What is the recommended dosage and use of lactulose for treating constipation and hepatic encephalopathy?

From the Guidelines

The recommended dosage of lactulose for treating constipation is 15-30 mL (10-20 grams) once or twice daily, while for hepatic encephalopathy, adults usually require 20-30 grams three to four times daily, adjusted to produce 2-3 soft bowel movements per day, as suggested by the most recent guidelines 1.

Key Considerations

• Lactulose works differently for constipation and hepatic encephalopathy: as an osmotic laxative for constipation and by reducing ammonia levels in hepatic encephalopathy.
• The solution is typically taken orally but can be administered as a retention enema for acute hepatic encephalopathy.
• Common side effects include bloating, gas, and abdominal cramps.
• Patients should maintain adequate hydration while taking lactulose and be aware that excessive dosing can cause diarrhea and electrolyte imbalances.
• Diabetic patients should note that lactulose contains small amounts of lactose and other sugars.

Dosage and Administration

• For constipation: 15-30 mL (10-20 grams) once or twice daily.
• For hepatic encephalopathy: 20-30 grams three to four times daily, adjusted to produce 2-3 soft bowel movements per day.
• Administration: orally or as a retention enema (200 g lactulose mixed with 700 mL water) for severe cases.

Additional Recommendations

• Rifaximin can be added to lactulose to prevent recurrence of hepatic encephalopathy in cases of failed prevention with lactulose alone 1.
• A therapeutic education program should be offered to the patient and caregiver to improve quality of life and limit hospitalizations 1.

Important Notes

• Lactulose should be titrated to achieve two to three soft stools per day, and the dose should be adjusted accordingly 1.
• Overuse of lactulose can lead to complications such as aspiration, dehydration, hypernatremia, and severe perianal skin irritation 1.

From the FDA Drug Label

The usual adult, oral dosage is 2 to 3 tablespoonfuls (30 mL to 45 mL, containing 20 grams to 30 grams of lactulose) three or four times daily. Hourly doses of 30 mL to 45 mL of lactulose solution may be used to induce the rapid laxation indicated in the initial phase of the therapy of portal-systemic encephalopathy. Continuous long-term therapy is indicated to lessen the severity and prevent the recurrence of portal-systemic encephalopathy. The dose of lactulose for this purpose is the same as the recommended daily dose Pediatric: ... the recommended initial daily oral dose in infants is 2. 5 mL to 10 mL in divided doses. For older children and adolescents the total daily dose is 40 mL to 90 mL.

The recommended dosage and use of lactulose for treating constipation and hepatic encephalopathy are as follows:

• Adults: 2 to 3 tablespoonfuls (30 mL to 45 mL) three or four times daily for constipation, and hourly doses of 30 mL to 45 mL for the initial phase of hepatic encephalopathy therapy.
• Pediatric:
  • Infants: 2.5 mL to 10 mL in divided doses
  • Older children and adolescents: 40 mL to 90 mL total daily dose The goal of treatment is to produce 2 or 3 soft stools daily for constipation, and to reverse the coma stage in hepatic encephalopathy 2.

From the Research

Dosage and Use of Lactulose

• The recommended dosage of lactulose for treating constipation and hepatic encephalopathy varies, but it is generally used due to its efficacy and good safety profile 3.
• Lactulose is a synthetic disaccharide that is not absorbed from the small intestine and is readily fermented by the colonic bacterial flora, producing short-chain fatty acids and various gases 3.
• Low doses of lactulose can be used as a prebiotic to stimulate the growth of health-promoting bacteria in the gastrointestinal tract, enhancing mineral absorption and improving gut health 4.

Treatment of Constipation and Hepatic Encephalopathy

• Lactulose is effective in the treatment of constipation and hepatic encephalopathy, with its primary site of action being the colon 3.
• The use of lactulose in combination with rifaximin has been shown to significantly reduce the risk of overt hepatic encephalopathy recurrence and hospitalization compared to lactulose therapy alone 5.
• Lactulose has been compared to lactitol, another unabsorbed sugar, in the treatment of hepatic encephalopathy, with both sugars having similar effects on colonic metabolism 6.

Prebiotic Properties of Lactulose

• Lactulose has patient- and dose-dependent prebiotic properties in humans, with its effects on gut microbiota composition and metabolomes varying depending on the individual and dosage 7.
• The use of lactulose as a prebiotic has been shown to enhance the growth of health-promoting bacteria, such as Bifidobacterium and Lactobacillus spp., and increase the production of beneficial metabolites 4.