Management of opioid-induced constipation in cancer patients: focus on methylnaltrexone

Acupuncture Relieves Opioid-Induced Constipation in Clinical Cancer Therapy - A Meta-Analysis and Systematic Review

Cancer pain is a common problem in clinical cancer therapy. Opioid analgesia is one of the most effective drugs for pain relief with satisfying performance besides the side effect of opioid-induced constipation (OIC). Acupuncture, as a Chinese traditional non-invasive intervention, has been applied to clinical cancer pain management and functional constipation therapy. However, only a few studies have adopted this treatment for OIC patients. Due to limited numbers of investigated subjects and variability of application methods, including treatment apparatus, acupoints, durations, and sessions, the interpretation of acupuncture’s therapy effects from single-site randomized clinical trials (RCT) is limited. Therefore, we conducted a meta-analysis by collecting published data from Pubmed, Embase, Cochrane library, and Web of Science. Five RCTs focusing on the application of acupuncture with or without medication in OIC patients were included. An overall remission rate of 86.8% in the acupuncture-treated group was achieved, higher than the control group (78.9%; RR, 1.10, 95% CI [1.03, 1.18]). The symptom scores, reporting on defecation frequency, defecation straining, abdominal pain, defection time, and stool property, in acupuncture groups were lower than control groups with a standardized mean difference (SMD) of −2.21 [−4.15, −0.27]. The quality of life (QOL) for patients in the acupuncture treated group increased compared to the control group with reduced PAC-QOL scores (SMD, −1.02 [−1.78, −0.26]). Referring to the effects from pure acupuncture treatment (SMD, −0.43 [−0.83, −0.03]), the co-intervention of acupuncture and drugs (SMD, −1.77 [−2.51, −1.02]) improved the life quality of patients more remarkably (P < 0.05). Overall, our data confirmed the therapeutic effects of acupuncture in the treatment of OIC. The co-intervention of acupuncture with drugs improves the outcomes of OIC patients better than a single strategy. Combined therapy with both medicine and acupuncture has insightful potential for future clinical cancer patient management on constipation problems.

HeTDR: Drug repositioning based on heterogeneous networks and text mining

Using existing knowledge to carry out drug-disease associations prediction is a vital method for drug repositioning. However, effectively fusing the biomedical text and biological network information is one of the great challenges for most current drug repositioning methods. In this study, we propose a drug repositioning method based on heterogeneous networks and text mining (HeTDR). This model can combine drug features from multiple drug-related networks, disease features from biomedical corpora with the known drug-disease associations network to predict the correlation scores between drug and disease. Experiments demonstrate that HeTDR has excellent performance that is superior to that of state-of-the-art models. We present the top 10 novel HeTDR-predicted approved drugs for five diseases and prove our model is capable of discovering potential candidate drugs for disease indications.

Peripherally acting μ-opioid receptor antagonists for treatment of opioid-induced constipation in children

BACKGROUND AND OBJECTIVE

Opioid-induced constipation (OIC) is a common and important problem in paediatric palliative care, critical care, and postoperative settings. Treatment for OIC is often ineffective and limited by enteral intake. A new class of drugs called peripherally acting mu-opioid receptor antagonists (PAMORAs) have been shown to be effective treatments of OIC in adults, including the agents methylnaltrexone and naloxegol. Data in children are limited to several small case reports, mostly in the palliative care setting. The goal of this study was to evaluate the effectiveness and safety of methylnaltrexone and naloxegol in hospitalized children, including those with critical illness.

METHODS

We conducted a retrospective study of all children admitted to the Stollery Children's Hospital in Edmonton (Canada) who received either methylnaltrexone or naloxegol for OIC. The primary outcome was median time to first bowel movement (BM) after the first dose of PAMORA.

RESULTS

A total of 27 patients were included in the study. Kaplan-Meier survival analysis showed the median time to the first BM after the first dose of PAMORA was 15.5 hours. Seventeen (63%) patients had laxation within 24 hours of first dose. No significant adverse events were observed.

CONCLUSION

This study is the largest to date to evaluate efficacy and safety of PAMORAs in children. Future studies should be prospective and include larger numbers of patients with critical illness and postoperative OIC as indications for treatment.

Rates of appropriate laxative prophylaxis for opioid-induced constipation in veterans with lung cancer: a retrospective cohort study

PURPOSE

Opioid-induced constipation (OIC) is the most common side effect in patient-prescribed opioids for cancer pain treatment. Current guidelines recommend routine prescription of a laxative for preventing OIC in all patients prescribed an opioid unless a contraindication exists. We determined patterns of prescription of laxative agents in patients with lung cancer initiating opioids.

METHODS

We performed a retrospective cohort study evaluating the prescription of laxatives for OIC to adult patients with incident lung cancer seen in the Veteran's Affairs (VA) system, between January 1, 2003, and December 31, 2016. Exposure to laxative agents was categorized as follows: none, docusate monotherapy, docusate plus another laxative, and other laxatives only. Prevalence of OIC prophylaxis was analyzed using descriptive statistics. Linear regression was performed to identify time trends in the prescription of OIC prophylaxis.

RESULTS

Overall, 130,990 individuals were included in the analysis. Of these, 87% of patients received inadequate prophylaxis (75% no prophylaxis and 12% docusate alone), while 5% received OIC prophylaxis with the unnecessary addition of docusate to another laxative. Through the study period, laxative prescription significantly decreased, while all other categories of OIC prophylaxis were unchanged. We noted an inverse relationship with OIC prophylaxis and likelihood of a diagnosis of constipation at 3 and 6 months.

CONCLUSIONS

In this study of veterans with lung cancer, almost 90% received inadequate or inappropriate OIC prophylaxis. Efforts to educate physicians and patients to promote appropriate OIC prophylaxis in combination with systems-level changes are warranted.

Evaluation of Quality of Life Outcomes Following Palliative Treatment of Bone Metastases with Magnetic Resonance-guided High Intensity Focused Ultrasound: An International Multicentre Study

AIMS

To determine quality of life (QoL) outcomes after palliation of pain from bone metastases using magnetic resonance-guided high intensity focused ultrasound (MR-guided HIFU), measured using the European Organization for Research and Treatment of Cancer (EORTC) QLQ-C15-PAL and the QLQ-BM22 questionnaires.

MATERIALS AND METHODS

Twenty patients undergoing MR-guided HIFU in an international multicentre trial self-completed the QLQ-C15-PAL and QLQ-BM22 questionnaires before and on days 7, 14, 30, 60 and 90 post-treatment. Descriptive statistics were used to represent changes in symptom and functional scales over time and to determine their clinical significance. QoL changes were compared in pain responders and non-responders (who were classified according to change in worst pain score and analgesic intake, between baseline and day 30).

RESULTS

Eighteen patients had analysable QoL data. Clinically significant improvements were seen in the QoL scales of physical functioning, fatigue, appetite loss, nausea and vomiting, constipation and pain in the 53% of patients who were classified as responders at day 30. No significant changes were seen in the 47% of patients who were non-responders at this time point.

CONCLUSION

Local treatment of pain from bone metastases with MR-guided HIFU, even in the presence of disseminated malignancy, has a substantial positive effect on physical functioning, and improves other symptomatic QoL measures. This indicated a greater response to treatment over and above pain control alone. MR-guided HIFU is non-invasive and should be considered for patients with localised metastatic bone pain and poor QoL.

Chemotherapy-Induced Constipation and Diarrhea: Pathophysiology, Current and Emerging Treatments

Gastrointestinal (GI) side-effects of chemotherapy are a debilitating and often overlooked clinical hurdle in cancer management. Chemotherapy-induced constipation (CIC) and Diarrhea (CID) present a constant challenge in the efficient and tolerable treatment of cancer and are amongst the primary contributors to dose reductions, delays and cessation of treatment. Although prevalence of CIC is hard to estimate, it is believed to affect approximately 16% of cancer patients, whilst incidence of CID has been estimated to be as high as 80%. Despite this, the underlying mechanisms of both CID and CIC remain unclear, but are believed to result from a combination of intersecting mechanisms including inflammation, secretory dysfunctions, GI dysmotility and alterations in GI innervation. Current treatments for CIC and CID aim to reduce the severity of symptoms rather than combating the pathophysiological mechanisms of dysfunction, and often result in worsening of already chronic GI symptoms or trigger the onset of a plethora of other side-effects including respiratory depression, uneven heartbeat, seizures, and neurotoxicity. Emerging treatments including those targeting the enteric nervous system present promising avenues to alleviate CID and CIC. Identification of potential targets for novel therapies to alleviate chemotherapy-induced toxicity is essential to improve clinical outcomes and quality of life amongst cancer sufferers.

Off-label uses of alvimopan and methylnaltrexone

PURPOSE

Off-label uses of the peripheral μ-opioid receptor antagonists alvimopan and methylnaltrexone are reviewed.

SUMMARY

Alvimopan is approved by the Food and Drug Administration (FDA) for postoperative ileus after surgeries that include partial bowel resection with primary anastomosis, while methylnaltrexone is approved for the treatment of opioid-induced constipation (OIC) in patients with advanced illness who are receiving palliative care. Literature describing the off-label use of alvimopan in the treatment of OIC and of methylnaltrexone in postoperative ileus was reviewed and included retrospective studies and prospective Phase II-IV trials. Randomized controlled trials did not demonstrate consistent benefit of alvimopan in OIC nor of methylnaltrexone in postoperative ileus. A greater proportion of patients receiving alvimopan for OIC experienced severe adverse cardiovascular events, leading to a risk evaluation and mitigation strategy and discontinuation of its study in this condition. Data are limited and unreplicated for the off-label use of alvimopan for postoperative ileus in patients undergoing abdominal hysterectomy. Individual studies suggest benefit with methylnaltrexone for OIC in unlabeled populations, including patients with non-cancer-related pain, opioid dependence, opioid sedation, and opioid use after orthopedic surgery; however, confirmatory evaluations have not been performed.

CONCLUSION

Trials of alvimopan in the FDA-approved use of methylnaltrexone (OIC) indicate potentially serious cardiovascular safety concerns and conflicting findings of efficacy. Similarly, trials of methylnaltrexone in the FDA-approved use of alvimopan (postoperative ileus) consistently showed no benefit. Evaluations of both drugs in their labeled conditions in populations not endorsed in their product labeling have been limited and largely unreplicated.

Methylnaltrexone: its pharmacological effects alone and effects on morphine in healthy volunteers

RATIONALE

Methylnaltrexone bromide (MTNX) is a peripherally acting mu-opioid receptor antagonist, prescribed for the treatment of opioid-induced constipation in patients with advanced illness who are receiving palliative care. Studies have used this drug to determine if other opioid-induced effects besides constipation are altered by MTNX in humans and have suggested, based on their results, that these other effects are altered by peripheral opioid actions.

OBJECTIVE

The primary objective of this report is to present results that provide indirect evidence that MTNX has centrally mediated effects, albeit slight, and secondarily to describe the effects of MTNX on psychopharmacological effects of morphine.

METHODS

In a crossover, randomized, placebo-controlled, double-blind study, 29 healthy volunteers received 0.45 mg/kg MTNX or saline subcutaneously, followed by saline intravenously. In three other conditions, 0.143 mg/kg of morphine sulfate administered intravenously was preceded by subcutaneous administration of 0, 0.225, or 0.45 mg/kg MTNX. Before and after drug administration, subjective and physiological measures, including pupil diameter, were assessed.

RESULTS

Two separate analyses confirmed that 0.45 mg/kg MTNX alone induced a slight degree of miosis, a centrally mediated opioid agonist effect. This dose had minimal subjective effects. MTNX at either or both the 0.225 and 0.45 mg/kg dose reduced some subjective effects of morphine without altering miosis.

CONCLUSIONS

We present indirect evidence that MTNX crosses the blood-brain barrier in humans. Therefore, whether the reductions in subjective effects of morphine by MTNX that were observed in past studies and in this study can be attributed to peripheral mechanisms is open to question.

Circular muscle contraction in the mice rectum plays a key role in morphine-induced constipation

BACKGROUND

Although opioids induce intestinal muscle contraction and provoke constipation, the intestinal region(s) that contribute to the constipation have remained unclear. We report here a region-specific response of intestinal muscle contraction to morphine and its correlation with in vivo constipation.

METHODS

Regions of mice small and large intestines were dissected histologically and circular muscle contractile responses were measured using isometric transducers. Bead expulsion assays were performed to assess in vivo constipation.

KEY RESULTS

The strongest contraction in response to morphine was detected in the rectum. The distal and transverse colon also showed strong contractions, whereas weak responses were detected in the proximal colon, jejunum, and ileum. Regarding the sustainability of muscle contractions during morphine exposure, prolonged waves were detected only in the rectum, while the waves diminished gradually in other regions. To identify the mechanism(s) underlying this difference, we focused on nitric oxide synthase (NOS). In the distal colon, decreased contraction during morphine exposure was recovered by application of a NOS inhibitor (L-NAME), while a NOS substrate (L-arginine) enhanced contractile degradation. In contrast L-NAME and L-arginine modestly affected the sustained contraction in the rectum. To confirm the correlation with constipation, beads were inserted into the transverse colon, distal colon, or rectum after morphine administration and expulsion times were examined. Beads tended to stop at the rectum even when inserted in the deeper colonic regions.

CONCLUSIONS & INFERENCES

The rectum showed the greatest response to morphine in both in vitro and in vivo analyses, therefore it may play a key role for opioid-induced constipation.

Comparative effectiveness of senna to prevent problematic constipation in pediatric oncology patients receiving opioids: a multicenter study of clinically detailed administrative data

CONTEXT

Pediatric oncology patients often receive prolonged courses of opioids, which can result in constipation.

OBJECTIVES

Comparing patients who received senna matched with similar patients who received other oral bowel medications, determine the subsequent risk of "problematic constipation," assessed as the occurrence of the surrogate markers of receiving an enema, escalation of oral bowel medications, and abdominal radiographic imaging.

METHODS

This was a retrospective cohort study of hospitalized pediatric oncology patients less than 21 years of age in 78 children's and adult hospitals between 2006 and 2011 who were started on seven consecutive days or more of opioid therapy and were started on an oral bowel medication within the first two days of opioid therapy. Clinically detailed administrative data were used from the Pediatric Health Information System and the Premier Perspective Database. After performing propensity score matching of similar patients who started senna and who started a different oral bowel medication, Cox regression modeling was used to compare the subsequent hazard of the surrogate markers.

RESULTS

The final matched sample of 586 patients averaged 11.5 years of age (range 0-20 years); 41.8% (n = 245) had blood cancer, 50.3% (n = 295) had solid tumor cancer, and 7.9% (n = 46) had brain cancer. Initiating senna therapy within two days of starting the prolonged opioid course, compared with initiating another oral bowel medication, was significantly associated with a lower hazard during the ensuing five days for receipt of an enema (hazard ratio [HR], 0.31; 95% CI, 0.11-0.91) or undergoing abdominal radiographic imaging (HR, 0.74; 95% CI, 0.55-0.98), was marginally associated with a lower hazard of oral bowel medicine escalation (HR, 0.78; 95% CI, 0.59-1.03), and overall was significantly associated with a lower hazard of the composite end point of problematic constipation (HR, 0.70; 95% CI, 0.56-0.88).

CONCLUSION

Initiating senna therapy, compared with other oral bowel medications, diminishes the subsequent risk of surrogate markers of problematic constipation in this population.

Efficacy and gastrointestinal tolerability of oral oxycodone/naloxone combination for chronic pain in outpatients with cancer: an observational study

Combination opioid agonist/antagonist therapy has been shown to preserve bowel function in patients with chronic cancer pain. This retrospective study evaluated the efficacy and tolerability of prolonged-released fixed-dose oxycodone-naloxone (PR OXN) in consecutive outpatients with chronic cancer pain. Of 206 patients prescribed PR OXN (mean age 61.3 ± 12.9 years; 52.9% female), 31.5% were opioid naïve. PR OXN was associated with a significant decrease in pain score measured on a visual analogue scale over 28 days (P < .0001), without adverse effects on bowel function, nor change in laxative use. PR OXN efficacy and tolerability were similar in opioid-naïve and -experienced patients, and among age-stratified subgroups. No severe side effects occurred. In a real-life outpatient setting, PR OXN provided analgesia without bowel dysfunction in patients with chronic cancer pain.

A critical appraisal of lubiprostone in the treatment of chronic constipation in the elderly

Chronic constipation is a common disorder in the general population, with higher prevalence in the elderly, and is associated with worse quality of life and with greater health care utilization. Lubiprostone is an intestinal type-2 chloride channel activator that increases intestinal fluid secretion, small intestinal transit, and stool passage. Lubiprostone is currently approved by the US Food and Drug Administration for the treatment of chronic idiopathic constipation and of irritable bowel syndrome with predominant constipation. This review outlines current approaches and limitations in the treatment of chronic constipation in the elderly and discusses the results, limitations, and applicability of randomized, controlled trials of lubiprostone that have been conducted in the general and elderly population, with additional focus on the use of lubiprostone in constipation in Parkinson's disease and in opioid-induced constipation, two clinical entities that can be comorbid in elderly patients.

Prolonged-release oxycodone/naloxone in nonmalignant pain: single-center study in patients with constipation

INTRODUCTION

Opioid treatment for chronic malignant and nonmalignant pain of moderateto-severe intensity is associated with bowel dysfunction leading to constipation; this often requires opioid dose reduction or interruption. Combination opioid agonist/antagonist therapy can restore normal bowel function. A prolonged-released (PR) fixed-dose combination of oxycodone and naloxone has been developed and efficacy has been demonstrated in phase 3 clinical trials.

METHODS

This 2-month, retrospective, singlecenter, observational study assessed the effectiveness and safety of PR oxycodone/naloxone in consecutive nononcological patients with constipation and chronic pain despite analgesic treatment; specific subgroup analyses were performed in opioid-experienced or opioid-naïve patients and in age subgroups. Efficacy was assessed by: intensity of pain; bowel function; effective oxycodone/naloxone dose; Patients' Global Impression of Change (PGIC) scale; rescue paracetamol; and laxative use. Safety evaluations were also performed.

RESULTS

Of 1,051 patients starting on the oxycodone/naloxone combination (32.0% male; mean age 67 ± 13 years, 53.9% opioid naïve), 1,012 completed 2 months of treatment. Overall, PR oxycodone/naloxone was associated with a significant decrease in pain intensity (P < 0.001), a reduced need for rescue paracetamol (P < 0.001), and PGIC score of "very much improved" or "much improved" in 84.0% of patients. Constipation markedly decreased (P < 0.001) despite reduced laxative use (P < 0.001 vs. baseline). The most frequent treatment-emergent adverse events were somnolence (2.0%), dizziness (1.1%), and confusion (1.0%). Clinical differences in endpoints were seen between opioid-naïve and opioid-experienced patients, and among agestratified groups, but efficacy was similar to the overall population.

CONCLUSIONS

Fixed combination PR oxycodone/naloxone was effective and well tolerated in moderate-to-severe chronic pain in patients with constipation, providing analgesia and relief from bowel dysfunction. Consistent efficacy across patient subgroups provides guidance for daily management of chronic pain when therapy options are limited due to bowel dysfunction, regardless of age or previous medication. Supplementary material belonging to this paper is available on SpringerLink.

Augmented breaths ('sighs') are suppressed by morphine in a dose-dependent fashion via naloxone-sensitive pathways in adult rats

Morphine treatment can eliminate augmented breaths (ABs; 'sighs') during spontaneous breathing. In the present study, unanesthetized rats were studied to: (1) determine the involvement of naloxone-sensitive receptor pathways, and (2) establish the dose-response relationship of this side effect. At a dosage of 5mg/kg (2-10mg/kg is recommended range for analgesia) morphine eliminated ABs from the breathing rhythm across nearly 100 min post-administration (vs. 6.2 ± 1.6 ABs in 15 min, control condition, p<0.001). This occurred despite no apparent effect on indices of ventilation. By contrast, when naloxone was co-administered with morphine, the occurrence of ABs was not different compared to control. The suppression of ABs by morphine followed a sigmoidal pattern across the low-mid dosage range (R(2)=0.83), whereas tidal volume and breathing frequency were unaffected. We conclude that the opioid-induced suppression of ABs is mediated by naloxone-sensitive opioid receptor pathways, and that this side effect is potent across the low-mid dosage range, and cannot be simply avoided by restricting dosage.