Methylnaltrexone Versus Naloxone for Opioid-Induced Constipation in the Medical Intensive Care Unit.
BACKGROUND
Opioid-induced constipation (OIC) is common in critically ill patients; it leads to complications that can increase hospital stay and, rarely, bowel perforation. Opioid antagonists are considered a logical approach to treat OIC; however, the agent of choice has yet to be determined.


OBJECTIVE
To assess the effectiveness and safety of enteral naloxone (NTX) versus subcutaneous methylnaltrexone (MNTX) for the treatment of OIC in the medical intensive care unit.


METHODS
This retrospective review evaluated patients who received fentanyl continuous infusions for at least 72 hours and were initiated on NTX or MNTX. Active colitis, mechanical gastrointestinal obstruction, and inability to receive NTX orally were exclusion criteria. The primary outcome was time to first bowel movement (BM). Secondary outcomes included total number of BMs within 48 hours, opioid requirements after NTX or MNTX, and change in any of the following after the opioid antagonist: heart rates, mean arterial pressures, and level of sedation. A post hoc subgroup analysis of patients on vasopressors was conducted.


RESULTS
Baseline characteristics were similar between patients receiving NTX (n = 52) and MNTX (n = 48), except the MNTX group required a higher median norepinephrine dose (0.22 vs 0.1 µg/kg/min, P = 0.001). The median times to first BM for NTX and MNTX were 30 and 24 hours ( P = 0.165). There was no difference in the primary outcomes for patients on vasopressors. Both groups did not require additional fentanyl equivalents, as evidenced by stable vitals and opioid requirements during treatment.


CONCLUSIONS
Both agents appear to be effective and safe for the treatment of OIC; however, future controlled prospective trials are warranted.
1 New York University Langone Medical Center, NY, USA.
Cristian
C
Merchan
1 New York University Langone Medical Center, NY, USA.
Diana
D
Altshuler
1 New York University Langone Medical Center, NY, USA.
John
J
Papadopoulos
D000328:Adult; D000701:Analgesics, Opioid / Q000009:adverse effects* / Q000627:therapeutic use; D003248:Constipation / Q000139:chemically induced / Q000188:drug therapy*; D016638:Critical Illness; D057286:Electronic Health Records; D005260:Female; D005283:Fentanyl / Q000009:adverse effects* / Q000627:therapeutic use; D006339:Heart Rate / Q000528:radiation effects; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D009271:Naltrexone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D009292:Narcotic Antagonists / Q000008:administration & dosage / Q000627:therapeutic use*; D011446:Prospective Studies; D000644:Quaternary Ammonium Compounds / Q000008:administration & dosage / Q000627:therapeutic use; D012189:Retrospective Studies
D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D000644:Quaternary Ammonium Compounds; C032257:methylnaltrexone; D009271:Naltrexone; D005283:Fentanyl
ICU analgesia; intensive care units; methylnaltrexone; naloxone; opioid antagonists; opioid-induced constipation; opioids