Switching from morphine to methadone to improve analgesia and tolerability in cancer patients: a prospective study

The impact of opioid administration on the incidence of postanaesthetic colic in horses

Effective management of postoperative pain is essential to ensure patient welfare, reduce morbidity and optimize recovery. Opioids are effective in managing moderate to severe pain in horses but concerns over their adverse effects on gastrointestinal (GI) motility and associated increased colic risk limit their widespread use. Studies investigating the impact of systemic opioids on both GI motility and colic incidence in horses have yielded inconclusive outcomes. Therefore, this retrospective study aims to assess the influence of systemic administration of butorphanol, morphine, and methadone on post-anaesthetic colic (PAC) incidence. Horses undergoing general anaesthesia for non-gastrointestinal procedures that were hospitalized for at least 72 h post-anaesthesia were included in this study. Anaesthetised horses were stratified by procedure type into horses undergoing diagnostic imaging without surgical intervention, emergency or elective surgery. In addition, patients were grouped by opioid treatment regime into horses receiving no opioids, intraanaesthetic, short- (<24 h) or long-term (>24 h) postoperative opioids. Administered opioids encompassed butorphanol, morphine and methadone. The number of horses showing signs of colic in the 72 h after anaesthesia was assessed for each group. A total of 782 horses were included, comprising 659 undergoing surgical procedures and 123 undergoing diagnostic imaging. The overall PAC incidence was 15.1%. Notably, horses undergoing diagnostic imaging without surgery had a significantly lower PAC rate of 6.5% compared to those undergoing surgery (16.7%, p = 0.0146). Emergency surgeries had a significantly lower PAC rate of 5.8% compared to elective procedures (18%, p = 0.0113). Of the 782 horses, 740 received intraoperative opioids and 204 postoperative opioids, 102 of which long-term (≥24 h). Neither intraoperative (p = 0.4243) nor short-term postoperative opioids (p = 0.5744) increased PAC rates. Notably, only the long-term (≥24 h) administration of morphine significantly increased PAC incidence to 34% (p = 0.0038). In contrast, long-term butorphanol (5.3% PAC, p = 0.8482) and methadone (18.4% PAC, p = 0.6161) did not affect PAC rates. In summary, extended morphine administration was the only opioid treatment associated with a significantly increased risk of PAC.

Methadone Dose and Timing of Administration as Predictors of Sleep Apnea Syndrome During Methadone Maintenance Treatment: A Retrospective Cross-sectional Study

Background

This study aimed to assess the association of sleep apnea syndrome (SAS) with methadone dose and timing of administration in patients receiving methadone maintenance treatment (MMT) for opioid use disorder (OUD).

Methods

This retrospective cross-sectional study was conducted on adult patients receiving MMT who had a nocturnal respiratory polygraphy between November 2015 and December 2021. Data on methadone treatment and polygraph recording, including the apnea-hypopnea index (AHI) were collected.

Findings

A total of 40 patients, mostly male (72.5%), with a mean age of 35±6.7 years and a mean body mass index (BMI) of 25.1±4.5 kg/m2 were included. The daily dose of methadone was significantly associated with an AHI≥15 events/h as well as an AHI≥30 events/h, even after adjustment for age, gender, BMI, and benzodiazepine use. However, these associations were not preserved when the time of administration (day vs evening) was considered, while the evening administration was significantly associated with an AHI≥15 events/h. The best sensitivity and specificity for the prediction of AHI≥15 events/h and AHI≥30 events/h were obtained with daily methadone doses of≥72.5 mg and 77.5 mg, respectively.

Conclusion

In this sample of MMT patients, methadone doses of 72.5 mg and 77.5 mg were the best cut-off values for predicting AHI≥15 and≥30 events/h, respectively, especially when taken in the evening. These results should draw clinicians' attention to the importance of SAS screening, and further studies are needed, notably comparisons with buprenorphine.

Clinical Presentation and Management of Malignant Psoas Syndrome: A Scoping Review of Case Reports and Case Series

Malignant psoas syndrome (MPS) is a rare and underreported clinical syndrome that significantly impacts the quality of life of cancer patients through metastatic infiltration of the iliopsoas muscle. Patients suffering from MPS often present with painful hip flexion, loss of mobility, and immense pain in their legs and back. The current literature describing the clinical presentation, management, and prognosis of MPS is limited primarily to case reports and outdated literature reviews. There remains a gap in the current knowledge of MPS and in the management of this complex cancer-related pain syndrome. Thus, this scoping review aimed to map current case reports and case series on MPS for clinical presentation, treatment modalities, and resulting prognoses of MPS in late-stage cancer patients. A systemized search using the databases Embase and PubMed (Medline) was conducted to access case reports and case series published between January 1990 and October 2022 that met the study's inclusion criteria: (1) adult patients with metastatic cancer; (2) MPS symptoms secondary to infiltration of iliopsoas; (3) clinical presentation, treatment modality, and prognosis; and (4) English-language text. Our search strategy yielded 1926 citations. After removing 629 duplicates, 1,283 reports were excluded due to failure to meet eligibility criteria (n=1,271) or inaccessibility (n=12). Using the JBI appraisal tools for case reports and case series, a total of 14 articles remained for the final review. With histories of either genitourinary, hepatic, gastric, or skin cancer, each case reported new onset intense pain in the legs, back, abdomen, or pelvis with associated symptoms such as flexion of the hip or gait disorder. A computerized tomography (CT) scan, magnetic resonance imaging (MRI), or positron emission tomography (PET) scan typically confirmed metastasis into the iliopsoas causing these symptoms, which suggested MPS. Each case utilized two to seven different pain management strategies to alleviate MPS symptoms. Many cases first used opioids for pain relief. Following a necessitated increase in morphine equivalent daily dose, a subsequent increase in the strength of analgesic, change in route of administration, and integration of combination drug therapy were generally added to the treatment regime. Many cases reported successful management of symptoms through utilizing methadone, radiation therapy, botulinum toxin injection, increased opioid dosage, or epidural catheter administration of opioids. A unified clinical definition of MPS may be required to inform physicians of this syndrome to help support clinical decisions regarding treatments for patients. The studies indicated that a clearer guideline for treatment protocol may be warranted as most cases reported utilizing various treatment medication dosages and procedures with vastly differing results.

Long-term deprescription in chronic pain and opioid use disorder patients: Pharmacogenetic and sex differences

More than half of patients with opioid use disorder for chronic non-cancer pain (CNCP) reduced their dose through a progressive opioid withdrawal supported by a rotation to buprenorphine and/or tramadol. The aim of this research is to analyse the long-term effectiveness of opioid deprescription taking into account the impact of sex and pharmacogenetics on the inter-individual variability. A cross-sectional study was carried out from October 2019 to June 2020 on CNCP patients who had previously undergone an opioid deprescription (n = 119 patients). Demographic, clinical (pain, relief and adverse events) and therapeutic (analgesic use) outcomes were collected. Effectiveness (< 50 mg per day of morphine equivalent daily dose without any aberrant opioid use behaviour) and safety (number of side-effects) were analysed in relation to sex differences and pharmacogenetic markers impact [OPRM1 genotype (rs1799971) and CYP2D6 phenotypes]. Long-term opioid deprescription was achieved in 49 % of the patients with an increase in pain relief and a reduction of adverse events. CYP2D6 poor metabolizers showed the lowest long-term opioid doses. Here, women showed a higher degree of opioid deprescription, but increased use of tramadol and neuromodulators, as well as an increased number of adverse events. Long-term deprescription was successful in half of the cases. Understanding sex and gender interaction plus a genetic impact could help to design more individualized strategies for opioid deprescription.

Methadone switching for refractory cancer pain

BACKGROUND

Methadone is commonly considered an alternative opioid treatment for refractory cancer pain. This study aims to investigate the efficacy, safety, and cost of methadone in the treatment of refractory cancer pain.

METHODS

A retrospective study was conducted in patients who used methadone for refractory cancer pain from April 2016 to December 2020 at a cancer specialized hospital. Pain control, evaluated via pain score and breakthrough pain frequency, and adverse events of methadone were compared with analgesic regimens prior to methadone administration. The factors potentially affecting the switching outcome were analyzed via multivariate analysis. Moreover, the cost of pain control was estimated.

RESULTS

Ninety patients received methadone for poor pain control (74.4%), intolerable adverse events (10.0%), or both (15.6%) after prior opioid treatments. Sixty-four patients (71.1%) were successfully switched to methadone with median pain score significantly decreased from 4.0 to 2.0 (p < 0.001) and median daily frequency of breakthrough pain from 3.0 to 0.0 (p < 0.001) at a maintained median conversion ratio of 6.3 [interquartile range (IQR): 4.0-10.0] to prior opioid treatment. Similar adverse event profiles of constipation, nausea, vomiting, and dizziness were observed between methadone and prior opioid regimens. The median daily cost of analgesic regimens was significantly reduced from $19.5 (IQR: 12.3-46.2) to $10.8 (IQR: 7.1-18.7) (p < 0.01) after switching to methadone. The 3-day switch method significantly improved the rate of successful switching compared with the stop and go method (odds ratio = 3.37, 95% CI: 1.30-8.76, p = 0.013).

CONCLUSION

Methadone is an effective, safe, and cost-saving treatment for patients with refractory cancer pain.

Treatment of Neuropathic Pain Directly Due to Cancer: An Update

Simple Summary

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

Abstract

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

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

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

Ultralow-Dose Adjunctive Methadone with Slow Titration, Considering Long Half-Life, for Outpatients with Cancer-Related Pain

Background: The unique properties of methadone make it attractive for use in cancer pain. The use of very low initial doses of adjunctive methadone is a promising strategy given its simplicity and potentially reduced risk profile.

Objective: To understand if an ultralow-dose (ULD) methadone protocol (1 mg by mouth daily initial dose with gradual titration) can improve pain control in outpatients with cancer-related pain not responsive to previous opioids and/or nonopioid analgesics. We also sought to assess if the use of ULD methadone resulted in improvement in mood and sleep among other outcomes.

Design and Setting/Subjects: This study is a retrospective chart review of outpatients at the cancer pain clinic at the Tom Baker Cancer Centre in Calgary, Alberta, Canada.

Measurements: The mean ratings in maximum and average pain before methadone initiation, and at the final follow-up point are reported. Paired sample t tests evaluate for statistically significant differences in pain ratings before methadone initiation and at final follow-up. We also report the proportion of participants with a subjective improvement in pain, sleep, and mood (dichotomous “yes/no”), and the mean number of weeks to initial documented pain improvement.

Results: 68.6% of patients (24/34) reported a subjective improvement in pain. Most patients reported improved sleep and mood (78.8% and 64.7%, respectively).

Conclusions: More than two-thirds of patients reported an improvement in pain with a protocol using very low initial doses of adjunctive methadone. Our report is a preliminary retrospective chart review and larger prospective trials are warranted.

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.

Switching Ratio from Parenteral to Oral Methadone 1:1.2 Is Safer Compared with Ratio 1:2 in Patients with Controlled Cancer Pain: A Multicenter Randomized-Controlled Trial (RATIOMTD-010810)

Background: The most commonly used switching ratio from parenteral to oral methadone is 1:2. Methadone is highly bioavailable and a lower ratio might result in similar analgesia with less toxicity. Objective: To compare success and side effects with two ratios from parenteral to oral methadone: 1:2 versus 1:1.2 in hospitalized patients with cancer pain. Design: A multicenter double-blind randomized clinical trial. Settings/Particiants: Inpatients with well-controlled cancer pain with parenteral methadone requiring rotation to the oral route. Measurements: Outcomes included pain intensity (Brief Inventory Pain), opioid toxicity (Common Toxicology Criteria for Adverse Events), and methadone dose. Success was defined as no toxicity with good pain control at 72 hours. Results: Thirty-nine of forty-four randomized patients were evaluable: 21 in ratio 1:2 and 18 in ratio 1:1.2. Seventy-one percent male. Median age 65 years. No significant differences in basal clinical characteristics between both groups. Median methadone dose pre/post switching was 24.5 mg ±13.5 and 49 mg ±27.3 for ratio 1:2, versus 23.3 mg ±9.4 (p: not significant) and 28 mg ±11.3 (p < 0.01) for ratio 1:1.2. Pain was well controlled without differences between both ratios. Drowsiness at day +1 (p < 0.017) and myoclonus at day +3 (p < 0.019) were more prevalent in group 1:2. Success was observed in 12 patients in ratio 1:2 versus 18 in ratio 1:1.2 (p < 0.001). Methadone side effects were observed in 12 patients in ratio 1:2 (mainly neurotoxicity symptoms) versus 2 in ratio 1:1.2 (p < 0.005). Conclusion: Ratio 1:1.2 when changing from parenteral to oral methadone resulted in lower toxicity and no difference in analgesia. More conservative dose adjustment during methadone route change should be considered. European Clinical Trials Register (EudraCT No. 2010-024092-39).

Breaking the barrier: Challenges of methadone use – An introductory observation

Background:

Palliative care physicians in India have achieved access to methadone for pain relief in cancer patients. Despite being an effective drug in terms of analgesia, there are a number of reasons why this opioid medication is not as much as popular as morphine. We identified and tried to overcome a few such barriers in treating cancer pain with methadone.

Methods:

The clinical information of ten adult cancer patients (six males and four females), who voluntarily received methadone for their severe pain in the month of August 2019 were analysed retrospectively. We converted morphine to methadone in all ten patients under the supervision of an experienced practitioner.

Results:

During the methadone therapy, eight out of ten patients who were given methadone exclusively for their pain had adequate pain relief initially. The barriers identified included difficult titration methods due to distinct pharmacology, patient selection, clinical inertia, communication and co-ordination among physicians, communication among patient and physician, and patient and caregivers, and vigilant monitoring.

Conclusion:

Methadone is still finding its place in India for cancer pain management. As the drug is new to Indian practitioners, we have to overcome these barriers and facilitate its judicious use in cancer pain management.

Emerging Challenges to the Safe and Effective Use of Methadone for Cancer-Related Pain in Paediatric and Adult Patient Populations

Methadone continues to be an important medication for the treatment of paediatric and adult cancer-related pain. Appropriate patient selection to ensure safe and effective treatment by a team of clinicians who appreciate and are familiar with methadone and its unique pharmacology is crucial. Unlike morphine and other more common opioids, methadone is purported to have involvement with delta-opioid receptor and higher affinity as an N-methyl-D-aspartate-receptor antagonist. Clinically this gives it the advantage of being effective for both nociceptive and neuropathic pain, but also may be useful in the setting of tolerance to other opioids. Methadone also comes in multiple available formulations that can be administrated through a variety of routes beyond the oral route. Challenges with methadone in treating cancer-related pain include drug interactions specifically as it relates to new targeted cancer therapies. Recent guidelines recommend electrocardiogram monitoring with methadone and there is potential for additive cardiac toxicity in the oncology setting. Appropriate dosing of methadone for pain management given age, organ dysfunction, and patients who are on methadone maintenance therapy are also key factors. This article aims to provide clinicians with evidence and clinical practice guidelines for safe and appropriate use of methadone including indication, initiation, and monitoring given its complexity for management of pain in the dynamic oncology setting.

Preliminary Validation for the "BJR method"-A Possible New Mathematical Approach to Methadone Conversion

Methadone has been effectively utilized in the palliative care setting as a second-line agent for pain management in cancer patients with refractory pain, or in those who cannot tolerate other opioid medications. The lack of reliable dosing ratios, substantial interindividual variability in methadone pharmacodynamics, the potential for extensive drug interactions, and the high potency of methadone compared with other opioids all pose significant barriers to the use of this drug in routine practice. This article describes a novel approach to methadone conversion, with case studies providing preliminary validation.

Palliative Pain Management: When Both Pain and Suffering Hurt

Patients with advanced cancer frequently experience intractable pain without sufficient response to a conventional pharmacological approach. One reason for refractory pain at the end of life can be the bidirectional nature of pain and suffering. Three terminally ill patients were assessed using a multidimensional palliative pain concept, including sensory, affective, cognitive, and existential components. In these patients, resistant pain did not equal insufficient eradication of the nociceptive input, but also suffering. Unrelieved emotions, depressive or anxious symptoms, delirium, difficulties communicating, or chemical coping influenced the expression of pain, illuminating the phenomenon of somatization. Palliative pain treatment integrated analgesic treatments, psychological, rehabilitative, and existential interventions, in consideration of individual expectations and outcomes. With the disciplined assessment and alternative multidisciplinary palliative approach, the quality of life of three terminally ill cancer patients with intractable pain could be enhanced, and unnecessary interventions and escalation of medications avoided.

[Opioid switch and change of route of administration in cancer patients treated by morphine]

This paper reviewed the 2002 guidelines established by the National Federation of Cancer Centres. A group of experts nominated by the 3 French Societies involved in the treatment of cancer pain (AFSOS, SFAP, SFETD), established new guidelines ratios for morphine switching and/or changing of route of administration, in patients for whom either pain was not adequatly managed or adverse effects were unbearable. After a rapid reminder of the pharmacokinetics and metabolism properties of morphine, experts explained why the theory of opioid rotation (oxycodone, hydromorphone, fentanyl, methadone, tapentadol) using fixed equianalgesic ratios is not any more appropriate for a secure clinical practice. In the light of recent publications enhancing our knowledge on the efficacy of new drug switching ratios and for changing the route of administration of morphine, the group of experts recommended to use reconsidered switching ratios favoring security upon efficacy, to minimize overdosing and adverse effects. Consequently, after the new conversion ratio (using slow release opioids) was applied, a second titration should be done by means of normal release rescue formulations for breakthrough pain episodes. A smartphone App. OpioConvert^® will be available for rapid and secure dose conversions.

Management of Symptoms Due to Inoperable Bowel Obstruction

Bowel obstruction is a common and distressing outcome in patients with abdominal or pelvic cancer. Although surgery should be the primary treatment for malignant obstruction, it is now recognized that some patients with advanced disease or in generally poor condition are unfit for surgery and require alternative management to relieve distressing symptoms. A number of treatment options are now available for the patient with advanced and terminal cancer who develops intestinal obstruction. Medical measures such as analgesics, anti-secretory drugs and antiemetics may be used alone or in combination to relieve symptoms.

Methadone against cancer: Lost in translation

Recently, the opioid analgesic d,l-methadone has gained much attention as a potential antineoplastic compound, considerably triggered through lay press and media. In consequence, physicians and pharmacists are currently confronted with numerous patients willing to use d,l-methadone against their malignancies. Well-performed in vitro and in vivo models have in fact shown pro-apoptotic effects of d,l-methadone or other opioids, but also proliferation-stimulating properties. Moreover, the mechanisms of proposed opioid-stimulated apoptosis are incompletely described or contradicting. Finally, the receptors mostly responsible for induction of apoptosis by d,l-methadone remain unclear as contributions of both µ-opioid receptors, Fas cell death receptors, toll-like receptors, N-Methyl-d-aspartate receptors and opioid growth factor receptors were suggested. Such ambiguity prevents rational application of d,l-methadone or patient stratification to enhance beneficial antineoplastic effects. From a clinical point of view, d,l-methadone and other opioids might in fact prolong survival, but such effects likely originate from their analgesic and neuro-psychotropic properties and, thus, improvements of quality of life. Crucial obstacles to the administration of d,l-methadone are incomplete knowledge about its systemic disposition, highly variable pharmacokinetics, profound drug-drug- or drug-disease interaction and QT-prolongation potential. This article summarizes and rates the pharmacological basis of d,l-methadone as an antineoplastic agent and puts its administration in clinical oncology into perspective. Despite enthralling experimental findings about d,l-methadone-mediated apoptosis in cancerous cells or tissues, clinicians should realize the current lack of evidence for the use of d,l-methadone as an antineoplastic agent. Its administration against cancer pain is, however, tenable, albeit restricted to certain clinical situations.

Methadone as a "Tumor Theralgesic" against Cancer

Methadone has beneficial characteristics as an analgesic against cancer pain, including high bioavailability, multiple receptor affinities, and lack of active metabolites that might induce adverse side effects. However, methadone has an own pharmacological profile that should be considered in the treatment of cancer patients. There is evidence from preclinical studies that methadone could also elicit antitumor activity by downregulating the threshold of apoptosis and to enhance the effects of different chemotherapeutic agents. This confirms the concept of using methadone as a chemosensitizer in the future treatment of cancer. Our article discusses major issues about the role of methadone as a possible “tumor theralgesic,” combining tumor therapeutic and analgesic activities.

Evaluation of Emergency Department Management of Opioid-Tolerant Cancer Patients With Acute Pain

CONTEXT

There are no previously published studies examining opioid doses administered to opioid-tolerant cancer patients during emergency department (ED) encounters.

OBJECTIVES

To determine if opioid-tolerant cancer patients presenting with acute pain exacerbations receive adequate initial doses of as needed (PRN) opioids during ED encounters based on home oral morphine equivalent (OME) use.

METHODS

We performed a retrospective cohort study of opioid-tolerant cancer patients who received opioids in our ED over a two-year period. The percentage of patients who received an adequate initial dose of PRN opioid (defined as ≥10% of total 24-hour ambulatory OME) was evaluated. Logistic regression was used to establish the relationship between 24-hour ambulatory OME and initial ED OME to assess whether higher home usage was associated with higher likelihood of being undertreated.

RESULTS

Out of 216 patients, 61.1% of patients received an adequate initial PRN dose of opioids in the ED. Of patients taking <200 OMEs per day at home, 77.4% received an adequate initial dose; however, only 3.2% of patients taking >400 OMEs per day at home received an adequate dose. Patients with ambulatory 24-hour OME greater than 400 had 99% lower odds of receiving an adequate initial dose of PRN opioid in the ED compared to patients with ambulatory 24-hour OME less than 100 (OR <0.01, CI 0.00-0.02, P < 0.001).

CONCLUSIONS

Patients with daily home use less than 200 OMEs generally received adequate initial PRN opioid doses during their ED visit. However, patients with higher home opioid usage were at increased likelihood of being undertreated.

Nanoconjugated NAP as a Potent and Periphery Selective Mu Opioid Receptor Modulator To Treat Opioid-Induced Constipation

Opioids are the mainstay for cancer and noncancer pain management. However, their use is often associated with multiple adverse effects. Among them, the most common and persistent one is probably opioid-induced constipation (OIC). Periphery selective opioid antagonists may alleviate the symptoms of OIC without compromising the analgesic effects of opioids. Recently our laboratories have identified one novel lead compound, 17-cyclopropylmethyl-3,14β-dihydroxy-4,5α-epoxy-6β-[(4'-pyridyl)acetamido]morphinan (NAP), as a peripherally selective mu opioid receptor ligand carrying subnanomolar affinity to the mu opioid receptor and over 100-folds of selectivity over both the delta and kappa opioid receptors, with reasonable oral availability and half-life, and potential to treat OIC. Nanoparticle-based drug delivery systems are now widely considered due to their technological advantages such as good stability, high carrier capacity, low therapeutic side effects, etc. Herein we report nanoparticle supported NAP as a potential candidate for OIC treatment with improved peripheral selectivity over the original lead compound NAP.

Opioid Conversions in Acute Care

Objective:

To discuss the historical basis and limitations of opioid conversion tables, review the relevant literature, and establish an evidence-based equianalgesic dose ratio (EDR) table for performing conversions in the acute care setting.

Data Sources:

Articles were identified through searches of MEDLINE (1966–January 2007) using the key words opioid, tolerance, conversion, dose, equianalgesic, equipotent, acute care, morphine, hydromorphone, fentanyl, methadone, and oxycodone. Additional references were located through a review of the bibliographies of articles cited and references cited in conversion tables.

Study Selection and Data Extraction:

All data sources identified were evaluated, and all information deemed relevant was included, with the exception of case series and case reports when higher level evidence was available.

Data Synthesis:

Opioid conversion tables are published in major textbooks, medical references, national guidelines, and review articles. Some conversion tables do not accurately reflect the dose ratios for which evidence is available. There is marginal evidence-based clinical data to support the dose ratios cited in these tables, particularly in the acute care setting where the clinical status of patients often changes rapidly. The barriers when performing route and opioid-to-opioid conversions in the acute care setting are formidable, but EDRs are provided, based on the best available evidence.

Conclusions:

In the acute care setting, calculation of dose ratios for opioids, based solely on opioid conversion tables, is an oversimplification of pain management, with a potential for adverse consequences. The calculation of EDRs is one step in an interdisciplinary process that must take into account patient- and institution-specific factors.

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.

Sedation and Analgesia-Prescribing Patterns in Terminally Ill Patients at the End of Life

The extensive use of sedative and analgesic medication at the end of life is often controversial due to the perception that death may be hastened as a result of progressive drug escalation. Physician attitudes toward prescribing medication in this setting vary, resulting in widely differing prescribing patterns for patients with advanced cancer. This investigation attempted to identify overall prescribing patterns and variation in the use of sedation and analgesia in an inpatient hospice setting at the end of life. A retrospective case review was undertaken of 102 consecutive patients who died in a palliative care hospice. A detailed review of medication prescription, with particular attention to sedation and analgesia in the last week of life, was performed. The review revealed that regular sedation was prescribed in 68 percent of the patients. Almost two-thirds of the patients began regular sedation on admission or within seven days of admission. Although survival was higher in patients who received regular sedation (mean, 36.5 days) versus those that did not (mean, 17 days), the difference was not significant (p = 0.1). Overall, regular sedation with moderate dose increases was observed. In patients prescribed morphine from the time of admission, morphine oral equivalents increased from a mean of 111 mg on admission to a mean of 346 mg at time of death for a mean escalation of 311 percent. The mean duration of admission was 26 days with an opioid-escalation index of 12 percent per day. Survival is a multifactorial phenomenon and was unrelated to the level of analgesia in this cohort. Findings showed that sedation dose increased modestly toward the end of life, and that the increase was not associated with a significant reduction in survival. Further, there was no significant impact on survival related to an individual physician's prescribing pattern at the end of life. These results suggest that, in the institution where the review was conducted, neither sedation nor individual variation in physician prescribing habits in terminally ill patients was associated with hastening of death. Overall, the amount of sedative drugs required for adequate symptom control during terminal care was moderate.

Pain Intensity and Opioid Utilization in Response to CPAP Therapy in Veterans with Obstructive Sleep Apnea on Chronic Opioid Treatment

STUDY OBJECTIVES

Sleep fragmentation has been linked to poor pain tolerance and lowered pain threshold. Little evidence exists on whether continuous positive airway pressure (CPAP) adherence in veterans with obstructive sleep apnea (OSA) who are taking opioids for non-malignant pain would ameliorate pain and reduce consumption of opioids.

METHODS

A retrospective case-control study was performed at a VA sleep center. Pain intensity was assessed using the Numerical Categorical Scale prior to CPAP treatment and 12-mo follow-up. Opioids intake was assessed using the morphine equivalent daily dose (MEDD). Adherence to CPAP was evaluated with the built-in meter.

RESULTS

We reviewed 113 patients with OSA (apnea-hypopnea index [AHI] 35.9 ± 29.5) using a MEDD of 61.6 mg (range 5-980 mg) and a control group of 113 veterans with OSA (AHI 33.4 ± 27.3) on no opioids treatment. CPAP adherence was significantly lower at 12 mo in opioid-treated patients compared to controls (37% versus 55%; p = 0.01). Greater pain intensity was the only independent variable associated with CPAP non-adherence at 12-mo follow-up (p = 0.03). Compared to baseline, no significant difference was observed in pain intensity or consumption of opioids in CPAP adherent patients.

CONCLUSIONS

CPAP treatment did not reduce pain intensity or consumption of opioids in veterans with chronic pain who have coexisting OSA. CPAP adherence was lower in opioid-treated veterans with OSA compared to opioid-free veterans with OSA. Pain intensity was the only determinant of CPAP adherence. Future studies are needed to evaluate pain management program on adherence to CPAP.

Pain management in trauma: A review study

Background:

Pain in trauma has a role similar to the double-edged sword. On the one hand, pain is a good indicator to determine the severity and type of injury. On the other hand, pain can induce sever complications and it may lead to further deterioration of the patient. Therefore, knowing how to manage pain in trauma patients is an important part of systemic approach in trauma. The aim of this manuscript is to provide information about pain management in trauma in the Emergency Room settings.

Methods:

In this review we searched among electronic and manual documents covering a 15-yr period between 2000 and 2016. Our electronic search included Pub Med, Google scholar, Web of Science, and Cochrane databases. We looked for articles in English and in peer-reviewed journals using the following keywords: acute pain management, trauma, emergency room and injury.

Results:

More than 3200 documents were identified. After screening based on the study inclusion criteria, 560 studies that had direct linkage to the study aim were considered for evaluation based World Health Organization (WHO) pain ladder chart.

Conclusions:

To provide adequate pain management in trauma patients require: adequate assessment of age-specific pharmacologic pain management; identification of adequate analgesic to relieve moderate to severe pain; cognizance of serious adverse effects of pain medications and weighting medications against their benefits, and regularly reassessing patients and reevaluating their pain management regimen. Patient-centered trauma care will also require having knowledge of barriers to pain management and discussing them with the patient and his/her family to identify solutions.

Hyperalgesia and opioid switching

Opioids, intended to abolish pain, can unexpectedly produce hyperalgesia, particularly during rapid opioid escalation. Opioid switching could be a therapeutic option in a condition of opioid-induced tolerance or hyperalgesia, but conversion ratios between opioids are difficult to apply in this context and require strict surveillance and expertise.

This situation is challenging, because the rapid escalation of opioid doses, possibly due to the development of opioid-induced tolerance, can cause hyperalgesia. To avoid this adverse effect, clinicians need to refine their assessment of pain treatment and consider opioid switching. The authors present a case report in which switching from fentanyl to methadone was effective in a patient who developed hyperalgesia as a consequence of a rapid opioid escalation. Regardless of the expected clinical improvement of opioid switching using lower doses of the second opioid, the final dose of the second opioid was exaggeratedly low, probably as a consequence of the disappearance of hyperalgesia induced by the first opioid.

The results of this case and others like it may help practitioners develop a meaningful approach during opioid escalation, possibly anticipating the need for opioid switching or other alternative measures for patients with uncontrolled cancer pain.

Acute Pain Management

Acute pain management is improving steadily over the past few years, but training and professional education are still lacking in many professions. Untreated or undertreated acute pain could have detrimental effects on the patient in terms of comfort and recovery from trauma or surgery. Acute undertreated pain can decrease a patient's vascular perfusion, increase oxygen demand, suppress the immune system, and possibly risk increased incidence of venous thrombosis. Although acute postoperative pain needs to be managed aggressively, patients are most vulnerable during this period for developing adverse effects, and therefore, patient assessment and careful drug therapy evaluation are necessary processes in therapeutic planning. Acute pain management requires careful and thorough initial assessment and follow-up reassessment in addition to frequent dosage adjustments, and managing analgesic induced side effects. Analgesic selection and dosing must be based on the patient's past and recent analgesic exposure. There is no single acute pain management regimen that is suitable for all patients. Analgesics must be tailored to the individual patient.

Efficacy and Safety of Methadone as a Second-Line Opioid for Cancer Pain in an Outpatient Clinic: A Prospective Open-Label Study

INTRODUCTION

Most clinical reports on methadone rotation describe outcomes in hospitalized patients. The few studies that have included outpatients are retrospective. The aim of this study was to assess the efficacy and safety of methadone as a second-line opioid in adult patients with advanced cancer after rotation in routine clinical practice at a palliative care outpatient clinic.

PATIENTS AND METHODS

This was a prospective, open-label study of 145 patients whose treatment was rotated from other opioids to methadone. Informed consent was obtained in all cases. The main outcome measure was change in the variable "worst pain" at day 28. Pain and pain interference were assessed with the Brief Pain Inventory, with side effects evaluated according to the Common Terminology Criteria for Adverse Events version 3.0. Pain levels were evaluated at study entry and at days 3, 7, 9, 14, 21, and 28.

RESULTS

Rotation to methadone was performed for the following reasons: poor pain control (77.9%), opioid side effects (2.1%), or both (20%). The mean daily oral morphine equivalent dose before rotation was 193.7 mg. The median worst and average pain scores decreased significantly (p < .0001) from baseline to day 28: The median worst pain score decreased from 9 (interquartile range [IQR]: 8-10) to 6 (IQR: 3-8), and the median average pain score decreased from 6 (IQR: 5-7) to 4 (IQR: 2-5). The proportions of patients with moderate to severe worst and average pain decreased by 30.3% and 47.5%, respectively, by day 28. No increase in opioid toxicity was observed during the study.

CONCLUSION

In outpatients with advanced cancer, rotation to methadone as a second-line opioid was efficacious and safe when using a tiered scheme with close follow-up by experienced health professionals.

IMPLICATIONS FOR PRACTICE

The results of this study, conducted prospectively under real clinical conditions, support the efficacy and safety of oral methadone as a second-line opioid in ambulatory patients with cancer. Moreover, these findings corroborate previously reported outcomes in retrospective outpatient studies and prospective studies that evaluated inpatient populations. Although more research into methadone rotation strategies is still needed, this study describes a successful tiered scheme of oral methadone rotation that was proven safe and effective during follow-up.

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.

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.

Methadone for Patients with Malignant Psoas Syndrome: Case Series of Three Patients

BACKGROUND

Malignant psoas syndrome (MPS) is a relatively rare syndrome that accompanies malignancy; the pain associated with MPS is often difficult to control. Methadone is known to be effective in relieving both nociceptive and neuropathic pain.

OBJECTIVE

Herein we describe treatment strategies for three patients with MPS, diagnosed by imaging and clinical findings, who responded to methadone treatment.

METHODS

Patient diagnoses, pain characteristics, and treatment were analyzed retrospectively. Subjects were three patients with MPS who presented to Hyogo Cancer Center with pain. A numeric rating scale (NRS; 0-10) was used to assess patients' pain levels.

RESULTS

All three patients were diagnosed with malignancies (prostate, cervical, and urachal) and had impaired gait and thigh extension. All had tumor invasion to the iliopsoas muscle, as determined by imaging, and were diagnosed with MPS. After starting methadone, symptoms improved in all patients and they were able to extend the thigh and walk normally. The NRS scores improved by an average of -7.3 points (95% confidence interval [CI] -4.97, -9.69) on Day 14; and the average time until symptom improvement after starting methadone was 2.3 days (95% CI 1.86, 2.80).

CONCLUSIONS

Methadone may be considered a treatment choice for MPS patients in whom pain is difficult to control.

Emerging therapies for patients with symptoms of opioid-induced bowel dysfunction

Opioid-induced bowel dysfunction (OIBD) comprises gastrointestinal (GI) symptoms, including dry mouth, nausea, vomiting, gastric stasis, bloating, abdominal pain, and opioid-induced constipation, which significantly impair patients’ quality of life and may lead to undertreatment of pain. Traditional laxatives are often prescribed for OIBD symptoms, although they display limited efficacy and exert adverse effects. Other strategies include prokinetics and change of opioids or their administration route. However, these approaches do not address underlying causes of OIBD associated with opioid effects on mostly peripheral opioid receptors located in the GI tract. Targeted management of OIBD comprises purely peripherally acting opioid receptor antagonists and a combination of opioid receptor agonist and antagonist. Methylnaltrexone induces laxation in 50%–60% of patients with advanced diseases and OIBD who do not respond to traditional oral laxatives without inducing opioid withdrawal symptoms with similar response (45%–50%) after an oral administration of naloxegol. A combination of prolonged-release oxycodone with prolonged-release naloxone (OXN) in one tablet (a ratio of 2:1) provides analgesia with limited negative effect on the bowel function, as oxycodone displays high oral bioavailability and naloxone demonstrates local antagonist effect on opioid receptors in the GI tract and is totally inactivated in the liver. OXN in daily doses of up to 80 mg/40 mg provides equally effective analgesia with improved bowel function compared to oxycodone administered alone in patients with chronic non-malignant and cancer-related pain. OIBD is a common complication of long-term opioid therapy and may lead to quality of life deterioration and undertreatment of pain. Thus, a complex assessment and management that addresses underlying causes and patomechanisms of OIBD is recommended. Newer strategies comprise methylnaltrexone or OXN administration in the management of OIBD, and OXN may be also considered as a preventive measure of OIBD development in patients who require opioid administration.

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.

Indication of Adequate Transdermal Fentanyl Dose in Opioid Switching From Oral Oxycodone in Patients With Cancer

OBJECTIVE

The present study aimed to examine affecting factors for conversion ratio and to predict adequate fentanyl dose for patients with cancer pain in opioid switching from oral oxycodone.

METHODS

Patient characteristics, biochemical parameters, daily oxycodone dose, and reasons for opioid switching were retrospectively collected. The effect of variables on the conversion ratio was analyzed by multiple regression analysis.

RESULTS

Regression analysis for the data from 122 patients suggested that the typical conversion ratio was 95:1; however, this ratio was significantly reduced in patients taking a daily oral morphine-equivalent dose of <45 mg/d and in patients with poor pain control to 52:1 and 64:1, respectively.

CONCLUSION

We should carefully and rapidly control pain in opioid switching based on the adequate dose indicated in this study.

WITHDRAWN: Opioid switching to improve pain relief and drug tolerability

The original authors were unable to complete an update of this review. A new protocol is in preparation with a new author team, who have revised the title. Publication of the new protocol is expected in 2014 with the title 'Opioid switching for cancer pain in adults'.

At November 2015, the new author team are no longer available to complete the replacement protocol. Please contact the PaPaS CRG for more information.

The editorial group responsible for this previously published document have withdrawn it from publication.

Methadone rotation for cancer patients with refractory pain in a palliative care unit: an observational study

BACKGROUND

Methadone has been reported to be as effective as morphine for cancer pain management. It is commonly used as an alternative opioid in case of insufficient relief.

OBJECTIVE

Our aim was to assess efficacy and tolerance of opioid rotation to methadone for refractory cancer pain management in palliative care unit (PCU) inpatients.

METHODS

All the patients undergoing opioid rotation to methadone from 2008 to 2011 in two PCUs (Lyon and Nice, France) were included. Pain assessments were undertaken on day 0 (D0), day 3 (D3), day 7 (D7), and day 14 (D14) using a visual analogue scale (VAS; 0-10) and the Douleur Neuropathique 4 (DN4) scale for neuropathic pain. Patients reported pain relief using a 4-point Likert scale (1=no relief; 4=important relief ).

RESULTS

Nineteen patients (7 females) with a median age of 55 (Q1-Q3; 44-58) underwent methadone rotation. The most common type of cancer was gastrointestinal. Seventeen patients had a diagnosis of mixed pain syndromes. Morphine equivalent daily dose (MEDD) prior to switching was 480 mg (Q1-Q3; 100-1021), and at least two nonmethadone opioid rotations had already been done for 13 patients. Between D0 and D7, the VAS score decreased by 4 points (p<0.001). The DN4 score became negative on D7 for 11 of 17 patients (65%). On D7, 16 of 18 patients (89%) expressed moderate to greater than moderate pain relief. Methadone was discontinued in one patient on D7 because it was deemed ineffective and for 8 patients, who were unable to take oral drugs, it was discontinued after D14.

CONCLUSION

Our results suggest that methadone is effective and well tolerated for refractory cancer pain.

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.

The use of very-low-dose methadone for palliative pain control and the prevention of opioid hyperalgesia

BACKGROUND

Opioid dose escalation may cause hyperalgesia, mediated by the N-methyl-D-aspartate (NMDA) pathway. Methadone is an atypical opioid that inhibits hyperalgesia through NMDA-blockade, especially at low doses.

OBJECTIVE

To evaluate the efficacy of using very-low-dose methadone as the sole long-acting opioid agent in a hospice practice.

DESIGN

A retrospective, observational study of the use of methadone, ≤15 mg daily, with as-needed short-acting opiates. Adjuvant nonopioid medications included haloperidol, which may have NMDA-blocking effects.

SETTING/SUBJECTS

We reviewed the records of 240 patients admitted to a community-based hospice from July 1, 2011 to April 1, 2012, with data collected until hospice discharge or until April 30, 2012.

MEASUREMENTS

Descriptive statistics were used to summarize patient demographics, medication regimens, and reported pain scores measured on a numeric rating scale from 0 to 10.

RESULTS

All patients received short-acting opiates, in a morphine-equivalent dose of 5 mg every 4 hours as needed, while 40% also received methadone at a median daily dose of 5 mg. Of those on methadone, almost half received scheduled haloperidol. The population had a median reported pain score of 0 and a peak score of 3, with similar results seen for cancer and noncancer groups. Two-thirds of patients never reported a pain score greater than 3.

CONCLUSION

The use of very-low-dose methadone in conjunction with adjuvant haloperidol resulted in excellent pain control without dose escalation or opioid-induced hyperalgesia, for both cancer and noncancer diseases. We conclude that low-dose methadone should be part of first-line treatment in palliative pain management.

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.

Anti-analgesic effect of the mu/delta opioid receptor heteromer revealed by ligand-biased antagonism

Delta (DOR) and mu opioid receptors (MOR) can complex as heteromers, conferring functional properties in agonist binding, signaling and trafficking that can differ markedly from their homomeric counterparts. Because of these differences, DOR/MOR heteromers may be a novel therapeutic target in the treatment of pain. However, there are currently no ligands selective for DOR/MOR heteromers, and, consequently, their role in nociception remains unknown. In this study, we used a pharmacological opioid cocktail that selectively activates and stabilizes the DOR/MOR heteromer at the cell surface by blocking its endocytosis to assess its role in antinociception. We found that mice treated chronically with this drug cocktail showed a significant right shift in the ED50 for opioid-mediated analgesia, while mice treated with a drug that promotes degradation of the heteromer did not. Furthermore, promoting degradation of the DOR/MOR heteromer after the right shift in the ED50 had occurred, or blocking signal transduction from the stabilized DOR/MOR heteromer, shifted the ED50 for analgesia back to the left. Taken together, these data suggest an anti-analgesic role for the DOR/MOR heteromer in pain. In conclusion, antagonists selective for DOR/MOR heteromer could provide an avenue for alleviating reduced analgesic response during chronic pain treatment.

A review of common methods to convert morphine to methadone

When dosed appropriately on carefully chosen patients, methadone can be a very safe and effective choice in managing chronic pain. Many authors have discussed important issues surrounding patient selection, drug interactions, screening for QTc prolongation and monitoring. This article will focus on the dosing dilemma that exists after the patient is deemed an appropriate candidate for methadone and a conversion is necessary from another opioid. Despite many publications dedicated to addressing this challenging topic, there is no consensus on the most appropriate method for converting an opioid regimen to methadone. Given the lack of concrete guidance, clinicians in a community setting are likely to be faced with an increased challenge if there are no available pain specialists to provide clinical support. Common methods for converting morphine to methadone will be reviewed and two clinical patient scenarios used to illustrate the outcomes of applying the methods.