A synthetic disaccharide used in the treatment of constipation and hepatic encephalopathy. It has also been used in the diagnosis of gastrointestinal disorders. (From Martindale, The Extra Pharmacopoeia, 30th ed, p887)
Indication
For the treatment of constipation and hepatic encephalopathy.
Pharmacology
Therapeutically, lactulose has laxative and ammonia-detoxifying actions. In treating constipation lactulose metabolites draw water into the bowel, causing a cathartic effect through osmotic action.
Toxicity
LD50=18.2 g/kg (oral, rat). Side effects include diarrhea and resultant dehydration.
Affected Organisms
Humans and other mammals
Biotransformation
Lactulose is completely metabolized in the colon by enteric bacteria, and no lactulose is excreted in the feces.
Absorption
Poorly absorbed from the gastrointestinal tract as no human enzyme that is capable of hydrolysis of this disaccharide is present in human gastrointestinal tissue.
Half Life
1.7-2 hours
Elimination
The primary route of elimination is fecal. Urinary excretion has been determined to be 3% or less and is essentially complete within 24 hours.
