Comparative Pharmacology
Head-to-head clinical analysis: CONSTILAC versus GLYCOPREP.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CONSTILAC versus GLYCOPREP.
CONSTILAC vs GLYCOPREP
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.
Glycopyrrolate is a competitive antagonist of acetylcholine at muscarinic receptors, thereby inhibiting the effects of parasympathetic nervous system activation. It does not cross the blood-brain barrier significantly, producing peripheral anticholinergic effects.
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.
Adults: 10 units subcutaneously 30 minutes before first meal of the day, then 5 units after each subsequent meal. Total daily dose should not exceed 30 units.
None Documented
None Documented
Not applicable due to negligible systemic absorption; lactulose acts locally in the colon.
Terminal half-life 1.5-2 hours in adults; prolonged in renal impairment (up to 10-12 hours in anuria).
Primarily fecal as unchanged drug (systemic absorption negligible). Renal excretion accounts for <2% of any absorbed fraction. Biliary excretion is minimal.
Primarily renal (90% unchanged) via glomerular filtration and tubular secretion; biliary/fecal <10%.
Category C
Category C
Osmotic Laxative
Osmotic Laxative