乳果糖-Lactulose

Lactulose (Overview)

Lactulose is a synthetic disaccharide derivative of lactose, composed of one molecule of galactose and one molecule of fructose.

It appears as a white powder, slightly soluble in ethanol but highly soluble in water.

Commercial preparations are viscous, sweet-tasting syrups with a pH range of 3–7.

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Storage

Lactulose syrup should be stored in tightly closed containers at room temperature, avoiding freezing.

Exposure to heat or light may cause darkening or turbidity of the solution, but this does not affect its efficacy.

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Pharmacology / Indications / Pharmacokinetics

Lactulose is a non-absorbable disaccharide that cannot be hydrolyzed by digestive enzymes in mammals or birds.

Upon reaching the colon, it is metabolized by resident bacteria to produce low-molecular-weight organic acids (mainly lactic, formic, and acetic acids) and CO₂.

These acids have two primary effects:

1.Osmotic effect – they increase osmotic pressure, drawing water into the intestinal lumen and promoting laxation.

2.Acidification – they acidify colonic contents, converting ammonia (NH₃) absorbed from the blood into ammonium ions (NH₄⁺), which are then excreted in feces, thereby reducing systemic ammonia levels.

In veterinary medicine, lactulose is mainly used for:

•Reducing blood ammonia concentration

•Preventing and treating hepatic encephalopathy (portosystemic encephalopathy, PSE) in small animals and pet birds

•Serving as a gentle laxative for dogs and cats

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Safety

Lactulose syrup contains free lactose and galactose, which may alter insulin requirements in diabetic patients.

Use cautiously in animals with fluid or electrolyte imbalances, as induced diarrhea may worsen their condition.

Do not combine lactulose with other laxatives, as watery stool formation may be misinterpreted as therapeutic failure in hepatic encephalopathy cases.

Drug interactions:

•Oral antibiotics (e.g., neomycin) may reduce bacterial metabolism of lactulose, potentially lowering its effect.

However, studies indicate synergistic benefits when both are used together for hepatic encephalopathy.

•Nonabsorbable antacids may reduce the acidification of colonic contents and thus diminish efficacy.

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Dosage

Dogs:

For hepatic encephalopathy:

•15–30 mL orally, four times daily, adjusting to achieve 2–3 soft stools per day.

•Alternatively, 5 mL per 2.5 lb (≈1.1 kg) body weight, orally three times daily, increasing as needed for desired stool consistency.

•In animals at risk of hepatic encephalopathy: administer 20–60 mL via gastric tube every 4–6 hours, or as an enema (diluted with water) 200–300 mL total (300–450 g).

•5–15 mL orally, three times daily, titrating to 2–3 soft stools per day.

If diarrhea occurs, reduce the dose.

Combination therapy with neomycin may yield better results than monotherapy.

For constipation:

•Initially 1 mL per 4.5 kg body weight, orally every 8 hours; adjust as needed based on clinical response.

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Source: Veterinary Drug Manual

Compiled and Published by: Mao Pipi Veterinary Care