Lactulose Retention Enema Duration
A lactulose retention enema should be held for 30 to 60 minutes before evacuation. 1
Recommended Retention Time
The FDA-approved labeling specifies that 300 mL of lactulose solution mixed with 700 mL of water or physiologic saline should be retained for 30 to 60 minutes. 1
This retention time applies specifically to patients with hepatic encephalopathy who are in impending coma or coma stages where aspiration risk exists or oral administration is not feasible. 1
The enema may be repeated every 4 to 6 hours if needed for reversal of hepatic encephalopathy. 1
Administration Technique
Mix 300 mL of lactulose solution with 700 mL of water or physiologic saline (not soap suds or alkaline solutions, which should be avoided). 1
Administer via a rectal balloon catheter to facilitate retention. 1
If the enema is inadvertently evacuated too promptly (before the 30-minute minimum), it may be repeated immediately. 1
Clinical Context and Pitfalls
The 30-60 minute retention window aligns with general retention enema principles, as ESMO guidelines note that retention enemas are typically held for "at least 30 minutes" for various formulations including warm oil enemas. 2
The goal is reversal of hepatic encephalopathy to allow transition to oral lactulose therapy, which should be started before discontinuing the enema route entirely. 1
Avoid using cleansing enemas with soap suds or alkaline agents before or during lactulose enema administration, as these can interfere with lactulose's acidifying mechanism. 1
Some patients may experience reversal of coma within 2 hours of the first enema, though response time varies. 1