Methylnaltrexone for opioid-induced constipation in advanced illness. Methylnaltrexone for reversal of constipation due to chronic methadone use: a randomized controlled trial. Methylnaltrexone for treatment of opioid-induced constipation in advanced illness patients. Subcutaneous methylnaltrexone for the treatment of opioid-induced constipation in patients with advanced illness: a double-blind, randomized, parallel group, dose-ranging study. Managing morphine-induced constipation: a controlled comparison of an Ayurvedic formulation and senna. A controlled trial of 'Senokot' in faecal soiling treated by behavioural methods. Randomised trial of laxatives in treatment of childhood encopresis. Lack of benefit of laxatives as adjunctive therapy for functional nonretentive fecal soiling in children. An investigation of the ability of oral naloxone to correct opioid-related constipation in patients with advanced cancer.
Constipation is a distressing side effect of opioid treatment. As a quaternary amine, methylnaltrexone, a mu-opioid-receptor antagonist, has restricted ability to cross the blood-brain barrier. We investigated the safety and efficacy of subcutaneous methylnaltrexone for treating opioid-induced constipation in patients with advanced illness.
                A total of 133 patients who had received opioids for 2 or more weeks and who had received stable doses of opioids and laxatives for 3 or more days without relief of opioid-induced constipation were randomly assigned to receive subcutaneous methylnaltrexone (at a dose of 0.15 mg per kilogram of body weight) or placebo every other day for 2 weeks. Coprimary outcomes were laxation (defecation) within 4 hours after the first dose of the study drug and laxation within 4 hours after two or more of the first four doses. Patients who completed this phase were eligible to enter a 3-month, open-label extension trial.
                In the methylnaltrexone group, 48% of patients had laxation within 4 hours after the first study dose, as compared with 15% in the placebo group, and 52% had laxation without the use of a rescue laxative within 4 hours after two or more of the first four doses, as compared with 8% in the placebo group (P<0.001 for both comparisons). The response rate remained consistent throughout the extension trial. The median time to laxation was significantly shorter in the methylnaltrexone group than in the placebo group. Evidence of withdrawal mediated by central nervous system opioid receptors or changes in pain scores was not observed. Abdominal pain and flatulence were the most common adverse events.
                Subcutaneous methylnaltrexone rapidly induced laxation in patients with advanced illness and opioid-induced constipation. Treatment did not appear to affect central analgesia or precipitate opioid withdrawal. (Clinical Trials.gov number, NCT00402038 [ClinicalTrials.gov].).
                Copyright 2008 Massachusetts Medical Society. Constipation is the most common chronic adverse effect of opioid pain medications in patients who require long-term opioid administration, such as patients with advanced cancer, but conventional measures for ameliorating constipation often are insufficient.
                To evaluate the efficacy of methylnaltrexone, the first peripheral opioid receptor antagonist, in treating chronic methadone-induced constipation.
                Double-blind, randomized, placebo-controlled trial conducted between May 1997 and December 1998.
                Clinical research center of a university hospital.
                Twenty-two subjects (9 men and 13 women; mean [SD] age, 43.2 [5.5] years) enrolled in a methadone maintenance program and having methadone-induced constipation.
                Laxation response, oral-cecal transit time, and central opioid withdrawal symptoms were compared between the 2 groups.
                The 11 subjects in the placebo group showed no laxation response, and all 11 subjects in the intervention group had laxation response after intravenous methylnaltrexone administration (P<.001). The oral-cecal transit times at baseline for subjects in the methylnaltrexone and placebo groups averaged 132.3 and 126.8 minutes, respectively. The average (SD) change in the methylnaltrexone-treated group was -77.7 (37.2) minutes, significantly greater than the average change in the placebo group (-1.4 [12.0] minutes; P<.001). No opioid withdrawal was observed in any subject, and no significant adverse effects were reported by the subjects during the study.
                Our data demonstrate that intravenous methylnaltrexone can induce laxation and reverse slowing of oral cecal-transit time in subjects taking high opioid dosages. Low-dosage methylnaltrexone may have clinical utility in managing opioid-induced constipation. Methylnaltrexone, a peripheral mu-opioid receptor antagonist with restricted ability to cross the blood-brain barrier, may relieve opioid-induced constipation (OIC) without reversing analgesia. A total of 154 patients with advanced illness and OIC enrolled in a double-blind, randomized, placebo-controlled trial, with optional open-label phases (up to 4 months) in hospice and palliative care centers during 2003-2005. They received a single subcutaneous injection of methylnaltrexone (0.15 mg/kg or 0.3 mg/kg) or placebo. Laxation response within 4 hours was 62% and 58% for methylnaltrexone 0.15 mg/kg and 0.3 mg/kg, respectively, compared with 14% for placebo (P < 0.0001; each dose vs placebo). Approximately half of the methylnaltrexone responders defecated within 30 minutes of dosing. Open-label phase response rates mirrored those for methylnaltrexone during the double-blind phase.There was no change in pain scores or evidence of central opioid withdrawal.The most common adverse events (AEs) were abdominal pain and flatulence.Three patients had serious AEs attributed to methylnaltrexone. Subcutaneous methylnaltrexone was efficacious in rapidly inducing laxation and was generally well tolerated in patients with advanced illness and OIC. Methylnaltrexone, a peripherally-acting quaternary opioid antagonist, is an investigational treatment for opioid-induced constipation in patients with advanced illness. This randomized, parallel-group, repeated dose, dose-ranging trial included a double-blind phase for one week followed by an open-label phase for a maximum of three weeks. Opioid-treated patients with advanced illness who met criteria for opioid-induced constipation despite laxative therapy were potentially eligible. Double-blind treatment occurred on Days 1, 3, and 5; open-label therapy could be administered as often as every other day. The initial dose range of 1mg, 5mg, or 12.5mg was extended by adding a 20mg group during the study while still maintaining the double blind; the initial open-label dose of 5mg could be titrated. The primary outcome was a laxation response within four hours after the first dose. Thirty-three patients received at least one dose of methylnaltrexone. Only one of 10 patients (10%) who received the 1mg dose experienced laxation within four hours of dosing. The median time to laxation was >48 hours for the 1mg dose group, compared to 1.26 hours for all patients receiving >or=5mg (P=0.0003). There was no apparent dose-response above 5mg. Most adverse events were related to the gastrointestinal system, were mild, and did not lead to discontinuation. In conclusion, methylnaltrexone relieved opioid-induced constipation at doses >or=5mg in patients with advanced illness, and did not reduce analgesia or cause opioid withdrawal symptoms. Constipation is a frequent cause of distress in advanced cancer. A palliative care unit in Kerala, a southern state of India, conducted a controlled trial comparing a liquid Ayurvedic (herbal) preparation (Misrakasneham) with a conventional laxative tablet (Sofsena) in the management of opioid-induced constipation in patients with advanced cancer. Although there was no statistically significant difference in the apparent degree of laxative action between the two, the results indicate that the small volume of the drug required for effective laxative action, the tolerable taste, the once-daily dose, the acceptable side effect profile, and the low cost make Misrakasneham a good choice for prophylaxis in opioid-induced constipation. There is a need for further studies of Ayurvedic medicines in palliative care. A double-blind randomly controlled trial of one particular laxative, Senokot, used in moderate dosage, was carried out on a group of 40 children with severe and persistent soiling and often with a history of faecal retention. Significant improvement occurred following three months of outpatient treatment using a behavioural approach and either Senokot, placebo or no medication. However, there was no evidence either during the trial or subsequently when Senokot was employed to supplement behavioural treatment in every child who continued with therapy that this laxative contributed in any way to relieving the problem in this group of cases. Primary faecal incontinence (encopresis) in children is usually treated with laxative medication and a behaviour modification programme aimed at promoting regular toileting, but the effectiveness of laxatives has never been adequately investigated. 169 children with encopresis and evidence of stool on plain abdominal radiograph were randomly allocated to receive multimodal (MM) therapy (laxatives plus behaviour modification; n = 83) or behaviour modification alone (BM; n = 86). Mean (SD) follow-up was 55.1 (27.0) weeks and 56.7 (32.0) weeks, respectively. By 12 months' follow-up 42 (51%) of the MM group and 31 (36%) of the BM group (p = 0.079) had achieved remission (at least one 4 week period with no soiling episodes) and 52 (63%) vs 37 (43%) (p = 0.016) had achieved at least partial remission (soiling no more than once a week). MM subjects achieved remission significantly sooner than BM subjects, and the difference in the Kaplan-Meier remission curves was most striking in the first 30 weeks of follow-up (p = 0.012). The patterns of compliance with toileting in the treatment groups were almost identical, although about 1 in 8 children overall did not comply with the sitting programme. After exclusion of the 24 poor compliers, there was no significant difference between BM and MM groups. This study shows a clear advantage overall for the use of laxative medication, although the benefit may not be as great for children who are able to maintain regular toileting. To determine whether the combination of laxative treatment and biofeedback therapy (BF) is more effective for management of functional nonretentive fecal soiling than biofeedback therapy alone.
                In a prospective nonblinded study, 48 children were randomized in 2 groups: treatment with oral laxatives (LAX) and 5 sessions of BF (BF + LAX) or 5 sessions of BF alone (BF) during a treatment intervention period of 7 weeks. Biofeedback was performed with perfused manometry catheters and rectal balloon distension. Training focused on awareness of balloon distension and instruction in correct defecation dynamics. Successful treatment was defined as <1 encopresis episode per 2 weeks.
                At the end of the intervention period, the number of encopresis episodes was significantly decreased in both groups: from 7 (2 to 24) to 2 (0 to 17) in the BF group and from 7 (3 to 25) to 2 (0 to 14) in the BF + LAX group. However, children given BF alone had significantly higher success rates than children treated with BF and additional oral laxatives (44% to 11%).
                There is no additional effect of laxative treatment in functional nonretentive fecal soiling. Children treated with BF in combination with laxatives showed a significantly lower success percentage compared with those treated with BF alone. These results suggest that children with functional nonretentive fecal soiling should be treated differently from children with constipation and encopresis. A dose-ranging study of the use of oral naloxone in opioid-related constipation in patients with far-advanced cancer is reported. Naloxone doses were calculated as a percentage of the morphine dose each patient was receiving. Seventeen patients entered the first phase of the study, which had a randomised, double-blind design. Outcome measures were small bowel transit time (SBTT) measured by the lactulose/hydrogen breath test, pain scores and the occurrence of adverse events. One subject was excluded before receiving naloxone. No significant difference between placebo and naloxone occurred in the 14 remaining patients receiving total daily doses of naloxone 10% or less of the 24 h dose of morphine. Two further patients experienced a marked laxative effect with naloxone at 20% of the 24 h dose of morphine. In one of these, SBTT was available and was unchanged from placebo. The other declined to continue with SBTT measurement. Phase two of the study had an open design, in which laxative effects were determined clinically. Naloxone at a maximum dose level of 20% was given to seven patients, up to 40% to two patients and up to 80% to one patient. Four out of the seven patients in the 20% dose level group, and all of the remainder, experienced laxative effects. Two patients experienced symptoms of opioid withdrawal, one of whom also had return of pain. It is concluded that oral naloxone at a daily dose of 20% or more of the prevailing 24 h morphine dose is a potentially valuable therapy for opioid-related constipation. However, opioid withdrawal was observed and it is suggested that initial individual naloxone doses should not exceed 5 mg. Further research is needed into the oral absorption of naloxone, as well as further studies of clinical efficacy and dosing.
The 2010 update found evidence on laxatives for management of constipation remains limited due to insufficient RCTs. However, the conclusions of this update have changed since the original review publication in that it now includes evidence on methylnaltrexone. Here it found that subcutaneous methylnaltrexone is effective in inducing laxation in palliative care patients with opioid-induced constipation and where conventional laxatives have failed. However, the safety of this product is not fully evaluated. Large, rigorous, independent trials are needed.