Drug Groups

approved

Description

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

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.

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