III. Mechanism

  1. Lactulose converts Ammonia to unabsorbed Ammonium
  2. Lactulose is metabolized in the intestinal tract to lactate which acts as an Osmotic Laxative
  3. Alters bowel flora

IV. Medications

  1. Lactulose (Chronulac) 70% Solution, 10 g/15 ml
  2. Lactitol
    1. As effective as Lactulose with less pain and Flatus
    2. Pitzalis (1995) Pediatr Med Chir 17(3):223-6 [PubMed]

V. Dosing: Constipation

  1. General
    1. Onset of action within 24-48 hours
    2. Polyethylene Glycol is typically preferred if available
    3. May also consider Sorbitol 70% as alternative agent
  2. Lactulose (Chronulac)
    1. Adults: 15 to 30 ml orally at bedtime as needed
    2. Children
      1. Give 1 to 2 g/kg of 70% Lactulose (10 g/15 ml) once to twice daily up to 3 ml/kg/day (max 60 ml/day)
      2. May be easier to administer to young children than other Osmotic Laxatives
      3. May mix with fruit juice, water or milk

VI. Dosing: Hepatic Encephalopathy

  1. Hepatic Encephalopathy
    1. Start 30-45 ml orally every hour until Diarrhea
    2. Next: 15-30 ml orally three to four times daily with target of 2-3 stools/day
  2. Hepatic Coma
    1. Lactulose 300 ml in 700 ml water retention enema every 4 to 6 hours

VII. Pharmacokinetics

  1. Poorly absorbed (may be used in Renal Failure, unlike most Osmotic Laxatives)

VIII. Adverse Effects

  1. Abdominal cramping
  2. Flatus

IX. Efficacy

  1. First line agent in Hepatic Encephalopathy
  2. For Constipation, not as effective or well tolerated as Polyethylene Glycol (Miralax)

X. Safety

  1. Pregnancy Category B
  2. Unknown safety in Lactation

XII. References

  1. Hamilton (2020) Tarascon Pocket Pharmacopoeia
  2. (2023) Management of Constipation, Presc Lett, #390108

Images: Related links to external sites (from Bing)

Related Studies

Cost: Medications

lactulose (on 9/13/2023 at Medicaid.Gov Survey of pharmacy drug pricing)
LACTULOSE 10 GM/15 ML SOLUTION Generic $0.01 per ml
enulose (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing)
ENULOSE 10 GM/15 ML SOLUTION Generic $0.01 per ml