Methylnaltrexone and Naloxone for Opioid-induced Constipation in the Critical Care Setting

Opioid antagonists in the ICU are often a last-line medication given to patients with opioid-induced constipation. Traditionally, patients have been administered nonopioid-based bowel regimens such as senna, peg, and docusate to treat constipation. Despite the obvious need to treat acute pain with opioids, side effects such as constipation can lead to multiple gastrointestinal (GI) complications such as bowel perforation and even death. Specifically, opioid-induced constipation (OIC) can be very difficult to treat. We examine naloxone and methylnaltrexone (MNTX) assessing GI complications and OIC as well as present a patient case which highlights the importance of treating OIC. We also evaluate the superior reversal agent of choice when treating OIC in the critical care and stepdown unit settings.