Comparative Pharmacology
Head-to-head clinical analysis: CONSTILAC versus GOLYTELY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CONSTILAC versus GOLYTELY.
CONSTILAC vs GOLYTELY
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.
Polyethylene glycol 3350 is an osmotic laxative that induces diarrhea by retaining water in the bowel lumen through osmotic activity. Electrolytes (sodium sulfate, potassium chloride, sodium bicarbonate) prevent significant electrolyte absorption or loss.
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.
240 mL (oral) every 10 minutes until 4 L consumed or rectal effluent is clear; typically 4 L total over 3-4 hours.
None Documented
None Documented
Not applicable due to negligible systemic absorption; lactulose acts locally in the colon.
Not applicable (PEG 3350 is not significantly absorbed; effective half-life in GI tract is approximately 2-4 hours for colonic clearance).
Primarily fecal as unchanged drug (systemic absorption negligible). Renal excretion accounts for <2% of any absorbed fraction. Biliary excretion is minimal.
Primarily fecal elimination of unabsorbed polyethylene glycol 3350. Minimal systemic absorption (<0.06%), less than 0.06% recovered in urine as intact PEG 3350; electrocytes and sulfate (from sodium sulfate) are renally excreted.
Category C
Category C
Osmotic Laxative
Osmotic Laxative