Final answer:
Methylnaltrexone can be used to prevent postoperative ileus in patients taking opioids for pain, as it does not affect the analgesic effects of opioids like oxycodone, morphine, and fentanyl but counteracts their constipating effects on the gut.
Step-by-step explanation:
To manage postoperative (PO) ileus in patients who are taking opioids for pain, a medication called methylnaltrexone can be used. Methylnaltrexone is a peripherally acting opioid antagonist that helps to prevent the constipating effects of opioids on the gut without affecting analgesia since it does not cross the blood-brain barrier. Opioids like oxycodone, morphine, and fentanyl are commonly used for managing moderate to severe pain but can cause gastrointestinal side effects such as ileus. By using methylnaltrexone, patients can continue their opioid regimen for pain relief while mitigating the risk of developing an ileus.