A randomized study on oral administration of morphine and methadone in the treatment of cancer pain

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.

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.

First-line methadone for cancer pain: titration time analysis

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Methadone for Pain Management: A Pharmacotherapeutic Review

Methadone is increasingly being used for its analgesic properties. Despite the increasing popularity, many healthcare providers are not familiar with methadone's complex pharmacology and best practices surrounding its use. The purpose of this narrative review article is to discuss the pharmacology of methadone, the evidence surrounding methadone's use in acute pain management and both chronic cancer and non-cancer pain settings, as well as highlight pertinent safety, monitoring, and opioid rotation considerations. Methadone has a unique mechanism of action when compared with all other opioids and for this reason methadone has come to hold a niche role in the management of opioid-induced hyperalgesia and central sensitization. Understanding of the mechanisms of variability in methadone disposition and drug interactions has evolved over the years, with the latest evidence revealing that CYP 2B6 is the major determinant of methadone elimination and plays a key role in methadone-related drug interactions. From an acute pain perspective, most studies evaluating the use of intraoperative intravenous methadone have reported lower pain scores and post-operative opioid requirements. Oral methadone is predominantly used as a second-line opioid treatment for select chronic pain conditions. As a result, several oral morphine to oral methadone conversion ratios have been proposed, as have methods in which to rotate to methadone. From an efficacy standpoint, limited literature exists regarding the effectiveness of methadone in the chronic pain setting with most of the available efficacy data pertaining to methadone's use in the treatment of cancer pain. Many of the prospective studies that exist feature low participant numbers. Few clinical trials investigating the role of methadone as an analgesic treatment are currently underway. The complicated pharmacokinetic properties of methadone and risks of harm associated with this drug highlight how critically important it is that healthcare providers understand these features before prescribing/dispensing methadone. Particular caution is required when converting patients from other opioids to methadone and for this reason only experienced healthcare providers should undertake such a task. Further randomized trials with larger sample sizes are needed to better define the effective and safe use of methadone for pain management.

Characterization of the Safety and Pharmacokinetic Profile of D-Methadone, a Novel N-Methyl-D-Aspartate Receptor Antagonist in Healthy, Opioid-Naive Subjects: Results of Two Phase 1 Studies

PURPOSE/BACKGROUND

N-methyl-D-aspartate (NMDA) receptor (NMDAR) antagonists are potential agents for the treatment of several central nervous system disorders including major depressive disorder. Racemic methadone, L-methadone, and D-methadone all bind the NMDAR with an affinity similar to that of established NMDAR antagonists, whereas only L-methadone and racemic methadone bind to opioid receptors with high affinity. Therefore, D-methadone is expected to have no clinically significant opioid effects at therapeutic doses mediated by its NMDAR antagonism.

METHODS

We conducted 2 phase 1, double-blind, randomized, placebo-controlled, single- and multiple-ascending-dose studies to investigate the safety and tolerability of oral D-methadone and to characterize its pharmacokinetic profile in healthy opioid-naive volunteers.

RESULTS

D-Methadone exhibits linear pharmacokinetics with dose proportionality for most single-dose and multiple-dose parameters. Single doses up to 150 mg and daily doses up to 75 mg for 10 days were well tolerated with mostly mild treatment-emergent adverse events and no severe or serious adverse events. Dose-related somnolence and nausea occurred and were mostly present at the higher dose level. There was no evidence of respiratory depression, dissociative and psychotomimetic effects, or withdrawal signs and symptoms upon abrupt discontinuation. An overall dose-response effect was observed, with higher doses resulting in larger QTcF (QT interval corrected using Fridericia formula) changes from baseline, but none of the changes were considered clinically significant by the investigators. Mild, dose-dependent pupillary constriction of brief duration occurred particularly at the 60-mg dose or above in the single-ascending-dose study and at the dose of 75 mg in the multiple-ascending-dose study. No detectable conversion of D-methadone to L-methadone occurred in vivo.

CONCLUSIONS

These results support the safety and continued clinical development of D-methadone as an NMDAR antagonist for the treatment of depression and other central nervous system disorders.

Oral Complications in Patients with Advanced Cancer

Disturbances caused by lesions of the oral cavity play an important part in the alteration of the qualtity of life of cancer patients. The main complications affecting the oral cavity are infections (fungal, viral, bacterial), neutropenic ulcers, drug-induced stomatitis, dry mouth, and taste alteration. Most of the information available about these entities has been acquired in the cancer patient without advanced disease. The little known about the epidemiology and physiopathology of such lesions in the advanced phase of cancer is presented and approaches to management are suggested.

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.

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.

Methadone prolongs cardiac conduction in young patients with cancer-related pain

OBJECTIVE

Methadone prolongs cardiac conduction, from mild corrected QT (QTc) prolongation to torsades de pointes and ventricular fibrillation, in adults. However, methadone use for pain and its effects on cardiac conduction have not been investigated in pediatric populations.

METHODS

A retrospective review of QTc intervals in patients receiving methadone analgesia was conducted. Medical records from a 4-year period (September 2006 to October 2010) at a pediatric oncology institution were reviewed, and correlations were tested between cardiac conduction and methadone dosage and duration of therapy, electrolyte levels, renal and hepatic dysfunction, and concurrent medications.

RESULTS

Of the 61 patients who received methadone, 37 met our inclusion criteria and underwent 137 electrocardiograms (ECGs). During methadone treatment, the mean QTc was longer than that at baseline (446.5 vs 437.55 ms). The mean methadone dose was 27.0±24.3 mg/d (range, 5-125 mg/d; median, 20 mg/d) or 0.47±0.45 mg/kg per day (range, 0.05-2.25 mg/kg per day; median, 0.37 mg/kg per day), and the mean duration of therapy was 49 days. The authors identified a correlation between automated and manual ECG readings by two cardiologists (Pearson r=0.649; p<0.0001), but the authors found no correlations between methadone dose or duration and concurrent QTc-prolonging medications, sex, age, electrolyte abnormalities, or renal or hepatic dysfunction.

CONCLUSION

At a clinically effective analgesic dose, methadone dosage and duration were not correlated with QTc prolongation, even in the presence of other risk factors, suggesting that methadone use may be safe in pediatric populations. The correlation between automated and manual ECG readings suggests that automated ECG readings are reliable for monitoring cardiac conductivity during the reported methadone-dosage regimens.

Methadone for cancer pain: What have we learned from clinical studies?

The analgesic ladder guideline proposed by the World Health Organization has been shown to be effective in controlling cancer pain in about 80 percent of patients, but the remaining 20 percent still experience pain. Several strategies have been used to manage refractory cancer pain and opioid toxicity. Switching opioids, alternative routes of opioid administration, optimizing adjuvants, and invasive procedures are proposed treatments. Extensive medical literature corroborates each one of those treatments. Rotation from one opioid to another is a noninvasive strategy to overcome opioid side effects and refractory pain. Frequently, methadone is used during opioid rotation. However, there is a lack of consensus on how to proceed on rotation from morphine to methadone. In the current era of evidence-based medicine, the medical literature fails to answer some cancer pain-management issues. The purpose of this review is to clarify a process for transitioning from morphine to methadone.

Methadone as a Coanalgesic for Palliative Care Cancer Patients

BACKGROUND

Methadone offers many advantages for treating cancer pain. However, its pharmacokinetic profile makes its use as a full-dose opioid challenging.

OBJECTIVES

To evaluate the efficacy and safety of low-dose methadone as an adjunct to opioids in the treatment of cancer pain in palliative care patients.

DESIGN

A cohort was followed retrospectively for up to 60 days after the initiation of methadone as a coanalgesic.

SETTING/SUBJECTS

Patients were eligible if they were prescribed methadone as a coanalgesic for cancer pain management and followed by the palliative care team.

MEASUREMENTS

The primary efficacy end point was reduction of pain intensity (11-point numerical rating scale). Variables associated with pain intensity reduction were explored using logistic regressions. Adverse events were collected throughout the follow-up.

RESULTS

Seventy-two of the 146 subjects (49%) qualified as significant responders (≥30% reduction in pain intensity). Median time to significant response was seven days, and pain intensity on the day of methadone initiation predicted the response to treatment. The most frequently reported adverse events were drowsiness, confusion, constipation, and nausea. As expected in a palliative care population, there was a substantial amount of missing data.

CONCLUSIONS

A significant reduction in pain can be seen rapidly after the addition of methadone as a coanalgesic, particularly among patients with high pain intensity. More studies are needed to corroborate the efficacy of methadone as an adjunct to opioids.

Oral morphine for cancer pain

BACKGROUND

This is the third updated version of a Cochrane review first published in Issue 4, 2003 of The Cochrane Library and first updated in 2007. Morphine has been used for many years to relieve pain. Oral morphine in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain, and to assess the incidence and severity of adverse events.

SEARCH METHODS

We searched the following databases: Cochrane Central Register of Controlled Trials (CENTRAL 2015, Issue 9); MEDLINE (1966 to October 2015); and EMBASE (1974 to October 2015). We also searched ClinicalTrials.gov (1 October 2015).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) using placebo or active comparators reporting on the analgesic effect of oral morphine in adults and children with cancer pain. We excluded trials with fewer than 10 participants.

DATA COLLECTION AND ANALYSIS

One review author extracted data, which were checked by another review author. There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers needed to treat (NNTs) for the analgesic effect. We extracted any available data on the number or proportion of participants with 'no worse than mild pain' or treatment success (very satisfied, or very good or excellent on patient global impression scales).

MAIN RESULTS

We identified seven new studies in this update. We excluded six, and one study is ongoing so also not included in this update. This review contains a total of 62 included studies, with 4241 participants. Thirty-six studies used a cross-over design ranging from one to 15 days, with the greatest number (11) for seven days for each arm of the trial. Overall we judged the included studies to be at high risk of bias because the methods of randomisation and allocation concealment were poorly reported. The primary outcomes for this review were participant-reported pain and pain relief.Fifteen studies compared oral morphine modified release (Mm/r) preparations with morphine immediate release (MIR). Fourteen studies compared Mm/r in different strengths; six of these included 24-hour modified release products. Fifteen studies compared Mm/r with other opioids. Six studies compared MIR with other opioids. Two studies compared oral Mm/r with rectal Mm/r. Three studies compared MIR with MIR by a different route of administration. Two studies compared Mm/r with Mm/r at different times and two compared MIR with MIR given at a different time. One study was found comparing each of the following: Mm/r tablet with Mm/r suspension; Mm/r with non-opioids; MIR with non-opioids; and oral morphine with epidural morphine.In the previous update, a standard of 'no worse than mild pain' was set, equivalent to a score of 30/100 mm or less on a visual analogue pain intensity scale (VAS), or the equivalent in other pain scales. Eighteen studies achieved this level of pain relief on average, and no study reported that good levels of pain relief were not attained. Where results were reported for individual participants in 17 studies, 'no worse than mild pain' was achieved by 96% of participants (362/377), and an outcome equivalent to treatment success in 63% (400/638).Morphine is an effective analgesic for cancer pain. Pain relief did not differ between Mm/r and MIR. Modified release versions of morphine were effective for 12- or 24-hour dosing depending on the formulation. Daily doses in studies ranged from 25 mg to 2000 mg with an average of between 100 mg and 250 mg. Dose titration was undertaken with both instant release and modified release products. A small number of participants did not achieve adequate analgesia with morphine. Adverse events were common, predictable, and approximately 6% of participants discontinued treatment with morphine because of intolerable adverse events.The quality of the evidence is generally poor. Studies are old, often small, and were largely carried out for registration purposes and therefore were only designed to show equivalence between different formulations.

AUTHORS' CONCLUSIONS

The conclusions have not changed for this update. The effectiveness of oral morphine has stood the test of time, but the randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants and did not provide appropriate data for meta-analysis. Only a few reported how many people had good pain relief, but where it was reported, over 90% had no worse than mild pain within a reasonably short time period. The review demonstrates the wide dose range of morphine used in studies, and that a small percentage of participants are unable to tolerate oral morphine. The review also shows the wide range of study designs, and inconsistency in cross-over designs. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing participants over in cross-over design studies. It was not clear if these trials were sufficiently powered to detect any clinical differences between formulations or comparator drugs. New studies added to the review for the previous update reinforced the view that it is possible to use modified release morphine to titrate to analgesic effect. There is qualitative evidence that oral morphine has much the same efficacy as other available opioids.

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.

Methadone overdose and cardiac arrhythmia potential: findings from a review of the evidence for an American Pain Society and College on Problems of Drug Dependence clinical practice guideline

The number of deaths associated with methadone use increased dramatically in parallel with marked increases in its use, particularly for treatment of chronic pain. To develop a clinical guideline on methadone prescribing to reduce potential harms, the American Pain Society commissioned a review of various aspects related to methadone safety. This article summarizes evidence related to unintentional overdose due to methadone and harms related to cardiac arrhythmia potential. We searched Ovid MEDLINE, the Cochrane Library, and PsycINFO databases through January 2014 for studies assessing harms associated with methadone use; we judged 70 studies to be relevant and to meet inclusion criteria. The majority of studies on overdose and cardiac arrhythmia risk are observational and provide weak evidence on which to base clinical guidelines. In patients prescribed methadone for treatment of opioid dependence, data suggest that mortality benefits related to reduction in illicit drug use outweigh harms. Despite epidemiologic data showing marked increases in the numbers of methadone-related deaths that have been primarily attributed to increased use of methadone for chronic pain, evidence on methadone and mortality risk in this population has been somewhat contradictory. There is some evidence that recent initiation of methadone, psychiatric admissions, and concomitant use of benzodiazepines are associated with a higher risk for overdose. Evidence on cardiac risks is primarily limited to case reports of torsades de pointes, primarily in patients on high doses of methadone, and to studies showing an association between methadone use and prolongation of QTc intervals. Research is needed to understand the effectiveness of dosing methods, electrocardiogram monitoring, and other risk mitigation strategies in patients prescribed methadone.

PERSPECTIVE

This systematic review synthesizes the evidence related to methadone use and risk for overdose and cardiac arrhythmia. Findings regarding the association between methadone use and QTc interval prolongation and risk factors for methadone-associated overdose suggest potential targets for risk mitigation strategies, though research is needed to determine the effectiveness of such strategies at reducing adverse outcomes.

Impact of morphine, fentanyl, oxycodone or codeine on patient consciousness, appetite and thirst when used to treat cancer pain

BACKGROUND

There is increasing focus on providing high quality care for people at the end of life, irrespective of disease or cause, and in all settings. In the last ten years the use of care pathways to aid those treating patients at the end of life has become common worldwide. The use of the Liverpool Care Pathway in the UK has been criticised. In England the LCP was the subject of an independent review, commissioned by a Health Minister. The Neuberger Review acknowledged that the LCP was based on the sound ethical principles that provide the basis of good quality care for patients and families when implemented properly. It also found that the LCP often was not implemented properly, and had instead become a barrier to good care; it made over 40 recommendations, including education and training, research and development, access to specialist palliative care services, and the need to ensure care and compassion for all dying patients. In July 2013, the Department of Health released a statement that stated the use of the LCP should be "phased out over the next 6-12 months and replaced with an individual approach to end of life care for each patient".The impact of opioids was a particular concern because of their potential influence on consciousness, appetite and thirst in people near the end of life. There was concern that impaired patient consciousness may lead to an earlier death, and that effects of opioids on appetite and thirst may result in unnecessary suffering. This rapid review, commissioned by the National Institute for Health Research, used standard Cochrane methodology to examine adverse effects of morphine, fentanyl, oxycodone, and codeine in cancer pain studies as a close approximation to possible effects in the dying patient.

OBJECTIVES

To determine the impact of opioid treatment on patient consciousness, appetite and thirst in randomised controlled trials of morphine, fentanyl, oxycodone or codeine for treating cancer pain.

SEARCH METHODS

We assessed adverse event data reported in studies included in current Cochrane reviews of opioids for cancer pain: specifically morphine, fentanyl, oxycodone, and codeine.

SELECTION CRITERIA

We included randomised studies using multiple doses of four opioid drugs (morphine, fentanyl, oxycodone, and codeine) in cancer pain. These were taken from four existing or ongoing Cochrane reviews. Participants were adults aged 18 and over. We included only full journal publication articles.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted adverse event data, and examined issues of study quality. The primary outcomes sought were numbers of participants experiencing adverse events of reduced consciousness, appetite, and thirst. Secondary outcomes were possible surrogate measures of the primary outcomes: delirium, dizziness, hallucinations, mood change and somnolence relating to patient consciousness, and nausea, vomiting, constipation, diarrhoea, dyspepsia, dysphagia, anorexia, asthenia, dehydration, or dry mouth relating to appetite or thirst.Comparative measures of harm were known to be unlikely, and we therefore calculated the proportion of participants experiencing each of the adverse events of interest with each opioid, and for all four opioid drugs combined.

MAIN RESULTS

We included 77 studies with 5619 randomised participants. There was potential bias in most studies, with small size being the most common; individual treatment groups had fewer than 50 participants in 60 studies. Participants were relatively young, with mean age in the studies typically between 50 and 70 years. Multiple major problems with adverse event reporting were found, including failing to report adverse events in all participants who received medication, all adverse events experienced, how adverse events were collected, and not defining adverse event terminology or whether a reporting system was used.Direct measures of patient consciousness, patient appetite, or thirst were not apparent. For opioids used to treat cancer pain adverse event incidence rates were 25% for constipation, 23% for somnolence, 21% for nausea, 17% for dry mouth, and 13% for vomiting, anorexia, and dizziness. Asthenia, diarrhoea, insomnia, mood change, hallucinations and dehydration occurred at incidence rates of 5% and below.

AUTHORS' CONCLUSIONS

We found no direct evidence that opioids affected patient consciousness, appetite or thirst when used to treat cancer pain. However, somnolence, dry mouth, and anorexia were common adverse events in people with cancer pain treated with morphine, fentanyl, oxycodone, or codeine.We are aware that there is an important literature concerning the problems that exist with adverse event measurement, reporting, and attribution. Together with the known complications concerning concomitant medication, data collection and reporting, and nomenclature, this means that these adverse events cannot always be attributed unequivocally to the use of opioids, and so they provide only a broad picture of adverse events with opioids in cancer pain. The research agenda includes developing definitions for adverse events that have a spectrum of severity or importance, and the development of appropriate measurement tools for recording such events to aid clinical practice and clinical research.

Oral morphine for cancer pain

BACKGROUND

This is the second updated version of a Cochrane review first published in Issue 4, 2003 of The Cochrane Library and first updated in 2007. Morphine has been used for many years to relieve pain. Oral morphine in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain, and assess the incidence and severity of adverse effects.

SEARCH METHODS

We searched the following databases: Cochrane Pain, Palliative and Supportive Care Group Trials Register (June 2013); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2013, Issue 5, May); MEDLINE (1966 to June 2013); and EMBASE (1974 to June 2013).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) using placebo or active comparators reporting on the analgesic effect of oral morphine in adults and children with cancer pain. Trials with fewer than ten participants were excluded.

DATA COLLECTION AND ANALYSIS

One review author extracted data, which were checked by another review author. There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers needed to treat (NNTs) for the analgesic effect. We extracted any available data on the number or proportion of participants with 'no worse than mild pain' or treatment success (very satisfied, or very good or excellent on patient global impression scales).

MAIN RESULTS

Ten new studies (638 participants) were identified for this update, bringing the total of included studies to 62, with 4241 participants. Thirty-six studies used a cross-over design ranging from one to 15 days, with the greatest number (11) for seven days for each arm of the trial.Fifteen studies compared oral morphine modified release (Mm/r) preparations with morphine immediate release (MIR). Fourteen studies compared Mm/r in different strengths; six of these included 24-hour modified release products. Fifteen studies compared Mm/r with other opioids. Six studies compared MIR with other opioids. Two studies compared oral Mm/r with rectal Mm/r. Three studies compared MIR with MIR by a different route of administration. Two studies compared Mm/r with Mm/r at different times and two compared MIR with MIR given at a different time. One study was found comparing each of the following: Mm/r tablet with Mm/r suspension; Mm/r with non-opioids; MIR with non-opioids; and oral morphine with epidural morphine.In this update a standard of 'no worse than mild pain' was set equivalent to a score of 30/100 mm or less on a visual analogue pain intensity scale (VAS), or the equivalent in other pain scales. Eighteen studies achieved this level of pain relief on average, and no study reported that good levels of pain relief were not attained. Where results were reported for individual participants in 17 studies, 'no worse than mild pain' was achieved by 96% of participants (362/377), and an outcome equivalent to treatment success in 63% (400/638).Morphine is an effective analgesic for cancer pain. Pain relief did not differ between Mm/r and MIR. Modified release versions of morphine were effective for 12- or 24-hour dosing depending on the formulation. Daily doses in studies ranged from 25 mg to 2000 mg with an average of between 100 mg and 250 mg. Dose titration was undertaken with both instant release and modified release products. A small number of participants did not achieve adequate analgesia with morphine. Adverse effects were common and approximately 6% of participants discontinued treatment because of intolerable adverse effects.

AUTHORS' CONCLUSIONS

The effectiveness of oral morphine has stood the test of time, but the randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants and did not provide appropriate data for meta-analysis. Only a few reported how many people had good pain relief, but where it was reported, over 90% had no worse than mild pain within a reasonably short time period. The review demonstrates the wide dose range of morphine used in studies, and that a small percentage of participants are unable to tolerate oral morphine. The review also shows the wide range of study designs, and inconsistency in cross-over designs. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing participants over in cross-over design studies. It was not clear if these trials are sufficiently powered to detect any clinical differences between formulations or comparator drugs. New studies added to the review reinforce the view that it is possible to use modified release morphine to titrate to analgesic effect. There is qualitative evidence that oral morphine has much the same efficacy as other available opioids.

Methadone in post-herpetic neuralgia: A pilot proof-of-concept study

OBJECTIVE

This research was designed as a pilot proof-of-concept study to evaluate the use of low-dose methadone in post-herpetic neuralgia patients who remained refractory after first and second line post-herpetic neuralgia treatments and had indications for adding an opioid agent to their current drug regimens.

METHODS

This cross-over study was double blind and placebo controlled. Ten opioid naïve post-herpetic neuralgia patients received either methadone (5 mg bid) or placebo for three weeks, followed by a 15-day washout period and a second three-week treatment with either methadone or placebo, accordingly. Clinical evaluations were performed four times (before and after each three-week treatment period). The evaluations included the visual analogue scale, verbal category scale, daily activities scale, McGill pain questionnaire, adverse events profile, and evoked pain assessment. All patients provided written informed consent before being included in the study. ClinicalTrials.gov: NCT01752699 RESULTS: Methadone, when compared to placebo, did not significantly affect the intensity of spontaneous pain, as measured by the visual analogue scale. The intensity of spontaneous pain was significantly decreased after the methadone treatment compared to placebo on the category verbal scale (50% improved after the methadone treatment, none after the placebo, p=0.031). Evoked pain was reduced under methadone compared to placebo (50% improved after the methadone treatment, none after the placebo, p=0.031). Allodynia reduction correlated with sleep improvement (r=0.67, p=0.030) during the methadone treatment. The side effects profile was similar between both treatments.

CONCLUSIONS

Methadone seems to be safe and efficacious in post-herpetic neuralgia. It should be tried as an adjunctive treatment for post-herpetic neuralgia in larger prospective studies.

Pain management

Despite published guidelines and educational programs on the assessment and treatment of cancer-related pain, in any stage of oncological disease, unrelieved pain continues to be a substantial worldwide public health concern either in patients with solid and haematological malignancies. The proper and regular self-reporting assessment of pain is the first step for an effective and individualized treatment. Opioids are the mainstay of analgesic therapy and can be associated with non-opioids drugs such as paracetamol or non-steroidal anti-inflammatory drugs and to adjuvant drugs (for neuropathic pain and symptom control). The role and the utility of weak opioids (i.e. codeine, dihydrocodeine, tramadol) are a controversy point. Morphine has been placed by World Health Organization on its Essential Drug List. In the comparative study with other strong opioids (hydromorphone, oxycodone), there is no evidence to show superiority or inferiority with morphine as the first choice opioid. Oral methadone is a useful and safe alternative to morphine. Methadone presents the potential to control pain difficult to manage with other opioids. although the oral route of opioid administration is considered the one of choice, intravenous, subcutaneous, rectal, transdermal, sublingual, intranasal, and spinal routes must be used in particular situation. Transdermal opioids such as fentanyl and buprenorphine are best reserved for patients whose opioid requirements are stable. Switching from one opioid to another can improve analgesia and tolerability.

Use of opioid analgesics in the treatment of cancer pain: evidence-based recommendations from the EAPC

Here we provide the updated version of the guidelines of the European Association for Palliative Care (EAPC) on the use of opioids for the treatment of cancer pain. The update was undertaken by the European Palliative Care Research Collaborative. Previous EAPC guidelines were reviewed and compared with other currently available guidelines, and consensus recommendations were created by formal international expert panel. The content of the guidelines was defined according to several topics, each of which was assigned to collaborators who developed systematic literature reviews with a common methodology. The recommendations were developed by a writing committee that combined the evidence derived from the systematic reviews with the panellists' evaluations in a co-authored process, and were endorsed by the EAPC Board of Directors. The guidelines are presented as a list of 16 evidence-based recommendations developed according to the Grading of Recommendations Assessment, Development and Evaluation system.

Methadone in cancer pain

Methadone is often considered as a second-choice drug alternative to morphine in cancer pain treatment. A lack of information regarding methadone's pharmacokinetic/pharmacodynamic relationships has contributed to limitation in its use in analgesic treatments. However, it has been recently re-evaluated in light of better knowledge of its pharmacological characteristics and wider experience. Concern about the safety of methadone therapy arising because of its long and unpredictable half-life should not deter clinicians from its appropriate use. Methadone is a very useful drug in cancer pain because of its low cost, lack of known metabolites, high oral bioavailability, rapid onset and time to peak analgesic effect, and the long duration of activity which allows for longer intervals between doses. Moreover, methadone has been demonstrated to have a high receptor reserve and to exert some NMDA receptor antagonist effect. A shift from one opioid to methadone is recommended when the side-effect/analgesic balance is unfavourable, as symmetrical patterns of cross-tolerance of opioid agonists have been demonstrated. Different approaches, including the oral PCA, have been proposed to circumvent problems related to its pharmacokinetic properties.

Systematic review of tapentadol in chronic severe pain

AIM

A systematic review of chronic pain treatment with strong opioids (step 3 WHO pain ladder) and a comparison to a new drug recently approved for the treatment of severe chronic pain in Europe, tapentadol (Palexia, Nucynta*), were performed.

METHODS

Thirteen electronic databases were searched as well as a number of other sources from 1980 up to November 2010 for relevant randomized controlled clinical trials in chronic moderate and severe pain investigating at least one step 3 opioid. Chronic pain could be nociceptive or neuropathic, malignant or non-malignant, all systemic administrations were considered as well as trials of different lengths. Two separate analyses were performed, one only for trials which reported (at least as sub-groups) the outcome in patients with severe pain, the other including both moderate and severe pain conditions. With the exception of the direct comparison between tapentadol, oxycodone and placebo, indirect comparisons were performed based on a network analysis. Trials with an enriched or an enriched withdrawal design were excluded. Primary (pain intensity) and a number of secondary endpoints were evaluated, including pain relief (30% and 50%), patient global impression of change, quality of life, quality of sleep, discontinuations, as well as serious adverse events and selected adverse events.

RESULTS

Only 10 trials were eligible for analysis of patients with severe pain (eight investigating tapentadol and two trials comparing buprenorphine patch vs placebo). For moderate and severe pain, 42 relevant trials were identified and indirect comparisons with transdermal buprenorphine, transdermal fentanyl, hydromorphone, morphine, and oxymorphone were performed. This report focuses on the network analysis. Tapentadol showed statistically favourable results over oxycodone for pain intensity, 30% and 50% pain relief, patient global impression of change (PGIC), and quality of life. Furthermore, some of the most important adverse events of chronic opioid treatment were significantly less frequent with tapentadol as compared to oxycodone, i.e. constipation, nausea, and vomiting; discontinuations due to these adverse events were found significantly reduced with tapentadol. Similar results were obtained for the network analysis, i.e. tapentadol was superior for the primary outcome (pain intensity) to hydromorphone and morphine, whereas fentanyl and oxymorphone showed trends in favour of these treatments. Significantly less frequent gastrointestinal adverse events of tapentadol were observed in comparison with fentanyl, hydromorphone, morphine, and oxymorphone, apparently leading to significantly reduced treatment discontinuations (for any reason).

CONCLUSIONS

Taken together, the benefit-risk ratio of tapentadol appears to be improved compared to step 3 opioids.

Is oral morphine still the first choice opioid for moderate to severe cancer pain? A systematic review within the European Palliative Care Research Collaborative guidelines project

The aim of this systematic review was to evaluate the evidence that oral morphine can be recommended as the first choice opioid in the treatment of moderate to severe cancer pain in updating the European Association for Palliative Care opioid recommendations. A systematic literature review was performed to update the 2007 Cochrane review 'Oral morphine for cancer pain'. The literature search was conducted on MedLine, EMBASE and Cochrane Central Register of Controlled Trials databases. The search strategy, limited in time (from 1 July 2006 to 31 October 2009), was aimed to be as extensive as possible using both text words and MeSH/EMTREE terms; a hand search of the reference lists of identified papers was also performed. Randomized clinical trials, containing data on efficacy and/or side effects of morphine, were identified. Among the papers retrieved from the cited databases and the Cochrane review, 17 eligible studies, for a total of 2053 patients, and a meta-analysis were selected. These studies do not add significant information to the previous Cochrane review confirming the limitation of efficacy and tolerability data on opioid-naïve and non-selected populations of cancer patients treated with morphine and suggesting that oral morphine, oxycodone and hydromorphone have similar efficacy and toxicity in this patient population.

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.

Can morphine still be considered to be the standard for treating chronic pain? A systematic review including pair-wise and network meta-analyses

OBJECTIVE

For chronic pain treatment many health care authorities consider morphine to be the reference standard for strategic decisions in pain therapy. Although morphine's effectiveness is clear and its cost is low, it's unclear whether morphine should remain the first choice or reference treatment.

RESEARCH DESIGN AND METHODS

We performed a systematic review to evaluate the evidence available to support the position of morphine as the reference standard for step III opioids based on efficacy and tolerability outcomes.

RESULTS

The search yielded 5,675 titles and 56 studies were included. Considerable heterogeneity precluded pair-wise meta-analysis on change of pain intensity and no difference between morphine and other opioids were found for tolerability outcomes. The network meta-analysis showed no statistically significant difference in change of pain intensity between morphine and oxycodone, methadone and oxymorphone. Compared to morphine, patients using buprenorphine are more likely to discontinue treatment due to lack of effect (OR 2.32, 95% CI 1.37 to 3.95). Patients using methadone are more likely to discontinue due to adverse events (OR 3.09, 95% CI 1.14 to 8.36), whereas this risk is decreased for patients using fentanyl (OR 0.29, 95% CI 0.17 to 0.50) or buprenorphine (OR 0.30, 95% CI 0.16 to 0.53). The most important limitation of this review is that the included studies are heterogeneous with regard to study population and intervention, which may affect the pooled effect estimates. The main strength is that we only included parallel RCTs, the strongest design for intervention studies.

CONCLUSIONS

The current evidence is moderate, both in respect to the number of directly comparative studies and in the quality of reporting of these studies. No clear superiority in efficacy and tolerability of morphine over other opioids was found in pair-wise and network analyses. Based on these results, a justification for the placement of morphine as the reference standard for the treatment of severe chronic pain cannot be supported.

Methadone for Cancer Pain

Pain is one of the most common and incapacitating symptoms experienced by patients with advanced cancer. Methadone is a potent opioid with strong affinity for the µ opioid receptor. In addition to being a potent µ opioid receptor ligand, methadone blocks the N-methyl-D-aspartic acid receptor and modulates neurotransmitters involved in descending pain modulation. These 3 properties enhance analgesic activity. Methadone's lack of active metabolites makes it an attractive option when opioid responsiveness declines and renal insufficiency complicates opioid therapy. A lipophilic opioid, methadone can be given by multiple routes. Clinical trial data show equivalence with morphine as an analgesic in moderate to severe cancer pain. Further investigations are needed to define the role of methadone in the management of breakthrough pain and neuropathic pain and to determine whether it is truly superior to morphine, the gold standard of cancer analgesia.

The effect of oral methadone on the QTc interval in advanced cancer patients: a prospective pilot study

BACKGROUND

Recent reports suggest that high doses of methadone may prolong QTc interval and occasionally cause torsades de pointes; however, few of these studies involved the palliative care population.

OBJECTIVE

The purpose of this study was to determine the effect of initiation of methadone on QTc interval in patients with cancer pain seen at the palliative care setting.

METHODS

We enrolled 100 patients with cancer in this prospective study. Patients were followed clinically and electrocardiographically for QTc changes at baseline, 2, 4, and 8 weeks. Contributing factors for QTc prolongation such as medications, cardiovascular diseases, and electrolytes disturbances were documented. QTc prolongation was defined as greater than 430 ms in males and greater than 450 ms in females, and significant QTc prolongation was defined as QTc interval greater than 25% increase from baseline or 500 ms or more.

RESULTS

Electrocardiographic (ECG) assessments were available for 100, 64, 41, and 27 patients at baseline, 2-, 4-, and 8-week follow-up, respectively. At baseline prior to initiation of methadone, 28 (28%) patients had QTc prolongation. Clinically significant increase in QTc occurred in only 1 of 64 (1.6%) patients at week 2, and none at weeks 4 and 8. There was no clinical evidence of torsades de pointes, ventricular fibrillation, or sudden death. QTc prolongation was more frequent among patients with increased baseline QTc interval.

CONCLUSIONS

Baseline QTc prolongation was common, whereas significant QTc interval 500 ms or more after methadone initiation rarely occurred, with no evidence of clinically significant arrhythmias. This study supports the safety of methadone use for pain control in patients with advanced cancer in the palliative care setting.

The role of methadone in cancer pain treatment--a review

BACKGROUND

Methadone is an opioid analgesic of step 3 of the World Health Organization (WHO) analgesic ladder.

AIM AND METHODS

To outline pharmacodynamics, pharmacokinetics, drug interactions, equianalgesic dose ratio with other opioids, dosing rules, adverse effects and methadone clinical studies in patients with cancer pain. A review of relevant literature on methadone use in cancer pain was conducted.

RESULTS

Methadone is used in opioid rotation and administered to patients with cancer pain not responsive to morphine or other strong opioids when intractable opioid adverse effects appear. Methadone is considered as the first strong opioid analgesic and in patients with renal impairment. Methadone possesses different pharmacodynamics and pharmacokinetics in comparison to other opioids. The advantages of methadone include multimode analgesic activity, high oral and rectal bioavailability, long lasting analgesia, lack of active metabolites, excretion mainly with faeces, low cost and a weak immunosuppressive effect. The disadvantages include long and changeable plasma half-life, high bound to serum proteins, metabolism through P450 system, numerous drug interactions, lack of clear equianalgesic dose ratio to other opioids, QT interval prolongation, local reactions when administered subcutaneously.

CONCLUSIONS

Methadone is an important opioid analgesic at step 3 of the WHO analgesic ladder. Future controlled studies may focus on establishment of methadone equianalgesic dose ratio with other opioids and its role as the first strong opioid in comparative studies with analgesia, adverse effects and quality of life taken into consideration.

Pain therapy

Cancer-related pain is a major issue of healthcare systems worldwide. The reported incidence, considering all stages of the disease, is 51%, which can increase to 74% in the advanced and terminal stages. For advanced cancer, pain is moderate to severe in about 40-50% and very severe or excruciating in 25-30% of cases. Pain is both a sensation and an emotional experience. Pain is always subjective; and may be affected by emotional, social and spiritual components thus it has been defined as "total pain". From a pathophysiological point of view, pain can be classified as nociceptive (somatic and visceral), neuropathic (central, peripheral, sympathetic) idiopathic or psychogenic. A proper pain assessment is fundamental for an effective and individualised treatment. In 1986 the World Health Organisation (WHO) published analgesic guidelines for the treatment of cancer pain based on a three-step ladder and practical recommendations. These guidelines serve as an algorithm for a sequential pharmacological approach to treatment according to the intensity of pain as reported by the patient. The WHO analgesic ladder remains the clinical model for pain therapy. Its clinical application should be employed only after a complete and comprehensive assessment and evaluation based on the needs of each patient. When applying the WHO guidelines, up to 90% of patients can find relief regardless of the settings of care, social and/or cultural environment. This is the standard treatment on a type C basis. Only when such an approach is ineffective are interventions such as spinal administration of opioid analgesics or neuroinvasive procedures recommended.

Opioids and the management of chronic severe pain in the elderly: consensus statement of an International Expert Panel with focus on the six clinically most often used World Health Organization Step III opioids (buprenorphine, fentanyl, hydromorphone, methadone, morphine, oxycodone)

SUMMARY OF CONSENSUS: 1. The use of opioids in cancer pain: The criteria for selecting analgesics for pain treatment in the elderly include, but are not limited to, overall efficacy, overall side-effect profile, onset of action, drug interactions, abuse potential, and practical issues, such as cost and availability of the drug, as well as the severity and type of pain (nociceptive, acute/chronic, etc.). At any given time, the order of choice in the decision-making process can change. This consensus is based on evidence-based literature (extended data are not included and chronic, extended-release opioids are not covered). There are various driving factors relating to prescribing medication, including availability of the compound and cost, which may, at times, be the main driving factor. The transdermal formulation of buprenorphine is available in most European countries, particularly those with high opioid usage, with the exception of France; however, the availability of the sublingual formulation of buprenorphine in Europe is limited, as it is marketed in only a few countries, including Germany and Belgium. The opioid patch is experimental at present in U.S.A. and the sublingual formulation has dispensing restrictions, therefore, its use is limited. It is evident that the population pyramid is upturned. Globally, there is going to be an older population that needs to be cared for in the future. This older population has expectations in life, in that a retiree is no longer an individual who decreases their lifestyle activities. The "baby-boomers" in their 60s and 70s are "baby zoomers"; they want to have a functional active lifestyle. They are willing to make trade-offs regarding treatment choices and understand that they may experience pain, providing that can have increased quality of life and functionality. Therefore, comorbidities--including cancer and noncancer pain, osteoarthritis, rheumatoid arthritis, and postherpetic neuralgia--and patient functional status need to be taken carefully into account when addressing pain in the elderly. World Health Organization step III opioids are the mainstay of pain treatment for cancer patients and morphine has been the most commonly used for decades. In general, high level evidence data (Ib or IIb) exist, although many studies have included only few patients. Based on these studies, all opioids are considered effective in cancer pain management (although parts of cancer pain are not or only partially opioid sensitive), but no well-designed specific studies in the elderly cancer patient are available. Of the 2 opioids that are available in transdermal formulation--fentanyl and buprenorphine--fentanyl is the most investigated, but based on the published data both seem to be effective, with low toxicity and good tolerability profiles, especially at low doses. 2. The use of opioids in noncancer-related pain: Evidence is growing that opioids are efficacious in noncancer pain (treatment data mostly level Ib or IIb), but need individual dose titration and consideration of the respective tolerability profiles. Again no specific studies in the elderly have been performed, but it can be concluded that opioids have shown efficacy in noncancer pain, which is often due to diseases typical for an elderly population. When it is not clear which drugs and which regimes are superior in terms of maintaining analgesic efficacy, the appropriate drug should be chosen based on safety and tolerability considerations. Evidence-based medicine, which has been incorporated into best clinical practice guidelines, should serve as a foundation for the decision-making processes in patient care; however, in practice, the art of medicine is realized when we individualize care to the patient. This strikes a balance between the evidence-based medicine and anecdotal experience. Factual recommendations and expert opinion both have a value when applying guidelines in clinical practice. 3. The use of opioids in neuropathic pain: The role of opioids in neuropathic pain has been under debate in the past but is nowadays more and more accepted; however, higher opioid doses are often needed for neuropathic pain than for nociceptive pain. Most of the treatment data are level II or III, and suggest that incorporation of opioids earlier on might be beneficial. Buprenorphine shows a distinct benefit in improving neuropathic pain symptoms, which is considered a result of its specific pharmacological profile. 4. The use of opioids in elderly patients with impaired hepatic and renal function: Functional impairment of excretory organs is common in the elderly, especially with respect to renal function. For all opioids except buprenorphine, half-life of the active drug and metabolites is increased in the elderly and in patients with renal dysfunction. It is, therefore, recommended that--except for buprenorphine--doses be reduced, a longer time interval be used between doses, and creatinine clearance be monitored. Thus, buprenorphine appears to be the top-line choice for opioid treatment in the elderly. 5. Opioids and respiratory depression: Respiratory depression is a significant threat for opioid-treated patients with underlying pulmonary condition or receiving concomitant central nervous system (CNS) drugs associated with hypoventilation. Not all opioids show equal effects on respiratory depression: buprenorphine is the only opioid demonstrating a ceiling for respiratory depression when used without other CNS depressants. The different features of opioids regarding respiratory effects should be considered when treating patients at risk for respiratory problems, therefore careful dosing must be maintained. 6. Opioids and immunosuppression: Age is related to a gradual decline in the immune system: immunosenescence, which is associated with increased morbidity and mortality from infectious diseases, autoimmune diseases, and cancer, and decreased efficacy of immunotherapy, such as vaccination. The clinical relevance of the immunosuppressant effects of opioids in the elderly is not fully understood, and pain itself may also cause immunosuppression. Providing adequate analgesia can be achieved without significant adverse events, opioids with minimal immunosuppressive characteristics should be used in the elderly. The immunosuppressive effects of most opioids are poorly described and this is one of the problems in assessing true effect of the opioid spectrum, but there is some indication that higher doses of opioids correlate with increased immunosuppressant effects. Taking into consideration all the very limited available evidence from preclinical and clinical work, buprenorphine can be recommended, while morphine and fentanyl cannot. 7. Safety and tolerability profile of opioids: The adverse event profile varies greatly between opioids. As the consequences of adverse events in the elderly can be serious, agents should be used that have a good tolerability profile (especially regarding CNS and gastrointestinal effects) and that are as safe as possible in overdose especially regarding effects on respiration. Slow dose titration helps to reduce the incidence of typical initial adverse events such as nausea and vomiting. Sustained release preparations, including transdermal formulations, increase patient compliance.

Oral morphine for cancer pain

BACKGROUND

This is an updated version of a previous Cochrane review first published in Issue 4, 2003 of The Cochrane Library. Morphine has been used for many years to relieve pain. Oral morphine in either immediate release or modified release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain and to assess the incidence and severity of adverse effects.

SEARCH STRATEGY

The following databases were searched: Cochrane Pain, Palliative and Supportive Care Group Trials Register (December 2006); Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2006, Issue 4); MEDLINE (1966 to December 2006); and EMBASE (1974 to December 2006).

SELECTION CRITERIA

Published randomised controlled trials (RCTs) reporting on the analgesic effect of oral morphine in adults and children with cancer pain. Any comparator trials were considered. Trials with fewer than ten participants were excluded.

DATA COLLECTION AND ANALYSIS

One review author extracted data, which was checked by the other review author. There were insufficient comparable data for meta-analysis to be undertaken or to produce numbers-needed-to-treat (NNT) for the analgesic effect.

MAIN RESULTS

In this update, nine new studies with 688 participants were added. Fifty-four studies (3749 participants) met the inclusion criteria. Fifteen studies compared oral modified release morphine (Mm/r) preparations with immediate release morphine (MIR). Twelve studies compared Mm/r in different strengths, five of these included 24-hour modified release products. Thirteen studies compared Mm/r with other opioids. Six studies compared MIR with other opioids. Two studies compared oral Mm/r with rectal Mm/r. Two studies compared MIR with MIR by a different route of administration. One study was found comparing each of the following: Mm/r tablet with Mm/r suspension; Mm/r with non-opioids; MIR with non-opioids; and oral morphine with epidural morphine. Morphine was shown to be an effective analgesic. Pain relief did not differ between Mm/r and MIR. Modified release versions of morphine were effective for 12 or 24-hour dosing depending on the formulation. Daily doses in studies ranged from 25 mg to 2000 mg with an average of between 100 mg and 250 mg. Dose titration were undertaken with both instant release and modified release products. Adverse effects were common but only 4% of patients discontinued treatment because of intolerable adverse effects.

AUTHORS' CONCLUSIONS

The randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants and did not provide appropriate data for meta-analysis. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing participants over in crossover design studies. It was not clear if these trials are sufficiently powered to detect any clinical differences between formulations or comparator drugs. Studies added to the review reinforce the view that it is possible to use modified release morphine to titrate to analgesic effect. There is qualitative evidence for effectiveness of oral morphine which compares well to other available opioids. There is limited evidence to suggest that transmucosal fentanyl provides more rapid pain relief for breakthrough pain compared to morphine.

Methadone for cancer pain

BACKGROUND

Methadone is an opioid used in the management of cancer pain. A particular role in neuropathic pain has been suggested. The quest for evidence based palliative care prompted a formal appraisal of methadone in comparison with other analgesics. This is an updated version of the original Cochrane review published in Issue 1, 2004.

OBJECTIVES

To determine effectiveness and safety of methadone analgesia in cancer pain patients.

SEARCH STRATEGY

MEDLINE, EMBASE, CancerLit, CINAHL and Cochrane databases were searched in 2002 using a strategy developed with the Cochrane Pain, Palliative and Supportive Care Group. Repeat searches were conducted in September 2006.

SELECTION CRITERIA

Randomised controlled trials (RCTs) of methadone against active or placebo comparator in patients with cancer pain were included. Outcome measures sought were reduction in pain intensity, adverse effects, attrition, patient satisfaction and quality of life. There were no language restrictions.

DATA COLLECTION AND ANALYSIS

Eligible studies were selected with independent collaboration from a colleague. Full text was retrieved if any uncertainty about eligibility remained. Non-English texts were screened by Cochrane contacts. Quality assessment and data extraction were conducted using standardised data forms. Drug and placebo dose, titration, route and formulation were compared and detail of all outcome measures (if available) recorded.

MAIN RESULTS

This updated review includes nine RCTs (six double blinded, two crossover) with 459 recruits and 392 completing patients. All studies involved active opioid comparators (morphine, dextromoramide, pethidine, diamorphine with cocaine mixture) with different dose and titration schedules and various pain scoring scales. One study differentiated cases by pain syndrome. Few presented complete pain data sets but complete adverse events data were recorded in every study. Efficacy and tolerability were broadly similar between methadone and morphine. No useful meta-analysis has been possible.

AUTHORS' CONCLUSIONS

The updated review contains new information supporting the previous conclusions that methadone has similar analgesic efficacy to morphine. The additional study examined neuropathic and non-neuropathic pain, finding no superiority for methadone in the former group. The new study also addresses a clinically relevant concern about short term/single dose studies. Use beyond a few days may result in methadone accumulation leading to delayed onset of adverse effects. In an assessment over 28 days there was a higher rate of withdrawal due to side effects in the methadone group. This observation reinforces the advice that experienced clinicians should take responsibility for initiation and careful dose adjustment and monitoring of methadone.

Oral methadone for chronic noncancer pain: a systematic literature review of reasons for administration, prescription patterns, effectiveness, and side effects

OBJECTIVE

To assess the indications, prescription patterns, effectiveness, and side effects of oral methadone for the treatment of chronic noncancer pain.

METHODS

We conducted searches of several electronic databases, textbooks and reference lists for controlled or uncontrolled studies in humans. Effectiveness was assessed using a dichotomous classification of "meaningful" versus "nonmeaningful" outcomes.

RESULTS

Twenty-one papers (1 small randomized trial, 13 case reports, and 7 case series) involving 545 patients with multiple noncancer pain conditions were included. In half of the patients, no specific diagnosis was reported. Methadone was administered primarily when previous opioid treatment was ineffective or produced intolerable side effects. Starting dose ranged from 0.2 to 80 mg/day and maximum dose ranged from 20 to 930 mg/day. Pain outcomes were meaningful in 59% of the patients in the uncontrolled studies. The randomized trial demonstrated a statistically significant improvement in pain for methadone (20 mg/day) compared to placebo. Side effects were considered minor.

DISCUSSION

Oral methadone is used for various noncancer pain syndromes, at different settings and with no prescription pattern that could be identifiable. Starting, maintenance, and maximum doses showed great variability. The figure of 59% effectiveness of methadone should be interpreted very cautiously, as it seems overrated due to the poor quality of the uncontrolled studies and their tendency to report positive results. The utilization of oral methadone for noncancer pain is based on primarily uncontrolled literature. Well-designed controlled trials may provide more accurate information on the drug's efficiency in pain syndromes and in particular neuropathic pain.

Methadone for cancer pain

BACKGROUND

Methadone is an opioid used in the management of cancer pain both in opioid naïve patients and in rotation from other opioids. A particular role in neuropathic pain has been suggested. The quest for evidence based palliative care prompted a formal appraisal of methadone in comparison with other analgesics.

OBJECTIVES

To determine the effectiveness and safety of methadone analgesia in cancer pain patients.

SEARCH STRATEGY

MEDLINE (1966 to August 2002), EMBASE (1980 to August 2002), CancerLit (1993 to August 2002), CINAHL (1982 to August 2002) and Cochrane databases were searched using a strategy developed with the Cochrane Pain, Palliative and Supportive Care Group. Assiduous efforts were made to identify unpublished or current trial work.

SELECTION CRITERIA

Randomised controlled trials of methadone against active or placebo comparator in patients with cancer pain were included. Outcome measures sought were reduction in pain intensity measured by an appropriate scale, adverse effects, attrition, patient satisfaction and quality of life. There were no language restrictions. Absence of patient reported data was an exclusion criterion.

DATA COLLECTION AND ANALYSIS

Eligible studies were selected with independent collaboration from a colleague in Bristol (AND). Full text was retrieved if any uncertainty about eligibility remained. Non-English texts were screened by Cochrane contacts aware of the eligibility criteria. Quality assessment and data extraction were conducted using standardised data forms. Drug and placebo dose, titration, route and formulation were compared and detail of all outcome measures (if available) recorded.

MAIN RESULTS

Eight randomised controlled trials (five double blinded, two crossover) with 356 recruits and 326 completing patients were included. All involved active placebo (five morphine, one dextromoramide or pethidine, one diamorphine with cocaine mixture). All employed different starting doses, titration regimens and pain scoring scales. Few presented complete pain data sets and no meta-analysis has been possible. No differentiation by cancer pain syndrome was made. Complete adverse events data were recorded in every study, and were similar in incidence and severity to those experienced with morphine.

REVIEWERS' CONCLUSIONS

There is evidence to suggest that methadone is an analgesic with similar efficacy to morphine and a comparable side effect profile. However, the majority of studies involved single dose comparisons or short term use. This methodology fails to reproduce clinical practice. Therefore there is a very significant danger that the effects of methadone accumulation leading to delayed onset of adverse effects which occurs with chronic administration has not been represented. Fixed interval dosing schedules conducted over several days are associated with a high risk of serious morbidity and mortality. There is no trial evidence to support the proposal that methadone has a particular role in neuropathic pain of malignant origin. Conclusions have been limited by the variations in trial design, dosing regimens and limited presentation of primary outcome data. The complex and highly individual pharmacokinetics of methadone require that experienced clinicians take responsibility for initiating, titrating and monitoring this drug.

Palliative care in a national cancer center: results in 1987 vs. 1993 vs. 2000

In the last few years, palliative care for advanced and terminal cancer patients has undergone considerable evolution. We determined the characteristics of patients admitted to the 4-bed Palliative Care Unit (PCU) of the National Cancer Institute (NCI) of Milan in 1987, 1993 and 2000 to evaluate how our diagnostic and therapeutic approaches have changed over the years. We reviewed the charts of every patient admitted to the PCU in 1987, 1993, and the first ten months of 2000. We recorded demographic data; the primary tumor sites; the main reason for admission; the types of therapies administered (oncologic, analgesic, surgical, neurosurgical analgesic procedures, and supportive therapy); the type and number of cardiological, radiological and endoscopic examinations, as well as specialist consultations; the duration of stay and eventual death on the Unit. There were no significant differences regarding gender, age, primary tumor site and death in hospital of the patients admitted during these years. The time spent in hospital increased over time (P = 0.006). A significant increase was observed in the percentage of patients admitted for supportive therapy (P < 0.001) and investigation concerning the stage of the disease (P < 0.001). There was a significant decrease in admission for invasive analgesic procedures (P < 0.001), as well as for pain diagnosis and/or uncontrolled pain. Uncontrolled pain remained the most frequent reason for admission. Over the years, during hospitalization, 7% to 12% of the patients underwent radiotherapy,1% to 9% had computerized tomography, and 4% to 8% had palliative surgery. More than 50% of the patients received intravenous hydration; a few patients received hypodermoclysis in 1987. Over time, there was a significant increase in "as needed" administration of nonsteroidal anti-inflammatory drugs and a significant reduction in their regular administration (from 24% in 1987 and 1993 to 3% in 2000) (P < 0.001). The use of codeine, tramadol and methadone increased (P < 0.001), whereas the use of oral morphine, buprenorphine and oxycodone decreased in 2000 (P < 0.001). There was a reduction in the use of antidepressants (no significant constant trend) and a significant increase in the use of anticonvulsants, laxatives and pamidronate (P < 0.001). Regularly administered hypnotics decreased in 1993 and increased in 2000 (P < 0.001). Over these years, no significant differences were found in the routes of opioid administration, in route switching and in the mean maximum oral opioid dose (ranging from 108 to 126 mg/day). The percentage of patients undergoing percutaneous cordotomy significantly decreased in 1993 and 2000 (P < 0.001). Over time, there was an increase in requests for specialist consultations, which was significant for neurological, cardiological and oncological consults (P < 0.001). Although the characteristics of the patients admitted to the PCU did not change over these years, there have been significant modifications in our therapeutic approaches, above all in the use of supportive therapy, adjuvant drugs, opioids and neurosurgical invasive procedures. Moreover, a major collaborative interaction with other specialists of the NCI took place with the aim to tailor treatment for each single patient.

Oral morphine for cancer pain

BACKGROUND

Morphine has been used to relieve pain for many years. Oral morphine in either immediate release or sustained release form remains the analgesic of choice for moderate or severe cancer pain.

OBJECTIVES

To determine the efficacy of oral morphine in relieving cancer pain. To assess the incidence and severity of adverse effects.

SEARCH STRATEGY

The following databases were searched: The Cochrane Central Register of Controlled Trials (CENTRAL), Cochrane Library, Issue 4, 2002; the trials register of the Cochrane Pain, Palliative and Supportive Care group (February 2002); MEDLINE 1966 to December 2002; EMBASE 1988 to December 2002; and the Oxford Pain Relief database 1950 to 1994.

SELECTION CRITERIA

Published randomised controlled trials (full reports) reporting on the analgesic effect of oral morphine in adults and children with cancer pain. Any comparator trials were considered. Trials with fewer than 10 subjects were excluded.

DATA COLLECTION AND ANALYSIS

One reviewer extracted data, and the findings were checked by two other reviewers. There were insufficient comparable data for meta-analysis to be undertaken, or to produce numbers-needed-to-treat (NNT) for the analgesic effect.

MAIN RESULTS

Forty five studies (3061 subjects) met the inclusion criteria. Fourteen studies compared oral sustained release morphine (MSR) preparations with immediate release morphine (MIR). Eight studies compared MSR and MSR in different strengths. Nine studies compared MSR with other opioids. Five studies compared MIR with other opioids. Two studies compared oral MSR with rectal MSR. One study was found comparing each of the following: MSR tablet with MSR suspension; MSR with MSR at different dose frequencies; MSR with non-opioids; MIR with non-opioids; oral morphine with epidural morphine; and MIR with MIR by a different route of administration. Morphine was shown to be an effective analgesic. Pain relief did not differ between MSR and MIR. Sustained release versions of morphine were effective for 12 or 24 hour dosing depending on the formulation. Adverse effects were common but only 4% of patients discontinued treatment because of intolerable adverse effects.

REVIEWER'S CONCLUSIONS

The randomised trial literature for morphine is small given the importance of this medicine. Most trials recruited fewer than 100 participants, and did not provide appropriate data for meta-analysis. Trial design was frequently based on titration of morphine or comparator to achieve adequate analgesia, then crossing subjects over in crossover design studies. It is not clear if these trials are sufficiently powered to detect any clinical differences between formulations or comparator drugs.

The use of methadone for cancer pain

Methadone is not a new analgesic drug [69]. Several studies have demonstrated that methadone is a valid alternative to morphine, hydromorphone, and fentanyl for the treatment of cancer-related pain, and extensive reviews on the subject have been published in recent years [10,23,25,64,70,71]. Most people involved in pain therapy, however, are not well informed about the properties of methadone. The authors believe that the low cost of methadone paradoxically contributes to the limited knowledge of its characteristics and to the restricted therapeutic use of this drug. The low cost of methadone means there is little financial incentive for pharmaceutical companies to invest in research or to disseminate scientific information. Unfortunately, the lack of scientific information from pharmaceutical companies frequently results in a lack of knowledge on the part of physicians. Unless the existing approach changes, both culturally and politically, ignorance about methadone will persist among medical experts. The low cost of methadone, rather than being an advantage, will result in the limited exploitation of an effective drug.

Strategies for the treatment of cancer pain in the new millennium

As was the case in the era before us, in the new millennium we will continue to see an abundance of patients experiencing cancer-related pain for different reasons. Although much needless pain and suffering still affects many of those with cancer, we are presented with a medical dichotomy. With the analgesic drugs available today, and the relatively simple and effective guidelines to treat cancer pain published and disseminated by the World Health Organization, why do people with cancer continue to experience pain? As we search for the answer, the horizon may hold promising new drugs, 'old drugs' with new interest and applications, and new strategies for the field of pain therapy. Possibilities include the isolation and development of analgesics or analgesic combinations that may minimise the adverse effects which are often associated with the current therapeutic class of opioid analgesics. In addition, current research points to promising results identifying the N-methyl D-aspartate non-opioid receptor as a likely component of neuropathic pain. Drugs such as gabapentin, the mechanism of action of which is not well known, have found favour within the clinical community for their analgesic properties and good tolerability. Methadone, in a phase of resurgence, has garnered the attention of the clinical community because of its unique receptor activity and pharmacoeconomic benefits. A number of clinical studies have demonstrated that methadone has a valuable role in treating cancer pain. Perhaps, an unbalanced focus on the risks of inappropriate use, rather than the benefits, should not compromise or distract from the use of methadone as an alternative to morphine. Studies are on going to assess the potential role of methadone in treating neuropathic pain. Drugs such as cannabinoids, although currently applicable for patients with anorexia, nausea and/or vomiting, may offer benefits to patients experiencing pain. Other opportunities exist with such compounds as alpha2-adrenergic agonists, nicotine, lidocaine and ketamine. New strategies such as the switching opioids and/or their route of administration may offer improved analgesia with fewer adverse effects, thus providing therapeutic alternatives for the clinical community. In addition, there is interest in the co-administration of opioids that act on different receptors. For instance, oxycodone appears to be a kappa opioid receptor agonist and may offer enhanced analgesia when combined with morphine.