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

The influence of tramadol on bowel function: A randomised, placebo-controlled trial

Tramadol is a weak opioid used to treat moderate pain. Stronger opioids inhibit gastrointestinal function, but little is known about the gastrointestinal effects of tramadol. Our aim was to investigate if tramadol causes opioid-induced bowel dysfunction (OIBD). Twenty healthy male participants (mean age 24 [range 20-31] years) were included. Tramadol (extended-release formulation, 200 mg/day) or placebo was administered for 10 days in two study periods separated by 3 weeks. Gastrointestinal transit times and segmental volume, motility and water content were investigated with the 3D-transit system and magnetic resonance imaging. Bowel movements and gastrointestinal symptoms were recorded daily. Tramadol prolonged colonic transit time (34 h vs. 25 h, p < 0.001) and increased small bowel motility (p < 0.01) and water content (p = 0.002) compared to placebo. Across all days of treatment, tramadol reduced the number of mean daily bowel movements (p = 0.001) and increased mean stool consistency (p = 0.006). Gastrointestinal symptom scores increased with tramadol (indigestion: +358%, p = 0.01; constipation: +475%, p = 0.01). Additionally, more participants fulfilled the diagnostic criteria for constipation after tramadol treatment compared to placebo (40% vs. 0%, p < 0.001). This study showed that tramadol treatment is associated with OIBD, and management of constipation and other bowel symptoms should, therefore, be prioritised when treating pain patients with tramadol.

Opioid-Induced Constipation and Associated Symptoms After Orthopedic Trauma

PURPOSE

Opioid-induced constipation is an adverse effect often experienced among patients taking prescription opioid medication. Despite frequent opioid prescribing after orthopedic injury, there is a dearth of research examining opioid-induced constipation presentations in this population. This analysis examines the frequency of opioid-induced constipation manifestations and association with patient-reported outcomes among participants prescribed opioid medication following orthopedic injury.

DESIGN

Secondary analysis of 86 clinical trial participants following orthopedic trauma.

METHODS

Participants were assessed 2-weeks postoperatively with the following measures: Patient-Reported Outcome Measurement Information System (PROMIS) Pain Interference, PROMIS Physical Function, past 24-hour average pain intensity captured on the numeric pain rating scale, and the Patient Assessment of Constipation Symptoms (PAC-SYM) questionnaire. Linear regressions examined the association between PAC-SYM scores and both pain intensity and PROMIS T-scores while accounting for injury severity and opioid medication dosage.

RESULTS

Most participants (69%) reported experiencing opioid-induced constipation symptoms and 7% reported moderate to severe symptoms. Compared to those without symptoms, participants reporting opioid-induced constipation symptoms were found to have a 3-point increase in PROMIS Pain Interference (95% Confidence Interval [CI]: 0.28-5.90; p = .032), a 3-point decline in PROMIS Physical Function (95% CI: -6.57 to -0.02; p = .049), and a 1.7-point increase in average pain scores (95% CI: 0.50-3.01; p = .007) at 2-weeks following surgery.

CONCLUSIONS

Opioid-induced constipation symptoms are common after orthopedic trauma and linked to increased pain interference and pain intensity as well as reduced physical function.

CLINICAL IMPLICATIONS

Nurse-led assessments of opioid-induced constipation can support the timely delivery of interventions to alleviate symptoms and potentially improve patient-reported outcomes after injury.

Naldemedine and Magnesium Oxide as First-Line Medications for Opioid-Induced Constipation: A Comparative Database Study in Japanese Patients With Cancer Pain

Introduction Naldemedine and magnesium oxide are common first-line early laxative medications used in the real-world scenario in Japan, for patients with cancer pain who receive opioid prescriptions, as per a nationwide hospital claims database study. However, the real-world prescription patterns and associated outcomes are unknown. Methods In this retrospective, cohort study using the Medical Data Vision (MDV) database (January 2018 to December 2020), data were collected from eligible patients (who had a long-term prescription of strong opioids, for >30 days) in Japan with naldemedine or magnesium oxide as the first-line laxative prescription, for a long-term opioid prescription for cancer pain with ≥6 months post-opioid observation period. A laxative prescription within three days after the opioid prescription date was termed an "early" prescription. The composite incidence of dose increase or addition/change of laxatives at three months after the start of the opioid prescription was the primary endpoint after adjusting baseline characteristics between the treatment arms by propensity score matching. Results After propensity score matching, 1717 and 544 patients who were prescribed naldemedine and magnesium oxide each were included in the early prescription and non-early prescription groups, respectively. Even after matching, the incidence of death was not adjusted enough and was significantly higher in the naldemedine arm than in the magnesium oxide arm in the non-early group but comparable in the early group. The incidence of addition, change, or dose increase was significantly higher in the naldemedine arm than in the magnesium oxide arm of the early prescription group (hazard ratio (95% confidence interval), 1.08 (1.00, 1.17); p=0.0402); the incidence was comparable between the arms of the non-early group. Conclusion These findings may provide valuable insights into real-world clinical treatment patterns and preliminary evidence for the selection of first-line medications to mitigate opioid-induced constipation in Japanese patients with cancer pain.

P2Y1 receptor in the colonic submucosa of rats and its association with opioid‑induced constipation

The aim of the present study was to explore the expression changes of P2Y purinergic receptor 1 (P2Y1) in the distal colonic submucosa of opioid-induced constipation (OIC) rats and its association with the occurrence of OIC, an OIC rat model was generated by intraperitoneal injection of loperamide hydrochloride, a selective agonist of µ-opioid receptors (MORs). At 7 days post-treatment, the model was assessed by analyzing stool scores and calculating the gastrointestinal (GI) transit ratio of rats. The distribution of P2Y1-expressing neurons in the colonic submucosal plexus was demonstrated by immunofluorescence (IF). Western blotting was performed to evaluate the expression changes of MOR, P2Y1 and ATP synthase subunit β (ATPB) proteins in the colonic submucosa, while reverse transcription-quantitative PCR (RT-qPCR) analysis was performed to determine the relative mRNA expression of MOR and P2Y1. After 7 days, the feces of OIC rats exhibited an appearance of sausage-shaped pieces and both the stool weight and GI transit ratio of OIC rats were significantly decreased. IF revealed co-expression of P2Y1 and calbindin and MOR and ATPB in the nerve cells of the distal colonic submucosal plexus. Moreover, RT-qPCR analysis showed that the MOR mRNA levels were significantly increased in the distal colonic submucosa of OIC rats, while mRNA levels of P2Y1 were decreased. WB showed that in the distal colonic submucosa of OIC rats, MOR protein expression was increased, whereas that of P2Y1 was significantly decreased. GI transit ratio analysis suggested that the P2Y agonist ATP significantly relieved constipation symptoms in rats, while the P2Y inhibitor MRS2179 aggravated these symptoms. Finally, P2Y1 expression change was shown to be associated with the occurrence of OIC, while expression of MOR and P2Y1 was associated with OIC development in rats.

Mu-opioid antagonists for opioid-induced bowel dysfunction in people with cancer and people receiving palliative care

BACKGROUND

Opioid-induced bowel dysfunction (OIBD) is characterised by constipation, incomplete evacuation, bloating, and gastric reflux. It is one of the major adverse events (AEs) of treatment for pain in cancer and palliative care, resulting in increased morbidity and reduced quality of life. This review is a partial update of a 2008 review, and critiques as previous update (2018) trials only for people with cancer and people receiving palliative care.

OBJECTIVES

To assess for OIBD in people with cancer and people receiving palliative care the effectiveness and safety of mu-opioid antagonists (MOAs) versus different doses of MOAs, alternative pharmacological/non-pharmacological interventions, placebo, or no treatment.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, and Web of Science (December 2021), clinical trial registries and regulatory websites. We sought contact with MOA manufacturers for further data.

SELECTION CRITERIA

Randomised controlled trials (RCTs) assessing the effectiveness and safety of MOAs for OIBD in people with cancer and people at a palliative stage irrespective of the type of terminal disease.

DATA COLLECTION AND ANALYSIS

Two review authors assessed risk of bias and extracted data. The appropriateness of combining data from the trials depended upon sufficient homogeneity across trials. Our primary outcomes were laxation response, effect on analgesia, and AEs. We assessed the certainty of evidence using GRADE and created summary of findings tables.

MAIN RESULTS

We included 10 studies (two new trials) randomising in-total 1343 adults with cancer irrespective of stage, or at palliative care stage of any disease. The MOAs were oral naldemedine and naloxone (alone or in combination with oxycodone), and subcutaneous methylnaltrexone. The trials compared MOAs with placebo, MOAs at different doses, or in combination with other drugs. Two trials of naldemedine and three of naloxone with oxycodone were in people with cancer irrespective of disease stage. The trial on naloxone alone was in people with advanced cancer. Four trials on methylnaltrexone were in palliative care where most participants had advanced cancer. All trials were vulnerable to biases; most commonly, blinding of the outcome assessor was not reported.  Oral naldemedine versus placebo Risk (i.e. chance) of spontaneous laxations in the medium term (over two weeks) for naldemedine was over threefold greater risk ratio (RR) 2.00, 95% confidence interval (CI) 1.59 to 2.52, 2 trials, 418 participants, I² = 0%. Number needed to treat for an additional beneficial outcome (NNTB) 3, 95% CI 3 to 4; moderate-certainty evidence). Earlier risk of spontaneous laxations and patient assessment of bowel change was not reported. Very low-certainty evidence showed naldemedine had little to no effect on opioid withdrawal symptoms. There was little to no difference in the risk of serious (non-fatal) AEs (RR 3.34, 95% CI 0.85 to 13.15: low-certainty evidence). Over double the risk of AEs (non-serious) reported with naldemedine (moderate-certainty evidence). Low-dose oral naldemedine versus higher dose Risk of spontaneous laxations was lower for the lower dose (medium term, 0.1 mg versus 0.4 mg: RR 0.69, 95% CI 0.53 to 0.89, 1 trial, 111 participants (low-certainty evidence)). Earlier risk of spontaneous laxations and patient assessment of bowel change not reported. Low-certainty evidence showed little to no difference on opioid withdrawal symptoms (0.1 mg versus 0.4 mg mean difference (MD) -0.30, 95% CI -0.85 to 0.25), and occurrences of serious AEs (0.1 mg versus 0.4 mg RR 0.25, 95% CI 0.03 to 2.17). Low-certainty evidence showed little to no difference on non-serious AEs. Oral naloxone versus placebo Risk of spontaneous laxations and AEs not reported. Little to no difference in pain intensity (very low-certainty evidence). Full data not given. The trial reported that no serious AEs occurred. Oral naloxone + oxycodone versus oxycodone Risk of spontaneous laxations within 24 hours and in the medium term not reported. Low-certainty evidence showed naloxone with oxycodone reduced the risk of opioid withdrawal symptoms. There was little to no difference in the risk of serious (non-fatal) AEs (RR 0.68, 95% CI 0.44 to 1.06), 3 trials, 362 participants, I² = 55%: very low-certainty evidence). There was little to no difference in risk of AEs (low-certainty evidence).  Subcutaneous methylnaltrexone versus placebo Risk of spontaneous laxations within 24 hours with methylnaltrexone was fourfold greater than placebo (RR 2.97, 95% CI 2.13 to 4.13. 2 trials, 287 participants, I² = 31%. NNTB 3, 95% CI 2 to 3; low-certainty evidence). Risk of spontaneous laxations in the medium term was over tenfold greater with methylnaltrexone (RR 8.15, 95% CI 4.76 to 13.95, 2 trials, 305 participants, I² = 47%. NNTB 2, 95% CI 2 to 2; moderate-certainty evidence). Low-certainty evidence showed methylnaltrexone reduced the risk of opioid withdrawal symptoms, and did not increase risk of a serious AE (RR 0.59, 95% CI 0.38 to 0.93. I² = 0%; 2 trials, 364 participants). The risk of AEs was higher for methylnaltrexone (low-certainty evidence). Lower-dose subcutaneous methylnaltrexone versus higher dose There was little to no difference in risk of spontaneous laxations in the medium-term (1 mg versus 5 mg or greater: RR 2.91, 95% CI 0.82 to 10.39; 1 trial, 26 participants very low-certainty evidence), or in patient assessment of improvement in bowel status (RR 0.98, 95% CI 0.71 to 1.35, 1 trial, 102 participants; low-certainty evidence). Medium-term assessment of spontaneous laxations and serious AEs not reported. There was little to no difference in symptoms of opioid withdrawal (MD -0.25, 95% CI -0.84 to 0.34, 1 trial, 102 participants) or occurrence of AEs (low-certainty evidence).

AUTHORS' CONCLUSIONS

This update's findings for naldemedine and naloxone with oxycodone have been strengthened with two new trials, but conclusions have not changed. Moderate-certainty evidence for oral naldemedine on risk of spontaneous laxations and non-serious AEs suggests in people with cancer that naldemedine may improve bowel function over two weeks and increase the risk of AEs. There was low-certainty evidence on serious AEs. Moderate-certainty evidence for methylnaltrexone on spontaneous laxations over two weeks suggests subcutaneous methylnaltrexone may improve bowel function in people receiving palliative care, but certainty of evidence for AEs was low. More trials are needed, more evaluation of AEs, outcomes patients rate as important, and in children.

Evaluation of a Pharmacist-Driven Protocol for the Treatment of Opioid-Induced Constipation

BACKGROUND

Opioid-induced constipation (OIC) treatment guidelines recommend over-the-counter laxatives as first-line therapy, followed by treatment with a peripherally-acting mu-opioid receptor antagonist (PAMORA) in refractory patients.

OBJECTIVE

To evaluate the ability of a pharmacist-driven OIC protocol to promote increased scheduled laxative use prior to escalation to PAMORA therapy.

METHODS

This retrospective, single-center cohort study evaluated patients 2 years pre- and post-protocol implementation. The primary outcome was the difference in the percentage of patients receiving 2 scheduled laxatives for ≥ 2 days prior to PAMORA therapy pre- and post-protocol. Secondary outcomes included difference in time to first bowel movement after PAMORA initiation, difference in total number of laxative/PAMORA doses administered, and difference in overall estimated total cost. Data was analyzed using chi-squared tests and Student's t tests.

RESULTS

Three-hundred patients were included (150 patients in the pre and post-protocol groups). In the pre-protocol group, 53 patients (35%) received 2 scheduled laxatives for 2 days prior to naloxegol/methylnaltrexone compared to 96 patients (64%) in the postprotocol group (p < 0.0001). One-thousand twenty-one scheduled laxative doses were given pre-protocol versus 1625 doses post-protocol. Average time to first bowel movement was similar between groups (17.7 hours vs 16.0 hours p = 0.441). Estimated total cost of OIC reversal therapy decreased from $20,896.95 to $13,405.47.

CONCLUSION

A pharmacist-driven OIC protocol is associated with an increase in the use of scheduled laxatives prior to PAMORA administration and decreased overall estimated total cost. A larger, prospective study is necessary to assess if this promotes more efficacious OIC.

[Tapentadol versus classical WHO-III opioids for chronic back pain. Health services research study based on representative data from health insurance funds]

BACKGROUND/OBJECTIVE

In clinical trials, tapentadol prolonged release (PR) showed a more favourable gastrointestinal tolerability profile compared to other strong opioids in the treatment of pain. The present analysis compared tapentadol PR and classical WHO-III PR opioids in routine clinical practice.

METHOD

Retrospective cohort study (matched pair approach) using anonymised health insurance data of patients with chronic low back pain who were prescribed strong opioids following pretreatment with WHO-I/II analgesics. Data were analysed from the date of first prescription in 2015 over a maximum period of two years. The primary analysis parameter was the prescription of laxatives.

RESULTS

Data of 227 patients per cohort could be included in the analysis. Significantly fewer tapentadol PR than WHO-III PR patients were prescribed laxatives (20.3% vs. 37%; p < 0.0001). In addition, laxative dosages were significantly lower in the tapentadol PR cohort (26.4 vs. 82.5 defined daily doses; p < 0.0001). A significant difference in laxative prescription was also observed under long-term treatment (tapentadol PR patients 27.7% vs. WHO-III PR patients 50%; p = 0.0029).

CONCLUSION

Routine clinical practice indirectly confirmed the more favourable gastrointestinal tolerability of tapentadol PR in the treatment of chronic pain which had previously been demonstrated in clinical trials and non-interventional studies.

Opioid-Related Constipation

Opioid-related constipation encompasses constipation directly caused by opioid use (opioid-induced constipation [OIC]) as well as pre-existing constipation worsened by opioid use (opioid-exacerbated constipation [OEC]). Over-the-counter laxatives should be used as first-line agents for both OIC and OEC, given their efficacy, low cost, and high safety profiles. Symptoms of OIC and responses to therapy can be assessed with the Bowel Function Index. Individuals with OIC refractory to laxatives may be responsive to peripherally acting μ-opioid receptor antagonists. Although data supporting the superiority of one prescription agent over another is lacking, all have proven effective for the treatment of OIC.

Impact and Consequences of Opioid-Induced Constipation: A Survey of Patients

INTRODUCTION

Opioids are a valuable tool to help achieve control of pain. However, opioid-induced constipation (OIC) is an important limitation of treatment with this class of drugs.

METHODS

To better understand the impact of OIC on patient-reported outcomes, we carried out a survey involving patients being treated with opioids. Both ad hoc questions and the PROMIS and PAC-SYM and PAC-QOL scores were used.

RESULTS

Of the 597 participants, 150 (25%) had cancer-related pain, and 447 (75%) had non-cancer pain; 66% experienced OIC. PROMIS pain interference questions indicated that pain is more likely to interfere with a patient's life when they have OIC. PAC-QOL and PAC-SYM revealed that 58% of patients with non-cancer pain and OIC reported at least one "severe" or "very severe" constipation symptom, compared to 83% with cancer-related pain. Younger age and less time on opioids were associated with greater impact of OIC on quality of life. Only 41% of patients were satisfied with how their constipation was managed. Over 50% of those with non-cancer pain said that they modified their opioid regimen due to constipation, vs. 6% of those with cancer pain. Constipation had been discussed with the healthcare provider (HCP) in 48% of non-cancer patients and in 73% of cancer patients. In those with chronic pain and OIC, 24% expressed varying degrees of dissatisfaction with the healthcare system, vs. 37% in those with cancer pain and OIC.

CONCLUSION

Our results provide additional evidence that management of OIC is inadequate in many cases. Moreover, they indicate that there is a definite need for better education about OIC among HCPs.

Naldemedine is effective in the treatment of opioid-induced constipation in patients with chronic non-cancer pain who had a poor response to laxatives

BACKGROUND

Two studies demonstrated the efficacy and safety of naldemedine in adult patients with chronic non-cancer pain and opioid-induced constipation (OIC). However, no studies have compared the efficacy of peripherally acting µ-opioid receptor antagonists in patients with adequate and inadequate responses to prior OIC therapy with laxatives. This post hoc analysis of integrated data from the two previous studies compared the efficacy of naldemedine in patients who were unsuccessfully treated with laxatives [poor laxative responders (PLRs)] with those who either did not receive laxatives >30 days prior to screening or those who only received rescue laxative at or after screening (non-PLRs).

METHODS

Patients with OIC were randomized to once-daily treatment with naldemedine 0.2 mg or placebo. The primary efficacy endpoint was the proportion of responders [⩾3 spontaneous bowel movements (SBMs)/week and an increase from baseline of ⩾1 SBM/week for ⩾9 weeks of the 12-week treatment period and ⩾3 weeks of the final 4 weeks of the 12-week treatment period]. Additional endpoints included change in SBM frequency, change in frequency of SBMs without straining, proportion of complete SBM (CSBM) responders, change in CSBM frequency, and time to first SBM. Treatment-emergent adverse events (TEAEs) were assessed.

RESULTS

The analysis included 538 (317 PLRs, 221 non-PLRs) and 537 (311 PLRs, 226 non-PLRs) patients in the naldemedine and placebo arms, respectively. There were significantly more responders in the naldemedine PLR (46.4%; p < 0.0001) and non-PLR (54.3%; p = 0.0009) subgroups versus the placebo groups (30.2% and 38.9%, respectively). In both the PLR and non-PLR subgroups, naldemedine treatment was superior to placebo on all additional endpoints. Overall incidence of TEAEs in the PLR subgroups treated with naldemedine or placebo was similar.

CONCLUSION

This integrated analysis further supports the efficacy and tolerability of naldemedine in the treatment of OIC and demonstrates a consistent effect in both PLR and non-PLR subgroups.[ClinicalTrials.gov identifier: NCT01965158 and NCT01993940].

Opioid-induced Constipation: A Review of Health-related Quality of Life, Patient Burden, Practical Clinical Considerations, and the Impact of Peripherally Acting μ-Opioid Receptor Antagonists

Objective:

The objective of this study was to provide an overview of opioid-induced constipation (OIC) and its influence on disease burden and quality of life (QOL).

Methods:

This is a narrative review.

Results:

For many patients, opioid-related side effects, the most common being OIC, have the potential to significantly impair patients’ QOL. Patients with OIC often experience substantial overall burden (ie, increases in anxiety and depression, impairments in activities of daily living, low self-esteem, feelings of embarrassment) and economic burden (ie, higher health care costs, more frequent doctor visits, increased out-of-pocket medication costs), which often causes patients to modify or discontinue opioid treatment despite the analgesic benefits. OIC occurs when opioids bind to peripheral μ-opioid receptors in the gastrointestinal tract. Currently, 4 Food and Drug Administration (FDA)-approved medications are available for OIC, 3 of which are peripherally acting µ-opioid receptor antagonists (PAMORAs). PAMORAs block µ-opioid receptors in the gastrointestinal tract without affecting the central analgesic effects of the opioid and thus provide a targeted approach to OIC management. Two PAMORAs, naldemedine and methylnaltrexone, have shown significant improvements in QOL based on the Patient Assessment of Constipation Symptoms questionnaire relative to placebo. Along with pharmacologic management for OIC, health care providers should institute comprehensive communication strategies with patients to ensure OIC is effectively recognized and managed.

Discussion:

OIC has both physical and psychological impacts on patients. PAMORAs provide effective relief of OIC while also improving QOL. To augment the pharmacologic management of OIC, proactive counseling approaches between physicians and patients may help relieve some of the patient burden associated with OIC and lead to improved outcomes.

Magnesium Oxide in Constipation

Magnesium oxide has been widely used as a laxative for many years in East Asia, yet its prescription has largely been based on empirical knowledge. In recent years, several new laxatives have been developed, which has led to a resurgence in interest and increased scientific evidence surrounding the use of magnesium oxide, which is convenient to administer, of low cost, and safe. Despite these advantages, emerging clinical evidence indicates that the use of magnesium oxide should take account of the most appropriate dose, the serum concentration, drug-drug interactions, and the potential for side effects, especially in the elderly and in patients with renal impairment. The aim of this review is to evaluate the evidence base for the clinical use of magnesium oxide for treating constipation and provide a pragmatic guide to its advantages and disadvantages.

Delphi consensus on strategies in the management of opioid-induced constipation in cancer patients

BACKGROUND

Opioid-induced constipation (OIC) is a frequent and bothersome adverse event related with opioid therapy in cancer patients. Despite the high prevalence, medical management of OIC is often uncertain. The current project aimed to investigate expert opinion on OIC management and provide practical recommendations to improve the clinical approach of OIC in cancer patient.

METHODS

A modified Delphi method was conducted involving 46 different physicians experts in OIC. Using a structured questionnaire of 67 items this project intended to seek consensus on aspects related to diagnosis, treatment, and quality of life of cancer patients suffering with OIC.

RESULTS

After two rounds, a consensus was reached in 91% of the items proposed, all in agreement. Agreement was obtained on OIC definition (95.7%). Objective and patient-reported outcomes included in that definition should be assessed routinely in clinical practice. Responsive to symptom changes and easy-to-use assessment tools were recommended (87.2%). Successful diagnosis of OIC requires increase clinicians awareness of OIC and proactivity to discuss symptoms with their patients (100%). Successful management of OIC requires individualization of the treatment (100%), regular revaluation once is established, and keeping it for the duration of opioid treatment (91.5%). Oral Peripherally Acting μ-Opioid Receptor Agonists (PAMORAs), were considered good alternatives for the treatment of OIC in cancer patients (97.9%). This drugs and laxatives can be co-prescribed if OIC coexist with functional constipation.

CONCLUSIONS

The panelists, based on their expert clinical practice, presented a set of recommendations for the management of OIC in cancer patients.

Systematic review with meta-analysis: efficacy and safety of treatments for opioid-induced constipation

BACKGROUND

When opioid-induced constipation is treated with centrally acting opioid antagonists, there may be opioid withdrawal or aggravation of pain due to inhibition of μ-opioid analgesia. This led to the development of peripherally acting μ-opioid receptor antagonists (PAMORAs).

AIM

To evaluate the efficacy of available PAMORAs and other approved or experimental treatments for relieving constipation in patients with opioid-induced constipation, based on a systematic review and meta-analysis of published studies.

METHODS

A search of MEDLINE, EMBASE and EBM Reviews Cochrane Central Register of Controlled Trials was completed in July 2019 for randomised trials compared to placebo. FDA approved doses or highest studied dose was evaluated. Efficacy was based on diverse endpoints, including continuous variables (the bowel function index, number of spontaneous bowel movements and stool consistency based on Bristol Stool Form Scale), or responder analysis (combination of >3 spontaneous bowel movements or complete spontaneous bowel movements plus 1 spontaneous bowel movement or complete spontaneous bowel movements, respectively, over baseline [so-called FDA endpoints]). Adverse effects evaluated included central opioid withdrawal, serious adverse events, abdominal pain and diarrhoea.

RESULTS

We included 35 trials at low risk of bias enrolling 13 566 patients. All PAMORAs demonstrated efficacy on diverse patient response endpoints. There was greater efficacy with approved doses of the PAMORAs (methylnaltrexone, naloxegol and naldemidine), with lower efficacy or lower efficacy and greater adverse effects with combination oxycodone with naloxone, lubiprostone and linaclotide.

CONCLUSIONS

Therapeutic response in opioid-induced constipation is best achieved with the PAMORAs, methylnaltrexone, naloxegol and naldemidine, which are associated with low risk of serious adverse events.

Efficacy and safety of linaclotide for opioid-induced constipation in patients with chronic noncancer pain syndromes from a phase 2 randomized study

Constipation is the most common adverse event (AE) of opioid therapy. This multicenter, phase 2 study evaluated the efficacy and safety of linaclotide in treating opioid-induced constipation (OIC) in patients with chronic noncancer pain syndromes (NCT02270983). Adults with OIC (<3 spontaneous bowel movements [SBMs]/week) related to chronic noncancer pain were randomized 1:1:1 to receive linaclotide 145 µg, linaclotide 290 µg, or placebo once daily for 8 weeks. The primary endpoint was change from baseline in 8-week SBM frequency rate (SBMs/week). Secondary efficacy endpoints included 6/8-week SBM 3 + 1 responders, time to first SBM, and changes from baseline in 8-week stool consistency, abdominal bloating, and straining. Additional endpoints included treatment satisfaction and adequate relief responders. In total, 254 patients were randomized: 87, 88, and 79 received linaclotide 145 µg, linaclotide 290 µg, and placebo, respectively. The mean changes from baseline in SBMs/week during the treatment period were 2.9 and 3.5 in the linaclotide 145 and 290 µg groups (P < 0.01 for both doses), respectively, vs 1.6 in the placebo group. Diarrhea, the most common AE, was generally mild, resulting in 1.1%, 5.7%, and 1.3% of patients discontinuing in the linaclotide 145 μg, linaclotide 290 μg, and placebo groups, respectively. No serious AEs related to diarrhea were reported in any treatment group. Compared with placebo, linaclotide-treated patients had significant improvements in stool consistency, straining, abdominal bloating, and treatment satisfaction scores (P < 0.05). Linaclotide significantly improved OIC symptoms and was well tolerated in patients with chronic noncancer pain.

Patients' Self-Assessment of the Symptoms and Impact of Opioid-Induced Constipation: Results From a Prospective Observational Cohort Study of Japanese Patients With Cancer

CONTEXT

Many patients who have cancer consider opioid-induced constipation (OIC) to be a burdensome side effect of opioid treatment.

OBJECTIVES

To evaluate patient-reported outcomes in Japanese patients with cancer pain and OIC.

METHODS

This prospective observational study evaluated OIC incidence for two weeks in patients with cancer after they initiated strong opioid therapy. Rome IV diagnostic criteria, a physician's diagnosis, spontaneous bowel movements, Bowel Function Index score, and patients' daily self-assessments were used. Changes from baseline in Patient Assessment of Constipation Symptoms and Patient Assessment of Constipation Quality of Life (PAC-QOL) scores were compared between patients with and without OIC. Patients and health care providers (HCPs) completed study-specific questionnaires regarding OIC burden, treatment satisfaction, and patient-provider communications.

RESULTS

Among 212 enrolled patients, the incidence of OIC was 47.6% by patients' self-assessments, with a cumulative incidence of 30.2% by Day 3 and 43.5% by Day 7. Patient Assessment of Constipation Symptoms and PAC-QOL overall scores from patients with OIC worsened significantly from baseline compared with patients without OIC by all diagnostic criteria, except for spontaneous bowel movement frequency for PAC-QOL. Patients and HCPs were generally satisfied with OIC treatment; however, 53.5% of patients and approximately 40.0% of HCPs reported that OIC affected pain management. Most patients and HCPs reported that OIC conditions were sufficiently or essentially communicated.

CONCLUSION

After starting opioid therapy, patients recognized OIC onset and its impact on cancer pain management, highlighting the need for effective patient-provider communications, diagnosis, and treatment of OIC to improve QOL for patients with cancer receiving opioid analgesics.

Prevalence and Risk Factors for Opioid-Induced Constipation in an Older National Veteran Cohort

Objectives

This research describes the prevalence and covariates associated with opioid-induced constipation (OIC) in an observational cohort study utilizing a national veteran cohort and integrated data from the Center for Medicare and Medicaid Services (CMS).

Methods

A cohort of 152,904 veterans with encounters between 1 January 2008 and 30 November 2010, an exposure to opioids of 30 days or more, and no exposure in the prior year was developed to establish existing conditions and medications at the start of the opioid exposure and determining outcomes through the end of exposure. OIC was identified through additions/changes in laxative prescriptions, all-cause constipation identification through diagnosis, or constipation related procedures in the presence of opioid exposure. The association of time to constipation with opioid use was analyzed using Cox proportional hazard regression adjusted for patient characteristics, concomitant medications, laboratory tests, and comorbidities.

Results

The prevalence of OIC was 12.6%. Twelve positively associated covariates were identified with the largest associations for prior constipation and prevalent laxative (any laxative that continued into the first day of opioid exposure). Among the 17 negatively associated covariates, the largest associations were for erythromycins, androgens/anabolics, and unknown race.

Conclusions

There were several novel covariates found that are seen in the all-cause chronic constipation literature but have not been reported for opioid-induced constipation. Some are modifiable covariates, particularly medication coadministration, which may assist clinicians and researchers in risk stratification efforts when initiating opioid medications. The integration of CMS data supports the robustness of the analysis and may be of interest in the elderly population warranting future examination.

Opioid-Induced Constipation in Oncological Patients: New Strategies of Management

OPINION STATEMENT

Cancer-associated pain has traditionally been treated with opioid analgesics, often in escalating doses. Opioid-induced constipation (OIC) is a common problem associated with chronic use of opioid analgesics. Typical treatment strategies to alleviate constipation are based on dietary changes, exercise, and laxatives. However, laxatives have a nonspecific action and do not target underlying mechanisms of OIC. This article will review prevalent, clinical presentation and recommendations for the treatment of OIC. An independent literature search was carried out by the authors. We reviewed the literature for randomized controlled trials that studied the efficacy of laxatives, naloxone, and naloxegol in treating OIC. Newer strategies addressing the causal pathophysiology of OIC are needed for a more effective assessment and management of OIC. Finally, traditional recommended therapies are appraised and compared with the latest pharmacological developments. Future research should address whether naloxegol is more efficacious by its comparison directly with first-line treatments, including laxatives.

Patient and provider differences in the treatment of opioid-induced constipation: a qualitative study

BACKGROUND

Patients using opioids to treat chronic non-cancer pain often experience side effects that may affect health-related quality of life (HRQOL). These side effects include opioid-induced constipation (OIC), sedation, dizziness, and nausea. OIC can significantly affect HRQOL for patients on a daily basis. However, it is not well understood whether patients and clinicians view OIC management similarly.

AIMS

In this study, we sought to elucidate the decision-making process around managing OIC by assessing patient and provider treatment preferences, experiences, and communication regarding this condition.

METHODS

We conducted semi-structured interviews with 33 clinicians, and held three focus groups with patients who were currently using or had used opioids for chronic non-cancer pain. We then analyzed transcribed interviews using descriptive qualitative methods based on grounded theory methodology.

RESULTS

Clinicians recognized OIC as a concern but prioritized pain management over constipation. They focused on medication-based treatments for OIC, but also recommended lifestyle changes (e.g., diet) and reducing opioids to relieve symptoms. Patients reported using over-the-counter treatments, but the majority focused on diet-related constipation management. Patients reported not receiving adequate information from clinicians about OIC and relevant treatments. Cost of treatment was a major concern for both patients and clinicians.

CONCLUSIONS

Assessing experiences with and preferences for OIC treatment, including cost, ease of access, and side effects, could improve patient-provider communication and HRQOL. Quality improvement efforts can target uncovered misalignments between patients and clinicians to improve communication about opioid medication adverse effects and relevant treatment options, which may help improve quality of life for patients with chronic pain.

Naldemedine: A Review in Opioid-Induced Constipation

Naldemedine [Symproic^® (Japan; USA); Rizmoic^® (EU)], an orally available peripherally acting μ-opioid receptor antagonist (PAMORA), is approved in several countries for the treatment of opioid-induced constipation. In phase III trials, naldemedine was more effective than placebo at increasing the frequency of bowel movements in patients with constipation induced by opioid treatment for cancer pain or chronic non-cancer pain. Naldemedine was also associated with improvements in patient-rated constipation-related symptoms and quality of life. Naldemedine was generally well tolerated, including over the longer term. Because naldemedine specifically targets opioid receptors in the gastrointestinal (GI) tract and does not cross the blood-brain barrier, it does not cause opioid withdrawal symptoms or interfere with centrally mediated opioid analgesia. Consistent with its mechanism of action, the most commonly reported adverse events were GI in nature. In conclusion, current data indicate that naldemedine is an effective and generally well-tolerated treatment option for opioid-induced constipation in patients with cancer pain or chronic non-cancer pain, with the convenience of once-daily oral dosing.

The Burden of Opioid-Induced Constipation in Younger Patients with Chronic Noncancer Pain

Objective

The purpose of this analysis was to evaluate the experience of opioid-induced constipation in younger patients and identify differences in the experience of opioid-induced constipation and its symptoms between younger patients (<50 years) and older patients (50-64 years).

Design

Post hoc analysis of data from a 24-week prospective, multinational, longitudinal observational cohort study (NCT01928953).

Setting

Outpatient clinics in the United States, Canada, Germany, and United Kingdom.

Subjects

Two age-based subgroups of adult patients with chronic noncancer pain receiving four or more weeks of daily opioid therapy and experiencing opioid-induced constipation within the previous two weeks.

Methods

The number of spontaneous bowel movements, frequency of constipation symptoms, amount of bother associated with symptoms, Patient Assessment of Constipation-Symptoms questionnaire, and health-related quality of life and function outcomes.

Results

Overall, 419 patients were included in this analysis (younger patients, N = 184; older patients, N = 235). Among younger and older patients, respectively, constipation occurred within the first week after initiating opioid therapy for 32.8% and 35.9%. At baseline, the mean numbers of spontaneous bowel movements/week were 1.3 and 1.5, and moderate opioid-induced constipation-related interference with pain management was reported by 46.6% and 44.5%. Younger patients generally reported that opioid-induced constipation symptoms were more bothersome than did older patients. The impact of opioid-induced constipation on health-related quality of life, work productivity, and day-to-day activities was comparable.

Conclusions

In these patients receiving opioid therapy for chronic noncancer pain, the burden of opioid-induced constipation was comparable or greater for patients aged <50 years compared with that for patients aged 50-64 years.

Associations of chronic diarrhoea with non-alcoholic fatty liver disease and obesity-related disorders among US adults

Mechanisms explaining observed associations between diarrhoea and obesity or increased body mass index (BMI) are unclear.

Peripherally acting μ-opioid antagonist for the treatment of opioid-induced constipation: Systematic review and meta-analysis

BACKGROUND AND AIM

Opioid-induced constipation (OIC) is a frequent adverse event (AE) that impairs patients' quality of life (QOL). Peripherally acting μ-opioid receptor antagonists (PAMORAs) have been recognized as a treatment option for OIC, but the effect consistent across the studies has not been evaluated.

METHODS

We conducted a quantitative meta-analysis to explore the efficacy of PAMORA for OIC (registered with PROSPERO: CRD42018085298). We systematically searched randomized controlled trials (RCTs) in Medline, Embase, and Central databases. Change from baseline in spontaneous bowel movements, pooled proportion of responders, QOL, and AEs were calculated and compared with results in placebo cases.

RESULTS

We included 31 RCTs with 7849 patients. A meta-analysis revealed that patients under PAMORA therapy had considerably improved spontaneous bowel movement from baseline compared with those given placebo (20 RCTs; mean difference, 1.43; 95% confidence interval [CI], 1.18-1.68; n = 5622) and more responded (21 RCTs; risk ratio [RR], 1.81; 95% CI, 1.55-2.12; n = 4821). Moreover, QOL of patients receiving PAMORA was significantly better (8 RCTs; mean difference, -0.22; 95% CI, -0.28 to -0.17; n = 2884). AEs were increased significantly in the PAMORA group (26 RCTs; RR, 1.10; 95% CI, 1.06-1.15; n = 7715), especially in gastrointestinal disorders, whereas serious AEs were not significant (17 RCTs; RR, 1.04; 95% CI, 0.85-1.28; n = 5890).

CONCLUSION

Peripherally acting μ-opioid receptor antagonist has been shown to be effective and durable for patients with OIC and is the only drug with confirmed evidence in meta-analysis. The possibility of publication bias was the limitation of this study.

Targeting mu opioid receptors to modulate gastrointestinal function: what have we learnt so far from the studies in functional bowel disorders?

Opioids have recently received much attention because of the epidemic in their use in some countries such as the USA and the UK. Concerns have been raised about the possibility that they can increase mortality in patients when used on a long-term basis. Moreover, they are known to induce paradoxical hyperalgesia as well as alterations of gut function. The analgesic properties of opioids are mediated by receptors located in the brain, but as opioid receptors are also expressed in the gastrointestinal tract, new drugs acting on these receptors have recently been developed to treat two functional disorders, namely irritable bowel syndrome with diarrhoea and opioid-induced constipation. The aim of this article is to highlight some interesting observations resulting from the development of these drugs in the field of functional gastrointestinal disorders.

Clinical Overview and Considerations for the Management of Opioid-induced Constipation in Patients With Chronic Noncancer Pain

OBJECTIVES

Opioid analgesics may be associated with chronic adverse effects, such as opioid-induced constipation (OIC). Available and emerging prescription medications for OIC in patients with chronic noncancer pain are described, including concerns and challenges associated with OIC management.

METHODS

Narrative review.

RESULTS

OIC is characterized by a change in bowel habits and defecation patterns that occurs when initiating opioid therapy and is associated with reduced bowel frequency, straining, sensation of incomplete evacuation, and/or patient distress related to bowel habits. Prescription medications are indicated when OIC persists despite conservative approaches (eg, increased fiber and fluid intake, exercise, over-the-counter laxatives and stool softeners). Phase 3 studies have demonstrated the efficacy of peripherally acting µ-opioid receptor antagonists (PAMORA; methylnaltrexone, naloxegol, naldemedine), and a chloride channel activator (lubiprostone) for improving OIC in patients with chronic noncancer pain. Although head-to-head studies are lacking, a meta-analysis demonstrated that μ-opioid receptor antagonists were more effective than placebo for the treatment of OIC. The most common adverse effects associated with prescription medications for OIC are gastrointestinal related (eg, nausea, diarrhea, abdominal pain, or distention), with most being mild or moderate in severity. Therapy currently in development for OIC includes the PAMORA axelopran.

DISCUSSION

Health care providers should be aware of this complication in patients receiving opioids and should monitor and address constipation-related symptoms to optimize pain management and improve patient quality of life.

Safety of oral methylnaltrexone for opioid-induced constipation in patients with chronic noncancer pain

Purpose

Oral methylnaltrexone was shown to be effective in treating opioid-induced constipation (OIC) in patients with chronic noncancer pain in a Phase III randomized controlled trial. This report provides a detailed safety analysis from that study.

Methods

Adults (n=803) with chronic noncancer pain for ≥2 months and confirmed OIC while receiving opioid doses ≥50 mg morphine equivalent per day for ≥14 days were randomized 1:1:1:1 to oral methylnaltrexone (150, 300, or 450 mg) or placebo once daily for 4 weeks, followed by as-needed use for 8 weeks. Safety was evaluated by examining treatment-emergent adverse events (TEAEs), clinical laboratory parameters, vital signs, electrocardiography, rescue-laxative and opioid use, Objective Opioid Withdrawal Scale (OOWS) and Subjective Opioid Withdrawal Scale (SOWS), and pain-intensity scores.

Results

TEAEs occurred at a similar incidence in the methylnaltrexone groups (59.0%) and placebo group (63.0%). The most common TEAEs with methylnaltrexone were abdominal pain (8.0% vs 8.5% with placebo), nausea (6.8% vs 9.0%), and diarrhea (6.0% vs 3.5%). Cardiac-related TEAEs occurred in 1.8% and 1.0% of patients, respectively, and no major adverse cardiovascular events were reported. No patient had a cluster of TEAEs associated with opioid withdrawal after excluding gastrointestinal TEAEs. Changes in laboratory parameters, vital signs, and electrocardiography were generally small and similar across treatment groups. Rescue-laxative use was more common with placebo than methylnaltrexone 450 mg (6.20% vs 4.27% of study days, P=0.024). Changes in opioid dose, OOWS and SOWS scores, and pain-intensity scores during treatment were minimal.

Conclusion

Oral methylnaltrexone had a safety profile comparable with placebo in the treatment of OIC in patients with chronic noncancer pain, with no evidence of cardiac toxicity or opioid withdrawal.

Peripherally Acting μ-Opioid Receptor Antagonists for the Treatment of Opioid-Related Side Effects: Mechanism of Action and Clinical Implications

Opioid receptors are distributed throughout the central and peripheral nervous systems and on many nonneuronal cells. Therefore, opioid administration induces effects beyond analgesia. In the enteric nervous system (ENS), stimulation of µ-opioid receptors triggers several inhibitory responses that can culminate in opioid-induced bowel dysfunction (OBD) and its most common side effect, opioid-induced constipation (OIC). OIC negatively affects patients' quality of life (QOL), ability to work, and pain management. Although laxatives are a common first-line OIC therapy, most have limited efficacy and do not directly antagonize opioid effects on the ENS. Peripherally acting µ-opioid receptor antagonists (PAMORAs) with limited ability to cross the blood-brain barrier have been developed. The PAMORAs approved by the U S Food and Drug Administration for OIC are subcutaneous and oral methylnaltrexone, oral naloxegol, and oral naldemedine. Although questions of cost-effectiveness and relative efficacy versus laxatives remain, PAMORAs can mitigate OIC and improve patient QOL. PAMORAS may also have applications beyond OIC, including reducing the increased cardiac risk or potential tumorigenic effects of opioids. This review discusses the burden of OIC and OBD, reviews the mechanism of action of new OIC therapies, and highlights other potential opioid-related side effects mediated by peripheral opioid receptors in the context of new OIC therapies.

Oral methylnaltrexone is efficacious and well tolerated for the treatment of opioid-induced constipation in patients with chronic noncancer pain receiving concomitant methadone

Purpose

To evaluate the safety and efficacy of oral methylnaltrexone for opioid-induced constipation (OIC).

Patients and methods

This was a post hoc analysis of patients receiving methadone in a randomized, double-blind, placebo-controlled, Phase 3 trial. The trial included adults with chronic noncancer pain for ≥2 months receiving opioid doses ≥50 mg/day of oral morphine equivalents for ≥14 days and with a history of OIC. Patients were assigned to oral methylnaltrexone (150, 300, or 450 mg) or placebo once daily (QD) for 4 weeks followed by 8 weeks as needed. Percentage of dosing days that resulted in a rescue-free bowel movement (RFBM) within 4 hours of dosing was assessed during QD dosing (primary efficacy endpoint). Other endpoints included percentage of responders (ie, ≥3 RFBMs/week, with an increase of ≥1 RFBM/week from baseline for ≥3 of the 4 weeks) during QD dosing and change in weekly number of RFBMs. Adverse events were assessed.

Results

Concomitant methadone was reported in 120 patients (oral methylnaltrexone: 150 mg [n=33], 300 mg [n=30], and 450 mg [n=31]; placebo [n=26]). Oral methylnaltrexone-treated patients had significant increases in mean percentage of dosing days with RFBMs within 4 hours of dosing during weeks 1–4 with 300 mg (33.6%; P<0.01) and 450 mg (38.2%; P<0.001) vs placebo; improvements with 150 mg (20.0%) vs placebo (15.1%) did not reach statistical significance. The percentage of responders was greater vs placebo, but not significant, for the higher doses during the QD period (150 mg [39.4%], 300 mg [60.0%], 450 mg [67.7%], and placebo [38.5%]). Change from baseline in the mean number of weekly RFBMs (weeks 1–4) was significantly greater with oral methylnaltrexone 450 mg vs placebo (least-squares mean difference vs placebo, 1.2; P=0.04); no significant differences were found for 300 or 150 mg. Oral methylnaltrexone was well tolerated at all doses; few patients discontinued treatment.

Conclusion

Oral methylnaltrexone, particularly 450 mg, was efficacious and safe for treating OIC in these patients.

The patient burden of opioid-induced constipation: New insights from a large, multinational survey in five European countries

BACKGROUND

Despite its high prevalence, opioid-induced constipation (OIC) remains under-recognised and undertreated, and its true impact on wellbeing and quality of life (QoL) may be underestimated.

METHODS

A quantitative, questionnaire-based international survey was conducted.

RESULTS

Weak-opioid users appeared as bothered by constipation as strong-opioid users (38% vs 40%, respectively; p = 0.40), despite it causing less-severe physical symptoms and impact on QoL. Strong-opioid users meeting Rome IV OIC criteria appeared to experience greater symptomatic and biopsychosocial burden from constipation than those not satisfying these criteria. Almost one-fifth of respondents were dissatisfied with their current constipation treatment and around one-third found balancing the need for adequate pain relief with constipation side effects challenging. Consequently, more than half failed to adhere to their prescribed treatment regimens, or resorted to suboptimal strategies, e.g. 40% reduced their opioid intake, to relieve constipation. Almost 60% of healthcare professionals did not adequately counsel patients about constipation as a common side effect of opioid use.

CONCLUSIONS

Findings suggest that both weak- and strong-opioid users suffer comparable bother and decreased QoL, Rome IV criteria can identify patients with more-severe OIC, but may underdiagnose patients showing fewer symptoms, and increased education is needed to manage patients' expectations and enable improved OIC self-management.

Chinese herbal medicine for opioid induced constipation in cancer patients: Protocol for a systematic review

BACKGROUND

Opioid induced constipation (OIC) is a symptom that is commonly encountered in cancer pain management. Chinese herbal medicine (CHM) has been widely used to improve OIC in China. Many clinical trials indicate that CHM could improve OIC. In this systematic review, we aim to evaluate the effectiveness and safety of CHM for OIC in cancer patients.

METHODS

We will search the following electronic databases for randomized controlled trials to evaluate the effectiveness and safety of CHM for OIC in cancer patients: CENTRAL, EMBASE, MEDILINE, CINAHL and China National Knowledge Infrastructure. Each database will be searched from inception to June 2018. The entire process will include study selection, data extraction, risk of bias assessment and meta-analyses.

RESULTS

This proposed study will evaluate the effectiveness and safety of CHM for OIC. The outcomes will include change in bowel movements, quality of life and adverse events.

CONCLUSIONS

This proposed systematic review will evaluate the existing evidence on the effectiveness and safety of CHM for OIC in cancer patients.

DISSEMINATION AND ETHICS

The results of this review will be disseminated through peer-reviewed publication. Because all of the data used in this systematic review and meta-analysis has been published, this review does not require ethical approval. Furthermore, all data will be analyzed anonymously during the review process.

Oral methylnaltrexone does not negatively impact analgesia in patients with opioid-induced constipation and chronic noncancer pain

Purpose

An oral formulation of methylnaltrexone has been developed for treating opioid-induced constipation (OIC). This manuscript examines the impact of oral methylnaltrexone, a peripherally acting µ-opioid receptor antagonist, on opioid analgesia.

Methods

This Phase III, randomized, double-blind, placebo-controlled trial, evaluated changes in pain intensity scores (0= no pain to 10= worst possible pain) and opioid use in adults with chronic noncancer pain. Patients taking ≥50 mg/day oral morphine equivalent dose (MED) for ≥14 days before screening with less than three rescue-free bowel movements/week received oral methylnaltrexone 150 mg/day (n=201), 300 mg/day (n=201), 450 mg/day (n=200), or placebo (n=201) once daily for 4 weeks followed by 8 weeks of oral methylnaltrexone as needed.

Results

The primary condition requiring opioid use was back pain (68.2% of 803 patients). Baseline pain intensity scores were similar among treatment groups (mean range, 6.2–6.4) and remained stable throughout the 4-week double-blind (mean range, 6.1–6.5) and 8-week as needed (mean range, 6.3–6.5) periods. Baseline mean MED was comparable between oral methylnaltrexone 150 mg (200.0 mg/day), methylnaltrexone 450 mg (218.0 mg/day), and placebo (209.7 mg/day), but was slightly higher in the oral methylnaltrexone 300-mg group (252.6 mg/day). Nonsignificant, minimal changes in mean MED were observed after 4 weeks of treatment (214.5–235.6 mg/day) and at the end of the as needed phase (202.3–234.9 mg/day). The percentage of patients who initiated new opioid medications during the 4-week, once-daily dosing period was generally similar among the oral methylnaltrexone 150-mg, 300-mg, and 450-mg groups (44.8%, 43.3%, and 35.0%, respectively), the oral methylnaltrexone combined group (41.0%), and the placebo group (39.8%). The most common newly initiated opioid medications during this once-daily period were oxycodone (oral methylnaltrexone groups combined, 14.6%; placebo, 12.4%) and morphine (oral methylnaltrexone combined, 10.1%; placebo, 7.0%).

Conclusion

Oral methylnaltrexone does not elicit opioid withdrawal or interfere with opioid analgesia.

Mu-opioid antagonists for opioid-induced bowel dysfunction in people with cancer and people receiving palliative care

BACKGROUND

Opioid-induced bowel dysfunction (OIBD) is characterised by constipation, incomplete evacuation, bloating, and gastric reflux. It is one of the major adverse events of treatment for pain in cancer and in palliative care, resulting in increased morbidity and reduced quality of life.This is an update of two Cochrane reviews. One was published in 2011, Issue 1 on laxatives and methylnaltrexone for the management of constipation in people receiving palliative care; this was updated in 2015 and excluded methylnaltrexone. The other was published in 2008, Issue 4 on mu-opioid antagonists (MOA) for OIBD. In this updated review, we only included trials on MOA (including methylnaltrexone) for OIBD in people with cancer and people receiving palliative care.

OBJECTIVES

To assess the effectiveness and safety of MOA for OIBD in people with cancer and people receiving palliative care.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, and Web of Science to August 2017. We also searched clinical trial registries and regulatory websites. We contacted manufacturers of MOA to identify further data.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that assessed the effectiveness and safety of MOA for OIBD in people with cancer and people at a palliative stage irrespective of the type of terminal disease they experienced.

DATA COLLECTION AND ANALYSIS

Two review authors assessed risk of bias and extracted data. The appropriateness of combining data from the trials depended upon sufficient homogeneity across the trials. Our primary outcomes were laxation, impact on pain relief, and adverse events. Impact on pain relief was a primary outcome because a possible adverse effect of MOAs is a reduction in pain relief from opioids. We assessed the evidence on these outcomes using GRADE.

MAIN RESULTS

We identified four new trials for this update, bringing the total number included in this review to eight. In total, 1022 men and women with cancer irrespective of stage or at a palliative care stage of any disease were randomised across the trials. The MOAs evaluated were oral naldemedine and naloxone (alone or in combination with oxycodone), and subcutaneous methylnaltrexone. The trials compared with MOA with a placebo or with the active intervention administered at different doses or in combination with other drugs. The trial of naldemedine and the two of naloxone in combination with oxycodone were in people with cancer irrespective of disease stage. The trial on naloxone alone was in people with advanced cancer. The four trials on methylnaltrexone were undertaken in palliative care where most participants had cancer. All trials were vulnerable to biases; four were at a high risk as they involved a sample of fewer than 50 participants per arm.In the trial of naldemedine compared to placebo in 225 participants, there were more spontaneous laxations over the two-week treatment for the intervention group (risk ratio (RR) 1.93, 95% confidence intervals (CI) 1.36 to 2.74; moderate-quality evidence). In comparison with higher doses, lower doses resulted in fewer spontaneous laxations (0.1 mg versus 0.2 mg: RR 0.73, 95% CI 0.55 to 0.95; 0.1 mg versus 0.4 mg: RR 0.69, 95% CI 0.53 to 0.89; moderate-quality evidence). There was moderate-quality evidence that naldemedine had no effect on opiate withdrawal. There were five serious adverse events. All were in people taking naldemedine (low-quality evidence). There was an increase in the occurrence of other (non-serious) adverse events in the naldemedine groups (RR 1.36, 95% CI 1.04 to 1.79, moderate-quality evidence). The most common adverse event was diarrhoea.The trials on naloxone taken either on its own, or in combination with oxycodone (an opioid) compared to oxycodone only did not evaluate laxation response over the first two weeks of administration. There was very low-quality evidence that naloxone alone, and moderate-quality evidence that oxycodone/naloxone, had no effect on analgesia. There was low-quality evidence that oxycodone/naloxone did not increase the risk of serious adverse events and moderate-quality evidence that it did not increase risk of adverse events.In combined analysis of two trials of 287 participants, we found methylnaltrexone compared to placebo induced more laxations within 24 hours (RR 2.77, 95% CI 1.91 to 4.04. I² = 0%; moderate-quality evidence). In combined analysis, we found methylnaltrexone induced more laxation responses over two weeks (RR 9.98, 95% CI 4.96 to 20.09. I² = 0%; moderate-quality evidence). The proportion of participants who had a rescue-free laxation response within 24 hours of the first dose was 59.1% in the methylnaltrexone arms and 19.1% in the placebo arm. There was moderate-quality evidence that the rate of opioid withdrawal was not affected. Methylnaltrexone did not increase the likelihood of a serious adverse event; there were fewer in the intervention arm (RR 0.59, 95% CI 0.38 to 0.93; I² = 0%; moderate-quality evidence). There was no difference in the proportion of participants experiencing an adverse event (RR 1.17, 95% CI 0.94 to 1.45; I² = 74%; low-quality evidence). Methylnaltrexone increased the likelihood of abdominal pain and flatulence.Two trials compared differing methylnaltrexone schedules of higher doses with lower doses. For early laxation, there was low-quality evidence of no clear difference between doses on analgesia and adverse events. Both trials measured laxation response within 24 hours of first dose (trial one: RR 0.82, 95% CI 0.41 to 1.66; trial two: RR 1.07, 95% CI 0.81 to 1.42).

AUTHORS' CONCLUSIONS

In this update, the conclusions for naldemedine are new. There is moderate-quality evidence to suggest that, taken orally, naldemedine improves bowel function over two weeks in people with cancer and OIBD but increases the risk of adverse events. The conclusions on naloxone and methylnaltrexone have not changed. The trials on naloxone did not assess laxation at 24 hours or over two weeks. There is moderate-quality evidence that methylnaltrexone improves bowel function in people receiving palliative care in the short term and over two weeks, and low-quality evidence that it does not increase adverse events. There is a need for more trials including more evaluation of adverse events. None of the current trials evaluated effects in children.

Resource use and costs associated with opioid-induced constipation following total hip or total knee replacement surgery

Purpose

Constipation is a well-known complication of surgery that can be exacerbated by opioid analgesics. This study evaluated resource utilization and costs associated with opioid-induced constipation (OIC).

Patients and methods

This retrospective, observational, and propensity-matched cohort study utilized the Premier Healthcare Database. The study included adults ≥18 years of age undergoing total hip or total knee replacement as inpatients who received an opioid analgesic and were discharged between January 1, 2012, and June 30, 2015. Diagnosis codes identified patients with OIC who were then matched 1:1 to patients without OIC. Generalized linear and logistic regression models were used to compare inpatient resource utilization, total hospital costs, inpatient mortality, and 30-day all-cause readmissions and emergency department visits.

Results

Of 788,448 eligible patients, 40,891 (5.2%) had OIC. Covariates were well balanced between matched patients with and without OIC (n=40,890 each). In adjusted analyses, patients with OIC had longer hospital lengths of stay (3.6 versus 3.3 days; p<0.001), higher total hospital costs (US$17,479 versus US$16,265; p<0.001), greater risk of intensive care unit admission (odds ratio [OR]=1.12, 95% CI: 1.01-1.24), and increased likelihood of 30-day hospital read-missions (OR=1.16, 95% CI: 1.11-1.22) and emergency department visits (OR=1.38, 95% CI: 1.07-1.79) than patients without OIC. No statistically significant difference was found with inpatient mortality (OR=0.89, 95% CI: 0.59-1.35).

Conclusion

OIC was associated with greater resource utilization and hospital costs for patients undergoing primarily elective total hip or total knee replacement surgery. These results support OIC screening and management strategies as part of perioperative care management.

Long-term use of naldemedine in the treatment of opioid-induced constipation in patients with chronic noncancer pain: a randomized, double-blind, placebo-controlled phase 3 study

The long-term safety of naldemedine, a peripherally acting µ-opioid receptor antagonist, was evaluated in patients with opioid-induced constipation and chronic noncancer pain in a 52-week, randomized, double-blind, phase 3 study. Eligible adults who could be on a routine laxative regimen were randomized 1:1 to receive once-daily oral naldemedine 0.2 mg (n = 623) or placebo (n = 623). The primary endpoint was summary measures of treatment-emergent adverse events (AEs). Additional endpoints included opioid withdrawal on the Clinical Opiate Withdrawal Scale and the Subjective Opiate Withdrawal Scale, pain intensity on Numeric Rating Scale, frequency of bowel movements, and constipation-related symptoms and quality of life on the Patient Assessment of Constipation Symptoms and Patient Assessment of Constipation Quality of Life scales, respectively. Treatment-emergent AEs (naldemedine, 68.4% vs placebo, 72.1%; difference: -3.6% [95% confidence interval: -8.7 to 1.5]) and treatment-emergent AEs leading to study discontinuation (6.3% vs 5.8%; difference: 0.5% [-2.2 to 3.1)] were reported for similar proportions of patients. Diarrhea was reported more frequently with naldemedine (11.0%) vs placebo (5.3%; difference: 5.6% [2.6-8.6]). There were no meaningful differences between groups in opioid withdrawal or pain intensity. Sustained significant improvements in bowel movement frequency and overall constipation-related symptoms and quality of life were observed with naldemedine (P ≤ 0.0001 vs placebo at all time points). Naldemedine was generally well tolerated for 52 weeks and did not interfere with opioid-mediated analgesia or precipitate opioid withdrawal. Naldemedine significantly increased bowel movement frequency, improved symptomatic burden of opioid-induced constipation, and increased patients' quality of life vs placebo.

Analgesic Efficacy and Safety of Prolonged-Release Oxycodone/Naloxone in Korean Patients with Chronic Pain from Spinal Disorders

Background

A prolonged-release formulation of oxycodone/naloxone has been shown to be effective in European populations for the management of chronic moderate to severe pain. However, no clinical data exist for its use in Korean patients. The objective of this study was to assess efficacy and safety of prolonged-release oxycodone/naloxone in Korean patients for management of chronic moderate-to-severe pain.

Methods

In this multicenter, single-arm, open-label, phase IV study, Korean adults with moderate-to-severe spinal disorder-related pain that was not satisfactorily controlled with weak opioids and nonsteroidal anti-inflammatory drugs received prolonged-release oral oxycodone/naloxone at a starting dose of 10/5 mg/day (maximum 80/40 mg/day) for 8 weeks. Changes in pain intensity and quality of life (QoL) were measured using a numeric rating scale (NRS, 0–10) and the Korean-language EuroQol-five dimensions questionnaire, respectively.

Results

Among 209 patients assessed for efficacy, the mean NRS pain score was reduced by 25.9% between baseline and week 8 of treatment (p < 0.0001). There was also a significant improvement in QoL from baseline to week 8 (p < 0.0001). The incidence of adverse drug reactions was 27.7%, the most common being nausea, constipation, and dizziness; 77.9% of these adverse drug reactions had resolved or were resolving at the end of the study.

Conclusions

Prolonged-release oxycodone/naloxone provided significant and clinically relevant reductions in pain intensity and improved QoL in Korean patients with chronic spinal disorders. (ClinicalTrials.gov identifier: NCT01811238)

Clinical Pharmacokinetics and Pharmacodynamics of Naloxegol, a Peripherally Acting µ-Opioid Receptor Antagonist

Naloxegol is a peripherally acting µ-opioid receptor antagonist approved for use as an orally administered tablet (therapeutic doses of 12.5 and 25 mg) for the treatment of opioid-induced constipation. Over a wide dose range (i.e. single supratherapeutic doses up to 1000 mg in healthy volunteers), the pharmacokinetic properties of naloxegol appear to be time- and dose-independent. Naloxegol is rapidly absorbed, with mean time to maximum plasma concentration of <2 h. Following once-daily administration, steady state is achieved within 2-3 days and minimal accumulation is observed. The primary route of naloxegol elimination is via hepatic metabolism, with renal excretion playing a minimal role. In clinical studies, six metabolites were found in feces, urine or plasma, none of which have been identified as unique or disproportionate human metabolites. The major plasma circulating species is naloxegol. There are small effects of mild and moderate renal impairment, age, race, and body mass index on the systemic exposure of naloxegol; however, gender has no effect on the pharmacokinetics of this agent. Naloxegol is a sensitive substrate of cytochrome P450 (CYP) 3A4 and its exposure can be significantly altered by strong or moderate CYP3A modulators. Food increases the bioavailability of naloxegol, and the relative bioavailability of the tablet formulation was not limited by dissolution. Naloxegol in the dose range of 8-125 mg can antagonize morphine-induced peripheral effects without impacting the effect of morphine on the central nervous system, consistent with a peripheral mode of action.

Prolonged-release oxycodone/naloxone reduces opioid-induced constipation and improves quality of life in laxative-refractory patients: results of an observational study

Background

Opioids are an effective treatment for moderate-to-severe pain. However, they are associated with a number of gastrointestinal side effects, most commonly constipation. Laxatives do not target the underlying mechanism of opioid-induced constipation (OIC), so many patients do not have their symptoms resolved. Fixed-dose prolonged-release (PR) oxycodone/naloxone (OXN) tablets contain the opioid agonist oxycodone and the opioid antagonist naloxone. Nal-oxone blocks the action of oxycodone in the gut without compromising its analgesic effects.

Aim

To evaluate the effectiveness of PR OXN in patients with severe pain who had laxative-refractory OIC with their previous opioid.

Methods

The study was carried out in 13 centers across the UK and Ireland, using a bespoke online tool to capture patients’ data. Patients were reviewed according to normal clinical practice of each center and rated any changes in their constipation and quality of life (QoL) since starting PR OXN. Any change in patients’ laxative use was also recorded.

Results

One hundred and seven patients were entered into the database, and 81 went on to attend at least one review. Of these, 54 (66.7%) reported an improvement in constipation and 50 (61.7%) reported an improvement in QoL since starting PR OXN. Fifty-seven patients (70.4%) said they had reduced laxative intake; 48 (59.3%) only needed laxatives as required.

Conclusion

PR OXN reduced symptoms of constipation, improved QoL and reduced laxative intake in patients with OIC. It has a potential place early in any treatment strategy for severe pain in patients using opioids, particularly in patients who may be predisposed to constipation.

Prolonged release oxycodone and naloxone treatment counteracts opioid-induced constipation in patients with severe pain compared to previous analgesic treatment

OBJECTIVE

Treatment with prolonged-release oxycodone/naloxone (PR OXN) has been shown to improve opioid induced constipation (OIC) in constipated patients. This publication reports on a real-life observational study investigating the efficacy of PR OXN with regard to bowel function in patients switching to PR OXN from WHO step 1, step 2 and step 3 opioids.

METHODS

Patients with chronic pain experiencing insufficient pain relief and/or unacceptable side effects were switched to PR OXN and monitored in this observational study with respect to efficacy regarding bowel function and efficacy regarding pain relief in comparison with previous analgesic therapy. A patient was considered a responder with respect to efficacy if this assessment was "slightly better", "better" or "much better" compared with previous therapy. Bowel function index, pain intensity, quality of life, laxative medication use, and safety analgesic were also evaluated.

RESULTS

A total of 1338 patients (mean [SD] age 64.3 [14.9], 63% female) were observed for 43 [3-166] days (median [range]) during treatment with PR OXN. Overall response rate regarding bowel function efficacy was 82.5%. Patients with symptoms of constipation at study entry obtained a clinically relevant improvement of the bowel function index (BFI) within the first 2 weeks of PR OXN treatment. Non-constipated patients at study entry maintained normal bowel function despite switching to treatment with the opioid PR OXN.

CONCLUSION

In conclusion, treatment with PR OXN results in a significant and clinically relevant improvement of bowel function. During the observation of the treatment with PR OXN patients reported an improvement of quality of life (QoL). More interestingly, non-constipated patients maintained a normal bowel function, showing prevention of constipation despite the use of an opioid.