S4499 Combined Efficacy of Methylnaltrexone and Naloxegol in Managing a Case of Neurogenic and Opioid-Induced Constipation

Introduction: Constipation is a prevalent gastrointestinal condition affecting a significant portion of people worldwide. In the setting of comorbidities and the reliance on certain medications, constipation can become a debilitating condition. We report a unique treatment method in a patient with constipation multifactorial to multiple sclerosis and chronic opioid use. Case Description: A 47-year-old man weighing 76 kg with a history of multiple sclerosis (MS) complicated by quadriplegia, chronic pain requiring opioids, and neurogenic bladder/bowel presented to the hospital with 9 days of constipation. His bowel regimen is polyethylene glycol 17 g 3 times a day, lubiprostone 24 mcg daily, 2 tablets of senna 8.6 mg twice daily, and naloxegol 12.5 mg daily. A computed tomography (CT) of the abdomen/pelvis without contrast on arrival showed a high stool burden in the rectosigmoid colon and moderate constipation in the remainder of the colon. The patient's constipation was attributable to a multifactorial etiology, encompassing opioid-induced effects and neurogenic bowel dysfunction secondary to multiple sclerosis. As a result, he was given a 12-mg injection of methylnaltrexone and several hours later he had a significant bowel movement. The following day he was given another 12-mg injection of methylnaltrexone with further relief of constipation. Due to recurrent hospitalization with constipation, he was recommended to follow up with general surgery outpatient for consideration of an ileostomy. Discussion: This case highlights the effectiveness of combining methylnaltrexone with naloxegol in managing refractory constipation in a patient with MS and chronic opioid use. Despite a comprehensive bowel regimen, including polyethylene glycol, lubiprostone, senna, and naloxegol, the patient’s constipation persisted, likely due to the multifactorial nature of his condition—opioid-induced constipation compounded by neurogenic bowel dysfunction from MS. Methylnaltrexone, a peripherally acting opioid antagonist, provided significant relief when administered in conjunction with naloxegol, resulting in prompt bowel movements. This approach mirrors findings in recent studies, such as Kalam, et al. (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.