lactulose: clinical use

Prescribing considerations

• Exclude obstruction, perforation risk or another significant cause before treating unexplained painful abdominal symptoms.
• Selected products contain manufacturing residues of sugars; consider hereditary sugar disorders, lactose intolerance and diabetes, especially where exposure is substantial.
• Use laxatives in children under medical supervision; product age restrictions and available formulations differ.
• Persistent diarrhoea or vomiting may require treatment review and correction of fluid or electrolyte disturbance.

Contraindications and cautions

• Hypersensitivity to lactulose or product components.
• Galactosaemia.
• Gastrointestinal obstruction, perforation or risk of perforation.
• For the selected constipation-only sachets: acute inflammatory bowel disease, subocclusive syndromes and painful abdominal syndromes of undetermined cause.
• Relevant rare hereditary disorders affecting galactose, fructose, lactase or glucose-galactose handling, as specified by the individual product.

Monitoring

• Clinical response and stool consistency.
• Hydration and symptoms of diarrhoea or vomiting.
• Electrolytes when clinically indicated, particularly with prolonged use, frailty or substantial gastrointestinal fluid loss.
• Blood glucose where higher exposure or prolonged treatment may be relevant in a person with diabetes.

Clinical pharmacology

Lactulose is a minimally absorbed synthetic disaccharide fermented by colonic bacteria. Organic-acid production lowers colonic pH and increases osmotic pressure, raising faecal water content and stimulating peristalsis. Altered bacterial nitrogen metabolism and increased faecal nitrogen excretion contribute in hepatic encephalopathy.

Formulation and product differences

• The selected sachet product is licensed for constipation only and contains no listed excipients, although manufacturing-related sugar residues may remain.
• The selected bottled oral solution is licensed for constipation and hepatic encephalopathy; it contains manufacturing residues including lactose, galactose, fructose and sulphite.
• Bottle and sachet presentations differ in measurement, handling, paediatric suitability and storage instructions; consult the product-specific prescribing information.

Oral solution

Route: Oral

Strengths: 3.335 g/5 mL, 10 g/15 mL