Comparative Pharmacology
Head-to-head clinical analysis: CONSTILAC versus NULYTELY.
Peer-Reviewed Evidence
Head-to-head clinical analysis: CONSTILAC versus NULYTELY.
CONSTILAC vs NULYTELY
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 (PEG) 3350 is an osmotic agent that induces diarrhea by drawing water into the gastrointestinal tract, thereby cleansing the bowel. Sodium sulfate and electrolytes (sodium, potassium, bicarbonate) are added to prevent fluid and electrolyte shifts.
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.
4 liters orally of the reconstituted solution as a single dose for colonoscopy preparation, typically administered in divided doses (e.g., 240 mL every 10 minutes) until rectal effluent is clear. Alternatively, a split-dose regimen: half the solution evening before, half on the day of procedure.
None Documented
None Documented
Not applicable due to negligible systemic absorption; lactulose acts locally in the colon.
Not applicable; NULYTELY is not systemically absorbed in significant amounts, so a terminal elimination half-life is not defined. The drug acts locally in the gastrointestinal tract.
Primarily fecal as unchanged drug (systemic absorption negligible). Renal excretion accounts for <2% of any absorbed fraction. Biliary excretion is minimal.
NULYTELY (polyethylene glycol 3350) is minimally absorbed systemically (<0.06%). The primary route of elimination is fecal excretion of the intact polymer. Renal excretion is negligible (<0.02%).
Category C
Category C
Osmotic Laxative
Osmotic Laxative