What is the recommended dosage of Duohalac (lactulose) for a 1-year-old patient in the disimpaction phase of constipation treatment?

Duohalac (Lactulose) Dosing for Disimpaction in a 1-Year-Old

For disimpaction in a 1-year-old, start with lactulose 2.5-10 mL daily divided into multiple doses, titrating upward based on response, with the goal of producing 2-3 soft stools daily. 1

Initial Dosing Strategy

• The FDA-approved dosing for infants specifies an initial daily oral dose of 2.5-10 mL in divided doses 1
• Start at the lower end (2.5-5 mL daily) and increase gradually every 1-2 days based on stool output 1
• Divide the total daily dose into 2-3 administrations to minimize cramping and improve tolerance 1

Critical Pre-Treatment Assessment

Before initiating lactulose therapy, you must:

• Perform a digital rectal examination to confirm fecal impaction versus simple constipation 2, 3
• Rule out mechanical bowel obstruction through physical examination and consider abdominal imaging if clinical suspicion exists 4, 2
• Ensure the child does not have undiagnosed acute abdominal pain, which is an absolute contraindication 5

Titration and Monitoring

• If diarrhea develops, reduce the dose immediately 1
• If diarrhea persists despite dose reduction, discontinue lactulose 1
• The therapeutic goal is 2-3 soft stools daily, not liquid diarrhea 1
• Clinical improvement may not occur for 24-48 hours or longer after initiation 1

When Lactulose May Not Be Sufficient

For true fecal impaction in a 1-year-old, lactulose alone may be inadequate for initial disimpaction:

• Consider starting with a glycerin suppository (pediatric formulation) to mechanically disrupt the impacted stool mass first 2, 5
• The suppository should be retained for 15-30 minutes if possible 5
• Once disimpaction is achieved, transition to maintenance therapy with lactulose 2

Alternative Consideration

While lactulose is safe and commonly used, polyethylene glycol (PEG) 3350 at 1-1.5 g/kg/day for 3 days has superior efficacy for disimpaction (95% success rate vs lower doses) in children, though this study included children aged 3-13 years 6. However, the FDA label for lactulose remains the primary guidance for infants under 2 years 1.

Common Pitfalls to Avoid

• Do not use adult dosing (30-45 mL three times daily) in an infant—this will cause severe diarrhea and electrolyte disturbances 1
• Do not give oral laxatives alone if there is hard, impacted stool in the rectal vault—mechanical disruption with a suppository is needed first 3, 5
• Avoid rectal enemas in this age group unless absolutely necessary, as the risk of trauma is higher 5

Adverse Effects to Monitor

Expected side effects include:

• Bloating (18% incidence in pediatric studies) 6
• Cramping (5%) 6
• Nausea (5%) 6
• Diarrhea (13%) if dose is too high 6

Maintenance After Disimpaction

Once disimpaction is achieved:

• Continue lactulose at the lowest effective dose to maintain 1 non-forced bowel movement every 1-2 days 4, 3
• Increase fluid intake and add dietary fiber if the child is eating solid foods 2, 5
• Establish proper toileting habits as the child develops 2