Case Presentation: We present the case of a 58 -year-old opioid naïve man admitted for elective knee arthroplasty received parenteral hydromorphone and enteral oxycodone for analgesia. On post-operative day one, he developed abdominal pain. Abdominal X-ray showed stool burden suggesting constipation (OIC) prompting management with laxatives; he was given 12 mg parenteral methylnaltrexone. Overnight he […]