Drug reference

Lactulose

Osmotic laxative / disaccharide / ammonia-lowering agent · Laxative; Ammonia detoxicant

Also known as Duphalac, Laevolac, Kristalose, Constilac

START

Constipation: 15 mL OD, titrate to 2-3 soft stools. HE: 30-45 mL TDS, titrate to 2-3 soft acidic stools (pH <6)

TYPICAL MAX

No fixed maximum; titrate to clinical endpoint; if >60 mL/day needed, consider adding rifaximin

STOP IF

Severe diarrhea, signs of dehydration, suspected bowel obstruction

WATCH

Stool frequency/consistency, mental status (HE), electrolytes (Na+, K+) with high doses

CDSCO approvedNon-scheduled or OTCJan AushadhiATC A06AD11

Dose laddermg/d

Renal dose adjustmenteGFR mL/min/1.73m²

KDIGO 2024 + manufacturer label

Pharmacokineticsplasma · t hours

ONSET: 1d · 24-48 hours for constipation; hours for HE
PEAK: 2d · Peak osmotic effect
t½: 0s · N/A - local colonic action
DURATION: 1d · Daily dosing

EXCRETION

Fecal (unchanged and fermented)

route + CYP

INTERACTIONS

—

none in our sources

PREGNANCY

Safe in pregnancy; not systemically absorbed; widely used

FDA category + note

Available in India

258 branded formulations and 7 fixed-dose combinations. Look up specific brands in the Drugs workspace.

Jan Aushadhi — generic available at GoI pharmacies

Mechanism

Synthetic disaccharide (galactose + fructose) not absorbed in small intestine. Reaches colon intact where bacterial fermentation produces short-chain fatty acids (acetate, lactate) and lowers pH. Osmotic effect draws water into bowel lumen. In hepatic encephalopathy, acidification of colonic contents converts ammonia (NH3) to non-absorbable ammonium (NH4+), reducing systemic ammonia absorption.

Indications

Constipation (chronic and acute)Hepatic encephalopathy (prevention and treatment)Pre-operative bowel preparation (adjunct)Portal-systemic encephalopathy

Dosing

Adult: Constipation: 15-30 mL/day (10-20 g), titrate to 2-3 soft stools/day. HE: 30-45 mL TDS-QDS (30-60 g/day), titrate to 2-3 soft acidic stools/day
Pediatric: Constipation: <1 year: 2.5-5 mL/day; 1-6 years: 5-10 mL/day; 7-14 years: 10-15 mL/day. HE: limited pediatric data
Renal adjustment: No adjustment needed; not systemically absorbed
Hepatic adjustment: No adjustment needed; primary indication is hepatic encephalopathy
Geriatric: Start low (10 mL/day) and titrate; monitor electrolytes with long-term use
Max dose: No strict maximum; titrate to effect (2-3 soft stools/day)