Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
CHOLAC vs ALCAINE
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. It is metabolized by colonic bacteria to short-chain fatty acids, primarily lactic acid and acetic acid, which lower the colonic p H. This acidification traps ammonia (NH3) as ammonium (NH4+) in the gut lumen, reducing serum ammonia levels. Additionally, the osmotic effect of lactulose draws water into the colon, producing a laxative effect.
Local anesthetic that stabilizes the neuronal membrane by inhibiting sodium ion influx, thereby blocking nerve impulse transmission.
Treatment of hepatic encephalopathy (portal-systemic encephalopathy) in patients with acute and chronic liver disease,Constipation (including chronic idiopathic constipation)
Ophthalmic anesthesia for procedures such as cataract extraction, tonometry, gonioscopy, and suture removal
15-30 m L (10-20 g lactulose) orally once daily, titrated to produce 2-3 soft stools per day; maximum dose 60 m L/day. For hepatic encephalopathy: 30-45 m L (20-30 g) orally 3-4 times daily, titrated to 2-3 soft stools per day.
1 to 2 drops of 0.5% solution topically to the eye, repeated as needed for anesthesia.
0.5-1.5 hours for lactulose; active metabolites (e.g., acetic acid) have negligible systemic half-life due to rapid local metabolism.
Terminal elimination half-life: 0.4–1.2 minutes (rapid enzymatic hydrolysis by plasma esterases); clinical significance: ultra-short duration limits systemic toxicity.
Not absorbed systemically. Metabolized by colonic bacteria (e.g., Lactobacillus, Bacteroides) to lactic acid, acetic acid, and other short-chain fatty acids.
Hydrolyzed by plasma esterases.
Primarily fecal (biliary excretion of unchanged drug and metabolites); minimal renal excretion (<5%).
Renal excretion of parent drug and metabolites: <5% unchanged.
Negligible (<1%); not significantly bound to plasma proteins.
Minimal; <5% bound to plasma proteins.
Approximately 0.2 L/kg; indicates distribution primarily in extracellular fluid.
Not clinically meaningful due to rapid hydrolysis; Vd estimated <0.5 L/kg (low, consistent with high water solubility and rapid clearance).
Oral: <2% systemic bioavailability due to extensive first-pass metabolism and local gut action; rectal: minimal systemic absorption.
Ophthalmic topical: negligible systemic absorption (minimal bioavailability); not applicable systemically.
No dose adjustment required for renal impairment.
No dose adjustment required; negligible systemic absorption.
No specific Child-Pugh based adjustments. Use with caution in severe hepatic impairment due to risk of electrolyte disturbances; monitor serum electrolytes.
No dose adjustment required; negligible systemic absorption.
Infants: 2.5-10 m L/day in divided doses. Children: 40-90 mg/kg/day (as lactulose) divided 1-2 times daily, titrated to produce soft stools. For hepatic encephalopathy: 2.5-10 m L (1.7-6.7 g) orally 3-4 times daily, titrated to 2-3 soft stools per day.
1 drop of 0.5% solution topically to the eye, repeated as needed; maximum 1 drop per dose in infants and young children to avoid systemic effects.
Initiate at lower end of dosing range (15 m L once daily) and titrate slowly to avoid diarrhea and electrolyte imbalance; monitor renal function and electrolytes.
No specific adjustment; use lowest effective dose due to potential increased corneal sensitivity and delayed healing.
No FDA black box warning.
Not for injection or prolonged use; corneal toxicity with repeated or prolonged use.
Electrolyte disturbances (e.g., hypernatremia) may occur, especially with prolonged use or in patients with renal impairment,Diarrhea can lead to fluid and electrolyte loss; dosage should be adjusted to produce 2-3 soft stools per day,Galactose content: lactulose contains galactose and lactose; use with caution in patients with galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption,Risk of colonic perforation in patients with severe colonic ulceration, toxic megacolon, or gastrointestinal obstruction
Prolonged use may cause corneal epithelial damage and delay wound healing. Avoid contamination of the dropper tip.
Patients with galactosemia (due to galactose content),Gastrointestinal obstruction (including ileus),Hypersensitivity to lactulose or any component of the formulation
Hypersensitivity to any component of the formulation.
No specific food restrictions. Mixing with fruit juice, water, or milk may improve taste. Avoid excessive intake of dairy products if lactose intolerant (lactulose may contain small amounts of lactose).
None known.
Lactulose is not absorbed systemically; no teratogenic effects reported in animal studies or human case reports. FDA Pregnancy Category B. Trimester-specific risks: no known fetal harm in any trimester.
Proparacaine (ALCAINE) is an ophthalmic local anesthetic. Systemic absorption is negligible after topical ocular administration. No adequate well-controlled studies in pregnant women. Animal studies showed no teratogenic effects at doses up to 0.5 mg/kg (SC). Potential fetal risk unlikely to exceed background risk. No known trimester-specific risks.
Excretion into breast milk is negligible due to minimal systemic absorption. M/P ratio not determined. Considered compatible with breastfeeding.
Proparacaine is excreted into breast milk in unknown amounts, but due to minimal systemic absorption, the expected dose to infant is negligible. Manufacturer advises caution. No M/P ratio available.
No dose adjustment required during pregnancy; pharmacokinetics unchanged due to localized GI action.
No dosing adjustment required for topical ophthalmic use due to negligible systemic absorption and lack of pharmacokinetic alterations in pregnancy.
Cholac (lactulose) is used for constipation and hepatic encephalopathy. Monitor for diarrhea and electrolyte imbalances. In hepatic encephalopathy, titrate dose to achieve 2-3 soft stools per day. Syrup can be mixed with fruit juice or water to improve palatability. Onset of action is 24-48 hours for constipation; for encephalopathy, effects may take several days.
ALCAINE (proparacaine) is a topical ophthalmic anesthetic. Onset within 20 seconds, duration ~15 minutes. Do not dispense for home use due to risk of corneal toxicity with prolonged use. Use a sterile, single-dose vial to prevent contamination. Monitor for stinging or burning on instillation. Avoid in patients with sulfite allergy (contains sodium bisulfite).
Take exactly as prescribed. Do not change dose without consulting your doctor.,For constipation, effects may take up to 48 hours. Do not use other laxatives unless advised.,For liver disease, it helps reduce ammonia levels. Aim for 2-3 soft bowel movements daily.,May cause gas, bloating, or stomach cramps, which usually decrease over time.,Contact doctor if you have severe diarrhea, vomiting, or signs of dehydration.,Store at room temperature, away from heat and direct light.
Temporary stinging or burning may occur upon application.,Do not touch the dropper tip to any surface to avoid contamination.,Do not use for more than instructed; prolonged use can damage the cornea.,Remove contact lenses before use and wait at least 15 minutes before reinserting.,Notify your doctor if you have a sulfite allergy.
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 CHOLAC vs ALCAINE, answered by our medical review team.
CHOLAC is a Laxative that works by Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. It is metabolized by colonic bacteria to short-chain fatty acids, primarily lactic acid and acetic acid, which lower the colonic p H. This acidification traps ammonia (NH3) as ammonium (NH4+) in the gut lumen, reducing serum ammonia levels. Additionally, the osmotic effect of lactulose draws water into the colon, producing a laxative effect.. ALCAINE is a Local Anesthetic that works by Local anesthetic that stabilizes the neuronal membrane by inhibiting sodium ion influx, thereby blocking nerve impulse transmission.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between CHOLAC and ALCAINE 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 CHOLAC is: 15-30 m L (10-20 g lactulose) orally once daily, titrated to produce 2-3 soft stools per day; maximum dose 60 m L/day. For hepatic encephalopathy: 30-45 m L (20-30 g) orally 3-4 times daily, titrated to 2-3 soft stools per day.. The standard adult dose of ALCAINE is: 1 to 2 drops of 0.5% solution topically to the eye, repeated as needed for anesthesia.. 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 CHOLAC and ALCAINE 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. CHOLAC is classified as Category C. Lactulose is not absorbed systemically; no teratogenic effects reported in animal studies or human case reports. FDA Pregnancy Category B. Trimester-specific risks: no known fetal . ALCAINE is classified as Category C. Proparacaine (ALCAINE) is an ophthalmic local anesthetic. Systemic absorption is negligible after topical ocular administration. No adequate well-controlled studies in pregnant wom. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.