Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PLENVU vs CHRONULAC
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
PLENVU is an osmotic laxative that induces bowel cleansing by causing water retention in the colon, leading to increased intraluminal pressure and stimulation of peristalsis. Its components (polyethylene glycol 3350, sodium ascorbate, ascorbic acid, sodium sulfate) act synergistically to produce a cathartic effect.
Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. It is hydrolyzed by colonic bacteria to form low molecular weight acids (mainly lactic and acetic acid), which osmotically draw water into the colon, softening stools and increasing stool frequency. Additionally, lactulose decreases colonic p H, which traps ammonia (NH3) as ammonium (NH4+), reducing serum ammonia levels.
FDA-approved: Bowel cleansing prior to colonoscopy in adults.,Off-label: Bowel preparation for colorectal surgery or other procedures requiring colonic cleansing.
Treatment of constipation,Hepatic encephalopathy (portal-systemic encephalopathy)
2 sachets (each containing ascorbic acid 4.7g, macrogol 3350 52.5g, sodium ascorbate 5.9g, sodium sulfate 3.75g) dissolved in water to a total volume of 500m L, administered orally as a split-dose regimen: first dose (2 sachets in 500m L water) at 6-9 pm on the day before colonoscopy, followed by additional 500m L of clear fluids; second dose (2 sachets in 500m L water) on the morning of colonoscopy, completed at least 2 hours before the procedure, followed by additional 500m L of clear fluids.
10-30 m L orally once daily to twice daily; for acute constipation, 20-30 m L initially; for hepatic encephalopathy, 30-60 m L every 1-2 hours to achieve 2-3 soft stools daily.
Not applicable (non-absorbed agent); systemic absorption is minimal, so no terminal half-life is defined.
Terminal elimination half-life approximately 1.5-2.5 hours in adults with normal renal function; may be prolonged to 4-8 hours in patients with renal impairment.
Polyethylene glycol 3350 is minimally absorbed and eliminated unchanged in feces. Ascorbic acid and sodium ascorbate are absorbed and metabolized via normal pathways (e.g., oxidation, conjugation). Sodium sulfate is absorbed and excreted primarily in urine.
Not absorbed systemically; metabolized by colonic bacteria (e.g., Lactobacillus, Bacteroides) to lactic acid, acetic acid, and other short-chain fatty acids.
Primarily fecal (90-95%) as unabsorbed drug; renal excretion is negligible (<1%).
Primarily renal (as unchanged drug and metabolites): ~40-50% of dose excreted in urine within 24 hours; biliary/fecal elimination accounts for the remainder, with approximately 2-5% recovered in feces as parent compound.
<5% bound to plasma proteins (due to minimal absorption).
Negligible (<5%), primarily to albumin.
Not applicable (confined to GI tract; systemic Vd not measurable).
Approximately 0.25 L/kg; distributes mainly into extracellular fluid.
Oral: <0.1% systemically available due to lack of absorption.
Oral: poorly absorbed; <3% reaches systemic circulation as intact lactulose; the remainder is metabolized by colonic bacteria.
Contraindicated in patients with estimated glomerular filtration rate (e GFR) < 30 m L/min/1.73 m² due to risk of acute phosphate nephropathy. No dose adjustment recommended for e GFR ≥ 30 m L/min/1.73 m².
No dose adjustment required for renal impairment; caution in severe renal impairment due to electrolyte disturbances.
No specific dosage adjustment based on Child-Pugh classification is provided by the manufacturer. Use with caution in patients with severe hepatic impairment due to potential electrolyte disturbances.
No adjustment needed; used in hepatic encephalopathy at higher doses.
Not approved for use in pediatric patients (age < 18 years). Safety and efficacy not established.
Infants: 2.5-5 m L orally once daily; Children 1-5 years: 5-10 m L once daily; Children 6-12 years: 10-15 m L once daily; Adolescents: 15-30 m L once daily; adjust based on response.
No specific dose adjustment required for elderly patients, but caution is advised due to increased risk of dehydration, electrolyte abnormalities, and renal impairment. Ensure adequate hydration and monitor renal function.
Start at low end of dosing range (10-15 m L once daily) due to increased risk of electrolyte imbalance and dehydration; monitor fluid/electrolyte status.
No FDA black box warning.
None.
Serious fluid and electrolyte abnormalities (e.g., hyponatremia, hypokalemia, seizures).,Cardiac arrhythmias in patients with electrolyte imbalances or prolonged QT interval.,Renal impairment: Risk of acute tubular necrosis and nephrocalcinosis.,Mucosal ulceration or colitis (rare).,Sulfate absorption may cause metabolic acidosis in susceptible patients.
Electrolyte disturbances (e.g., hypernatremia, hypokalemia) with prolonged use or high doses,Diarrhea may cause fluid and electrolyte loss,Risk of colonic distention or fecal impaction,Use caution in patients with galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption (contains galactose and lactose)
Gastrointestinal obstruction or ileus.,Perforation of the gastrointestinal tract.,Gastric retention or gastroparesis.,Toxic colitis or toxic megacolon.,Known hypersensitivity to any component of PLENVU.
Patients with galactosemia,Intestinal obstruction,Known hypersensitivity to lactulose
Avoid solid foods, dairy products, and any colored liquids (especially red, purple, or orange) during preparation. Patients must consume only clear liquids (e.g., water, clear broth, apple juice, clear gelatin, black coffee or tea without milk) to maintain hydration. Alcohol should be avoided due to dehydrating effects and potential interaction with preparation.
No specific food interactions, but avoid concurrent use with other laxatives. Ensure adequate fluid intake to reduce risk of hypernatremia.
PLENVU (polyethylene glycol 3350, sodium ascorbate, sodium sulfate, ascorbic acid, and macrogol) is classified as FDA Pregnancy Category C. There are no adequate and well-controlled studies in pregnant women. In animal studies, no evidence of teratogenicity was observed at doses up to 2 times the maximum recommended human dose. However, the osmotic laxative effect may cause fluid and electrolyte shifts, potentially affecting fetal perfusion. Use during pregnancy should be reserved for cases where bowel cleansing is essential and benefits outweigh risks, particularly in the first trimester due to theoretical concerns of dehydration or electrolyte imbalance.
Lactulose (CHRONULAC) is not absorbed systemically; no teratogenic effects are expected. No adequate and well-controlled studies in pregnant women; animal reproduction studies not conducted. Based on lack of systemic absorption, risk to fetus is low across all trimesters.
It is unknown whether PLENVU or its components are excreted in human breast milk. Polyethylene glycol is poorly absorbed systemically after oral administration, suggesting minimal transfer into breast milk. However, because many drugs are excreted in human milk, caution should be exercised when PLENVU is administered to a nursing woman. The M/P ratio has not been established for this combination product. Consider the developmental and health benefits of breastfeeding along with the mother's clinical need for PLENVU.
Lactulose is not absorbed orally; therefore, excretion into breast milk is negligible. Considered compatible with breastfeeding; no M/P ratio available due to lack of systemic absorption.
No specific dosing adjustments are recommended for PLENVU in pregnancy; however, clinical trials excluded pregnant women. The standard dose (two sachets: split-dose regimen) should be used cautiously with close monitoring for dehydration and electrolyte imbalances. Pharmacokinetic changes in pregnancy (increased volume of distribution, altered GI motility) may affect drug dispersal, but no formal studies exist. Consider reducing fluid volume if contraindicated, but no dose reduction has been established.
No dose adjustment required during pregnancy. Pharmacokinetics of lactulose are unchanged due to lack of systemic absorption. Use standard dosing for constipation (15-30 m L daily, titrated to effect).
PLENVU is a polyethylene glycol (PEG)-based bowel preparation used for colonoscopy. Adequate hydration is critical to prevent electrolyte abnormalities; ensure patients drink additional clear fluids as directed. Split-dose regimen (half dose evening before, remainder morning of procedure) improves tolerance and colon cleansing. Caution in patients with renal impairment, CHF, or electrolyte disturbances; monitor for volume depletion. Not recommended in patients with GI obstruction, ileus, or toxic colitis. May reduce absorption of oral medications (e.g., contraceptives, antidiabetics, anticoagulants); advise temporal separation.
Chronulac (lactulose) is a non-absorbable disaccharide used for constipation and hepatic encephalopathy. Onset of action for constipation is 24-48 hours; monitor for electrolyte disturbances (hypernatremia) with prolonged use. Do not use with other laxatives in acute abdomen. For hepatic encephalopathy, titrate to 2-3 soft stools daily.
Take PLENVU exactly as prescribed; follow the split-dose regimen for best results.,Drink the full amount of clear liquids recommended (including water) to prevent dehydration.,Avoid solid foods, dairy, red/purple liquids, and alcohol during preparation.,Expect frequent, watery bowel movements; stay near a bathroom.,If you miss a dose, consult your healthcare provider; do not double the dose.,Inform your doctor about all medications you take, especially diabetes meds, blood thinners, and diuretics.,Stop taking oral medications (e.g., contraceptives, hypoglycemics) as directed during prep; discuss alternative contraception.,Seek medical help if you experience severe vomiting, dizziness, fainting, or signs of allergic reaction.
May take 24-48 hours to produce a bowel movement; do not use if you have abdominal pain, nausea, or vomiting.,Mix with fruit juice, milk, or water to improve taste.,Store at room temperature; do not freeze.,Report excessive diarrhea or electrolyte imbalance symptoms (muscle cramps, weakness).
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about PLENVU vs CHRONULAC, answered by our medical review team.
PLENVU is a Osmotic Laxative that works by PLENVU is an osmotic laxative that induces bowel cleansing by causing water retention in the colon, leading to increased intraluminal pressure and stimulation of peristalsis. Its components (polyethylene glycol 3350, sodium ascorbate, ascorbic acid, sodium sulfate) act synergistically to produce a cathartic effect.. CHRONULAC is a Osmotic Laxative that works by Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. It is hydrolyzed by colonic bacteria to form low molecular weight acids (mainly lactic and acetic acid), which osmotically draw water into the colon, softening stools and increasing stool frequency. Additionally, lactulose decreases colonic p H, which traps ammonia (NH3) as ammonium (NH4+), reducing serum ammonia levels.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between PLENVU and CHRONULAC depend on the specific clinical indication. These are both Osmotic Laxative agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of PLENVU is: 2 sachets (each containing ascorbic acid 4.7g, macrogol 3350 52.5g, sodium ascorbate 5.9g, sodium sulfate 3.75g) dissolved in water to a total volume of 500m L, administered orally as a split-dose regimen: first dose (2 sachets in 500m L water) at 6-9 pm on the day before colonoscopy, followed by additional 500m L of clear fluids; second dose (2 sachets in 500m L water) on the morning of colonoscopy, completed at least 2 hours before the procedure, followed by additional 500m L of clear fluids.. The standard adult dose of CHRONULAC is: 10-30 m L orally once daily to twice daily; for acute constipation, 20-30 m L initially; for hepatic encephalopathy, 30-60 m L every 1-2 hours to achieve 2-3 soft stools daily.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between PLENVU and CHRONULAC in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. PLENVU is classified as Category C. PLENVU (polyethylene glycol 3350, sodium ascorbate, sodium sulfate, ascorbic acid, and macrogol) is classified as FDA Pregnancy Category C. There are no adequate and well-controlle. CHRONULAC is classified as Category C. Lactulose (CHRONULAC) is not absorbed systemically; no teratogenic effects are expected. No adequate and well-controlled studies in pregnant women; animal reproduction studies not . Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.