Lactulose Fresenius (Lactulose)

Lactulose is used as an osmotic laxative and as a ammonia‑lowering agent in liver disease.

• Constipation: Increases stool water content to facilitate bowel movements.
• Hepatic encephalopathy: Lowers systemic ammonia by converting it to non‑absorbable ammonium in the colon.
• Prevention of recurrent hepatic encephalopathy: Maintains lower ammonia levels to reduce episodes in chronic liver disease patients.

• Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. In the colon it is metabolised by bacterial flora, producing acidic metabolites that raise osmotic pressure, drawing water into the lumen and softening stools. The acidified environment also converts ammonia (NH3) to ammonium (NH4+), which is poorly absorbed, thereby decreasing systemic ammonia concentrations.

Lactulose may cause a range of adverse reactions, most of which are related to its osmotic activity in the gut.

Common Side Effects

• Abdominal bloating: sensation of fullness due to gas production.
• Flatulence: increased intestinal gas.
• Nausea: mild stomach upset.
• Diarrhea: loose stools from excess water retention.
• Stomach cramps: intermittent abdominal pain.
• Thirst: increased fluid loss.

Serious or Rare Side Effects

• Severe dehydration: excessive fluid loss leading to electrolyte imbalance.
• Electrolyte disturbances: notably low potassium or sodium levels.
• Allergic reaction: rash, itching, or swelling.
• Severe abdominal pain: persistent or worsening discomfort.
• Hypernatremia: elevated blood sodium from water loss.

When prescribing Lactulose, clinicians should consider several safety measures to minimise risk.

• Dose adjustment: Reduce dose in patients with renal impairment to avoid accumulation.
• Electrolyte monitoring: Check serum potassium and sodium regularly during prolonged therapy.
• Diabetes caution: Monitor blood glucose as lactulose may affect carbohydrate metabolism.
• Discontinuation: Avoid abrupt cessation in patients dependent on laxatives to prevent rebound constipation.
• Pregnancy and lactation: Use only if clearly needed and after professional consultation.
• Store at ambient temperature: Keep below 25 °C in the original container, protect from moisture and direct sunlight.

Lactulose can interact with other medicines that affect gut flora or electrolyte balance.

Major Interactions (Avoid)

• Rifaximin: Combined use may excessively alter intestinal bacteria and increase gas.
• Oral phosphate binders: May reduce lactulose efficacy by binding in the gut.
• Loop diuretics: Heightened risk of electrolyte disturbances when used together.

Moderate Interactions (Monitor Closely)

• Antacids: May lower the acidity of the colon, slightly reducing lactulose action.
• Probiotics: Can increase gas production, worsening bloating.
• Other laxatives: Concurrent use may amplify dehydration and electrolyte loss.