported in a percentage of patients independently of the dosages or other variables. The majority of studies considered the use of methadone to be safe and effective in children. Despite methadone possessing interesting properties that make this drug unique in a pediatric context, data is limited, and the literature available is based on retrospective studies. Methadone could be an effective, inexpensive, and versatile medication in children with cancer who have pain. This drug deserves more interest and should prompt studies of better quality with a larger number of patients.

Effect of gene variants on opioid dose, pain and adverse effect outcomes in advanced cancer: an explorative study

Aim: Associations between gene variants and opioid net effect are unclear. We conducted an exploratory pharmacogenetic analysis of 35 gene variants and opioid response in advanced cancer. Patients & methods: This multi-center prospective cohort study included clinical data, questionnaires (pain and adverse effects) and DNA (blood). Negative binomial regression and logistic regression were used. Results: Within 54 participants, eight statistically significant associations (p = 0.002-0.038) were observed between gene variants and opioid dose, pain scores or adverse effects, the majority being within the neuroimmune TLR4 pathway (IL1B [rs1143634], IL2 [rs2069762], IL6 [rs1800795], BDNF [rs6265]) and ARRB2 pathway (ARRB2 [rs3786047], DRD2 [rs6275]). Conclusion: Neuroimmune pathway genes may contribute to differences in opioid response in cancer and may be included in future similar studies.

Fentanyl in cancer pain management: avoiding hasty judgments and discerning its potential benefits

Cancer pain is an important challenge in treatment and requires a rapid onset of action for its control. In particular, breakthrough cancer pain (BTcP) should be adequately controlled with a stable dose of a short-acting oral opioid. Fentanyl is a synthetic, highly selective opioid with many advantageous chemical properties, including high lipophilicity and distinct pharmacokinetic properties. It is recommended for pain management in a variety of settings, including acute pain, chronic pain and BTcP. To date, its variously designed formulations allow non-invasive administration; amongst others, sublingual fentanyl has proven useful in the management of BTcP and in improving the quality of life of patients with cancer. This review provides an update on the management of BTcP with fentanyl, with consideration of safety, as it remains an important tool in the treatment of cancer pain.

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.

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

CONTEXT

Information about opioid switching to intravenous methadone is lacking.

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSION

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

Effectiveness of Opioid Switching in Advanced Cancer Pain: A Prospective Observational Cohort Study

Opioid switching is a common practice of substituting one opioid for another to improve analgesia or adverse effects; however, it has limited evidence. This study aimed to examine the effectiveness of opioid switching in advanced cancer. This multi-center prospective cohort study recruited patients assessed to switch opioids (opioid switch group) or to continue ongoing opioid treatment (control group). Clinical data (demographics, opioids) and validated instruments (pain and adverse effects) were collected over two timepoints seven days apart. Descriptive analyses were utilized. Non-parametric tests were used to determine differences. Fifty-four participants were recruited (23 control group, 31 switch group). At the follow-up, opioid switching reduced pain (worst, average, and now) (p < 0.05), uncontrolled breakthrough pain (3-fold reduction, p = 0.008), and psychological distress (48% to 16%, p < 0.005). The switch group had a ≥25% reduction in the reported frequency of seven moderate-to-severe adverse effects (score ≥ 4), compared to a reduction in only one adverse effect in the control group. The control group experienced no significant pain differences at the follow-up. Opioid switching is effective at reducing pain, adverse effects, and psychological distress in a population with advanced cancer pain, to levels of satisfactory symptom control in most patients within 1 week.

Therapeutic Potential of Orally Administered Rubiscolin-6

Rubiscolins are naturally occurring opioid peptides derived from the enzymatic digestion of the ribulose bisphosphate carboxylase/oxygenase protein in spinach leaves. They are classified into two subtypes based on amino acid sequence, namely rubiscolin-5 and rubiscolin-6. In vitro studies have determined rubiscolins as G protein-biased delta-opioid receptor agonists, and in vivo studies have demonstrated that they exert several beneficial effects via the central nervous system. The most unique and attractive advantage of rubiscolin-6 over other oligopeptides is its oral availability. Therefore, it can be considered a promising candidate for the development of a novel and safe drug. In this review, we show the therapeutic potential of rubiscolin-6, mainly focusing on its effects when orally administered based on available evidence. Additionally, we present a hypothesis for the pharmacokinetics of rubiscolin-6, focusing on its absorption in the intestinal tract and ability to cross the blood-brain barrier.

A better interpretation of data regarding the opioid switching to methadone

In a recent study methadone has been reported more effective witha 3-day switch (3DS) was more effective than the stop and go strategy (SAG). Many shorcomings, however, are of concerns. The poor selection fo patients with low level of pain intensity, the incomprehensibile choice of of SAG or 3DS, and considerations reported in a previous controlled study with evident methodological limits, make their conclusion inaccurate. Controlled studies are fundamental in research. However, a pragmatic approach reflecting daily practice should be carefully taken into consideration. A more flexible use of SAG strategy and strict clinical observation to change doses according to the clinical response may provide the optimal treatment in patients receiving high doses of opioids.

Reply to "A better interpretation of data regarding the opioid switching to methadone"

In our article ?Methadone switching for refractory cancer pain' (BMC palliative care, 2022) we explore the efficacy, safety and economics of methadone in treatment of patients with refractory cancer pain in China. Professor Mercadante provided a better interpretation of data regarding the opioid switching to methadone in the Matters Arising. In this article, we answered the questions in Mercadante et al.'s comments one by one.

Pain Treatment and Cancer Patients: Are we Heeding Quality of Life?

The use of opioid analgesics remains the primary therapy for pain control in cancer patients. However, ample evidence persists showing that treatment is still inadequate. This cross-sectional study was carried out during one year in a Brazilian Cancer Hospital to evaluate the impact of opioid use on analgesia and patients' quality of life. The Pain Management Index (PMI), EORTC QLQ.C30 (Quality of Life of Cancer Patients), Karnofsky Performance Status (KPS), Douleur Neuropathique 4 (DN4), and Brief Pain Inventory-Short Form (BPI-SF) were used. A hundred patients with advanced solid tumors and using opioids were included, with 82% of them reporting daily pain with 58% having intense pain. Morphine with a mean dose of 49 Morphine Milligram Equivalent were used by 57% of them, and PMI was negative in 34% of the sample. Neuropathic pain was found in 72% of patients. The pain was related to all BPI variables. Despite the substantial negative impact of pain on QOL, no association was found between the clinical factors assessed and QOL itself. This gap can be related to the persistence of high levels of sub-treatment, depression, and neuropathic pain associated with the use of low doses of opiates and adjuvant medications in the sample.

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.

Conversion ratios for opioid switching: a pragmatic study

BACKGROUND

The final conversion ratios among opioids used for successful switching are unknown. The aim of this study was to determine the initial and final conversion ratios used for a successful opioid switching in cancer patients, and eventual associated factors.

METHODS

Ninety-five patients who were successfully switched were evaluated. The following data were collected: age, gender, Karnofsky performance score, primary cancer, cognitive function, the presence of neuropathic, and incident pain. Opioids, route of administration, and their doses expressed in oral morphine equivalents used before OS were recorded as well as opioids use for starting opioid switching, and at time of stabilization. Physical and psychological symptoms were routinely evaluated by Edmonton Symptom Assessment Scale.

RESULTS

No statistical changes were observed between the initial conversion ratios and those achieved at time of stabilization for all the sequences of opioid switching. When considering patients switched to methadone, there was no association between factors taken into considerations.

CONCLUSION

Opioid switching is a highly effective and safe technique, improving analgesia and reducing the opioid-related symptom burden. The final conversion ratios were not different from those used for starting opioid switching. Patients receiving higher doses of opioids should be carefully monitored for individual and unexpected responses in an experienced palliative care unit, particularly those switched to methadone. Future studies should provide data regarding the profile of patients with difficult pain to be hospitalized.

Cancer Pain Treatment Strategies in Patients with Cancer

Management of cancer pain is challenging. Despite the poor evidence, opioid therapy still remains the cornerstone for the management of cancer-related pain. Opioids should be given according to the clinical presentation in the different stages of disease. There is no drug of choice, as most opioids are effective. Thus, the choice should be based on the individual characteristics of patients. Optimization of opioid therapy may allow individual treatment according to the patient's characteristics and pain syndromes, providing timely alternatives in the different stages of disease. While most patients respond to an appropriate treatment associated with a comprehensive assessment and symptom control, a high level of experience and knowledge is necessary in determining conditions to maximize the analgesic response, eventually adding adjuvants in some specific circumstances. Alternative opioids may improve the balance between analgesia and adverse effects in the presence of a poor response to the first opioid in a large number of patients. Finally, a selected population can benefit from some interventional procedures.

Management of Physical Symptoms in Patients with Advanced Cancer During the Last Weeks and Days of Life

Patients with advanced cancer are faced with many devastating symptoms in the last weeks and days of life, such as pain, delirium, dyspnea, bronchial hypersecretions (death rattle), and intractable seizures. Symptom management in the last weeks of life can be particularly challenging because of the high prevalence of delirium complicating symptom assessment, high symptom expression secondary to psychosocial and spiritual factors, limited life-expectancy requiring special considerations for prognosis-based decision-making, and distressed caregivers. There is a paucity of research involving patients in the last weeks of life, contributing to substantial variations in clinical practice. In this narrative review, we shall review the existing literature and provide a practical approach to in-patient management of several of the most distressing physical symptoms in the last weeks to days of life.

Treatment of Neuropathic Pain Directly Due to Cancer: An Update

Simple Summary

This review discusses treatment approaches for providing pain relief to oncological patients affected by pain caused by nerve damage due to the tumor, also known as neuropathic cancer pain. Although being encountered often and causing a relevant burden to these patients, neuropathic cancer pain remains still difficult to diagnose and treat. Strong evidence about the best drugs to be used remain limited, as do therapeutic choices.

Abstract

Neuropathic pain can be defined as pain related to abnormal somatosensory processing in either the peripheral or central nervous system. In this review article, with neuropathic cancer pain (NCP), we refer to pain due to nervous tissue lesions caused by the tumor or its metastases. Nervous tissue damage is the cause of cancer pain in approximately 40% of those experiencing cancer pain. Recognizing a neuropathic pathophysiology in these cases may be difficult and requires specific criteria that are not homogenously applied in clinical practice. The management of this type of pain can be challenging, requiring the use of specific non-opioid adjuvant drugs. The majority of the criteria for NCP diagnosis and management have been based mainly on results from the noncancer population, risking the failure of addressing the specific needs of this population of patients. In this review, we summarize current management options available for NCP and provide some insights on new promising treatments.

When the game is hard, more complex weapons are needed

OBJECTIVES

The aim of this paper is to illustrate how to manage a very difficult pain condition.

METHODS

This is a clinical note of a complex approach using multiple analgesic regimens to effectively afford challenging pain situations.

RESULTS

A man underwent an opioid dose titration, followed by dose stabilisation for some months. Then he underwent two opioid substitutions, unsuccessfully. A spinal analgesia provided good analgesia for a prolonged period of time, necessitating variable interventions to counteract the evolving, challenging clinical situation.

CONCLUSIONS

The description of this case illustrates the need of a high level of experience and knowledge to elaborate complex strategies step by step every time the pain syndrome was worsening. Recommendations are unlikely in these extreme circumstances, and treatment should be based on continuous clinical counteraction to the evolving clinical conditions.

OUP accepted manuscript

Aim

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

Methods

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

Results

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

Conclusion

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

Current management of cancer pain in Italy: Expert opinion paper

Introduction

Chronic pain and breakthrough cancer pain (BTcP) have a high prevalence in all cancer types and cancer stages, combined with a significant physical, psychological, and economic burden. Despite efforts to improve appropriate management of cancer pain, a poor assessment and guilty undertreatment are still reported in many countries. The purpose of this expert opinion paper is to contribute to reduce and clarify these issues with a multidisciplinary perspective in order to share virtuous paths of care.

Methods

Common questions about cancer pain assessment and treatment were submitted to a multidisciplinary pool of Italian clinicians and the results were subsequently discussed and compared with the findings of the published literature.

Conclusion

Despite a dedicated law in Italy and effective treatments available, a low percentage of specialists assess pain and BTcP, defining the intensity with validated tools. Moreover, in accordance with the findings of the literature in many countries, the undertreatment of cancer pain is still prevalent. A multidisciplinary approach, more training programs for clinicians, personalised therapy drug formulations, and virtuous care pathways will be essential to improve cancer pain management.

Assistance of a Palliative Care Certified Nurse in the Alleviation of Refractory Cancer Pain by Switching Opioids to Oral Methadone in a Japanese Outpatient Setting

Although methadone has the potential to improve the management of cancer pain, it has some serious problems, such as respiratory depression and QT interval prolongation. Therefore, patients who are prescribed methadone must be educated, monitored, and supported by specialized medical staff, especially in the outpatient setting. We assessed the effectiveness of support from the palliative care certified nurse who used the checklists in opioid switching to oral methadone for patients with refractory pain. Through the multidisciplinary palliative care team at our hospital, 15 outpatients with cancer pain were prescribed oral methadone between April 2013 and December 2020, and 14 cases were successful in switching to methadone. After taking medication, the certified nurse called the patient's home daily for 3 to 5 days and confirmed that the patient had taken the methadone, the degree of pain, the number of rescue medications, and the appearance of side effects, such as respiratory depression. Careful management by a multidisciplinary team is essential for opioid switching to oral methadone administration for outpatients. Certified nurses may play an important role in maintaining safety and resolving the patients' and families' anxieties with respect to the prescription of methadone.

In Vitro Analyses of Spinach-Derived Opioid Peptides, Rubiscolins: Receptor Selectivity and Intracellular Activities through G Protein- and β-Arrestin-Mediated Pathways

Activated opioid receptors transmit internal signals through two major pathways: the G-protein-mediated pathway, which exerts analgesia, and the β-arrestin-mediated pathway, which leads to unfavorable side effects. Hence, G-protein-biased opioid agonists are preferable as opioid analgesics. Rubiscolins, the spinach-derived naturally occurring opioid peptides, are selective δ opioid receptor agonists, and their p.o. administration exhibits antinociceptive effects. Although the potency and effect of rubiscolins as G-protein-biased molecules are partially confirmed, their in vitro profiles remain unclear. We, therefore, evaluated the properties of rubiscolins, in detail, through several analyses, including the CellKey^TM assay, cADDis^® cAMP assay, and PathHunter^® β-arrestin recruitment assay, using cells stably expressing µ, δ, κ, or µ/δ heteromer opioid receptors. In the CellKey^TM assay, rubiscolins showed selective agonistic effects for δ opioid receptor and little agonistic or antagonistic effects for µ and κ opioid receptors. Furthermore, rubiscolins were found to be G-protein-biased δ opioid receptor agonists based on the results obtained in cADDis^® cAMP and PathHunter^® β-arrestin recruitment assays. Finally, we found, for the first time, that they are also partially agonistic for the µ/δ dimers. In conclusion, rubiscolins could serve as attractive seeds, as δ opioid receptor-specific agonists, for the development of novel opioid analgesics with reduced side effects.

Evaluation of Buprenorphine Rotation in Patients Receiving Long-term Opioids for Chronic Pain: A Systematic Review

IMPORTANCE

Individuals with chronic pain who use long-term opioid therapy (LTOT) are at risk of opioid use disorder and other harmful outcomes. Rotation to buprenorphine may be considered, but the outcomes of such rotation in this population have not been systematically reviewed.

OBJECTIVE

To synthesize the evidence on rotation to buprenorphine from full μ-opioid receptor agonists among individuals with chronic pain who were receiving LTOT, including the outcomes of precipitated opioid withdrawal, pain intensity, pain interference, treatment success, adverse events or adverse effects, mental health condition, and health care use.

EVIDENCE REVIEW

PubMed, CINAHL, Embase, and PsycInfo were searched from inception through November 3, 2020, for peer-reviewed original English-language research that reported the prespecified outcomes of rotation from prescribed long-term opioids to buprenorphine among individuals with chronic pain. Two independent reviewers extracted data as well as assessed risk of bias and study quality according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines. Quality of evidence was assessed with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system.

FINDINGS

A total of 22 studies were analyzed, of which 5 (22.7%) were randomized clinical trials, 7 (31.8%) were case-control or cohort studies, and 10 (45.5%) were uncontrolled pre-post studies, which involved 1616 unique participants (675 female [41.8%] and 941 male [58.2%] individuals). Six of the 22 studies (27.3%) were primary or secondary analyses of a large randomized clinical trial. Participants had diverse pain and opioid use histories. Rationale for buprenorphine rotation included inadequate analgesia, intolerable adverse effects, risky opioid regimens (eg, high dose and/or sedative coprescriptions), and aberrant opioid use. Most protocols were adapted from protocols for initiating treatment in patients with opioid use disorder and used buccal or sublingual buprenorphine. Very low-quality evidence suggested that buprenorphine rotation was associated with maintained or improved analgesia, with a low risk of precipitating opioid withdrawal. Steady-dose buprenorphine was better tolerated than tapered-dose buprenorphine. Adverse effects were manageable, and severe adverse events were rare. Only 2 studies evaluated mental health outcomes, but none evaluated health care use. Limitations included a high risk of bias in most studies.

CONCLUSIONS AND RELEVANCE

In this systematic review, buprenorphine was associated with reduced chronic pain intensity without precipitating opioid withdrawal in individuals with chronic pain who were receiving LTOT. Future studies are necessary to ascertain the ideal starting dose, formulation, and administration frequency of buprenorphine as well as the best approach to buprenorphine rotation.

Relevance of Mu-Opioid Receptor Splice Variants and Plasticity of Their Signaling Sequelae to Opioid Analgesic Tolerance

Opioid dose escalation to effectively control pain is often linked to the current prescription opioid abuse epidemic. This creates social as well as medical imperatives to better understand the mechanistic underpinnings of opioid tolerance to develop interventions that minimize it, thereby maximizing the analgesic effectiveness of opioids. Profound opioid analgesic tolerance can be observed in the absence of mu-opioid receptor (MOR) downregulation, aggregate MOR G protein uncoupling, and MOR desensitization, in the absence of impaired G protein coupled receptor kinase phosphorylation, arrestin binding, or endocytosis. Thus, we have explored alternative biochemical sequelae that might better account for opioid analgesic tolerance. Our findings indicate that substantial plasticity among upstream and downstream components of opioid receptor signaling and the emergence of alternative signaling pathways are major contributors to opioid analgesic tolerance. An exemplar of this plasticity is our findings that chronic morphine upregulates the MOR variants MOR-1B2 and MOR-1C1 and phosphorylation of their C-terminal sites not present in MOR-1, events causally associated with the chronic morphine-induced shift in MOR G protein coupling from predominantly Gi/Go inhibitory to Gs-stimulatory adenylyl cyclase signaling. The unique feature(s) of these variants that underlies their susceptibility to adapting to chronic morphine by altering the nature of their G protein coupling reveals the richness and pliability of MOR signaling that is enabled by generating a wide diversity of MOR variants. Furthermore, given differential anatomical expression patterns of MOR variants, MOR splice variant-dependent adaptations to chronic morphine could enable mechanistic underpinnings of tolerance and dependence that are CNS region- and cell-specific.

α-Phellandrene exhibits antinociceptive and tumor-reducing effects in a mouse model of oncologic pain

Medical reports indicate a prevalence of pain in 50% of patients with cancer. In this context, this article investigated the antinociceptive activity of α-PHE using in vivo Sarcoma-180-induced hypernociception in mice to detail its mechanism(s) of antinociception under different conditions of treatment and tumor progression. Firsty, in vitro cytotoxic action was assessed using melanoma B-16/F-10 and S-180 murine cells and colorimetric MTT assays. For in vivo studies, acute treatment with α-PHE (6.25, 12.5, 25 and 50 mg/kg orally by gavage) was performed on the 1st day after S-180 inoculation. Subacute treatments were performed for 8 days starting on the next day (early protocol) or on day 8 after S-180 inoculation (late protocol). For all procedures, mechanical nociceptive evaluations were carried out by von Frey's technique in the subaxillary region peritumoral tissue (direct nociception) and in right legs of S-180-bearing mice (indirect nociception). α-PHE showed in vitro cytotoxic action on B-16/F-10 and S-180 (CI₅₀ values of 436.0 and 217.9 μg/mL), inhibition of in vivo tumor growth (ranging from 47.3 to 82.7%) and decreased direct (peritumoral tissue in subaxillary region) and indirect (right leg) mechanical nociception in Sarcoma 180-bearing mice with early and advanced tumors under acute or subacute conditions of treatment especially at doses of 25 and 50 mg/kg. It improved serum levels of GSH as well as diminished systemic lipid peroxidation, blood cytokines (interleukin-1β, -4, -6, and tumor necrosis factor-α). Such outcomes highlight α-PHE as a promising lead compound that combines antinociceptive and antineoplasic properties. Its structural simplicity make it a cost-effective alternative, justifying further mechanistic investigations and the development of pharmaceutical formulations. Moreover, the protocols developed and standardized here make it possible to use Sarcoma-180 hypernociception model to evaluate the capacity of new antinociceptive molecules under conditions of cancer-related allodynia.

Reducing Pain by Artificial Ascites Infusion During Radiofrequency Ablation for Subcapsular Hepatocellular Carcinoma

PURPOSE

To evaluate therapeutic effects of artificial ascites (AA) infusion in patients with subcapsular hepatocellular carcinoma (HCC) treated with radiofrequency ablation (RFA) and to determine whether this infusion can reduce pain.

METHODS AND MATERIALS

From 2011 to 2016, 123 patients with treatment-naïve single subcapsular HCC (≤ 2.5 cm) who underwent RFA were retrospectively included. Patients were divided into two groups according to AA infusion. After RFA, medical records were used to analyze pain scores during a 24-h period and to determine the opioid used that compared using Mann-Whitney U test. We also conducted subgroup analysis of the patients with HCCs located adjacent to parietal peritoneum. After follow-up period, we analyzed local tumor progression (LTP) and recurrence-free survival using Kaplan-Meier method.

RESULTS

AA was infused in 76 patients (61.8%, 76/123). Pain score using numeric rating scale (NRS) was significantly lower in AA infusion group than in control group (2.54 ± 2.8 vs. 3.66 ± 3.2, p = 0.048). Dose of opioids used was not significantly different between two groups (1.62 ± 3.4 mg vs. 1.66 ± 3 mg, p = 0.698). However, in subgroup analysis (N = 45), NRS score and dose of opioids used were significantly lower in AA infusion group (p = 0.03, p = 0.032, respectively). LTP rate was not significantly different between two groups (p = 0.673).

CONCLUSION

AA infusion was an effective and safe way to reduce pain when performing RFA for subcapsular HCC. In particular, in patients with subcapsular HCC adjacent to parietal peritoneum, dose of opioid to use pain control was significantly lower with AA infusion.

Modular transitional nursing intervention improves pain-related self-management for cancer patients: Study protocol for a randomized controlled trial

OBJECTIVE

To explore the effect of modular transitional nursing intervention on the improvement of self-management of the patients with cancer pain.

METHOD

This study will be conducted from March 2021 to May 2022 at Affiliated Hospital of Beihua University. The experiment was granted through the Research Ethics Committee of Affiliated Hospital of Beihua University (4348-019). Eighty patients are analyzed in our study. The patients will be included if they are between 18 and 70 years old and are diagnosed with cancer, the pain intensity score on moderate level, the pain lasts for more than 3 days, and the patients who have signed the written informed consent. While the patients will be excluded if they have a documented history of drug or alcohol abuse, and patients with limited performance, and patients have a surgery in the past 3 days. The primary result mainly expresses as intergroup differences in self-management disorders (Barriers Questionnaire-II) associated with the cancer pain. And the secondary results include the quality of life (QOL) and pain intensity. All the analyses are implemented with SPSS for Windows Version 20.0.

RESULTS

Table 1 will show the clinical outcomes between the 2 groups.

CONCLUSION

A modular transitional nursing intervention appears to reduce pain in cancer patients.

TRIAL REGISTRATION NUMBER

researchregistry6262.

Prescription switching: Rationales and risks

BACKGROUND

Therapeutic drug switching is commonplace across a broad range of indications and, within a drug class, is often facilitated by the availability of multiple drugs considered equivalent. Such treatment changes are often considered to improve outcomes via better efficacy or fewer side effects, or to be more cost-effective. Drug switching can be both appropriate and beneficial for several reasons; however, switching can also be associated with negative consequences.

AIM

To consider the impact of switching in two situations: the use of statins as a well-studied example of within-class drug switching, and gonadotropin-releasing hormone (GnRH)-targeting drug switching as an example of cross-class switching.

RESULTS

With the example of statins, within-class switching may be justified to reduce side effects, although the decision to switch is often also driven by the lower cost of generic formulations. With the example of GnRH agonists/antagonists, switching often occurs without the realisation that these drugs belong to different classes, with potential clinical implications.

CONCLUSION

Lessons emerging from these examples will help inform healthcare practitioners who may be considering switching drug prescriptions.

Impact of Patient-Controlled Analgesia (PCA) Smart Pump-Electronic Health Record (EHR) Interoperability with Auto-Documentation on Chart Completion in a Community Hospital Setting

INTRODUCTION

Complete and accurate documentation of opioids administered by patient-controlled analgesia (PCA) pumps is critical for ensuring a high-quality medication record and an accurate conversion of the intravenous (IV) regimen to oral therapy. Incomplete charting of PCA usage through a manual process may be associated with fragmented documentation of delivered therapy affecting the completeness of the medical record and the IV to oral dose conversion. This study is the first to evaluate the association between auto-documentation of opioid administration provided by PCA smart pump-electronic health record (EHR) interoperability and the completion of PCA opioid administration charting tasks.

METHODS

This retrospective cohort study was conducted at Lancaster General Hospital, Lancaster, Pennsylvania. Patients were assigned to pre-auto-documentation (n = 55) or post-auto-documentation groups (n = 58) based on whether they received PCA therapy prior to or after PCA-EHR interoperability was implemented. Charting of PCA therapy included documentation of the number of patient attempts, number of doses given, and total volume infused for both pre- and post-auto-documentation groups. In addition, total dose delivered was documented for the post-auto-documentation group. The overall chart-field completion rate was evaluated as the primary outcome. Individual chart completion percentages were assessed by stratified groups as secondary outcomes.

RESULTS

PCA smart pump-EHR interoperability with auto-documentation was associated with an increase in overall chart-field completion rate from 69.9 to 97.0% (p < 0.001). Auto-documentation was also associated with an increase in fully completed charts from 38 to 91% (139.3% increase, p < 0.001) and reductions of incomplete records in each stratified group (p < 0.001).

CONCLUSIONS

PCA smart pump-EHR interoperability with auto-documentation is associated with significant improvements in the completion of opioid administration chart-fields. Improved documentation of PCA administered opioids may have implications for the safety of opioid administration. Additional studies will be needed to assess the potential clinical impact of these results.

FUNDING

ICU Medical, Inc.

Opioid-Induced Tolerance and Hyperalgesia

Opioids are very potent and efficacious drugs, traditionally used for both acute and chronic pain conditions. However, the use of opioids is frequently associated with the occurrence of adverse effects or clinical problems. Other than adverse effects and dependence, the development of tolerance is a significant problem, as it requires increased opioid drug doses to achieve the same effect. Mechanisms of opioid tolerance include drug-induced adaptations or allostatic changes at the cellular, circuitry, and system levels. Dose escalation in long-term opioid therapy might cause opioid-induced hyperalgesia (OIH), which is a state of hypersensitivity to painful stimuli associated with opioid therapy, resulting in exacerbation of pain sensation rather than relief of pain. Various strategies may provide extra-opioid analgesia. There are drugs that may produce independent analgesic effects. A tailored treatment provided by skilled personnel, in accordance with the individual condition, is mandatory. Any treatment aimed at reducing opioid consumption may be indicated in these circumstances. Interventional techniques able to decrease the pain input may allow a decrease in the opioid dose, thus reverting the mechanisms producing tolerance of OIH. Intrathecal therapy with local anesthetics and a sympathetic block are the most common techniques utilized in these circumstances.

A Unique Case Report on Methadone Used for Treatment of Opioid-induced Hyperalgesia in a Cancer Patient at the End of Life

Opioids are the cornerstone of palliative pain management. Opioids work on the mu-opioid receptor as an agonist for the treatment of pain. Repeated exposure to opioids over time can lead to undesired desensitization of the antinociceptive receptor while sensitizing the N-methyl-D-aspartate (NMDA) pathway, causing a paradoxical effect where the treatment of pain creates more sensitivity to certain stimuli. This phenomenon is known as opioid-induced hyperalgesia (OIH). Methadone, a synthetic opioid, may be more effective for pain and offers advantages over other opioids in specific clinical situations due to its partial antagonistic effect on the NMDA pathway. We describe a unique case where as needed (prn) and continuous intravenous (IV) methadone was effective in relieving OIH caused by high doses of IV Dilaudid for intractable cancer pain at the end of life. Given its unique pharmacokinetics, effective pain control, and the prevention of suffering from OIH, methadone should be considered earlier on in palliative pain management, especially in those patients predicted to require high levels of opioid dosing.

The desire to hasten death in advanced cancer patients at a Mexican palliative care service

Introduction. The desire to hasten death (DHD) might be present in patients with advanced cancer. Multiple distressing physical and psychosocial symptoms may be related to it. There is limited literature about the characteristics of these patients in México. Objective. To describe the prevalence and factors associated with DHD in advanced cancer patients evaluated by a palliative care psychiatrist. Method. We conducted a cross-sectional study, including all patients referred to psychiatric assessment at the Servicio de Cuidados Paliativos of the Instituto Nacional de Cancerología in Mexico City, from January to December 2016. DHD was defined as the presence of death ideas, suicidal ideation, and/or request for euthanasia or medically assisted suicide. Patients with delirium, dementia, psychosis, or uncontrolled physical symptoms were excluded. Results. Sixty-four patients were included in the study. Most of them were women (59%); the mean age was 49 years old (SD = 16). Of them, 64% met criteria for a major depressive disorder, 64% for generalized anxiety disorder and/or panic disorder, and 11% for substance use disorders. 44% expressed DHD. In a multivariate regression analysis predicting DHD, only one factor emerged: clinical depression (OR = 13.5, p = .002, 95% CI [02.562, 71.726]). Discussion and conclusion. The desire to hasten death is a frequent issue for the patients evaluated at the psychiatric palliative care clinic. Depression and other distressing psychiatric pathologies were associated with DHD. Interdisciplinary interventions are needed to treat DHD. More research is warranted in order to understand the factors associated with the expression of DHD.

Balancing opioid analgesia with the risk of nonmedical opioid use in patients with cancer

The current opioid crisis has brought renewed attention and scrutiny to opioid prescriptions. When patients receiving opioid therapy for pain engage in nonmedical opioid use (NMOU) or diversion, untoward consequences can occur. New evidence suggests that patients with cancer might be at a higher risk of NMOU than was previously thought, but clinical evidence still supports the use of opioid analgesics as the gold standard to treat cancer-related pain, creating a dilemma in patient management. Clinicians are encouraged to adopt a universal precautions approach to patients with cancer receiving opioids, which includes screening all patients; discussing the risks, benefits, adverse effects and alternatives of opioid therapy; and providing education on safe use, storage and disposal. Use of urine drug tests, prescription drug monitoring programmes and close observation of behaviours related to opioid use help to ensure treatment adherence, detect NMOU and support therapeutic decision-making. These measures can optimize the risk-benefit ratio while supporting safe opioid use. In this Review, we examine the role of opioids in cancer pain, the risk of substance use disorder and methods to achieve the right balance between the two in order to ensure safe opioid use.

Prevalence of pain and treatment outcomes among cancer patients in a Malaysian palliative care unit

Background:

Pain remains one of the most common and debilitating symptoms of advanced cancer. To date, there is a lack of studies on pain and its treatment among Malaysian palliative care patients.

Objective:

This study aimed to explore the prevalence of pain and its treatment outcomes among adult cancer patients admitted to a palliative care unit in Sabah, Malaysia.

Methods:

Of 327 patients screened (01/09/15-31/12/17), 151 patients with assessed self-reported pain scores based on the numerical rating scale of 0-10 (current, worst and least pain within the past 24 hours) upon admission (baseline), 24, 48 and 72 hours post-admission and discharge were included. Pain severity and pain score reductions were analysed among those who experienced pain upon admission or in the past 24 hours. Treatment adequacy was measured by the Pain Management Index (PMI) among discharged patients. The PMI was constructed upon worst scores categorised as 0 (no pain), 1 (1-4, mild pain), 2 (5-6, moderate pain), or 3 (7-10, severe pain) which is then subtracted from the most potent level of prescribed analgesic drug scored as 0 (no analgesia), 1 (non-opioid), 2 (weak opioid) or 3 (strong opioid). PMI≥0 indicated adequate treatment.

Results:

Upon admission, 61.1% [95%CI 0.54:0.69] of 151 patients presented with pain. Of 123 patients who experienced pain upon admission or in the past 24 hours, 82.1% had moderate to severe worst pain. Throughout patients’ ward stay until discharge, there was an increased prescribing of analgesics and adjuvants compared to baseline, excluding weak opioids, with strong opioids as the mainstay treatment. For all pain score types (current, worst and least pain within the past 24 hours), means decreased at each time point (24, 48 and 72 hours post-admission and discharge) from baseline, with a significant decrease at 24 hours post-admission (p<0.001). Upon discharge (n=100), treatment adequacy significantly improved (PMI≥0 100% versus 68% upon admission, p<0.001).

Conclusions:

Accounting for pain’s dynamic nature, there was a high prevalence of pain among cancer patients in the palliative care unit. Continuous efforts incorporating comprehensive pain assessments, evidence-based treatments and patient education are necessary to provide adequate pain relief and end-of-life comfort care.

A Comparative Study of Opioid Switching to Methadone for Cancer Pain Control in Successful and Unsuccessful Cases

Background: Methadone may play a role in the control of refractory cancer pain in opioid switching, although some cases fail to switch to methadone. Objective: To evaluate the differences in the clinical aspects in switching to methadone between successful cases (SCs) and unsuccessful cases (UCs). Design: This was a retrospective study of the clinical aspects of cancer patients who experienced opioid switching from other opioids to methadone. Setting/Subjects: Eighty-seven patients who were prescribed oral methadone in our hospital were analyzed. Methadone was initiated from other opioids due to refractory pain in the stop-and-go switching. Among the 87 cases, 7 cases were excluded from further analysis because methadone administration was stopped due to vomiting or self-cessation within six days from switching. Results: Among the 80 cases who had methadone for seven days or more, 70 cases (SCs) were successful in switching to methadone, according to the Japanese definition, although 10 cases (UCs) who experienced the rapid progression of illness failed due to oral difficulty in the course of titration. In comparison of the clinical characteristics between SCs and UCs, the number of days alive from the start of the administration of methadone was significantly greater in the SCs than in the UCs (SCs: 87.1, UCs: 19, p < 0.0001), but no significant differences were observed for any other factors. Conclusion: From this comparative retrospective study of opioid switching to methadone for cancer pain control between SCs and UCs, early switching to methadone may be useful for patients with advanced cancer pain.

Practical management of opioid rotation and equianalgesia

Purpose

To review the recent literature on opioid rotation (ie, switching from one opioid drug to another or changing an opioid’s administration route) in cancer patients experiencing severe pain and to develop a novel equianalgesia table for use in routine clinical practice.

Methods

The MEDLINE database was searched with terms “cancer pain,” “opioid rotation,” “opioid switching,” “opioid ratio,” “opioid conversion ratio,” and “opioid equianalgesia” for the major opioids (morphine, oxycodone, fentanyl, and hydromorphone) and the intravenous, subcutaneous, oral, and transdermal administration routes. Selected articles were assessed for the calculated or cited opioid dose ratio, bidirectionality, and use of the oral morphine equivalent daily dose or a direct drug-to-drug ratio.

Results

Twenty publications met our selection criteria and were analyzed in detail. We did not find any large-scale, prospective, double-blind randomized controlled trial with robust design, and most of the studies assessed relatively small numbers of patients. Bidirectionality was investigated in seven studies only.

Conclusion

The updated equianalgesic table presented here incorporates the latest data and provides information on bidirectionality. Despite the daily use of equianalgesic tables, they are not based on high-level scientific evidence. More clinical research is needed on this topic.

Opioid switching and variability in response in pain cancer patients

INTRODUCTION

Opioid switching is a possible strategy for inadequate analgesia or unmanageable side effects. Its effectiveness ranges from 50 to 90% and is still debated.

PURPOSE

We analyzed the impact of opioid switching in a cancer pain population treated with strong opioids for pain.

METHODS

This is a post hoc analysis from a multicenter, randomized, four-arm, controlled, phase IV clinical trial. Outcome variables included the percentages of switches, the reasons for the switch, the dose changes before and after the switch, depending on the starting opioid, the response in case of inadequate analgesia, and unmanageable toxicity, and the variability of response among and within patients.

RESULTS

We analyzed 498 patients. The opioid was switched in 79 patients (15.9%) 87 times, mainly for uncontrolled pain (52.3%), adverse opioid reactions (22.1%), both of these (4.8%), and dysphagia (20.8%). The reasons for switching varied depending on the starting opioid. Pain reduction was good after 51.45% of switches and control of opioid side effects was good after 43.5%. The relief of opioid-induced toxicity varied among adverse events and within each patient. The daily doses were higher after switching oral opioids and lower after transdermal drugs.

CONCLUSIONS

Half of the patients who underwent switching experienced improved relief of pain or amelioration of opioid toxicity. The switch can help in the management of some cases but with many limits and uncertainties.

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

AIM

The objective of this review was to assess the existent evidence for the use of methadone as a first-line therapy in cancer pain management.

METHODS

A systematic literature search on MEDLINE and Embase databases was carried out from each database, setting up the date to August 30, 2017. Studies were included if methadone was a first-line drug as a Step 3 of World Health Organization analgesic ladder, or at low doses (Step 2), if they were conducted in adult patients with cancer pain, and if they contained outcomes on pain- and opioid-related adverse effects.

RESULTS

The initial search yielded 219 records. Ten articles were considered after the initial screening according to inclusion and exclusion criteria. They included three longitudinal open-label studies. In two studies methadone was initiated at low doses (≤10 mg/day). These studies suggested that methadone was effective in providing analgesia and well tolerated as first opioid at different starting doses and in different conditions and settings. Five additional studies were randomized controlled studies with morphine in patients who had received opioids for moderate pain. Methadone, compared with oral morphine, or transdermal fentanyl, either at low (Step 2 level) or relatively higher doses (Step 3 level), provided similar analgesia with similar adverse effects profile with limited dose escalation in time.

CONCLUSION

Available data are not sufficient to draw net conclusion. However, open-label and controlled studies have shown that methadone may be effective as first-line drug in the management of cancer pain, providing analgesia and adverse effect profiles similar to those produced by other opioids. The finding that methadone doses tend to remain stable suggests that metabolic characteristics and extraopioid analgesic effects, as its well antihyperalgesic properties may be interesting potential advantages. Further studies should provide information regarding the long-term use of methadone or the need to switch from methadone to other opioids when a loss of analgesic response occurs.

Progress in understanding mechanisms of opioid-induced gastrointestinal adverse effects and respiratory depression

Opioids evoke analgesia through activation of opioid receptors (predominantly the μ opioid receptor) in the central nervous system. Opioid receptors are abundant in multiple regions of the central nervous system and the peripheral nervous system including enteric neurons. Opioid-related adverse effects such as constipation, nausea, and vomiting pose challenges for compliance and continuation of the therapy for chronic pain management. In the post-operative setting opioid-induced depression of respiration can be fatal. These critical limitations warrant a better understanding of their underpinning cellular and molecular mechanisms to inform the design of novel opioid analgesic molecules that are devoid of these unwanted side-effects. Research efforts on opioid receptor signalling in the past decade suggest that differential signalling pathways and downstream molecules preferentially mediate distinct pharmacological effects. Additionally, interaction among opioid receptors and, between opioid receptor and non-opioid receptors to form signalling complexes shows that opioid-induced receptor signalling is potentially more complicated than previously thought. This complexity provides an opportunity to identify and probe relationships between selective signalling pathway specificity and in vivo production of opioid-related adverse effects. In this review, we focus on current knowledge of the mechanisms thought to transduce opioid-induced gastrointestinal adverse effects (constipation, nausea, vomiting) and respiratory depression.

Chronic Cancer Pain: Diagnostic Dilemma and Management Challenges

A 32-year-old female, diagnosed case of neuroendocrine tumor of pancreas, was admitted to the pain and palliative care unit with complaints of diffuse abdominal pain which was severe in intensity with score on numerical rating scale-9/10. Pain was not relieved even after taking tablet morphine immediate release 360 mg every 4 hourly, paracetamol 500 mg 6 hourly, and gabapentin 300 mg 8 hourly. She had undergone distal pancreatectomy with splenectomy and also received multiple lines of chemotherapy. After making a diagnosis of opioid-induced hyperalgesia, opioid rotation from morphine to fentanyl was done. This case report reflects various conditions where strong opioids fail to relieve cancer pain, and a multimodal approach is needed for its management.