Opioid switching to improve pain relief and drug tolerability

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Conversion ratios: Why is it so challenging to construct opioid conversion tables?

Standardizing opioid management is challenging due to the absence of a ceiling dose, the unknown ideal therapeutic plasma level, and the lack of an clear relationship between dose and therapeutic response. Opioid rotation or conversion, which is switching from one opioid, route of administration, or both, to another, to improve therapeutic response and reduce toxicities, occurs in 20-40 percent of patients treated with opioids. Opioid conversion is often needed when there are adverse effects, toxicities, or inability to tolerate a certain opioid formulation. A majority of patients benefit from opioid conversion, leading to improved analgesia and less adverse effects. There are different published ways of converting opioids in the literature. This review of 20 years of literature is centered on opioid conversions and aims to discuss the complexity of converting opioids. We discuss study designs, outcomes and measures, pain phenotypes, patient characteristics, comparisons of equivalent doses between opioids, reconciling conversion ratios between opioids, routes, directional differences, half-lives and metabolites, interindividual variability, and comparison to package insert information. Palliative care specialists have not yet come to a consensus on the ideal opioid equianalgesic table; however, we discuss a recently updated table, based on retrospective evidence, that may serve as a gold standard for practical use in the palliative care population. More robust, well-designed studies are needed to validate and guide future opioid conversion data.

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

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

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Diamorphine pharmacokinetics and conversion factor estimates for intranasal diamorphine in paediatric breakthrough pain:systematic review

BACKGROUND

Intranasal diamorphine is a potential treatment for breakthrough pain but few paediatric data are available to assist dose estimation.

AIM

To determine an intranasal diamorphine dose in children through an understanding of pharmacokinetics.

DESIGN

A systematic review of the literature was undertaken to seek diamorphine pharmacokinetic parameters in neonates, children and adults. Parenteral and enteral diamorphine bioavailability were reviewed with respect to formation of the major metabolite, morphine. Clinical data quantifying equianalgesic effects of diamorphine and morphine were reviewed.

REVIEW SOURCES

PubMed (1960-2020); EMBASE (1980-2020); IPA (1973-2020) and original human research studies that reported diacetylmorphine and metabolite after any dose or route of administration.

RESULTS

The systematic review identified 19 studies: 16 in adults and 1 in children and 2 neonatal reports. Details of study participants were extracted. Age ranged from premature neonates to 67 years and weight 1.4-88 kg. Intranasal diamorphine bioavailability was predicted as 50%. The equianalgesic intravenous conversion ratio of morphine:diamorphine was 2:1. There was heterogeneity between pharmacokinetic parameter estimates attributed to routes of administration, lack of size standardisation, methodology and pharmacokinetic analysis. Estimates of the pharmacokinetic parameters clearance and volume of distribution were reduced in neonates. There were insufficient paediatric data to characterise clearance or volume maturation of either diamorphine or its metabolites.

CONCLUSIONS

We estimate equianalgesic ratios of intravenous morphine:diamorphine 2:1, intravenous morphine:intranasal diamorphine 1:1 and oral morphine:intranasal diamorphine of 1:3. These ratios are based on adult literature, but are reasonable for deciding on an initial dose of 0.1 mg/kg in children 4-13 years.

Conversion ratios for opioid switching: a pragmatic study

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

The Role of Pharmacogenomics in Opioid Prescribing

Pharmacogenomics is increasingly important to guide objective, safe, and effective individualised prescribing. Personalised prescribing has revolutionised treatments in the past decade, allowing clinicians to maximise drug efficacy and minimise adverse effects based on a person’s genetic profile. Opioids, the gold standard for cancer pain relief, are among the commonest medications prescribed in palliative care practice. This narrative review examines the literature surrounding opioid pharmacogenomics and its applicability to the palliative care cancer population. There is currently limited intersection between the fields of palliative care and pharmacogenomics, but growing evidence presents a need to build linkages between the two disciplines. Pharmacogenomic evidence guiding opioid prescribing is currently available for codeine and tramadol, which relates to CYP2D6 gene variants. However, these medications are prescribed less commonly for pain in palliative care. Research is accelerating with other opioids, where oxycodone (CYP2D6) and methadone (CYP2B6, ABCB1) already have moderate evidence of an association in terms of drug metabolism and downstream analgesic response and side effects. OPRM1 and COMT are receiving increasing attention and have implications for all opioids, with changes in opioid dosage requirements observed but they have not yet been studied widely enough to be considered clinically actionable. Current evidence indicates that incorporation of pharmacogenomic testing into opioid prescribing practice should focus on the CYP2D6 gene and its actionable variants. Although opioid pharmacogenomic tests are not widely used in clinical practice, the progressively reducing costs and rapid turnover means greater accessibility and affordability to patients, and thus, clinicians will be increasingly asked to provide guidance in this area. The upsurge in pharmacogenomic research will likely discover more actionable gene variants to expand international guidelines to impact opioid prescribing. This rapidly expanding area requires consideration and monitoring by clinicians in order for key findings with clinical implications to be accessible, meaningfully interpretable and communicated.

Continuous subcutaneous infusion for pain control in dying patients: experiences from a tertiary palliative care center

BACKGROUND

Continuous subcutaneous infusion (CSCI) via ambulatory infusion pump (AIP) is a valuable method of pain control in palliative care. When using CSCI, low-dose methadone as add-on to other opioids might be an option in complex pain situations. This study aimed to investigate the effects, and adverse effects, of CSCI for pain control in dying patients, with particular interest in methadone use.

METHODS

This was an observational cohort study. Imminently dying patients with pain, admitted to specialized palliative inpatient wards and introduced on CSCI, were monitored daily by staff for symptoms (Integrated Palliative Care Outcome Scale - IPOS), sedation (Richmond Agitation and Sedation Scale - RASS), performance status (Eastern Cooperative Oncology Group - ECOG) and delirium (Confusion Assessment Method - CAM).

RESULTS

Ninety-three patients with a median survival of 4 days were included. Of the 47 patients who survived ≥3 days, the proportion of patients with severe/overwhelming pain decreased from 45 to 19% (p < 0.001) after starting CSCI, with only a moderate increase in morphine equivalent daily dose of opioids (MEDD). Alertness was marginally decreased (1 point on the 10-point RASS scale, p = 0.001), whereas performance status and prevalence of delirium, regardless of age, remained unchanged. Both patients with methadone as add-on (MET, n = 13) and patients with only other opioids (NMET, n = 34), improved in pain control (p < 0.05 and 0.001, respectively), despite that MET patients had higher pain scores at baseline (p < 0.05) and were on a higher MEDD (240 mg vs.133 mg). No serious adverse effects demanding treatment stop were reported.

CONCLUSIONS

CSCI via AIP is an effective way to reduce pain in dying patients without increased adverse effects. Add-on methadone may be beneficial in patients with severe complex pain.

Technologies for Opioid Use Disorder Management: Mobile App Search and Scoping Review

Background

Advances in technology engender the investigation of technological solutions to opioid use disorder (OUD). However, in comparison to chronic disease management, the application of mobile health (mHealth) to OUD has been limited.

Objective

The overarching aim of our research was to design OUD management technologies that utilize wearable sensors to provide continuous monitoring capabilities. The objectives of this study were to (1) document the currently available opioid-related mHealth apps, (2) review past and existing technology solutions that address OUD, and (3) discuss opportunities for technological withdrawal management solutions.

Methods

We used a two-phase parallel search approach: (1) an app search to determine the availability of opioid-related mHealth apps and (2) a scoping review of relevant literature to identify relevant technologies and mHealth apps used to address OUD.

Results

The app search revealed a steady rise in app development, with most apps being clinician-facing. Most of the apps were designed to aid in opioid dose conversion. Despite the availability of these apps, the scoping review found no study that investigated the efficacy of mHealth apps to address OUD.

Conclusions

Our findings highlight a general gap in technological solutions of OUD management and the potential for mHealth apps and wearable sensors to address OUD.

The Complex Balance between Analgesic Efficacy, Change of Dose and Safety Profile Over Time, in Cancer Patients Treated with Opioids: Providing the Clinicians with an Evaluation Tool

Background: Scanty data exist on the integration between the analgesic effect of opioids, dose changes, and adverse events in cancer patients. Methods: To provide further information on this issue, we analysed data on 498 advanced-stage cancer patients treated with strong opioids. At baseline and three visits (at days 7, 14, and 21), pain intensity, oral morphine-equivalent daily dose, and the prevalence of major adverse events were measured. The proportion of responders (pain intensity decrease ≥30% from baseline) and non-responders, as well as of patients with low or high dose escalation, was calculated. Results: Pain intensity strongly decreased from baseline (pain intensity difference −4.0 at day 7 and −4.2 at day 21) in responders, while it was quite stable in non-responders (pain intensity difference −0.8 at day 7 and −0.9 at day 21). In low dose escalation patients (82.4% at final visit), daily dose changed from 52.3 to 65.3 mg; in high dose escalation patients (17.6%), it varied from 94.1 to 146.7 mg. Among responders, high dose escalation patients experienced significantly more frequent adverse events compared to low or high dose escalation patients, while no differences were observed in non-responders. Conclusions: The response to opioids results from the combination of three clinical aspects, which are strongly interrelated. These results provide some thoughts to help clinical evaluations and therapeutic decisions regarding opioid use.

Practical management of opioid rotation and equianalgesia

Purpose

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

Methods

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

Results

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

Conclusion

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

Opioid Rotation in Cancer Pain Treatment

BACKGROUND

Rotating several different WHO level III opioid drugs is a therapeutic option for patients with chronic cancer-related pain who suffer from inadequate analgesia and/or intolerable side effects. The evidence favoring opioid rotation is controversial, and the current guidelines in Germany and other countries contain only weak recommendations for it.

METHODS

This review is based on pertinent publications retrieved by a systematic review of the literature on opioid rotation for adult patients with chronic cancerrelated pain who are regularly taking WHO level III opioids by the oral or trans - dermal route.

RESULTS

9 individual studies involving a total of 725 patients were included in the analysis, and 3 previous systematic reviews of studies involving a total of 2296 patients were also analyzed. Morphine, oxycodone, fentanyl, hydromorphone, and buprenorphine were used as first-line opioid drugs, and hydromorphone, bupre - norphine, tapentadol, fentanyl, morphine, oxymorphone, and methadone were used as second-line opioid drugs. In all of the studies, pain control was achieved for 14 days after each rotation. In most of them, the dose of the new drug introduced in each rotation needed to be increased above the dose initially calculated from a rotation ratio, with the exception of rotations to methadone. The frequency of side effects was only rarely lessened, but patients largely considered the result of opioid rotation to be positive. No particular opioid drug was found to be best.

CONCLUSION

Opioid rotation can improve analgesia and patient satisfaction. The success of opioid rotation appears to depend on the magnitude of the initial dose, among other factors. Tables of equianalgesic doses should be considered no more than a rough guide for determining the dose of the new drug. Rotations to methadone should be carried out under clinical supervision in experienced hands.

The switch from buprenorphine to tapentadol: is it worth?

Opioid analgesia continues to be the primary pharmacologic intervention for managing acute pain and malignant pain in both hospitalized and ambulatory patients. The increasing use of opioids in chronic nonmalignant pain is more problematic. Opioid treatment is complicated with the risks raised by adverse effects, especially cognitive disturbance, respiratory depression but also the risk of tolerance, opioid abuse and drug-disease interactions. Despite the growing number of available opioids within the last years, adequate trials of opioid rotation are lacking and most of the information is anecdotal. This article reviews the clinical evidence surrounding the switch from transdermal buprenorphine to tapentadol in malignant and non-malignant pain. Tapentadol acts on both the μ-opioid receptors (MOR) and on the neuronal reuptake of noradrenaline with a limited usefulness in acute pain management while buprenorphine is a mixed agonist-antagonist, and both present some advantages over other opioids. Both drugs show particular pharmacodynamic and pharmacokinetic properties which reduce the risks of development of tolerance, opioid abuse, diversion and determine fewer hormone changes than the "classical opioids" making these opioids more attractive than other opioids in long term opioid treatment. However, in the absence of powered clinical trials, the evidence to support the method used for transdermal buprenorphine rotation to tapentadol is weak.

[Special medical problems in end-of-life care : Crisis at the end of life - Which therapy is adequate and when is redefining treatment goals appropriate?]

Crisis at the end of life are exceptional challenges for patients, relatives and therapists. With respect to the individual treatment goals and the patients' autonomy, therapeutic action should be commenced in an adequate manner in order to preserve the patients' quality of life as much as possible. Advance care planning for specific critical scenarios may be helpful in order to treat patients according to their wishes and values even if they are not capable to express themselves. Furthermore, a crisis plan can define the scope of action for therapists in emergency situations. Dyspnea, pain and delirium are symptoms that may often lead to emergency calls. In such cases, pharmacological and other treatment options are available. Options for causal therapy should be checked and performed if adequate. Opioids are used to relieve pain and dyspnea. In a state of delirium, highly potent neuroleptics and atypical antipsychotics are used. For the treatment of anxiety or restlessness benzodiazepines can be prescribed. Sedative medication may reduce stress, for instance in the case of acute catastrophic bleeding. Palliative sedation is an ultima ratio concept for refractory symptoms at the end of life. Clinical practice guidelines (such as the German guideline "Palliative care for patients with incurable cancer") may provide an overview of the evidence base on symptom-guided therapy at the end of life.

Ketamine Infusion as a Counter Measure for Opioid Tolerance in Mechanically Ventilated Children: A Pilot Study

BACKGROUND

Drug rotation to prevent opioid tolerance is well recognized in chronic pain management. However, ketamine infusion as a counter measure for opioid tolerance is rarely described in mechanically ventilated children developing tolerance from prolonged opioid infusion.

PATIENTS AND METHODS

We performed a retrospective study in a 14-bed medical-surgical-cardiac pediatric intensive care unit. Thirty-two mechanically ventilated children who had developed tolerance from prolonged intravenous infusion of opioids received a continuous intravenous infusion of ketamine as an opioid substitute for more than 2 days, scheduled in a drug rotation protocol.

RESULTS

Thirty-two children (median age 2.5 years, range 0.1-16.0; weight 11.2 kg [3.8-62.0]) were included. Patients had received continuous intravenous infusion of opioids and benzodiazepines for 16.0 days (4.0-34.0) when drug rotation was started. The median dose of continuous intravenous infusion of ketamine was 4.0 mg·kg^-1·h^-1 (1.8-6.0) and the median duration was 3.0 days (2.0-6.0). After having restarted opioids, fentanyl doses were significantly lower compared with the time before the drug rotation began (after, 2.9 µg·kg^-1·h^-1 [0.8-4.9] vs before, 4.15 µg·kg^-1·h^-1 [1.2-10.0]; p < 0.001). Continuous intravenous infusion of midazolam and clonidine were unchanged during drug rotation. COMFORT-B scoring was significantly lower after having started drug rotation (after, 14.5 [8-19] vs before, 16 [11-22]; p < 0.001).

CONCLUSION

Drug rotation with ketamine in mechanically ventilated children with opioid tolerance is feasible and seems to reduce the rate of fentanyl infusion.

TRV0109101, a G Protein-Biased Agonist of the µ-Opioid Receptor, Does Not Promote Opioid-Induced Mechanical Allodynia following Chronic Administration

Prescription opioids are a mainstay in the treatment of acute moderate to severe pain. However, chronic use leads to a host of adverse consequences including tolerance and opioid-induced hyperalgesia (OIH), leading to more complex treatment regimens and diminished patient compliance. Patients with OIH paradoxically experience exaggerated nociceptive responses instead of pain reduction after chronic opioid usage. The development of OIH and tolerance tend to occur simultaneously and, thus, present a challenge when studying the molecular mechanisms driving each phenomenon. We tested the hypothesis that a G protein-biased µ-opioid peptide receptor (MOPR) agonist would not induce symptoms of OIH, such as mechanical allodynia, following chronic administration. We observed that the development of opioid-induced mechanical allodynia (OIMA), a model of OIH, was absent in β-arrestin1^-/- and β-arrestin2^-/- mice in response to chronic administration of conventional opioids such as morphine, oxycodone and fentanyl, whereas tolerance developed independent of OIMA. In agreement with the β-arrestin knockout mouse studies, chronic administration of TRV0109101, a G protein-biased MOPR ligand and structural analog of oliceridine, did not promote the development of OIMA but did result in drug tolerance. Interestingly, following induction of OIMA by morphine or fentanyl, TRV0109101 was able to rapidly reverse allodynia. These observations establish a role for β-arrestins in the development of OIH, independent of tolerance, and suggest that the use of G protein-biased MOPR ligands, such as oliceridine and TRV0109101, may be an effective therapeutic avenue for managing chronic pain with reduced propensity for opioid-induced hyperalgesia.

Opioids and GI Motility-Friend or Foe?

OPINION STATEMENT

The use of opioids for the treatment of chronic non-cancer pain is growing at an alarming rate. Opioid-induced bowel dysfunction (OBD) is a common adverse effect of long-term opioid treatment manifesting as constipation, nausea, and vomiting. These effects are primarily mediated by peripheral μ-opioid receptors with resultant altered GI motility and function. As a result, patients may present with opioid-induced constipation (OIC), opioid-induced nausea and vomiting (OINV), and/or narcotic bowel syndrome (NBS). This often leads to decreased quality of life and in many cases, discontinuation of opioid therapy. There is limited evidence to support the use of traditional anti-emetics and laxatives in the treatment of OBD. Tapering the dose of opioids, switching to transdermal application, opioid rotation, or dual-action opioids, such as tapentadol, may be helpful in the treatment of OBD. Novel agents, such as peripherally acting μ-opioid receptor antagonists which target the cause of OIC, show promise in the treatment of OBD and should be considered when conventional laxatives fail. This chapter will review the pathophysiology of OBD, including OINV and OIC, and treatment options available.

Pain Management in Elderly Patients

In elderly patients, persistent pain negatively impacts quality of life. An interdisciplinary approach to pain management and emphasis on quality improvement will help to achieve better therapeutic outcomes. Managing pain in the geriatric population is challenging because of age-related changes in pain perception, cognition, pharmacokinetics, and drug effects. Improvement and maintenance of physical and emotional function is the goal. Pharmacotherapy should be initiated conservatively and titrated to effective doses with minimal adverse effects. Milder pain should be treated with non-opioid analgesics with a progression toward opioids and/or adjuvant medications as the pain intensifies. Acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs), opioids, and adjuvant medications represent most of the analgesic agents used in pain management. Knowing the underlying mechanism of pain will help guide pharmacologic therapy. The patient should be monitored initially, with every dose change, and periodically to assess efficacy and severity of adverse effects.

Definition, diagnosis and treatment strategies for opioid-induced bowel dysfunction–Recommendations of the Nordic Working Group

Background and aims

Opioid-induced bowel dysfunction (OIBD) is an increasing problem due to the common use of opioids for pain worldwide. It manifests with different symptoms, such as dry mouth, gastro-oesophageal reflux, vomiting, bloating, abdominal pain, anorexia, hard stools, constipation and incomplete evacuation. Opioid-induced constipation (OIC) is one of its many symptoms and probably the most prevalent. The current review describes the pathophysiology, clinical implications and treatment of OIBD.

Methods

The Nordic Working Group was formed to provide input for Scandinavian specialists in multiple, relevant areas. Seven main topics with associated statements were defined. The working plan provided a structured format for systematic reviews and included instructions on how to evaluate the level of evidence according to the GRADE guidelines. The quality of evidence supporting the different statements was rated as high, moderate or low. At a second meeting, the group discussed and voted on each section with recommendations (weak and strong) for the statements.

Results

The literature review supported the fact that opioid receptors are expressed throughout the gastrointestinal tract. When blocked by exogenous opioids, there are changes in motility, secretion and absorption of fluids, and sphincter function that are reflected in clinical symptoms. The group supported a recent consensus statement for OIC, which takes into account the change in bowel habits for at least one week rather than focusing on the frequency of bowel movements. Many patients with pain receive opioid therapy and concomitant constipation is associated with increased morbidity and utilization of healthcare resources. Opioid treatment for acute postoperative pain will prolong the postoperative ileus and should also be considered in this context. There are no available tools to assess OIBD, but many rating scales have been developed to assess constipation, and a few specifically address OIC. A clinical treatment strategy for OIBD/OIC was proposed and presented in a flowchart. First-line treatment of OIC is conventional laxatives, lifestyle changes, tapering the opioid dosage and alternative analgesics. Whilst opioid rotation may also improve symptoms, these remain unalleviated in a substantial proportion of patients. Should conventional treatment fail, mechanism-based treatment with opioid antagonists should be considered, and they show advantages over laxatives. It should not be overlooked that many reasons for constipation other than OIBD exist, which should be taken into consideration in the individual patient.

Conclusion and implications

It is the belief of this Nordic Working Group that increased awareness of adverse effects and OIBD, particularly OIC, will lead to better pain treatment in patients on opioid therapy. Subsequently, optimised therapy will improve quality of life and, from a socio-economic perspective, may also reduce costs associated with hospitalisation, sick leave and early retirement in these patients.

A multicenter, primary-care-based, open-label study to assess the success of converting opioid-experienced patients with chronic moderate-to-severe pain to morphine sulfate and naltrexone hydrochloride extended-release capsules using a standardized conversion guide

OBJECTIVE

To evaluate the conversion of opioid-experienced patients with chronic moderate-to-severe pain to extended-release morphine sulfate with sequestered naltrexone hydrochloride (MSN) using a standardized conversion guide.

METHODS

This open-label, single-arm study was conducted in 157 primary care centers in the United States. A total of 684 opioid-experienced adults with chronic moderate-to-severe pain were converted to oral administration of MSN from transdermal fentanyl and oral formulations of hydrocodone, hydromorphone, methadone, oxycodone, oxymorphone, and other morphine products using a standardized conversion guide. The primary endpoint was the percentage of patients achieving a stable MSN dose within a 6-week titration phase. Secondary endpoints included duration of time to stable dose, number of titration steps, safety and efficacy measures, and investigator assessment of conversion guide utility.

RESULTS

Of the 684 patients, 51.3% were converted to a stable dose of MSN (95% confidence interval: 47.5%, 55.1%). The mean (standard deviation) number of days to stable dose was 20 (8.94), and number of titration steps to stable dose was 2.4 (1.37). The majority of adverse events were mild/moderate and consistent with opioid therapy. Mean pain scores at stable dose decreased from baseline. Investigators were generally satisfied with the conversion guide and, in 94% of cases, reported they would use it again.

CONCLUSION

Conversion to MSN treatment using the standardized MSN conversion guide was an attainable goal in approximately half of the population of opioid-experienced patients with chronic moderate-to-severe pain. Investigators found the guide to be a useful tool to assist conversion of opioid-experienced patients to MSN.

A naloxone admixture to prevent opioid-induced pruritus in children: a randomized controlled trial

PURPOSE

Morphine administered by continuous opioid infusion (COI) or by patient-controlled analgesia (PCA) is associated with opioid-induced pruritus (OIP). Intravenous naloxone administered separately to the morphine infusion at a dose of 0.25-1.65 μg·kg(-1)·hr(-1) can provide effective prevention from OIP. Nevertheless, this strategy requires a dedicated intravenous line and an additional infusion pump. The purpose of this study was to determine whether an admixture of naloxone with morphine in normal saline administered via COI or PCA would also prevent OIP in children without attenuation of analgesia or increased opioid utilization.

METHODS

In this randomized controlled trial, children meeting the inclusion criteria (aged 8-18 yr, American Society of Anesthesiologists physical status I-III, normal developmental profile and prescribed COI/PCA morphine for postoperative analgesia) were randomized to receive an infusion containing a naloxone, opioid, and saline admixture (NOSA) of 12 μg naloxone per 1 mg morphine per 1 mL normal saline or morphine only (control). The severity of opioid-induced pruritus was assessed by self-report using a modified colour analogue scale (mCAS; score 0-10). The groups were also compared for opioid utilization, pain scores, and administration of antipruritic medications, which were recorded for up to 48 hr or until the COI/PCA was discontinued.

RESULTS

Ninety-two participants were enrolled in the study. The median [interquartile range] dose of naloxone administered to the NOSA participants was 0.37 [0.30-0.48] μg·kg(-1)·hr(-1). The incidence of OIP, determined by self-report and treatment, was not different between groups: 22% in the NOSA group vs 36% in the control group (mean difference, -15%; 95% confidence interval [CI], -33 to 4; P = 0.164). The severity of opioid-induced pruritus was similar in the two groups, with a median difference in the participants' mean mCAS score of -0.29 (95% CI, -0.75 to 0.26; P = 0.509). Opioid utilization did not differ between groups, with a median difference of -1.35 μg·kg(-1)·hr(-1) (95% CI, -5.85 to 7.55; P = 0.518), and pain scores did not differ, with a median difference of 0.0 (95% CI, -1.0 to 1.5; P = 0.659).

CONCLUSION

This admixture of naloxone and morphine in normal saline did not decrease the incidence or severity of OIP in this sample. Separate administration of naloxone may be the more effective strategy for prevention of OIP. This trial was registered at ClinicalTrials.gov (NCT01071057).

Buprenorphine for treating cancer pain

BACKGROUND

Many patients with cancer experience moderate to severe pain that requires treatment with strong analgesics. Buprenorphine, fentanyl and morphine are examples of strong opioids used for cancer pain relief. However, strong opioids are ineffective as pain treatment in all patients and are not well-tolerated by all patients. The aim of this Cochrane review is to assess whether buprenorphine is associated with superior, inferior or equal pain relief and tolerability compared to other analgesic options for patients with cancer pain.

OBJECTIVES

To assess the effectiveness and tolerability of buprenorphine for pain in adults and children with cancer.

SEARCH METHODS

We searched CENTRAL (the Cochrane Library) issue 12 or 12 2014, MEDLINE (via OVID) 1948 to 20 January 2015, EMBASE (via OVID) 1980 to 20 January 2015, ISI Web of Science (SCI-EXPANDED & CPCI-S) to 20 January 2015, ISI BIOSIS 1969 to 20 January 2015. We also searched ClinicalTrials.gov (http://clinicaltrials.gov/; metaRegister of Controlled Trials (mRCT) (http://www.controlled-trials.com/mrct/), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) search portal (http://apps.who.int/trialsearch/) and the Proceedings of the Congress of the European Federation of International Association for the Study of Pain (IASP; via European Journal of Pain Supplements) on 16 February 2015. We checked the bibliographic references of identified studies as well as relevant studies and systematic reviews to find additional trials not identified by the electronic searches. We contacted authors of included studies for other relevant studies.

SELECTION CRITERIA

We included randomised controlled trials, with parallel-group or crossover design, comparing buprenorphine (any formulation and any route of administration) with placebo or an active drug (including buprenorphine) for cancer background pain in adults and children.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data pertaining to study design, participant details (including age, cancer characteristics, previous analgesic medication and setting), interventions (including details about titration) and outcomes, and independently assessed the quality of the included studies according to standard Cochrane methodology. As it was not feasible to meta-analyse the data, we summarised the results narratively. We assessed the overall quality of the evidence for each outcome using the GRADE approach.

MAIN RESULTS

In this Cochrane review we identified 19 relevant studies including a total of 1421 patients that examined 16 different intervention comparisons.Of the studies that compared buprenorphine to another drug, 11 studies performed comparative analyses between the randomised groups, and five studies found that buprenorphine was superior to the comparison treatment. Three studies found no differences between buprenorphine and the comparison drug, while another three studies found treatment with buprenorphine to be inferior to the alternative treatment in terms of the side effects profile or patients preference/acceptability.Of the studies that compared different doses or formulations/routes of administration of buprenorphine, pain intensity ratings did not differ significantly between intramuscular buprenorphine and buprenorphine suppository. However, the average severity of dizziness, nausea, vomiting and adverse events as a total were all significantly higher in the intramuscular group relatively to the suppository group (one study).Sublingual buprenorphine was associated with faster onset of pain relief compared to subdermal buprenorphine, with similar duration analgesia and no significant differences in adverse event rates reported between the treatments (one study).In terms of transdermal buprenorphine, two studies found it superior to placebo, whereas a third study found no difference between placebo and different doses of transdermal buprenorphine.The studies that examined different doses of transdermal buprenorphine did not report a clear dose-response relationship.The quality of this evidence base was limited by under-reporting of most bias assessment items (e.g., the patient selection items), by small sample sizes in several included studies, by attrition (with data missing from 8.2% of the enrolled/randomised patients for efficacy and from 14.6% for safety) and by limited or no reporting of the expected outcomes in a number of cases. The evidence for all the outcomes was very low quality.

AUTHORS' CONCLUSIONS

Based on the available evidence, it is difficult to say where buprenorphine fits in the treatment of cancer pain with strong opioids. However, it might be considered to rank as a fourth-line option compared to the more standard therapies of morphine, oxycodone and fentanyl, and even there it would only be suitable for some patients. However, palliative care patients are often heterogeneous and complex, so having a number of analgesics available that can be given differently increases patient and prescriber choice. In particular, the sublingual and injectable routes seemed to have a more definable analgesic effect, whereas the transdermal route studies left more questions.

Patient preferences for change in symptoms associated with opioid-induced constipation

Introduction

While opioids have become a standard treatment option for those experiencing moderate to severe chronic pain, side effects of constipation and related symptoms have interfered with their usage in as many as 40–50% of treated patients. Prior research has elucidated the range of these symptoms, but no study has determined which of these symptoms patients most desire improving or whether improving constipation itself by as little as one more bowel movement per week is deemed an important change.

Methods

We conducted an online patient survey of 513 participants residing in one of six countries who reported having chronic pain, were taking opioids, and experiencing opioid-induced constipation (OIC) to address these questions.

Results

Respondents rank ordered their preferences and the following eight symptoms generated >80% endorsement as important to improve: improvement in having bowel movements without rectal pain, soft stools that are not loose or watery, regular bowel movements, a reduction in rectal straining, relief from feeling bloated, feeling less fear about having OIC when following their opioid medication regime, a desire to worry less overall about having a bowel movement, and with less ‘stomach’ area pain. When asked ‘how important is it you to have 1 more bowel movement per week”, over 90% endorsed it was ‘somewhat’, ‘very’, or ‘extremely important’ with nearly 70% (n = 354) endorsing the ‘extremely’ or ‘very important’ response options. In multivariate models, being in more overall pain or reporting fewer than 3 bowel movements per week were found to be independent predictors of the importance.

Conclusions

These results highlight the notable range of OIC symptoms most desired by patients to improve and demonstrate that bowel movements of only one more per week were important to register a meaningful improvement. The latter is particularly helpful for those assessing the minimal clinically important difference in treating this condition.

Electronic supplementary material

The online version of this article (doi:10.1007/s12325-014-0169-x) contains supplementary material, which is available to authorized users.

Toward a systematic approach to opioid rotation

Patients requiring chronic opioid therapy may not respond to or tolerate the first opioid prescribed to them, necessitating rotation to another opioid. They may also require dose increases for a number of reasons, including worsening disease and increased pain. Dose escalation to restore analgesia using the primary opioid may lead to increased adverse events. In these patients, rotation to a different opioid at a lower-than-equivalent dose may be sufficient to maintain adequate tolerability and analgesia. In published trials and case series, opioid rotation is performed either using a predetermined substitute opioid with fixed conversion methods, or in a manner that appears to be no more systematic than trial and error. In clinical practice, opioid rotation must be performed with consideration of individual patient characteristics, comorbidities (eg, concurrent psychiatric, pulmonary, renal, or hepatic illness), and concurrent medications, using flexible dosing protocols that take into account incomplete opioid cross-tolerance. References cited in this review were identified via a search of PubMed covering all English language publications up to May 21, 2013 pertaining to opioid rotation, excluding narrative reviews, letters, and expert opinion. The search yielded a total of 129 articles, 92 of which were judged to provide relevant information and subsequently included in this review. Through a review of this literature and from the authors’ empiric experience, this review provides practical information on performing opioid rotation in clinical practice.

Pain care for patients with epidermolysis bullosa: best care practice guidelines

BACKGROUND

Inherited epidermolysis bullosa (EB) comprises a group of rare disorders that have multi-system effects and patients present with a number of both acute and chronic pain care needs. Effects on quality of life are substantial. Pain and itching are burdensome daily problems. Experience with, and knowledge of, the best pain and itch care for these patients is minimal. Evidence-based best care practice guidelines are needed to establish a base of knowledge and practice for practitioners of many disciplines to improve the quality of life for both adult and pediatric patients with EB.

METHODS

The process was begun at the request of Dystrophic Epidermolysis Bullosa Research Association International (DEBRA International), an organization dedicated to improvement of care, research and dissemination of knowledge for EB patients worldwide. An international panel of experts in pain and palliative care who have extensive experience caring for patients with EB was assembled. Literature was reviewed and systematically evaluated. For areas of care without direct evidence, clinically relevant literature was assessed, and rounds of consensus building were conducted. The process involved a face-to-face consensus meeting that involved a family representative and methodologist, as well as the panel of clinical experts. During development, EB family input was obtained and the document was reviewed by a wide variety of experts representing several disciplines related to the care of patients with EB.

RESULTS

The first evidence-based care guidelines for the care of pain in EB were produced. The guidelines are clinically relevant for care of patients of all subtypes and ages, and apply to practitioners of all disciplines involved in the care of patients with EB. When the evidence suggests that the diagnosis or treatment of painful conditions differs between adults and children, it will be so noted.

CONCLUSIONS

Evidence-based care guidelines are a means of standardizing optimal care for EB patients, whose disease is often times horrific in its effects on quality of life, and whose care is resource-intensive and difficult. The guideline development process also highlighted areas for research in order to improve further the evidence base for future care.

Patient-controlled analgesia in the pediatric population: morphine versus hydromorphone

Objective

Patient controlled analgesia (PCA) is commonly used to provide analgesia following surgical procedures in the pediatric population. Morphine and hydromorphone remain the most commonly used opioids for PCA. Although both are effective, adverse effects may occur. When these adverse effects are unremitting or severe, opioid rotation may be required. In this study, we retrospectively evaluated PCA use, the adverse effect profile, and the frequency of opioid rotation.

Methods

This retrospective study was performed at Nationwide Children’s Hospital (Columbus, OH). The hospital’s electronic registry was queried for PCA use delivering either morphine or hydromorphone from January 1, 2008 to December 31, 2010.

Results

A total of 514 patients were identified, that met study entry criteria. Of the 514 cases, 298 (56.2%) were initially started on morphine and 225 (43.8%) were initially started on hydromorphone. There were a total of 26 (5.1%) opioid changes in the cohort of 514 patients. Of the 26 switches, 23 of 298 (7.7%) were from morphine to hydromorphone, and 3 of 225 (1.3%) were from hydromorphone to morphine (P=0.0008). Of the 17 morphine-to-hydromorphone switches with adverse effects, pruritus (64.7%), and inadequate pain control (47.1%) were the most common side effects. The most common side effect resulting in a hydromorphone-to-morphine switch was nausea (66.7%).

Conclusion

PCA switches from morphine-to-hydromorphone (88.5%) were more common than vice-versa (11.5%). The most common reasons for morphine-to-hydromorphone switch were pruritus and inadequate pain control. These data suggest that a prospective study is necessary to determine the side effect differences between morphine and hydromorphone in pediatric PCA.

Opioid-induced constipation in patients with chronic noncancer pain in the USA, Canada, Germany, and the UK: descriptive analysis of baseline patient-reported outcomes and retrospective chart review

BACKGROUND

The characteristics of patients who suffer from noncancer pain and opioid-induced constipation are not well understood.

METHODS

Cross-sectional patient survey and chart review data from the baseline assessment of an ongoing longitudinal study in the USA, Canada, Germany, and the UK were evaluated via descriptive statistics. Participants had confirmation of daily opioid therapy ≥30 mg for ≥4 weeks and self-reported opioid-induced constipation. Response to laxatives was defined by classifying participants into categories of laxative use and evaluating the prevalence of inadequate response to one laxative agent and two or more agents from at least two different laxative classes. Outcomes included the Patient Assessment of Constipation-Symptoms, Work Productivity and Activity Impairment Questionnaire-Specific Health Problem, EuroQOL 5 Dimensions, and Global Assessment of Treatment Benefit, Satisfaction, and Willingness to Continue.

RESULTS

Patients reported a mean of 1.4 bowel movements not preceded by laxatives and 3.7 bowel movements with laxative use per week; 83% wanted at least one bowel movement per day. Most commonly reported on Patient Assessment of Constipation-Symptoms were straining/squeezing to pass bowel movements (83%), bowel movements too hard (75%), flatulence (69%), and bloating (69%). Eighty-four percent were taking natural or behavioral therapies; 60% were taking at least one over-the-counter laxative; and 19% were taking at least one prescription laxative. Prevalence of inadequate response to one laxative agent was 94%; inadequate response to two or more agents from at least two different laxative classes was 27%. Mean Work Productivity and Activity Impairment Questionnaire-Specific Health Problem values for percent work time missed, percent impairment while working, and percent activity impairment were 9%, 32% (equivalent of 14 hours of lost productivity per week), and 38%. Mean EuroQOL 5 Dimensions index and visual analog scale scores were 0.49 and 50.6, respectively. Forty-four percent reported being satisfied with their treatment for constipation.

CONCLUSION

Patients treated with opioids for noncancer pain commonly endure constipation symptoms that limit their work productivity and overall health-related quality of life while adhering to treatments that provide little relief. Further research is needed to identify more efficacious constipation therapies for this patient population.

A meta-analysis of efficacy and tolerability of buprenorphine for the relief of cancer pain

This study aimed to synthesize available evidence on the analgesic efficacy of buprenorphine in treating cancer pain and related adverse effects. We searched electronic databases for randomized controlled trials, assessing the efficacy of buprenorphine, regardless of delivery system. The primary endpoints were patient-reported 'pain intensity' and 'pain relief'. Statistical heterogeneity among included studies was assessed with the I (2) test. The summary relative risk (RR) and 95% CI were derived, if two or more studies reported the similar outcome. Sixteen RCTs (n = 1329) with buprenorphine were included: 8 transdermal (TD), 5 sublingual (SL), 2 intramuscular injection (IM) and 1 subcutaneous infusion (SC) studies; with both SL and IM routes being assessed in one study. Only a few studies reported the same outcome in a similar way, creating difficulty for pooling of the outcome data. Many studies had a high risk of bias. In 2 studies (n = 241), the 'global impression change' was significantly different between TD buprenorphine and the combined placebo and morphine (RR 1.35, 95% CI 1.14-1.59; I (2): 42%); the 'number-needed-to-treat' (NNT) was 4.9 (95% CI: 3.1-10.9). In 2 studies (n = 331), 'requirement for rescue SL buprenorphine' was comparable between TD buprenorphine and placebo (RR 1.25, 95% CI 0.71-2.18; I (2) : 40%). In 2 studies (n = 141), 'incidence of nausea' was less in TD buprenorphine (RR: 0.38, 95% CI: 0.2-0.71, I (2): 0%, NNT: 9.3, 5.6-28.5). Due to the small number of participants in a small number of studies, the results of the present review provide insufficient evidence to position adequately the use of buprenorphine in treatment of cancer pain. Large multicenter RCTs that compare TD buprenorphine with standard analgesic treatment is needed to position TD buprenorphine in the therapeutic armamentarium of cancer pain treatment.

Treatment of opioid-induced constipation: focus on the peripheral μ-opioid receptor antagonist methylnaltrexone

Most prescribed opioids exert their analgesic effects via activation of central μ-opioid receptors. However, μ-opioid receptors are also located in the gastrointestinal (GI) tract, and activation of these receptors by opioids can lead to GI-related adverse effects, in particular opioid-induced constipation (OIC). OIC has been associated with increased use of healthcare resources, increased healthcare costs, and decreased quality of life for patients. Nonpharmacologic (e.g., increased fiber uptake) and pharmacologic agents (e.g., laxatives) may be considered for the treatment and prevention of OIC. However, many interventions, such as laxatives alone, are generally insufficient to reverse OIC because they do not target the underlying cause of OIC, opioid activation of μ-opioid receptors in the GI tract. Therefore, there has been keen interest in antagonism of the μ-opioid receptor in the periphery to inhibit the effects of opioids in the GI tract. In this review, currently available pharmacologic therapies for the treatment and prevention of OIC are summarized briefly, with a primary focus on the administration of the peripheral μ-opioid receptor antagonist methylnaltrexone bromide in patients with OIC and advanced illness who are receiving palliative care. Also, clinical trial data of methylnaltrexone treatment in patients with OIC and other pain conditions (i.e., chronic noncancer pain and pain after orthopedic surgery) are reviewed. Data support that methylnaltrexone is efficacious for the treatment of OIC and has a favorable tolerability profile.

Differences between opioids: pharmacological, experimental, clinical and economical perspectives

Clinical studies comparing the response and side effects of various opioids have not been able to show robust differences between drugs. Hence, recommendations of the regulatory authorities have been driven by costs with a general tendency in many countries to restrict physician's use of opioids to morphine. Although this approach is recognized as cost-effective in most cases there is solid evidence that, on an individual patient basis, opioids are not all equal. Therefore it is important to have an armamentarium of strong analgesics in clinical practice to ensure a personalized approach in patients who do not respond to standard treatment. In this review we highlight differences between opioids in human studies from a pharmacological, experimental, clinical and health economics point of view. We provide evidence that individuals respond differently to opioids, and that general differences between classes of opioids exist. We recommend that this recognition is used to individualize treatment in difficult cases allowing physicians to have a wide range of treatment options. In the end this will reduce pain and side effects, leading to improved quality of life for the patient and reduce the exploding pain related costs.

A comparison of the reliability of smartphone apps for opioid conversion

BACKGROUND

Many medical professionals use smartphone applications (apps) on a daily basis to support clinical decision making. Opioid switching (conversion of one opioid to another at equianalgesic dose) is common in clinical practice and often challenging for doctors. Apps providing an opioid conversion tool can therefore be a useful resource. Despite rapid growth in the use of medical apps, the lack of robust regulation and peer review to ensure the accuracy and reliability of app content is currently an area of concern.

METHOD

We searched major online app stores for apps providing an opioid dose conversion tool. We assessed output variability between apps in the dose calculation of seven opioid switches, as well as assessing the level of professional medical involvement in the authorship, creation and design of the apps.

RESULTS

Of 23 different apps identified, more than half (n = 12; 52 %) had no stated medical professional involvement and only 11 (48 %) apps provided direct references to primary sources for their opioid conversion ratios. Conversion of 1 mg of oral morphine to oral codeine demonstrated the largest conversion output range (median 6.67 mg, range 3.333-12 mg). Conversion of 1 mg of oral morphine to methadone ranged from 0.05-0.67 mg, with only 44 % of methadone-converting apps (n = 4) commenting that the conversion ratio changes with magnitude of methadone dose. Overall, 35 % of apps (n = 8) did not warn the user about the standard practice of dose reduction when opioid switching. There was a statistically significant difference in the mean conversion output for hydromorphone (oral) between apps with and without medical professional involvement (0.2256 vs 0.2536; p = 0.0377).

CONCLUSIONS

There are significant concerns with regard to the reliability of information provided by apps offering opioid dose conversion, with lack of information regarding evidence-based content and peer review in many cases. It is crucial that better regulation of medical apps is instigated in order to ensure that patient safety is maintained.

Opioid rotation in patients initiated on oxycodone or morphine: a register study

Purpose

Strong opioids are recommended for the treatment of moderate to severe pain. However, some patients do not achieve a successful treatment outcome due to intolerable adverse events and/or inadequate analgesia, thus may benefit from switching to another opioid, a procedure known as “opioid rotation.” The type of opioid at treatment initiation may influence the risk of opioid rotation and the objective of this study was to assess such rotation after treatment initiation with two alternative treatments, controlled-release (CR) oxycodone versus CR morphine in patients suffering from non-cancer pain.

Method

The study reported here was a real-life study based on Swedish register data: the Prescribed Drug, National Patient, and Cause of Death registers. The captured data cover the entire Swedish population treated in specialist care. A statistical analysis plan was agreed and signed before data were accessed.

Results

Data from 50,223 cases were included in the analyses. The risk of rotation was 19% higher in patients initiating treatment with morphine compared with oxycodone (hazard ratio 1.19; 95% confidence interval 1.11–1.27; P < 0.001), after adjusting for such baseline variables that were both significantly correlated with the outcome variable (time to rotation) and significantly different between the groups; age at index date, osteoarthritis and number of pain-related drugs.

Conclusion

Patients with non-cancer pain who initiated treatment with CR morphine had a higher risk of opioid rotation than patients initiated with CR oxycodone.

Frequency, outcome, and predictors of success within 6 weeks of an opioid rotation among outpatients with cancer receiving strong opioids

BACKGROUND

Opioid rotation is used to treat uncontrolled pain and/or opioid-related adverse effects. Our aim was to determine the frequency, indications, outcomes, and predictors of successful opioid rotation in outpatients with cancer.

METHODS

Medical records of consecutive outpatients with cancer who received strong opioids and returned for follow-up visit within ≤6 weeks to our supportive care center from January to December 2008 were reviewed. Data on patient characteristics, symptoms, opioid use, indications for opioid rotation, outcomes, and morphine equivalent daily dose were collected. Successful opioid rotation was defined as a two-point or 30% reduction in the symptom score or the resolution of opioid-induced neurotoxicity and continuation of the new opioid at follow-up.

RESULTS

Opioid rotation was performed in 120 of 385 patients (31%). The median patient age was 55 years. There were 6/120 patients with missing data. Of the 114 evaluable patients, 68 (60%) were men, 81 (71%) were white, 27 (24%) had gastrointestinal cancer, and 90 (80%) had advanced-stage disease. The median Eastern Cooperative Oncology Group score was 1 (interquartile range: 1-2) and the median time between opioid rotation and follow-up was 14 days (interquartile range: 7-21 days). The most common indications for opioid rotation were uncontrolled pain (95/114; 83%) and opioid-induced neurotoxicity (13/114; 12%). A total of 35 patients (31%) had partial opioid rotation. The median improvements in pain and symptom distress score were -2 (interquartile range: -4 to 0; p < .001) and -5 (interquartile range: -14 to 7; p = .004), respectively. The morphine equivalent daily dose did not change significantly after opioid rotation (p = .156). A total of 65% of patients (74/114) had successful opioid rotation. There were no clinically significant independent predictors for successful opioid rotation.

CONCLUSION

Opioid rotation was conducted in 31% of outpatients with cancer, with a 65% success rate. The most frequent reason for opioid rotation was uncontrolled pain. There were no independent predictors for successful opioid rotation.

Opioids for the treatment of chronic noncancer pain

Increasingly, opioids are used to treat chronic noncancer pain. While opioids are well recognized for their effectiveness in treating acute pain, the evidence supporting the benefits for the treatment of chronic pain is less well established. Improvement of both pain and function should be considered goals of therapy. Patients with chronic pain have a higher incidence of preexisting psychological disorders. Adverse effects of opioid therapy include dependence, overdose, and withdrawal. Risk factors for poor outcomes with opioid therapy are identified, and include preexisting mental illness and dose prescribed. Recommended strategies to more safely use opioids are discussed, including tools for identifying high-risk patients. The evidence supporting the use of treatment agreements and urine drug testing to reduce the effects of adverse outcomes is limited.

Clinical management of pain in advanced lung cancer

Lung cancer is the most common cancer in the world and pain is its most common symptom. Pain can be brought about by several different causes including local effects of the tumor, regional or distant spread of the tumor, or from anti-cancer treatment. Patients with lung cancer experience more symptom distress than patients with other types of cancer. Symptoms such as pain may be associated with worsening of other symptoms and may affect quality of life. Pain management adheres to the principles set out by the World Health Organization's analgesic ladder along with adjuvant analgesics. As pain can be caused by multiple factors, its treatment requires pharmacological and non-pharmacological measures from a multidisciplinary team linked in with specialist palliative pain management. This review article examines pain management in lung cancer.

Opioid switching to methadone: a pharmacoepidemiological study from a national prescription database

BACKGROUND

Opioid switching to methadone is reported frequently to improve pain control in patients with an unacceptable balance between pain control and side effects during treatment with first line opioids, but carries a risk of drug accumulation and respiratory depression. To justify this risk it is required that less risky treatments are tried beforehand and that a sufficiently large proportion of patients experience a long-lasting improvement in pain control.

RESEARCH QUESTIONS

How large was the proportion of patients remaining on long term methadone treatment after a switch from a strong opioid to methadone? How long had the patients been treated with opioids before the switch to methadone?

METHODS

Longitudinal pharmacoepidemiological study from the complete national Norwegian Prescription Database.

RESULTS

One hundred and thirty (77%) cancer patients received more than one dispensed prescription of methadone. Forty-nine (40%) chronic non-malignant pain (CNMP) patients continued to have methadone prescriptions dispensed more than 6 months after the switch. Of 168 cancer patients, 48 (29%) had tried two strong opioids prior to the switch to methadone whereas 21 (12.5%) had tried three or more strong opioids. Similar numbers for 124 CNMP patients were 26 (21%) and 34 (27%), respectively.

INTERPRETATION

Opioid switching to methadone appears to provide a long lasting improvement in pain control in a significant proportion of patients. However, the study raises concerns that treatment options with less risk are not being exhausted prior to switching to methadone.

Pharmacogenomic considerations in opioid analgesia

Translating pharmacogenetics to clinical practice has been particularly challenging in the context of pain, due to the complexity of this multifaceted phenotype and the overall subjective nature of pain perception and response to analgesia. Overall, numerous genes involved with the pharmacokinetics and dynamics of opioids response are candidate genes in the context of opioid analgesia. The clinical relevance of CYP2D6 genotyping to predict analgesic outcomes is still relatively unknown; the two extremes in CYP2D6 genotype (ultrarapid and poor metabolism) seem to predict pain response and/or adverse effects. Overall, the level of evidence linking genetic variability (CYP2D6 and CYP3A4) to oxycodone response and phenotype (altered biotransformation of oxycodone into oxymorphone and overall clearance of oxycodone and oxymorphone) is strong; however, there has been no randomized clinical trial on the benefits of genetic testing prior to oxycodone therapy. On the other hand, predicting the analgesic response to morphine based on pharmacogenetic testing is more complex; though there was hope that simple genetic testing would allow tailoring morphine doses to provide optimal analgesia, this is unlikely to occur. A variety of polymorphisms clearly influence pain perception and behavior in response to pain. However, the response to analgesics also differs depending on the pain modality and the potential for repeated noxious stimuli, the opioid prescribed, and even its route of administration.

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.