Comparative Pharmacology
Head-to-head clinical analysis: CONSTILAC versus GENERLAC.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CONSTILAC versus GENERLAC.
CONSTILAC vs GENERLAC
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Constilac (lactulose) is a synthetic disaccharide that is not absorbed in the small intestine. In the colon, it is metabolized by bacteria to short-chain fatty acids (e.g., lactic acid), which osmotically draw water into the bowel, producing a laxative effect. Additionally, in hepatic encephalopathy, the acidification of colonic contents traps ammonia (NH3) as ammonium (NH4+), reducing its absorption.
Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. It is metabolized by colonic bacteria to short-chain fatty acids (e.g., lactic, acetic, and formic acids), which osmotically increase intraluminal water content, soften stool, and stimulate peristalsis. In hepatic encephalopathy, the acidic environment reduces intestinal ammonia production and absorption by promoting conversion of NH3 to NH4+.
Oral, 15-45 mL (10-20 g lactulose) once daily, titrated to produce 2-3 soft stools daily; may be given as a single dose or divided twice daily. Onset of action 24-48 hours.
10-45 mL orally once daily, adjusted to produce 2-3 soft stools per day. Maximum 60 mL/day.
None Documented
None Documented
Not applicable due to negligible systemic absorption; lactulose acts locally in the colon.
Not applicable; lactulose is a non-absorbable disaccharide that exerts a local osmotic effect in the colon without systemic absorption. Systemic half-life is not relevant as it does not enter circulation.
Primarily fecal as unchanged drug (systemic absorption negligible). Renal excretion accounts for <2% of any absorbed fraction. Biliary excretion is minimal.
Primarily fecal (≥90%) as unchanged drug via colonic excretion; renal elimination is negligible (<1%).
Category C
Category C
Osmotic Laxative
Osmotic Laxative