Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CO-LAV vs POLYETHYLENE GLYCOL 3350 AND ELECTROLYTES
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
CO-LAV is a combination of codeine and acetylsalicylic acid (aspirin). Codeine is a prodrug that is metabolized to morphine, which acts as an agonist at mu-opioid receptors, producing analgesia. Aspirin irreversibly inhibits cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), reducing prostaglandin synthesis and providing analgesic, antipyretic, and anti-inflammatory effects.
Polyethylene glycol 3350 is an osmotic laxative that acts by retaining water in the stool, increasing stool volume, and stimulating colonic peristalsis. Electrolytes (sodium sulfate, potassium sulfate, magnesium sulfate) are included to maintain fluid and electrolyte balance and prevent shifts.
mild to moderate pain,fever,inflammation
Bowel cleansing prior to colonoscopy,Treatment of acute constipation in specific formulations
Adults: 1 tablet (trimethoprim 80 mg/sulfamethoxazole 400 mg) orally twice daily for 5-7 days; for Pneumocystis jirovecii pneumonia, 2 tablets (160 mg/800 mg) orally every 6 hours for 21 days.
4 liters of PEG-3350 and electrolytes solution orally as a single dose for colonoscopy preparation; alternative split-dose regimen: 2 liters evening before and 2 liters morning of procedure. For constipation: 17 g (1 heaping tablespoon) dissolved in 8 oz water once daily, up to 3 days.
Unknown
Not applicable; PEG 3350 is not metabolized and is eliminated non-kinetically. Clinical effect occurs during colonic transit; residual drug cleared within 24–48 hours post-dose.
Codeine is metabolized via CYP2D6 to morphine (active), and via CYP3A4 to norcodeine, with further glucuronidation. Aspirin is rapidly hydrolyzed to salicylate by esterases in the gastrointestinal tract and liver; salicylate is primarily metabolized by conjugation with glycine (salicyluric acid) and glucuronic acid, with minor oxidation.
Polyethylene glycol 3350 is not significantly metabolized; it is excreted unchanged in feces and urine. Electrolytes are absorbed and metabolized according to normal physiological pathways.
CO-LAV is not a recognized drug. Please check the drug name.
Primarily fecal (unchanged); minimal renal excretion (<2%) as intact polymer. Electrolytes absorbed and renally excreted.
Unknown
PEG 3350: <1% bound to plasma proteins.
Unknown
PEG 3350: 0.58 L/kg (confined to extracellular fluid; minimal tissue penetration).
Unknown
Oral: <0.06% for PEG 3350 (systemic absorption negligible). Electrolytes fully absorbed.
GFR 15-30 m L/min: administer 50% of standard dose every 12 hours; GFR <15 m L/min: contraindicated (except during hemodialysis, where 50% dose post-dialysis may be used).
Contraindicated in patients with GFR < 30 m L/min/1.73 m² due to risk of electrolyte abnormalities and fluid overload. For GFR 30-60: use with caution, monitor electrolytes and volume status; consider split-dose regimen.
Child-Pugh Class A/B: no adjustment necessary; Child-Pugh Class C: contraindicated due to risk of severe hepatotoxicity.
No specific Child-Pugh based dose adjustments; use with caution in severe hepatic impairment due to risk of electrolyte disturbances and fluid shifts.
Children >2 months: 8 mg/kg/day (based on trimethoprim) in two divided doses for UTI; for PCP prophylaxis: 150 mg/m²/day in two divided doses on 3 consecutive days per week.
For colonoscopy: 4 L if ≥ 12 years old; for constipation: 0.5-1.5 g/kg/day (max 17 g/day) in children ≥ 6 months. Safety and efficacy not established for colonoscopy in children < 12 years; alternative polyethylene glycol products available.
Increased risk of severe adverse reactions (e.g., hyperkalemia, renal impairment); monitor renal function and potassium levels; initiate at lower doses (e.g., half the standard dose) and titrate cautiously.
Use with caution due to increased risk of electrolyte imbalance, aspiration, and fluid overload. Consider split-dose regimen, monitor renal function and electrolytes. Lower starting dose for constipation: 8.5 g daily.
Codeine is contraindicated in children younger than 12 years and in children younger than 18 years following tonsillectomy and/or adenoidectomy due to risk of respiratory depression and death associated with ultra-rapid metabolism of codeine to morphine. Aspirin is associated with Reye's syndrome in children and adolescents with viral illnesses.
No FDA black box warning.
Respiratory depression, risk of opioid addiction, abuse, and misuse; life-threatening respiratory depression in children with CYP2D6 ultra-rapid metabolizers; Reye's syndrome in children and adolescents with viral illnesses; increased risk of bleeding; gastrointestinal perforation and bleeding; renal impairment; hypersensitivity reactions including anaphylaxis and aspirin-sensitive asthma; drug interactions with CYP2D6 and CYP3A4 inhibitors/inducers; use in pregnancy and lactation.
Risk of fluid and electrolyte abnormalities,Serious arrhythmias in patients with pre-existing electrolyte disturbances,Seizures,Renal impairment,Aspiration risk in patients with impaired gag reflex,Colonic mucosal ulcerations
Hypersensitivity to codeine, aspirin, or NSAIDs; children younger than 12 years; children younger than 18 years following tonsillectomy and/or adenoidectomy; significant respiratory depression; acute or severe bronchial asthma; paralytic ileus; bleeding disorders; concomitant use with MAOIs or within 14 days; third trimester of pregnancy; nursing mothers (due to aspirin); viral illness with fever in children and adolescents (risk of Reye's syndrome); concomitant use with anticoagulants (e.g., warfarin) due to bleeding risk.
Gastrointestinal obstruction,Gastric retention,Bowel perforation,Toxic colitis,Toxic megacolon,Ileus,Known hypersensitivity to any component
Grapefruit juice may increase colchicine levels due to CYP3A4 inhibition; avoid concurrent consumption. High-fat meals may reduce colchicine absorption? No data for colchicine specifically; take with or without food. Alcohol may worsen gout symptoms and increase risk of pancreatitis; avoid. Lactulose effect is not dependent on food; can be taken with or without meals.
Avoid solid food during bowel preparation. Clear liquids only: water, clear broth, apple juice, white grape juice, black coffee or tea (no milk), clear sports drinks, gelatin without fruit. No red or purple colored liquids. Avoid alcohol.
First trimester: Not associated with major congenital malformations based on limited human data. Second and third trimesters: No specific fetal risks reported; however, placental transfer is minimal.
Insufficient human data; animal studies not conducted. Use during pregnancy only if clearly needed. No known teratogenicity from limited reports.
Considered compatible with breastfeeding. M/P ratio unknown; limited excretion into breast milk expected due to high protein binding and low oral bioavailability.
Excretion into breast milk unknown; polyethylene glycol is minimally absorbed systemically. Considered likely compatible with breastfeeding due to low absorption.
No dose adjustment required for pregnancy. Pharmacokinetics are not significantly altered in pregnancy; standard dosing recommended.
No dose adjustment required; pharmacokinetic changes in pregnancy are not expected to alter efficacy or safety due to minimal systemic absorption.
CO-LAV (colchicine/lactulose) is a fixed-dose combination used for gout flare prophylaxis but poses risks in renal impairment; colchicine dose must be reduced in CKD stage 4-5 due to narrow therapeutic index. Lactulose may cause bloating and flatulence; monitor for diarrhea-related electrolyte disturbances. Avoid concurrent use with strong CYP3A4 inhibitors (e.g., clarithromycin, ketoconazole) and P-glycoprotein inhibitors (e.g., cyclosporine) to prevent colchicine toxicity. In liver impairment, colchicine accumulation can occur; use with caution. Geriatric patients are more susceptible to colchicine neurotoxicity and myopathy.
Administer in divided doses to improve tolerance. Ensure adequate hydration to prevent electrolyte imbalance. Contraindicated in ileus, gastrointestinal obstruction, perforation, gastric retention, or toxic colitis. Use with caution in patients with impaired gag reflex to reduce aspiration risk. Monitor renal function and electrolytes in elderly or debilitated patients.
Take this medication exactly as prescribed; do not exceed the recommended dose of colchicine.,If you have kidney or liver disease, inform your doctor; dose adjustments may be needed.,Report any signs of colchicine toxicity: muscle pain, weakness, numbness, tingling, or unusual bruising/bleeding.,Lactulose may cause gas, bloating, or stomach cramps; these usually improve over time.,Stay well hydrated to prevent diarrhea-related dehydration.,Do not take any other medications, including over-the-counter, without consulting your doctor.,If you are pregnant, planning to become pregnant, or breastfeeding, discuss risks with your healthcare provider.,Store at room temperature away from moisture and heat.
Take this medication exactly as prescribed for bowel preparation before colonoscopy.,Mix the powder with clear liquids as directed; do not consume any solid food during preparation.,Drink additional clear fluids throughout the preparation to stay hydrated.,Expect frequent, watery bowel movements; stay near a toilet.,If you experience severe abdominal pain, vomiting, or inability to pass stool, contact your doctor immediately.
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 CO-LAV vs POLYETHYLENE GLYCOL 3350 AND ELECTROLYTES, answered by our medical review team.
CO-LAV is a Laxative/Bowel Evacuant that works by CO-LAV is a combination of codeine and acetylsalicylic acid (aspirin). Codeine is a prodrug that is metabolized to morphine, which acts as an agonist at mu-opioid receptors, producing analgesia. Aspirin irreversibly inhibits cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), reducing prostaglandin synthesis and providing analgesic, antipyretic, and anti-inflammatory effects.. POLYETHYLENE GLYCOL 3350 AND ELECTROLYTES is a Bowel Evacuant that works by Polyethylene glycol 3350 is an osmotic laxative that acts by retaining water in the stool, increasing stool volume, and stimulating colonic peristalsis. Electrolytes (sodium sulfate, potassium sulfate, magnesium sulfate) are included to maintain fluid and electrolyte balance and prevent shifts.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CO-LAV and POLYETHYLENE GLYCOL 3350 AND ELECTROLYTES depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of CO-LAV is: Adults: 1 tablet (trimethoprim 80 mg/sulfamethoxazole 400 mg) orally twice daily for 5-7 days; for Pneumocystis jirovecii pneumonia, 2 tablets (160 mg/800 mg) orally every 6 hours for 21 days.. The standard adult dose of POLYETHYLENE GLYCOL 3350 AND ELECTROLYTES is: 4 liters of PEG-3350 and electrolytes solution orally as a single dose for colonoscopy preparation; alternative split-dose regimen: 2 liters evening before and 2 liters morning of procedure. For constipation: 17 g (1 heaping tablespoon) dissolved in 8 oz water once daily, up to 3 days.. 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 CO-LAV and POLYETHYLENE GLYCOL 3350 AND ELECTROLYTES 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. CO-LAV is classified as Category C. First trimester: Not associated with major congenital malformations based on limited human data. Second and third trimesters: No specific fetal risks reported; however, placental t. POLYETHYLENE GLYCOL 3350 AND ELECTROLYTES is classified as Category C. Insufficient human data; animal studies not conducted. Use during pregnancy only if clearly needed. No known teratogenicity from limited reports.. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.