Methadone and the hospice patient: prescribing trends in the home-care setting

Methadone in Cancer Pain

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

Cross-sectional pilot study to monitor the availability, dispensed prices, and affordability of opioids around the globe

CONTEXT

Opioids are essential medicines. The World Health Organization and Health Action International monitor the price of essential medicines. However, their surveys do not include opioids, and there is no information on their affordability.

OBJECTIVES

To provide information on access to pain treatment, as measured by the availability and dispensed price of five opioids in 13 formulations, and the affordability of oral immediate-release (IR) morphine.

METHODS

The International Association for Hospice and Palliative Care members were distributed by their countries' Gross National Income (GNI) level using the World Bank categories, i.e., high income country (HIC), upper middle income country (UMIC), lower middle income country (LMIC), low income country (LIC), and randomized. A total of 10 participants were selected from each (n=40) domain. Participants were asked to identify a pharmacy located closest to a public facility that provides diagnosis/treatment for life-threatening conditions and report the lowest dispensed price of the smallest selling unit and strength of each formulation. Availability and median (Me) price were calculated for each. Affordability and percentage of international buyer price (IBP) were calculated for morphine oral solid IR.

RESULTS

A total of 30 participants from 26 countries (response rate=75%) responded. Significant correlation was found between availability and GNI (range: 65-68% [HIC and LIC]; R=0.781; P<0.0001). Injectable and morphine oral solid sustained release (SR) were the most available (59% and 55%). Methadone (oral) was the least expensive (Me=0.5) followed by fentanyl (transdermal; Me=2.2). The Me price for morphine oral solid IR and ratios between dispensed and IBP were lower in HIC than in LMIC (price=0.03 vs. 0.16; ratio=2.23 vs. 0.03). Affordability for morphine oral solid IR was five days (Me=0.1; range=29-0.25).

CONCLUSION

Patients in LMIC and LIC have limited access to opioids, and there are subsidies in place for more expensive medications and formulations in all GNI levels, but not for morphine oral solid IR. Additional research is necessary to identify the reasons behind these findings.

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.

Myoclonus associated with high-dose parenteral methadone

Methadone is generally believed to be devoid of neuroexcitatory properties, and its use is increasing. This paper reports two cases of myoclonus with high-dose parenteral methadone in patients with cancer under hospice care. This side effect may be dose related and/or due to the parenteral route of administration. Reduction of the dose and change of route was sufficient to eliminate the myoclonus while maintaining an adequate pain control. Possible mechanisms for methadone causing myoclonus include a redistribution of receptor saturation in the N-methyl-D-aspartate (NMDA) and delta receptors. Ketamine may be an option for patients with intractable pain who develop methadone-induced myoclonus.

Actual and potential drug interactions associated with methadone

OBJECTIVE

To identify and characterize methadone-related drug interactions, as well as factors accounting for the variability in manifesting these interactions clinically.

DESIGN

Systematic review of the primary literature.

METHODS

Over 200 articles, reports of clinical trials, and case reports were reviewed. Studies and case reports were included if they revealed either quantitative or qualitative methods to identify, evaluate severity of, or compare methadone-related drug interactions.

RESULTS OF DATA SYNTHESIS

The evidence base associated with methadone drug interactions is underdeveloped in general, as the majority of references found were case reports or case series. Most of the studies and reports focused on inpatients receiving methadone maintenance treatment (MMT) that were between 20 and 60 years of age, taking 200 mg/day of methadone or less. Evidence supporting the involvement of lesser known cytochrome P450 enzymes such as 2B6 is emerging, which may partially explain the inconsistencies previously found in studies looking specifically at 3A4 in vitro and in vivo. Genetic variability may play a role in the pharmacokinetics and pharmacodynamics of many medications, including methadone.

CONCLUSIONS

Drug interactions associated with methadone and their clinical significance are still poorly understood in general. Many tertiary drug information references and review articles report interactions associated with methadone in a general sense, much of which is theoretical and not verified by case reports, much less well-designed clinical trials. The majority of drug interaction reports that do exist were performed in the MMT population, which may differ significantly from chronic pain or cancer pain populations.

Toward evidence-based prescribing at end of life: a comparative analysis of sustained-release morphine, oxycodone, and transdermal fentanyl, with pain, constipation, and caregiver interaction outcomes in hospice patients

OBJECTIVE

The primary goal of this investigation was to examine selected outcomes in hospice patients who are prescribed one of three sustained-release opioid preparations. The outcomes examined include: pain score, constipation severity, and ability of the patient to communicate with caregivers.

PATIENTS AND SETTINGS

This study included 12,000 terminally ill patients consecutively admitted to hospices and receiving pharmaceutical care services between the period of July 1 and December 31, 2002.

DESIGN

We retrospectively examined prescribing patterns of sustained-release morphine, oxycodone, and transdermal fentanyl. We compared individual opioids on the aforementioned outcome markers, as well as patient gender, terminal diagnosis, and median length of stay.

RESULTS

Patients prescribed a sustained-release opioid had similar average ratings of pain and constipation severity, regardless of the agent chosen. Patients prescribed transdermal fentanyl were reported to have more difficulty communicating with friends and family when compared with patients prescribed either morphine or oxycodone. On average, patients prescribed transdermal fentanyl had a shorter length of stay on hospice as compared with those receiving morphine or oxycodone.

CONCLUSION

There was no difference in observed pain or constipation severity among patients prescribed sustained-release opioid preparations. Patients receiving fentanyl were likely to have been prescribed the medication due to advanced illness and associated dysphagia. Diminished ability to communicate with caregivers and a shorter hospice course would be consistent with this profile. Further investigation is warranted to examine the correlation between a patient's ability to interact with caregivers and pain control achieved.