Emerging therapies for opioid-induced constipation: what can we expect?

INTRODUCTION

The rise in opioid use for managing chronic and oncologic pain has led to a significant increase in opioid-induced constipation (OIC) that impacts patient quality of life and pain management.

AREAS COVERED

In this study, emerging therapies for OIC were criticized for refining advancements and novel treatment options. Key topics included the efficacy of peripherally acting mu-opioid receptor antagonists (PAMORAs) such as methylnaltrexone, naloxegol, and naldemedine, which specifically target opioid-induced gut dysfunction. Other treatment options, including intestinal secretagogues like lubiprostone and linaclotide, selective 5-HT receptor agonists such as prucalopride, and emerging adjunctive therapies like transcutaneous electrical nerve stimulation (TENS) and electroacupuncture were mentioned. Current guidelines from the American Gastroenterological Association (AGA) and the European consensus were criticized.

EXPERT OPINION

Experts stress the importance of a stepwise approach to managing OIC, considering patient-specific factors and the efficacy of various treatments. While PAMORAs have demonstrated effectiveness in improving bowel function, their high cost and lack of extensive head-to-head comparisons with traditional laxatives are significant concerns. Emerging therapies and adjunctive treatments offer promising results but require further validation through rigorous studies. Future research should focus on long-term outcomes, cost-effectiveness, and comparative effectiveness to better address the complex needs of patients with OIC and refine treatment protocols.

Constipation in Cancer Patients - an Update of Clinical Evidence

OPINION STATEMENT

Constipation is one of the most frequent problems in cancer patients, and its etiology is multifactorial. It leads to decreased quality of life and impedes optimal pain treatment. Despite the high prevalence, constipation is frequently underdiagnosed mainly because of lack of validated diagnostic criteria or widely accepted definition of constipation in cancer patients. All cancer patients should be evaluated regularly for constipation, and concomitant causes and risk factors were assessed. Opioids are responsible for a much of the secondary constipation in cancer patients. The management of constipation in cancer patients should be multifaceted, addressing dietary and behavioral issues and optimizing pharmacological interventions. Prevention of opioid-induced constipation (OIC) is pivotal, as treatment is often unsatisfactory or inefficient. Dietary and behavioral interventions should be considered. Non-pharmacological measures include hydration and nutrition, ensuring privacy during defecation, using a commode or footstool, and the availability of a caregiver. Abdominal massage may be of value. Traditional laxatives are recommended in prevention but not in the treatment of OIC. Peripherally acting mu-opioid receptor antagonists (PAMORA) appear the first choice in the treatment and an alternative to laxatives in some recent clinical practice guidelines in preventing OIC. Naldemedine, naloxegol, and methylnaltrexone are supported by quality evidence for OIC management. Naloxone or naltrexone, taken orally in combined formulations with opioids, may be valuable in preventing or reducing OIC symptoms.

Use of Peripheral μ-Opioid Receptor Antagonists for Treating Opioid-Induced Constipation among US Medicare Beneficiaries from 2014 to 2018

Background: Opioid-induced constipation (OIC) remains the most common adverse event associated with opioid use. Treatment with more novel and costly agents (such as peripheral μ-opioid receptor antagonists [PAMORAs]) may be indicated in patients with laxative-refractory OIC. Three PAMORAs are U.S. Food and Drug Administration approved for managing OIC-methylnaltrexone (FDA approved in 2008), naloxegol (in 2014), and naldemedine (in 2017). These drugs are indicated only in limited scenarios. Their contemporary patterns of use and burden of spending remain unknown. Objective: To evaluate the trends in use and expenditures for the three PAMORAs approved for treating OIC. Design: Retrospective cross-sectional study using the 2014-2018 Medicare Part D Prescription Drug Event data and the 2018 Part D Prescriber Public Use File. Setting: Prescribers and beneficiaries using PAMORAs. Measurements: The annual spending, number of beneficiaries, number of claims, and spending per beneficiary and claim for each PAMORA. The distribution by prescriber specialty using PAMORA. Results: From 2014 to 2018, aggregate spending on PAMORAs increased, from $13.6 to $150.9 million, and use increased, from 4221 to 72,592 beneficiaries. After FDA approval in 2014, naloxegol overtook methylnaltrexone in the number of users in 2015 and spending in 2016. In 2018, 6989 unique prescribers used any PAMORA. Among them, the most common specialties/professions were family practice (20.2%), internal medicine (18.0%), and nurse practitioner (15.4%). Conclusions: Our findings-significant and increasing expenditure on PAMORAs, and broad use across specialties-serve as a call for defining and implementing appropriate use of PAMORAs.

Dejection and self-assessment of quality of life in patients with lung cancer subjected to palliative care

AIM OF THE STUDY

To evaluate the intensity of dejection and self-assessment of quality of life in patients with lung cancer from the start of palliative care until death.

MATERIAL AND METHODS

The study included 63 patients with lung cancer from the start of care until death in palliative medicine centers in Bydgoszcz in 2012-2013. The visual-analogue scale constituting part of the ESAS scale was used to assess dejection, while question number 30 of the EORTC QLQ-C30 was used for self-assessment of quality of life.

RESULTS

"Moderate" and "very" intense dejection initially occurred in 19 (30%) and 24 (38%), and in the 2(nd) assessment in as many as 23 (36%) and 30 (48%) patients. Average quality of life deteriorated in this respect by 0.09 in the two-step scale (p = 0.005). Increase in the intensity of "moderate" dejection occurred between the 1(st) and 3(rd) assessment. Initially it occurred in 2 (9%) patients and in 14 (66%) during the 3(rd) assessment. In contrast, the levels of "very" severe dejection did not change significantly between the 1(st) and the 3(rd) assessment. The average quality of life deteriorated by 0.23 points (p = 0.004). A significant relationship was found only between analgesic treatment and quality of life (p < 0.0005). Other factors such as age, time from diagnosis to start of treatment, place of residence, sex, or financial condition did not affect the quality of life.

CONCLUSIONS

Self-assessment of the quality of life worsens with time. The intensity of dejection does not change in the last 3 weeks of life. In multivariate analysis, among the selected variables such as age, sex, place of residence, time from diagnosis to start of palliative care, financial condition, and type of painkillers used, only the latter has an impact on self-assessed quality of life.

Management of opioid-induced constipation for people in palliative care

Constipation is common in the palliative population. Opioid medications, which are frequently prescribed to this cohort, represent a significant risk factor for this condition. Opioid-induced constipation may be of such severity that opioid doses are reduced or missed, and analgesia and quality of life are therefore reduced. However, underlying chronic constipation, local and systemic disease effects, and other medications may also precipitate constipation in this population. The assessment and treatment of constipation in a palliative individual should be undertaken in a fashion similar to that used in non-palliative patients. Initial management should include minimising exposure to predisposing factors and general measures such as encouraging hydration, fibre intake and mobility. Pharmacological treatment should commence with a stool softener and a stimulant laxative. Recently published literature demonstrates that newer laxatives, including lubiprostone (a chloride channel activator) and prucalopride (a 5-HT4 receptor agonist) can effectively treat opioid-induced constipation. For patients not responding to laxatives, opioid antagonists (non-specific or peripherally acting μ-opioid receptor antagonists) can be co-prescribed with laxatives. These agents have also proven efficacy in treating opioid-induced constipation. This review discusses the recent literature regarding the management of opioid-induced constipation and provides a rational approach to assessing and managing constipation in the palliative population.

Constipation in palliative care: what do we use as definitions and outcome measures?

CONTEXT

Advances in the management of constipation in palliative care remain hindered by the lack of agreed-upon diagnostic criteria.

OBJECTIVES

The objective of this work was to emphasize this issue by systematically examining the eligibility and primary outcome measures in studies of constipation in the hospice and palliative care population.

METHODS

A palliative care-specific electronic literature search was undertaken using the validated domain filter "palliative care" and topic filter "constipation" in CareSearch (www.caresearch.com.au), which interrogates PubMed in real time (1965-2011). Studies were included if they were primary reports of the treatment of constipation in a palliative care setting. Articles could be prospective or retrospective; randomized controlled trials, cohort studies, or case series.

RESULTS

Twenty articles on the palliative care population were included in which there were six different definitions of constipation. Only 12 of 20 articles used their cited definitions of constipation as the studies' primary outcome measures and four of four blinded, randomized, controlled trials. Articles that used the time between bowel actions or the use of laxatives as the definition of constipation were most likely to report outcomes based on these criteria.

CONCLUSION

Constipation is a significant problem in palliative care; however, not having an agreed-upon definition limits research initiatives and the ability to apply these results clinically to people with constipation. Four domains are suggested as pivotal to the diagnosis: any life-long history of constipation (using the Rome Criteria), evaluation of physical changes that may cause or worsen constipation, the subjective sensation (such as feelings of incomplete defecation or bloating or fullness), and objective changes (such as frequency or consistency of stools).

Methylnaltrexone for the treatment of opioid-induced constipation

Opioids are the drugs of choice for treating moderate-to-severe pain, especially for patients in the end stage of cancer or other advanced illnesses, and also in critical care or for the treatment of chronic pain. Side effects such as nausea, pruritus, dizziness and constipation have to be controlled in order to use these drugs to their full potential. Opioid-induced bowel syndrome and constipation caused by activation of μ-receptors in the gut can have such distressing effects that some patients prefer to forego adequate pain control. Methylnaltrexone is a μ-opioid receptor antagonist that, unlike naltrexone or naloxone, does not pass the blood-brain barrier, and therefore does not impair the centrally mediated analgesic effect of opioids. It is licensed for the treatment of opioid-induced constipation in palliative care in more than 50 countries. This article presents practically relevant pharmacological data, basic research results and evidence from clinical research about methylnaltrexone, and outlines potential future therapeutic options for this promising drug.