Comparative Pharmacology
Head-to-head clinical analysis: GLYCOLAX versus PORTALAC.
Peer-Reviewed Evidence
Head-to-head clinical analysis: GLYCOLAX versus PORTALAC.
GLYCOLAX vs PORTALAC
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Osmotic laxative. Polyethylene glycol (PEG) increases intraluminal water volume in the colon by osmosis, promoting stool passage and relieving constipation.
Lactulose is a synthetic disaccharide that is not absorbed from the gastrointestinal tract. It is metabolized by colonic bacteria to short-chain fatty acids (e.g., acetic, lactic, and formic acid), resulting in acidification of colonic contents and an increase in osmotic pressure, which stimulates bowel evacuation. In hepatic encephalopathy, acidification reduces blood ammonia levels by converting NH3 to NH4+ in the colon, inhibiting ammonia absorption.
17 g (1 heaping tablespoon) dissolved in 4-8 ounces of liquid once daily, orally.
Initial: 15-30 mL (10-20 g lactulose) orally, 2-3 times daily; titrate to 2-3 soft stools daily. For acute hepatic encephalopathy: 30-45 mL (20-30 g) orally every hour until evacuation, then 3-4 times daily.
None Documented
None Documented
Not applicable due to negligible systemic absorption; local colonic transit time approximately 2-4 hours.
1.7-2.0 hours (terminal); clinical context: short t1/2 allows rapid dose adjustment in hepatic encephalopathy.
Minimally absorbed; excreted primarily unchanged in feces via osmotic action. Renal excretion negligible (<0.2% absorbed dose).
Renal: ~40% as unchanged drug; fecal: ~60% as metabolites (biliary excretion of conjugates and lactulose).
Category C
Category C
Osmotic Laxative
Osmotic Laxative