Early switching from morphine to methadone is not improved by acetaminophen in the analgesia of oncologic patients: a prospective, randomized, double-blind, placebo-controlled study

Is Acetaminophen Beneficial in Patients With Cancer Pain Who are on Strong Opioids? A Randomized Controlled Trial

CONTEXT

Pain is common among cancer patients. The evidence recommends using strong opioids in moderate to severe cancer pain. No conclusive evidence supports the effectiveness of adding acetaminophen to patients with cancer pain who are already using this regime.

OBJECTIVES

To assess the analgesic efficacy of acetaminophen in hospitalized cancer patients with moderate to severe pain receiving strong opioids.

METHODS

In this randomized blinded clinical trial, hospitalized cancer patients with moderate or severe acute pain managed with strong opioids were randomized to acetaminophen or placebo. The primary outcome was pain intensity difference between baseline and 48 hours using the Visual Numeric Rating Scales (VNRS). Secondary outcomes included change in morphine equivalent daily dose (MEDD), and patients' perception of improved pain control.

RESULTS

Among 112 randomized patients, 56 patients received placebo, 56 acetaminophen. Mean (standard deviation [SD]) decrease in pain intensity (VNRS) at 48 hours were 2.7 (2.5) and 2.3 (2.3), respectively (95% Confidence Interval (CI) [-0.49; 1.32]; P = 0.37). Mean (SD) change in MEDD was 13.9 (33.0) mg/day and 22.4 (57.7), respectively (95% CI [-9.24; 26.1]; P = 0.35). The proportion of patients perceiving pain control improvement after 48 hours was 82% in the placebo and 80% in the acetaminophen arms (P = 0.81).

CONCLUSION

Among patients with cancer pain on strong opioid regime, acetaminophen may not improve pain control, or decrease total opioid use. These results add to the current evidence available suggesting not to use acetaminophen as an adjuvant for advanced cancer patients with moderate to severe cancer pain who are on strong opioids.

Methadone rotation versus other opioid rotation for refractory cancer induced bone pain: protocol of an exploratory randomised controlled open-label study

BACKGROUND

A third of patients with advanced cancer and bone metastasis suffer from cancer induced bone pain (CIBP), impeding quality of life, psychological distress, depression and anxiety. This study will evaluate the impact of an opioid rotation, comparing methadone rotation with other opioid rotation in patients with refractory CIBP.

METHODS

This open-label randomised controlled trial will recruit cancer patients with CIBP and inadequate pain control despite established baseline opioid and/or intolerable opioid side effects from cancer and palliative care services. Participants will be at least 18 years old, with a predicted prognosis of greater than 8 weeks, meet the core diagnostic criteria for CIBP, have a worst pain score of ≥ 4 of 10 from CIBP and/ or have opioid toxicity (graded ≥ 2 on Common Terminology Criteria for Adverse Events). Participants will have sufficiently proficient English to complete questionnaires and provide informed consent. Participants will be randomised 1:1 to be rotated to methadone to another opioid. The primary objective is to examine the impact of opioid rotation in improving CIBP by comparing analgesic efficacy, safety and tolerability in the two arms. Secondary objectives will assess changes in the intensity, duration and frequency of breakthrough pain, requirement of breakthrough analgesia, overall opioid escalation index, and time taken to observe improvement in pain reduction, pain interference and quality of life.

DISCUSSION

Laboratory studies suggest the involvement of neuropathic involvement in the mechanism of CIBP, though there remains no clear evidence of the routine use of neuropathic agents. Methadone as an analgesic agent may have a role to play in this cohort of patients, thus warranting further exploratory studies.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry No: ACTRN12621000141842. Registered 11 February 2021.

Randomized double-blind controlled trial to assess the efficacy of intravenous acetaminophen associated with strong opioids in the treatment of acute pain in adult cancer patients: study protocol

Background

Cancer pain is one of the most frequent and relevant symptoms in cancer patients and impacts on patient’s quality of life. International and local standards recommend as an initial strategy the use of an analgesic scheme composed of strong opioids associated with adjuvants such as acetaminophen, based upon the assumption that combining drugs could have a better analgesic effect, could allow lowering opioid dosing, and could prevent the occurrence of adverse effects of opioids. However, there is uncertainty about the impact of acetaminophen as an adjuvant in patients who use strong opioids for moderate to severe pain management in cancer patients. The aim of this study is to assess the efficacy and safety of intravenous acetaminophen associated with strong opioids in hospitalized adult cancer patients who have moderate to severe cancer-related pain.

Methods

We will perform a randomized double-blinded controlled study comparing intravenous acetaminophen 1 g 4 times a day versus placebo for 48 h as an adjuvant to strong opioids. We will assess pain intensity as a primary outcome, using the verbal numerical rating scale (VNRS, I0 to 10 scale with higher scores meaning higher pain intensity), and we will compare the mean difference in pain intensity between baseline and 48 h among the placebo and intervention groups. We estimate that a decrease of 1 point in the VNRS would be clinically significant. Assuming a standard deviation in pain intensity of 1.7 points, an alpha of 0.025, and a power of 0.8, we estimate a sample size of 112 patients, with 56 patients in each arm. Secondary outcomes include the difference in total opioid use between baseline and at 48 h among the groups, and adverse effects such as drowsiness, constipation, nausea, and vomiting would be evaluated.

Discussion

The randomized, double-blind, placebo-controlled design is the best strategy to assess the efficacy of acetaminophen as an adjuvant in adult cancer patients with moderate to severe pain who are receiving strong opioids. We expect to contribute to national and international guidelines with these results.

Trial registration

Clinicaltrials.gov NCT04779567. Registered on March 3, 2021. Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06442-2.

Revision of Pharmacological Treatment Recommendations for Cancer Pain: Clinical Guidelines from the Japanese Society of Palliative Medicine

Background: Pain is one of the most common symptoms in cancer patients. The Japanese Society for Palliative Medicine (JSPM) first published its clinical guidelines for the management of cancer pain in 2010. Since then, more research on cancer pain management has been reported, and new drugs have become available in Japan. Thus, the JSPM has now revised the clinical guidelines using a validated methodology. Methods: This guideline was developed through a systematic review, discussion, and the Delphi method, following a formal guideline development process. Results: Thirty-five recommendations were created: 19 for the pharmacological management of cancer pain, 6 for the management of opioid-induced adverse effects, and 10 for pharmacological treatment procedures. Due to the lack of evidence that directly addressed our clinical questions, most of the recommendations had to be based on consensus among committee members and other guidelines. Discussion: It is critical to continue to build high-quality evidence in cancer pain management, and revise these guidelines accordingly.

Methadone Switching for Cancer Pain: A New Classification of Initiation Protocols, Based on a Critical Literature Review

Background: The initiation of methadone, a known effective analgesic for cancer pain, is complex. The existing protocols are often inadequately described; therefore, a classification of literature is needed. We reviewed and classified the recent literature on methadone initiation protocols in cancer patients experiencing severe pain. Objective: To provide a new classification of initiation protocols, based on a critical literature review. Data Sources: The MEDLINE database was searched for articles published until March 25, 2021, using the terms "cancer pain," "methadone," "methadone introduction," or "methadone initiation." The search was limited to human studies, randomized controlled trials (RCTs), other clinical trials, meta-analyses, and case reports. Selected articles were assessed for initiation details (rapid or progressive), administered dose (fixed rescue dose or ad libitum), and dose calculation (fixed or progressive ratios using morphine equivalent daily dose [MEDD] for daily or unitary dose). Results: Twenty-four publications that met our inclusion criteria were analyzed. No large-scale prospective double-blind RCTs with robust design were identified. Most studies assessed relatively small numbers of patients. Eight initiation types were identified, of which three involved seven "high quality" studies: "rapid switch-fixed doses and rescue dose-progressive daily ratio," "progressive switch-fixed dose and rescue dose-progressive daily ratio," and "rapid switch-ad libitum-fixed ratio for unitary dose" protocols. This classification provides the latest information on methadone initiation protocols. The total daily dose of methadone varied largely across protocols. Conclusion: We recommend a maximal daily methadone dose of 100 mg (3 doses of 30 mg or 5 doses of 20 mg) for MEDD <500 mg, when the two "ad libitum" protocols are used. Further clinical research on this topic is warranted.

Acetaminophen in Patients Receiving Strong Opioids for Cancer Pain

The mainstay of treatment in advanced cancer pain is opioids; however, non-opioid medications such as acetaminophen continue to be included in guidelines despite a lack of clear, convincing evidence for their use. The aim of our study was to determine if acetaminophen improves pain control or reduces opioid utilization in hospitalized patients receiving strong opioids for cancer pain managed by the palliative care consult service (PCCS). We carried out at single-center retrospective cohort study of 194 adult cancer patients seen by the PCCS and who received strong opioids. Patients who received acetaminophen during their admission were compared to those who did not. The primary outcome was a 30% reduction in average daily pain score from admission to discharge using a numeric rating scale. There was no difference between groups in achieving a 30% reduction in pain (35.8% vs. 35.4%, adjusted odds ratio 0.87, 95% confidence interval [CI] 0.46 to 1.63). Acetaminophen was associated with a longer LOS (8 days vs. 6 days, adjusted relative risk 1.67, 95% CI 1.30 to 2.15). In this study of cancer patients receiving strong opioids, acetaminophen use was not associated with improved pain control or reduced opioid utilization, but was associated with a greater LOS.

Methadone in Cancer Pain

Methadone has been an unique, versatile, cost effective, synthetic opioid utilized in nociceptive as well as neuropathic pain. Pain and palliative care physicians started accepting methadone in treatment of complex pain associated with advanced cancer and neuropathic pain syndromes in which conventional opioids were no longer effective. The challenge is in accepting methadone as a main stream first line opioid, from being considered as a second line replacement/substitution drug all these years. Methadone has a significant role as opioid rotation in refractory cancer pain, especially when started early leading to successful conversion. Advantages of methadone in paediatric patients with advanced cancer were its safety and efficacy as a first-choice opioid, availability as a liquid formulation and its infrequent dose requirements. Methadone is neither recommended nor justified to be used as an anti-cancer drug and its role as an anti-cancer agent is a misconception. Many guidelines were proposed after 2008 to address methadone safety. Most of them emphasized on prevention of cardiac arrhythmia and association of methadone with QTc prolongation rather than address the real issue. Methadone has been established to be safe when used in opioid naïve patients with careful titration instituted in an ambulatory setting and has equal success in opioid rotation in outpatient setup. Methadone prescription should be carried out by experienced pain and palliative care providers with careful dose titration and clinical monitoring.

Treatment of Pain in Cancer: Towards Personalised Medicine

Despite increased attention to cancer pain, pain prevalence in patients with cancer has not improved over the last decade and one third of cancer patients on anticancer therapy and half of patients with advanced disease still suffer from moderate to severe pain. In this review, we explore the possible reasons for the ongoing high prevalence of cancer pain and discuss possible future directions for improvement in personalised pain management. Among possible reasons for the lack of improvement are: Barriers for patients to discuss pain with clinicians spontaneously; pain measurement instruments are not routinely used in daily practice; limited knowledge concerning the assessment of undertreatment; changes in patients’ characteristics, including the ageing of the population; lack of significant improvement in the treatment of neuropathic pain; limitations of pharmacological treatment and lack of evidence-based nonpharmacological treatment strategies. In order to improve cancer pain treatment, we recommend: (1) Physicians proactively ask about pain and measure pain using assessment instruments; (2) the development of an optimal tool measuring undertreatment; (3) educational interventions to improve health care workers’ skills in pain management; (4) the development of more effective and personalised pharmacological and nonpharmacological pain treatment.

Systematic review and meta-analysis on non-opioid analgesics in palliative medicine

Non-opioid analgesics are widely used for pain relief in palliative medicine. However, there is a lack of evidence-based recommendations addressing the efficacy, tolerability, and safety of non-opioids in this field. A comprehensive systematic review and meta-analysis on current evidence can provide a basis for sound recommendations in clinical practice. A database search for controlled trials on the use of non-opioids in adult palliative patients was performed in Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, PsycINFO, and EMBASE from inception to 18 February 2018. Endpoints were pain intensity, opioid-sparing effects, safety, and quality of life. Studies with similar patients, interventions, and outcomes were included in the meta-analyses. Our systematic search was able to only identify studies dealing with cancer pain. Of 5991 retrieved studies, 43 could be included (n = 2925 patients). There was no convincing evidence for satisfactory pain relief by acetaminophen alone or in combination with strong opioids. We found substantial evidence of moderate quality for a satisfactory pain relief in cancer by non-steroidal anti-inflammatory drugs (NSAIDs), flupirtine, and dipyrone compared with placebo or other analgesics. There was no evidence for a superiority of one specific non-opioid. There was moderate quality of evidence for a similar pain reduction by NSAIDs in the usual dosage range compared with up to 15 mg of morphine or opioids of equianalgesic potency. The combination of NSAID and step III opioids showed a beneficial effect, without a decreased tolerability. There is scarce evidence concerning the combination of NSAIDs with weak opioids. There are no randomized-controlled studies on the use of non-opioids in a wide range of end-stage diseases except for cancer. Non-steroidal anti-inflammatory drugs, flupirtine, and dipyrone can be recommended for the treatment of cancer pain either alone or in combination with strong opioids. The use of acetaminophen in the palliative setting cannot be recommended. Studies are not available for long-term use. There is a lack of evidence regarding pain treatment by non-opioids in specific cancer entities.

Methadone versus Fentanyl in Patients with Radiation-Induced Nociceptive Pain with Head and Neck Cancer: A Randomized Controlled Noninferiority Trial

BACKGROUND

Pain is still a burden for many patients with cancer. A recent trial showed the superiority of methadone over fentanyl in neuropathic pain, and we expect that this finding could influence the number of patients treated with methadone.

METHODS

We performed a randomized controlled noninferiority trial in patients with nociceptive pain. Eighty-two strong-opioid-naïve patients with head and neck cancer with substantial pain (pain numeric rating scale [NRS] score ≥ 4) due to radiation therapy were included. Forty-two patients were treated with methadone, and 40 with fentanyl. Patients were evaluated at 1, 3, and 5 weeks. The primary outcomes were reduction in average pain and clinical success (50% pain decrease). We set the predefined noninferiority margin at 1 on the NRS and 10% clinical success. Secondary outcomes were pain interference, global perceived effect (GPE), side effects, and opioid escalation index.

RESULTS

Noninferiority was shown for decrease in NRS for maximum and mean pain scores at 1 and 3 weeks. Noninferiority was shown for clinical success at 1 week only. The opioid escalation index was lower in the methadone group at 3 and 5 weeks as compared to fentanyl (1.44 vs. 1.99, P = 0.004; and 1.50 vs. 2.32, P = 0.013). The pain interference in the methadone group was significantly decreased at 3 weeks only. GPE and side effects were not different.

CONCLUSION

This is the first study to show noninferiority of methadone compared to fentanyl at 1 and 3 weeks in the treatment of radiation-induced nociceptive pain in patients with head and neck cancer.

Paracetamol (acetaminophen) for chronic non-cancer pain in children and adolescents

BACKGROUND

Pain is a common feature of childhood and adolescence around the world, and for many young people, that pain is chronic. The World Health Organization guidelines for pharmacological treatments for children's persisting pain acknowledge that pain in children is a major public health concern of high significance in most parts of the world. While in the past, pain was largely dismissed and was frequently left untreated, views on children's pain have changed over time, and relief of pain is now seen as important.We designed a suite of seven reviews on chronic non-cancer pain and cancer pain (looking at antidepressants, antiepileptic drugs, non-steroidal anti-inflammatory drugs, opioids, and paracetamol as priority areas) in order to review the evidence for children's pain utilising pharmacological interventions in children and adolescents.As the leading cause of morbidity in children and adolescents in the world today, chronic disease (and its associated pain) is a major health concern. Chronic pain (lasting three months or longer) can arise in the paediatric population in a variety of pathophysiological classifications: nociceptive, neuropathic, idiopathic, visceral, nerve damage pain, chronic musculoskeletal pain, and chronic abdominal pain, and other unknown reasons.Paracetamol (acetaminophen) is one of the most widely used analgesics in both adults and children. The recommended dosage in the UK, Europe, Australia, and the USA for children and adolescents is generally 10 to 15 mg/kg every four to six hours, with specific age ranges from 60 mg (6 to 12 months old) up to 500 to 1000 mg (over 12 years old). Paracetamol is the only recommended analgesic for children under 3 months of age. Paracetamol has been proven to be safe in appropriate and controlled dosages, however potential adverse effects of paracetamol if overdosed or overused in children include liver and kidney failure.

OBJECTIVES

To assess the analgesic efficacy and adverse events of paracetamol (acetaminophen) used to treat chronic non-cancer pain in children and adolescents aged between birth and 17 years, in any setting.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) via the Cochrane Register of Studies Online, MEDLINE via Ovid, and Embase via Ovid from inception to 6 September 2016. We also searched the reference lists of retrieved studies and reviews, and searched online clinical trial registries.

SELECTION CRITERIA

Randomised controlled trials, with or without blinding, of any dose and any route, treating chronic non-cancer pain in children and adolescents, comparing paracetamol with placebo or an active comparator.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for eligibility. We planned to use dichotomous data to calculate risk ratio and numbers needed to treat, using standard methods where data were available. We assessed GRADE (Grading of Recommendations Assessment, Development and Evaluation) and planned to create a 'Summary of findings' table.

MAIN RESULTS

No studies were eligible for inclusion in this review. We rated the quality of the evidence as very low. We downgraded the quality of evidence by three levels due to the lack of data reported for any outcome.

AUTHORS' CONCLUSIONS

There was no evidence from randomised controlled trials to support or refute the use of paracetamol (acetaminophen) to treat chronic non-cancer pain in children and adolescents. We are unable to comment about efficacy or harm from the use of paracetamol to treat chronic non-cancer pain in children and adolescents.We know from adult randomised controlled trials that paracetamol, can be effective, in certain doses, and in certain pain conditions (not always chronic).This means that no conclusions could be made about efficacy or harm in the use of paracetamol (acetaminophen) to treat chronic non-cancer pain in children and adolescents.

Oral paracetamol (acetaminophen) for cancer pain

BACKGROUND

Pain is a common symptom with cancer, and 30% to 50% of all people with cancer will experience moderate to severe pain that can have a major negative impact on their quality of life. Non-opioid drugs are commonly used to treat mild to moderate cancer pain, and are recommended for this purpose in the WHO cancer pain treatment ladder, either alone or in combination with opioids.A previous Cochrane review that examined the evidence for nonsteroidal anti-inflammatory drugs (NSAIDs) or paracetamol, alone or combined with opioids, for cancer pain was withdrawn in 2015 because it was out of date; the date of the last search was 2005. This review, and another on NSAIDs, updates the evidence.

OBJECTIVES

To assess the efficacy of oral paracetamol (acetaminophen) for cancer pain in adults and children, and the adverse events reported during its use in clinical trials.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and Embase from inception to March 2017, together with reference lists of retrieved papers and reviews, and two online study registries.

SELECTION CRITERIA

We included randomised, double-blind, studies of five days' duration or longer, comparing paracetamol alone with placebo, or paracetamol in combination with an opioid compared with the same dose of the opioid alone, for cancer pain of any intensity. Single-blind and open studies were also eligible for inclusion. The minimum study size was 25 participants per treatment arm at the initial randomisation.

DATA COLLECTION AND ANALYSIS

Two review authors independently searched for studies, extracted efficacy and adverse event data, and examined issues of study quality and potential bias. We did not carry out any pooled analyses. We assessed the quality of the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

Three studies in adults satisfied the inclusion criteria, lasting up to one week; 122 participants were randomised initially, and 95 completed treatment. We found no studies in children. One study was parallel-group, and two had a cross-over design. All used paracetamol as an add-on to established treatment with strong opioids (median daily morphine equivalent doses of 60 mg, 70 mg, and 225 mg, with some participants taking several hundred mg of oral morphine equivalents daily). Other non-paracetamol medication included non-steroidal anti-inflammatory drugs (NSAIDs), tricyclic antidepressants, or neuroleptics. All studies were at high risk of bias for incomplete outcome data and small size; none was unequivocally at low risk of bias.None of the studies reported any of our primary outcomes: participants with pain reduction of at least 50%, and at least 30%, from baseline; participants with pain no worse than mild at the end of the treatment period; participants with Patient Global Impression of Change (PGIC) of much improved or very much improved (or equivalent wording). What pain reports there were indicated no difference between paracetamol and placebo when added to another treatment. There was no convincing evidence of paracetamol being different from placebo with regards to quality of life, use of rescue medication, or participant satisfaction or preference. Measures of harm (serious adverse events, other adverse events, and withdrawal due to lack of efficacy) were inconsistently reported and provided no clear evidence of difference.Our GRADE assessment of evidence quality was very low for all outcomes, because studies were at high risk of bias from several sources.

AUTHORS' CONCLUSIONS

There is no high-quality evidence to support or refute the use of paracetamol alone or in combination with opioids for the first two steps of the three-step WHO cancer pain ladder. It is not clear whether any additional analgesic benefit of paracetamol could be detected in the available studies, in view of the doses of opioids used.

Is it useful to add acetaminophen to high-potency opioids in cancer-related pain?

Pain is one of the most frequent and relevant symptoms in cancer patients. The World Health Organization's analgesic ladder proposes the use of strong opioids associated with adjuvants such as acetaminophen or nonsteroidal anti-inflammatory drugs in step III. However, it is unclear whether adding acetaminophen to an analgesic regimen based on strong opioids has any benefit in cancer patients with moderate to severe pain. To answer this question we searched in Epistemonikos database, which is maintained by screening multiple information sources. We identified two systematic reviews including five randomized trials overall. We extracted data and generated a summary of findings table using the GRADE approach. We concluded that adding acetaminophen to strong opioids might make little or no difference in improving pain management in cancer patients.

Methadone for cancer pain

BACKGROUND

This is an updated review originally published in 2004 and first updated in 2007. This version includes substantial changes to bring it in line with current methodological requirements. Methadone is a synthetic opioid that presents some challenges in dose titration and is recognised to cause potentially fatal arrhythmias in some patients. It does have a place in therapy for people who cannot tolerate other opioids but should be initiated only by experienced practitioners. This review is one of a suite of reviews on opioids for cancer pain.

OBJECTIVES

To determine the effectiveness and tolerability of methadone as an analgesic in adults and children with cancer pain.

SEARCH METHODS

For this update we searched CENTRAL, MEDLINE, Embase, CINAHL, and clinicaltrials.gov, to May 2016, without language restriction. We also checked reference lists in relevant articles.

SELECTION CRITERIA

We sought randomised controlled trials comparing methadone (any formulation and by any route) with active or placebo comparators in people with cancer pain.

DATA COLLECTION AND ANALYSIS

All authors agreed on studies for inclusion. We retrieved full texts whenever there was any uncertainty about eligibility. One review author extracted data, which were checked by another review author. There were insufficient comparable data for meta-analysis. We extracted information on the effect of methadone on pain intensity or pain relief, the number or proportion of participants with 'no worse than mild pain'. We looked for data on withdrawal and adverse events. We looked specifically for information about adverse events relating to appetite, thirst, and somnolence. We assessed the evidence using GRADE and created a 'Summary of findings' table.

MAIN RESULTS

We revisited decisions made in the earlier version of this review and excluded five studies that were previously included. We identified one new study for this update. This review includes six studies with 388 participants. We did not identify any studies in children.The included studies differed so much in their methods and comparisons that no synthesis of results was feasible. Only one study (103 participants) specifically reported the number of participants with a given level of pain relief, in this case a reduction of at least 20% - similar in both the methadone and morphine groups. Using an outcome of 'no worse than mild pain', methadone was similar to morphine in effectiveness, and most participants who could tolerate methadone achieved 'no worse than mild pain'. Adverse event withdrawals with methadone were uncommon (12/202) and similar in other groups. Deaths were uncommon except in one study where the majority of participants died, irrespective of treatment group. For specific adverse events, somnolence was more common with methadone than with morphine, while dry mouth was more common with morphine than with methadone. None of the studies reported effects on appetite.We judged the quality of evidence to be low, downgraded due to risk of bias and sparse data. For specific adverse events, we considered the quality of evidence to be very low, downgraded due to risk of bias, sparse data, and indirectness, as surrogates for appetite, thirst and somnolence were used.There were no data on the use of methadone in children.

AUTHORS' CONCLUSIONS

Based on low-quality evidence, methadone is a drug that has similar analgesic benefits to morphine and has a role in the management of cancer pain in adults. Other opioids such as morphine and fentanyl are easier to manage but may be more expensive than methadone in many economies.

Methods of Rotation From Another Strong Opioid to Methadone for the Management of Cancer Pain: A Systematic Review of the Available Evidence

CONTEXT

Up to 44% of patients with cancer-related pain require opioid rotation (OR) because of inadequate analgesia or side effects. No consensus exists regarding the most efficacious method for rotation to methadone.

OBJECTIVES

To define the available evidence regarding methods of rotation to methadone and to determine if sufficient evidence exists regarding the superiority of one method.

METHODS

A predefined search strategy, using Medical Subject Headings (MeSH) search terms and keywords combined using Boolean operators, was performed. Study selection was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidance. Data were extracted, quality of studies assessed, and narrative synthesis undertaken.

RESULTS

A total of 3214 potentially relevant studies were identified. Twenty-five studies were included: 15 retrospective and 10 prospective (n = 1229). One trial compared three-day switch (3DS) and rapid conversion (RC) methods; two, 3DS; 10, RC; nine, ad libitum (AL). Success rates were as follows: 3DS-93%, RC-71.7%, and AL-92.8%. The single clinical trial and retrospective studies demonstrated poorer analgesia and an excess of adverse events (AEs) in the RC group (five dropouts because of AEs) compared with the 3DS group (no severe AEs). Time to stable analgesia was as follows: RC <4.3 days and AL <6 days.

CONCLUSION

Evidence identified was mainly from uncontrolled observational studies, making causality difficult to establish. Studies were heterogeneous in methodology and outcome measures. There was a trend toward excess AEs using the RC method, in comparison to the AL and 3DS methods. The methodological quality of the AL studies was low. A direct comparison of AL and 3DS methods would be informative.

Research gaps on methadone harms and comparative harms: findings from a review of the evidence for an American Pain Society and College on Problems of Drug Dependence clinical practice guideline

Methadone-associated overdose deaths have dramatically increased. In order to inform an evidence-based clinical practice guideline to improve safety of methadone prescribing, the American Pain Society commissioned a systematic review on various aspects related to methadone safety. We searched Ovid MEDLINE, Cochrane Library, and PsycINFO databases through July 2012 to identify studies that addressed 1 or more of 17 Key Questions related to methadone safety; an update search was performed in 2014 for new studies related to methadone-related overdose and risks related to cardiac arrhythmias. A total of 168 studies met inclusion criteria for the review. The purpose of this article is to highlight critical research gaps in the literature related to methadone safety. These include lack of evidence on risk factors associated with methadone-overdose deaths and adverse events, limited evidence to evaluate the comparative mortality of methadone versus other opioids, insufficient evidence to fully understand the harms associated with methadone use during pregnancy, and insufficient evidence to determine effects of risk mitigation strategies such as electrocardiogram monitoring, strategies for managing patients with prolonged QTc intervals on screening, urine drug testing, alternative dosing regimens for initiation and titration of therapy, and timing of follow-up. Therefore, most guideline recommendations are based on weak evidence. More research is needed to guide safe methadone prescribing practices and decrease the adverse events associated with methadone.

PERSPECTIVE

This article summarizes critical research gaps in the literature related to methadone safety, based on a systematic review commissioned by the American Pain Society. Critical research gaps were identified in a number of areas, highlighting the need for additional research to guide safer prescribing and risk mitigation strategies.

Nonopioid Drugs in the Treatment of Cancer Pain

The WHO analgesic ladder for the treatment of cancer pain provides a three-step sequential approach for analgesic administration based on pain severity that has global applicability. Nonopioids were recommended for mild pain, with the addition of mild opioids for moderate pain and strong opioids for severe pain. Here, we review the evidence for the use of nonopioid analgesic agents in patients with cancer and describe the mode of action of the main drug classes. Evidence supports the use of anti-inflammatory drugs such as acetaminophen/paracetamol and nonsteroidal anti-inflammatory drugs (NSAIDs) for mild cancer pain. Adding an NSAID to an opioid for stronger cancer pain is efficacious, but the risk of long-term adverse effects has not been quantified. There is limited evidence to support using acetaminophen with stronger opioids. Corticosteroids have a specific role in spinal cord compression and brain metastases, where improved analgesia is a secondary benefit. There is limited evidence for adding corticosteroids to stronger opioids when pain control is the primary objective. Systematic reviews suggest a role for antidepressant and anticonvulsant medications for neuropathic pain, but there are methodologic issues with the available studies. Bisphosphonates improve pain in patients with bony metastases in some tumor types. Denosumab may delay worsening of pain compared with bisphosphonates. Larger studies of longer duration are required to address outstanding questions concerning the use of nonopioid analgesia for stronger cancer pain.

The role of paracetamol and nonsteroidal anti-inflammatory drugs in addition to WHO Step III opioids in the control of pain in advanced cancer. A systematic review of the literature

BACKGROUND

Nonsteroidal anti-inflammatory drugs (NSAIDs) and paracetamol are used widely in the management of mild to moderate cancer pain and are frequently combined with opioids in the treatment of moderate to severe pain.

AIM

To perform a systematic literature review of the evidence of the efficacy and toxicity of NSAIDs or paracetamol added to WHO Step III opioid treatment for cancer pain.

DESIGN AND DATA SOURCES

A systematic literature review of MedLine, EMBASE and Cochrane Central register of controlled trials database was carried out using both text words and MeSH/EMTREE terms.

RESULTS

Seven eligible papers were retrieved from the new search and five from the Cochrane review. Five of seven studies showed an additive effect of NSAIDs when combined with opioids either by improving analgesia (three studies) or by reducing the opioid dose (two studies). Paracetamol was only marginally effective in one of five trials. The study designs were not adequate to assess differences in side effects between the opioids alone and opioids in combination with NSAIDs or paracetamol.

CONCLUSIONS

The evidence from the available clinical trials is of limited amount and quality, but it weakly supports the proposal that the addition of an NSAIDs to WHO Step III opioids can improve analgesia or reduce opioid dose requirement. There is insufficient evidence to support the use of paracetamol in combination with Step III opioids. Data on the toxicity of NSAIDs in this indication are insufficient owing to the small number of patients and the short duration of treatment reported in the studies.

The effect of age on opioid switching to methadone: a systematic review

BACKGROUND

The aim of this review was to assess from the existing literature the effect of age on the outcome of opioid switching to methadone, and the possible influence on conversions ratios.

DISCUSSION

Older patients represent a challenge for physicians, as a further factor may play a role in dosing methadone and possibly on successful switching. Although existing data are not conclusive because this aspect did not receive particular attention in most studies, at the present time age has not been found to be independently associated with the dose ratio. Further prospective studies in a large sample of patients, subgrouped for classes of age, opioid doses, and reasons to switch, should be designed to provide more information.

Is oral methadone better than placebo or other oral/transdermal opioids in the management of pain?

AIM

To address the question: is oral methadone better than placebo, or other oral/transdermal opioids in the management of cancer pain?

METHOD

A literature search was performed to identify relevant studies. Search strategies included: (1) methadone (title) AND placebo (title or abstract) AND pain (title or abstract); (2) methadone (title) AND randomized (title or abstract) AND pain (title or abstract) AND cancer (title or abstract). Papers were reviewed for relevance to first-line opioid therapy.

RESULTS

No studies were identified comparing methadone to placebo for cancer pain. A single study compared methadone to placebo for neuropathic pain and demonstrated evidence of analgesic effect at a dose of 20 mg/day but not at a dose of 10 mg/day. Four studies compared oral methadone to either oral morphine, or oral morphine and transdermal fentanyl in a first-line setting: Gourlay 1986 (N = 18), Ventafridda 1986 (N =54), Bruera 2004 (N = 106) and Mercadante 2008 (N = 108). All studies demonstrated comparable, but not superior, analgesia with, overall, a comparable adverse effect profile. The duration of the study period for the three largest studies was 28 days. Two of these studies, Ventafridda 1986 and Mercadante 2008, indicated that, over time, the opioid escalation index was lower for methadone than for morphine. One study that used a 2:1 dose ratio between morphine and methadone was associated with a high attrition rate in the first week because of excessive sedation. This effect was not seen in the study that used a 4:1 morphine to methadone dose ratio with dose titration.

CONCLUSION

This limited data suggests that (1) methadone may be an equally effective candidate for first-line opioid therapy, (2) that it is possibly less expensive, (3) that there may be a propensity to sedation and dose accumulation unless there is close monitoring and conservative dose selection and (4) that it should be initiated with a calculated dose based on a morphine to methadone dose ratio of not less than 4:1.