Lactulose

General

• Type: osmotic laxative
• Dosage Forms: 10g/15mL solution
• Routes of Administration: oral, NG, rectal
• Common Trade Names: Kristalose

Adult Dosing

Hepatic encephalopathy

• 30-45mg PO TID or QID or (300mL in 700cc H2O retention enema x30min)
• titrate for 2-3 soft stools per day

Constipation

• 15-50mL PO Qday - BID
• max 60mL/day

Pediatric Dosing

Portal systemic encephalopathy

• infants
  • 2.5-10ml/day PO divided TID-QID
  • titrate for 2-3 soft stools per day

• children
  • 40-90ml/day PO divided TID-QID
  • titrate for 2-3 soft stools per day

Constipation

• 1ml/kg PO Qday - BID
• max 60mL/day

Special Populations

• Pregnancy Rating: B (no evidence of risk)
• Lactation risk: safety unknown
• Renal Dosing
  • Adult: not defined
  • Pediatric: not defined
• Hepatic Dosing
  • Adult: not defined
  • Pediatric: not defined

Contraindications

• Allergy to class/drug
• galactosemia
• caution in DM
• caution if colorectal electrocautery procedures

Adverse Reactions

Serious

• diarrhea, severe (excessive dose)
• electrolyte disorders (excessive dose)
• metabolic acidosis (excessive dose)

Common

• flatulence
• intestinal cramping
• abdominal distention
• nausea/vomiting

Pharmacology

• Half-life: unknown
• Metabolism: colon, <3% systemic absorption
• Excretion: feces (100% unchanged), urine < 3%

Mechanism of Action

• Undigestible disaccharide consumed by large bowel bacteria and broken down to lactic acid
• Acidification of colonic contents attracts ammonia from bloodstream leading to excretion in stool

Indications by Condition

The following table is automatically generated from disease/condition pages across WikEM.

Indication	Dose	Context	Route	Population
Hepatic encephalopathy	20g PO or 300mL in 700mL H2O retention enema x 30min	First-line treatment for hepatic encephalopathy	PO or rectal	Adult

See Also

• Hepatic encephalopathy
• Constipation