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Postgraduate Medicine 2016Constipation is a common adverse effect in patients requiring long-term opioid therapy for pain control. Methylnaltrexone, a quaternary peripheral mu-opioid receptor... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
Constipation is a common adverse effect in patients requiring long-term opioid therapy for pain control. Methylnaltrexone, a quaternary peripheral mu-opioid receptor antagonist, is an effective treatment of opioid induced constipation (OIC) without affecting centrally mediated analgesia. Our objective was to conduct a review and meta-analysis to evaluate the efficacy of methylnaltrexone for treatment of OIC, as well as to provide a clinical discussion regarding newly developed alternatives and provide the current treatment algorithm utilized at our institution.
METHODS
We performed a systematic review and meta-analysis of randomized control trials using Cochrane Collaboration Databases and MEDLINE from 2007-present. Literature related to methylnaltrexone, opioids, opioid receptors, opioid antagonists, opioid-induced constipation were reviewed. A meta-analysis was completed with the primary outcome of rescue-free bowel movement (RFBM) within four hours of administration. All pooled analyses were based on random-effects models.
RESULTS
1239 patients were analyzed; 599 received methylnaltrexone and 640 received placebo. With a 95% CI calculated, the true risk difference is between 0.267 and 0.385, demonstrating a statistically significant difference in RFBM between treatment and placebo groups (p < 0.0001). Both the 0.15 mg/kg, 0.30 mg/kg doses every other day, and 12 mg/day dose were found to have increased risk of RFBM compared to placebo.
CONCLUSION
Results support the use of methylnaltrexone. Furthermore, the use of methylnaltrexone to induce laxation may decrease use of health care resources, increase work productivity, and improve cost utilization. New treatments have been made available; however, controlled clinical studies are needed to demonstrate long-term efficacy, safety and cost-effectiveness. Possible limitations of this study include the relatively small number of randomized, placebo-controlled trials investigating the efficacy of methylnaltrexone versus placebo. There is also the possibility of publication bias, which may lead to overestimating the efficacy of methylnaltrexone in treating OIC.
Topics: Analgesics, Opioid; Chronic Pain; Constipation; Humans; Naltrexone; Narcotic Antagonists; Quaternary Ammonium Compounds; Receptors, Opioid, mu; Treatment Outcome
PubMed: 26839023
DOI: 10.1080/00325481.2016.1149017 -
The Cochrane Database of Systematic... May 2015This article describes the second update of a Cochrane review on the effectiveness of laxatives for the management of constipation in people receiving palliative care.... (Review)
Review
BACKGROUND
This article describes the second update of a Cochrane review on the effectiveness of laxatives for the management of constipation in people receiving palliative care. Previous versions were published in 2006 and 2010 where we also evaluated trials of methylnaltrexone; these trials have been removed as they are included in another review in press. In these earlier versions, we drew no conclusions on individual effectiveness of different laxatives because of the limited number of evaluations. This is despite constipation being common in palliative care, generating considerable suffering due to the unpleasant physical symptoms and the availability of a wide range of laxatives with known differences in effect in other populations.
OBJECTIVES
To determine the effectiveness and differential efficacy of laxatives used to manage constipation in people receiving palliative care.
SEARCH METHODS
We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library), MEDLINE, EMBASE, CINAHL and Web of Science (SCI & CPCI-S) for trials to September 2014.
SELECTION CRITERIA
Randomised controlled trials (RCTs) evaluating laxatives for constipation in people receiving palliative care.
DATA COLLECTION AND ANALYSIS
Two authors assessed trial quality and extracted data. The appropriateness of combining data from the studies depended upon clinical and outcome measure homogeneity.
MAIN RESULTS
We identified five studies involving the laxatives lactulose, senna, co-danthramer, misrakasneham, docusate and magnesium hydroxide with liquid paraffin. Overall, the study findings were at an unclear risk of bias. As all five studies compared different laxatives or combinations of laxatives, it was not possible to perform a meta-analysis. There was no evidence on whether individual laxatives were more effective than others or caused fewer adverse effects.
AUTHORS' CONCLUSIONS
This second update found that laxatives were of similar effectiveness but the evidence remains limited due to insufficient data from a few small RCTs. None of the studies evaluated polyethylene glycol or any intervention given rectally. There is a need for more trials to evaluate the effectiveness of laxatives in palliative care populations. Extrapolating findings on the effectiveness of laxatives evaluated in other populations should proceed with caution. This is because of the differences inherent in people receiving palliative care that may impact, in a likely negative way, on the effect of a laxative.
Topics: Analgesics, Opioid; Anthraquinones; Cathartics; Constipation; Humans; Lactulose; Magnesium Hydroxide; Naltrexone; Palliative Care; Paraffin; Quaternary Ammonium Compounds; Randomized Controlled Trials as Topic; Senna Extract
PubMed: 25967924
DOI: 10.1002/14651858.CD003448.pub4 -
Expert Opinion on Pharmacotherapy Mar 2015Opioid-induced constipation (OIC) is one of the most frequent and burdening adverse events (AE) of opioid therapy. This systematic review aimed to evaluate efficacy and... (Review)
Review
INTRODUCTION
Opioid-induced constipation (OIC) is one of the most frequent and burdening adverse events (AE) of opioid therapy. This systematic review aimed to evaluate efficacy and safety of drugs in randomized controlled trials (RCTs) with adult OIC patients.
AREAS COVERED
Efficacy assessment focused on objective outcome measures (OOMs): bowel movement (BM) frequency, BM within 4 h and time to first BM. Twenty-one studies examining seven drugs were identified. Methylnaltrexone showed improvements in all three OOMs. RCTs in naloxone and alvimopan tended to be effective for BM frequency measures. Naloxegol (≥ 12.5 mg) improved all OOMs. Though effectiveness of lubiprostone was demonstrated for all OOMs, group differences were small to moderate. CB-5945 and prucalopride tended to increase BM frequency, especially for 0.1 mg twice daily and 4 mg daily, respectively. Besides nausea and diarrhea, abdominal pain was the most frequent AE for all drugs (risk ratio, range: 1.52 - 5.06) except for alvimopan. Treatment-related serious AEs were slightly higher for alvimopan (cardiac events) and prucalopride (severe abdominal pain, headache). Pain scores for placebo and intervention groups were similar for all drugs.
EXPERT OPINION
Finding a consensus definition and inclusion criteria for OIC plus a rational balance between efficacy and AEs of drugs remain future challenges.
Topics: Abdominal Pain; Analgesics, Opioid; Constipation; Diarrhea; Gastrointestinal Motility; Headache; Humans; Nausea; Pain; Randomized Controlled Trials as Topic
PubMed: 25539282
DOI: 10.1517/14656566.2015.995625