What is the effect of repeated administration of lactulose (Lactulose) until bowel movement (BM) is achieved?

From the Guidelines

Lactulose should be administered repeatedly until a bowel movement (BM) is achieved, typically starting with 10-20 g (15-30 mL or 1-2 packets) orally every 4-6 hours, with dosing adjusted based on response, as recommended by the American Gastroenterological Association and American College of Gastroenterology clinical practice guideline 1.

Key Considerations

• The goal is to produce 2-3 soft bowel movements daily, and for acute constipation or hepatic encephalopathy, more frequent dosing may be needed initially.
• If no response occurs after 24-48 hours, consider increasing the dose or adding another laxative.
• Lactulose works as an osmotic laxative by drawing water into the intestinal lumen and also reduces ammonia absorption in the colon by acidifying the environment.
• Common side effects include bloating, flatulence, abdominal cramping, and diarrhea if overdosed, which are dose-dependent and may limit its use in clinical practice 1.

Monitoring and Precautions

• Patients should be monitored for dehydration and electrolyte imbalances, especially with prolonged use.
• Adequate fluid intake should be maintained while using lactulose.
• If severe abdominal pain develops or no bowel movement occurs despite multiple doses, medical evaluation is necessary to rule out bowel obstruction or other serious conditions.

Evidence-Based Recommendation

The recommendation to use lactulose is based on the American Gastroenterological Association and American College of Gastroenterology clinical practice guideline, which suggests the use of lactulose in adults with chronic idiopathic constipation who fail or are intolerant to over-the-counter therapies 1. However, the evidence for lactulose is considered very low, and its use may be limited by common side effects such as bloating and flatulence.

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. The dosage may be adjusted every day or two to produce 2 or 3 soft stools 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. When the laxative effect has been achieved, the dose of lactulose may then be reduced to the recommended daily dose The effect of repeated administration of lactulose until bowel movement (BM) is achieved is to induce rapid laxation and produce 2 or 3 soft stools daily. The dose may be adjusted to achieve this effect, and once achieved, the dose can be reduced to the recommended daily dose 2.

• The goal is to produce a laxative effect, which may occur within 24 to 48 hours or later.
• Continuous long-term therapy is indicated to lessen the severity and prevent the recurrence of portal-systemic encephalopathy.

From the Research

Effect of Repeated Administration of Lactulose

The effect of repeated administration of lactulose until bowel movement (BM) is achieved can be understood through various studies:

• A study published in the Journal of the American Geriatrics Society 3 found that lactulose was superior to glucose in increasing the mean number of bowel movements per day and the percentage of days with at least one bowel movement.
• Another study published in the Annals of thoracic medicine 4 found that prophylactic use of lactulose can be used successfully to prevent constipation in ICU patients, with 18% of patients in the interventional group having a bowel movement in less than 72 hours.
• A study published in the European journal of gastroenterology & hepatology 5 found that a small dose of lactulose (10 g per day) was effective in preventing slow colonic transit and constipation in hospitalized patients, with a significant reduction in mean colonic transit times.

Comparison with Other Laxatives

Comparing lactulose with other laxatives:

• A study published in the Journal of pain and symptom management 6 found that amidotrizoate was effective in treating constipation resistant to laxatives, including lactulose, in advanced cancer patients.
• A study published in Alimentary pharmacology & therapeutics 7 found that bisacodyl had a more pronounced laxative effect compared to lactulose, with a significant shortening of colonic transit time and increase in stool weight.

Key Findings

Key findings related to the effect of repeated administration of lactulose until bowel movement is achieved include:

• Lactulose is effective in increasing the frequency of bowel movements and preventing constipation in various patient populations 3, 4, 5.
• The effectiveness of lactulose may vary depending on the dose and individual patient characteristics 5, 7.
• Lactulose may be used in combination with other laxatives or therapies to achieve optimal bowel movement outcomes 6.