Comparative Pharmacology
Head-to-head clinical analysis: POLYETHYLENE GLYCOL 3350 versus PORTALAC.
Peer-Reviewed Evidence
Head-to-head clinical analysis: POLYETHYLENE GLYCOL 3350 versus PORTALAC.
POLYETHYLENE GLYCOL 3350 vs PORTALAC
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Osmotic laxative. Polyethylene glycol 3350 is a non-absorbable polymer that retains water in the colon via hydrogen bonding, increasing stool water content and stimulating defecation.
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 capful or packet) dissolved in 4–8 oz (120–240 mL) water, administered orally once daily for constipation; for colonoscopy preparation, 240 g (4 L of solution) ingested at 240 mL every 10–15 minutes.
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
Terminal elimination half-life is 1-2 hours in patients with normal renal function; prolonged in renal impairment, but clinical impact minimal due to primarily fecal elimination.
1.7-2.0 hours (terminal); clinical context: short t1/2 allows rapid dose adjustment in hepatic encephalopathy.
Renal: approximately 20% excreted unchanged; Fecal: approximately 80% eliminated unchanged in feces.
Renal: ~40% as unchanged drug; fecal: ~60% as metabolites (biliary excretion of conjugates and lactulose).
Category C
Category C
Osmotic Laxative
Osmotic Laxative