Relistor (methylnaltrexone bromide) / Ono Pharmaceutical, Lantheus, Bausch Health - LARVOL DELTA

Small Bowel Pseudo-Obstruction Mimicking Ogilvie Syndrome: A Case of Extreme Intestinal Dilation in a Post-Colectomy Patient (ACG 2026) - "Neostigmine was contraindicated due to chronic hypotension on midodrine...Methylnaltrexone was administered adjunctively, though evidence for PAMORAs in postoperative ileus remains limited...Figure: Abdominal CT and pelvis without contrast showing diffuse small bowel dilation up to 9cm without mechanical transition point. Figure: Abdominal radiograph confirming persistent dilation measuring 9.3cm."

Clinical • Hypotension • Infectious Disease • Septic Shock

Diagnosis and Treatment Gaps in Opioid-Induced Constipation: A National Real-World Analysis Using the Epic Cosmos EHR Network (ACG 2026) - "Adults â¥18 years with chronic opioid exposure (â¥3 prescription orders spanning â¥90 days; hydrocodone, oxycodone, morphine, fentanyl, tramadol, or methadone) were included...During 12 months of follow-up, we assessed formal OIC diagnosis (K59.03), laxative prescriptions, PAMORA prescriptions (methylnaltrexone, naloxegol, naldemedine), and constipation-related ED visits or hospitalizations (K59.0x, K56.41)... Among chronic opioid users, 40.73% received laxatives, while only 8.81% had a formal OIC diagnosis, representing a >4-fold gap between treatment and documented coding. PAMORA prescribing was 13.97%, exceeding formal diagnosis rates and suggesting targeted therapy may occur despite absent structured OIC coding. Constipation-related complications increased with age (18â44: 0.48%; â¥85: 1.37%), whereas PAMORA prescribing was lowest in patients â¥85 years (11.57%) despite higher complication burden."

Clinical • Real-world • Real-world evidence • Constipation • Gastroenterology • Gastrointestinal Disorder

From Ileus to Small Bowel Obstruction to Cecal Bascule: A Rare but Significant Diagnostic Conundrum With Morbid Implications (ACG 2026) - "After stabilization, patient reported constipation on hospital day (HD) 3, and after failed multimodal laxative therapy, daily methylnaltrexone, and CT abdomen/pelvis with dilated small bowel (SB) and colon concerning for ileus, nasogastric tube (NGT) was placed for decompression on HD 6...Our case highlights the importance of clinician vigilance and diagnostic flexibility when managing patients with persistent obstructive symptoms, as repeat imaging and early surgical consultation may limit morbidity. Figure: Coronal CT imaging of apparent ileus with possible bascule morphology Figure: KUB with perceived SBO with likely underlying bascule physiology"

Constipation • Gastroenterology • Gastrointestinal Disorder • Musculoskeletal Pain

Chronic Widespread Pain in HIV: Novel Mechanisms and Therapeutics (clinicaltrials.gov) - P=N/A | N=200 | Recruiting | Sponsor: Florida International University | Trial completion date: Jul 2026 ➔ May 2027 | Trial primary completion date: Jul 2026 ➔ May 2027

Trial completion date • Trial primary completion date • Human Immunodeficiency Virus • Infectious Disease • Pain

Acute Colonic Pseudo-obstruction Following Massive Bupropion Overdose. (PubMed, J Investig Med High Impact Case Rep) - "Sedation was initiated with propofol and fentanyl; fentanyl was rapidly discontinued...Subcutaneous methylnaltrexone (12 mg) was administered to reverse potential opioid-related ileus without effect...Colonic complications remain rare, with only isolated reports describing colonic ischemia or pseudo-obstruction associated with bupropion toxicity. Clinicians should consider severe gastrointestinal dysmotility when managing sustained-release bupropion toxicity."

Journal • Addiction (Opioid and Alcohol) • Anesthesia • Cardiovascular • CNS Disorders • Epilepsy

A targetable opioid/cancer associated fibroblast axis drives extracellular matrix remodeling and tumor aggressiveness in pancreatic cancer. (PubMed, bioRxiv) - "We find that the commonly prescribed opioid morphine promotes the development of poorly differentiated tumors and increases collagen bundling and maturation in a mouse model of PDAC. Finally, treatment with the FDA-approved peripherally restricted OPRM1 antagonist methylnaltrexone (MNTX) reduces desmoplasia, tumor weight, and ascites burden in a mouse model of PDAC. Therefore, we have identified a novel opioid-mediated signaling axis driving PDAC desmoplasia and reveal MNTX as a potential therapeutic to inhibit both exogenous and endogenous opioid-induced ECM remodeling and tumor aggressiveness."

Journal • Fibrosis • Oncology • Pain • Pancreatic Cancer • Pancreatic Ductal Adenocarcinoma • Solid Tumor • CAFs • OPRM1

Peripherally Acting Mu-Opioid Receptor Antagonist Use in Opioid-Induced Constipation in Patients With Cancer: A Scoping Review. (PubMed, Clin J Oncol Nurs) - "Most adverse effects were gastrointestinal in nature but were generally mild to moderate in severity. Naloxegol and naldemedine were shown to be effective for long-term OIC management, and methylnaltrexone was effective for short-term relief."

Journal • Constipation • Gastroenterology • Gastrointestinal Disorder • Oncology • Pain

German Expert Consensus on Opioid-Induced Constipation (OIC): Recommendations and a Treatment Algorithm for Clinical Practice. (PubMed, J Clin Med) - "In Europe, the PAMORAs methylnaltrexone, naloxegol and naldemedine are approved for the treatment of OIC. This consensus paper provides both evidence-based and practice-oriented recommendations for the systematic management of OIC. By promoting patient education, early recognition, structured evaluation and stepwise treatment escalation, the presented statements and algorithm aim to improve patient outcomes and quality of life under opioid therapy including better adherence to opioid therapy."

Journal • Constipation • Gastroenterology • Gastrointestinal Disorder • Oncology • Pain • Palliative care

A Novel Clinical Calculator to Identify Patients at Risk for Ileus after Short-Segment Lumbar Fusion (AAOS 2026) - "Ileus was defined as the presence of an abdominal XR or administration of methylnaltrexone... This study created a novel clinical calculator that accurately predicts post-operative ileus after short-segment lumbar fusion. We recommend utilization of this calculator peri-operatively to identify high risk patients so that prophylactic intervention can be taken to prevent development of ileus. These low-cost interventions can decrease the incidence of ileus, decrease LOS, and improve outcomes after short-segment lumbar fusion."

Clinical

Chronic Widespread Pain in HIV: Novel Mechanisms and Therapeutics (clinicaltrials.gov) - P=N/A | N=200 | Recruiting | Sponsor: Florida International University | Trial completion date: Dec 2025 ➔ Jul 2026 | Trial primary completion date: Nov 2025 ➔ Jul 2026

Trial completion date • Trial primary completion date • Human Immunodeficiency Virus • Infectious Disease • Pain

Methylnatrexone In Resectable Head and Neck Squamous Cell Carcinoma (MINK). A "Window of Opportunity" Pilot Study. (clinicaltrials.gov) - P4 | N=25 | Recruiting | Sponsor: M.D. Anderson Cancer Center | Trial completion date: Dec 2025 ➔ Dec 2026 | Trial primary completion date: Dec 2025 ➔ Dec 2026

Trial completion date • Trial primary completion date • Head and Neck Cancer • Oncology • Solid Tumor • Squamous Cell Carcinoma • Squamous Cell Carcinoma of Head and Neck

Medication Use Evaluation of Methylnaltrexone at an Academic Hospital (ASHP 2025) - No abstract available

Clinical

Evaluation of Bowel Regimen Optimization Prior to Methylnaltrexone Use for Opioid-Induced Constipation at a Large Academic Medical Center (ASHP 2025) - No abstract available

Constipation • Gastroenterology • Gastrointestinal Disorder

Combined Efficacy of Methylnaltrexone and Naloxegol in Managing a Case of Neurogenic and Opioid-Induced Constipation (ACG 2025) - "His bowel regimen is polyethylene glycol 17g 3 times a day, lubiprostone 24mcg daily, 2 tablet of senna 8.6mg twice daily, and naloxegol 12.5mg daily. (2020), which show methylnaltrexone's efficacy in opioid-treated patients. While promising, further research is needed to assess the long-term safety and efficacy of this combined approach in similar patient populations."

Clinical • CNS Disorders • Constipation • Gastroenterology • Gastrointestinal Disorder • Inflammatory Bowel Disease • Multiple Sclerosis

The Double Duct Dilemma: When Methadone Mimics Malignancy (ACG 2025) - "The hospitalization was complicated by persistent opioid-induced constipation, which responded to methylnaltrexone, and the patient was discharged with outpatient surgical referral for elective cholecystectomy. This case highlights a clinically relevant association between chronic methadone use and the double duct sign. While MMT use remains prevalent, specialists should remain vigilant for its potential to mimic more serious conditions. Recognizing this association may help avoid unnecessary invasive procedures and guide individualized diagnostic and therapeutic strategies.Figure: Double Duct on MRCPFigure: Double Duct EUS"

Cholestasis • Constipation • Gastroenterology • Gastrointestinal Disorder • Oncology • Substance Abuse

BUPROPRION OVERDOSE LEADING TO MEDICATION-INDUCED COLONIC PSEUDO-OBSTRUCTION (CHEST 2025) - "Patient was initiated on propofol and fentanyl for sedation, though the fentanyl was rapidly titrated off due to interactive effects with bupropion. The patient briefly required hydromorphone for pain adjunct...Additionally, opioid confounding was also reversed with methylnaltrexone. This case adds to the case log of patients who develop colonic pseudo-obstructions in the setting of bupropion overdose."

Addiction (Opioid and Alcohol) • Anesthesia • Bipolar Disorder • Cardiovascular • CNS Disorders • Depression • Epilepsy • Mood Disorders • Psychiatry

METHYLNALTREXONE-INDUCED OPIOID WITHDRAWAL CASE REPORT (CHEST 2025) - "He was not currently on methadone or suboxone at time of arrival. In the hospital, patient was started on methadone alongside ketamine, oxycodone and nonopioid agents...Patient tolerated the initial dilaudid well with improvement of his symptoms... Our case today highlights a rare occurrence of methylnaltrexone inducing opioid withdrawals which illustrates that further additional studies are needed to better understand other mechanisms of action that could have triggered this event."

Case report • Clinical • Cardiovascular • Constipation • Gastroenterology • Gastrointestinal Disorder • Hepatitis C • Hepatology • Infectious Disease • Inflammation

Roles of Peripheral and Central µ1-Opioid Receptors in the Fentanyl-Induced Cardiorespiratory Responses. (PubMed, Am J Physiol Lung Cell Mol Physiol) - "The same protocols were performed after: naloxone (NLX) and naloxone methiodide (NLM) to systemically and peripherally antagonize ORs respectively (Study II); CTAP and methylnaltrexone (MNTX) to systemically and peripherally block μ-ORs (Study III); and naloxonazine (NLZ) to systemically block μ1-ORs (Study IV). NLZ nearly abolished the fentanyl-evoked responses. Our results indicate that peripherally restricted OR (particularly μ1-OR) antagonism prevents the fentanyl-induced immediate apnea, but fails to change the subsequent respiratory depression."

Journal • Addiction (Opioid and Alcohol) • Anesthesia • Cardiovascular • CNS Disorders • Depression • Psychiatry

Management of constipation in people receiving palliative care. (PubMed, Aust J Gen Pract) - "Management involves treatment of reversible causes, if appropriate, as well as both non-pharmacological and pharmacological interventions. Recommended laxatives for use in palliative care are osmotic laxatives and stimulant laxatives. Prophylactic use of laxatives when prescribing opioids is essential. Methylnaltrexone can be used to manage opioid-induced constipation but should be avoided in patients with bowel obstruction."

Journal • Constipation • Gastroenterology • Gastrointestinal Disorder • Palliative care

Treatment of Opioid-Induced Constipation: Inducing Laxation and Understanding the Risk of Gastrointestinal Perforation. (PubMed, J Clin Gastroenterol) - "Management of OIC includes treatment with over-the-counter laxatives and peripherally acting μ-opioid receptor antagonists (PAMORAs; methylnaltrexone, naloxegol, naldemedine). Appropriate patient selection during laxation therapy for OIC, regardless of treatment plan, involves consideration of the overall risk versus benefit in patients at increased risk of perforation due to comorbid medical conditions, concurrent medications, or recent gastrointestinal procedures. After initiating treatment for OIC, clinicians should assess the effectiveness of laxation therapy and carefully monitor for signs of gastrointestinal perforation."

Journal • Constipation • Gastroenterology • Gastrointestinal Disorder • Pain

RATES OF MEDICAL TREATMENT FOR ALCOHOL USE DISORDER DURING ADMISSION FOR ACUTE PANCREATITIS (DDW 2025) - "Treatments for AUD included consult to addiction medicine or social worker or discharge prescription for disulfiram, naltrexone, methylnaltrexone IM, acamprosate, topiramate, gabapentin, or baclofen. Even lower rates (~20%) received a prescription for AUD at hospital discharge. Additional investigations are needed to understand barriers to implementation of alcohol risk factor reduction and its effect on pancreatitis-related outcomes."

Addiction (Opioid and Alcohol) • Gastroenterology • Hepatology • Pancreatitis

Substrate-specific inhibition of organic cation transporter 1 revealed using a multisubstrate drug cocktail. (PubMed, Drug Metab Dispos) - "Here, we describe a multisubstrate drug cocktail that allows for the simultaneous testing of drug-drug interactions using 8 different victim drugs: fenoterol, salbutamol, sumatriptan, zolmitriptan, ipratropium, trospium, methylnaltrexone, and metformin...Group 1 comprised verapamil, quinidine, fenoterol, and ipratropium, and group 2 comprised metformin, sumatriptan, and trimethoprim...Here, we demonstrate this for organic cation transporter 1 (OCT1, SLC22A1) and presents a drug cocktail designed to identify varying inhibitory potencies in vitro and prevent false-negative drug-drug interaction results during early drug development. This approach can be extended to other polyspecific drug transporters."

Journal • SLC22A1

SEVERE DYSPHAGIA FOLLOWING MAGNETIC SPHINCTER AUGMENTATION: A CASE REPORT (DDW 2025) - "The patient had constipation despite Relistor and stool softeners...GERD symptoms did not improve with lansoprazole twice daily and Pepcid at bedtime... The LINX procedure is one of the GERD treatments. We must balance disease management with awareness of treatment-related complications, which can significantly impact patient outcomes, as shown in this case. To maximize the benefits of this promising intervention, more research is needed to improve patient selection criteria, procedural safety, and adverse event risk."

Case report • Clinical • Barrett Esophagus • Cardiovascular • Constipation • Gastroesophageal Reflux Disease • Gastrointestinal Disorder • Genetic Disorders • Hypertension • Obesity • Pain

SEVERE DYSPHAGIA FOLLOWING MAGNETIC SPHINCTER AUGMENTATION: A CASE REPORT (SSAT 2025) - "The patient had constipation despite Relistor and stool softeners...GERD symptoms did not improve with lansoprazole twice daily and Pepcid at bedtime... The LINX procedure is one of the GERD treatments. We must balance disease management with awareness of treatment-related complications, which can significantly impact patient outcomes, as shown in this case. To maximize the benefits of this promising intervention, more research is needed to improve patient selection criteria, procedural safety, and adverse event risk."

Case report • Clinical • Barrett Esophagus • Cardiovascular • Constipation • Gastroenterology • Gastroesophageal Reflux Disease • Gastrointestinal Disorder • Genetic Disorders • Hypertension • Obesity • Pain

Gastrointestinal Transit Time Assessed Using a CT-Based Radiopaque Marker Method in Patients With Acute Pancreatitis During Methylnaltrexone Treatment. (PubMed, Neurogastroenterol Motil) - "Our CT-based method was feasible in hospitalized patients with AP. Methylnaltrexone did not change gastrointestinal transit compared with placebo. However, laxative therapy was more frequent with the placebo."

Journal • Gastrointestinal Disorder • Immunology • Inflammation • Pancreatitis • Systemic Inflammatory Response Syndrome