Lactulose Dosing in Hepatic Encephalopathy
For hepatic encephalopathy, the recommended initial lactulose dose is 30-45 mL (20-30g) orally every 1-2 hours until achieving at least 2 bowel movements, followed by maintenance dosing titrated to maintain 2-3 soft stools daily. 1, 2
Oral Administration Protocol
Initial Phase (Acute Encephalopathy)
- Initial dose: 30-45 mL (20-30g) orally every 1-2 hours 1, 2
- Continue hourly dosing until rapid laxation is achieved 2
- Goal: Produce 2-3 soft stools daily 1, 2
Maintenance Phase
- Adjust to 30-45 mL (20-30g) three or four times daily 2
- Titrate dose every 1-2 days to maintain 2-3 soft stools daily 2
- Clinical improvement may occur within 24 hours but may take 48 hours or longer 2
Alternative Administration Routes
Nasogastric Administration
- Same dosing as oral when oral administration isn't possible 1
Rectal Administration (for severe cases/coma)
- Preparation: 300 mL lactulose mixed with 700 mL water or physiologic saline 1, 2
- Administer as retention enema via rectal balloon catheter 2
- Retain for 30-60 minutes 2
- May repeat every 4-6 hours if evacuated too promptly 2
- Switch to oral administration as soon as patient is able 2
Monitoring and Adjustment
- Assess mental status regularly using West Haven criteria (Grade I-IV) 1
- Clinical assessment is more important than ammonia levels 1
- Monitor for dehydration and electrolyte imbalances 1
- Maintain sodium levels above 135 mmol/L if possible 1
Treatment Considerations
- Lactulose is the first-line treatment for hepatic encephalopathy 3, 1, 4
- Mechanism: Reduces intestinal pH, increases lactobacillus count, converts ammonia to less absorbable ammonium, and creates osmotic laxative effect 1
- If response is inadequate, consider adding rifaximin (400 mg three times daily or 550 mg twice daily) 1
- Lactulose is effective for secondary prophylaxis of hepatic encephalopathy 3, 1, 5
Clinical Pearls and Pitfalls
- Avoid cleansing enemas containing soap suds or alkaline agents when administering rectal lactulose 2
- Avoid excessive dosing that may cause diarrhea and dehydration, which can worsen encephalopathy 2
- For patients with Grade III-IV encephalopathy, consider ICU admission for airway protection 1
- Patients with recurrent or persistent HE should be considered for liver transplantation 3
- Presence of two or more abnormal psychometric tests after recovery from an HE episode is associated with higher risk of recurrence 5