Mode of action
Poorly absorbed, metabolized by colonic bacteria; it exerts an osmotic effect in the colon. Increase in intraluminal pressure stimulates peristalsis.
Beneficial effects in hepatic encephalopathy are thought to result from prevention of absorption of ammonia by lowering faecal pH as well as its laxative effect.
Indications
Constipation; Hepatic encephalopathy.
Contraindications
Intestinal obstruction, partial or complete, Galactose or lactose intolerance (products contain galactose
<1.65 g/15 mL and lactose <0.9 g/15 mL).
Specific considerations
Pregnancy: Safe to use.
Breastfeeding: Safe to use.
Adverse effects
Common: flatulence, abdominal discomfort.
Infrequent: diarrhoea, electrolyte imbalances.
Dosage
Constipation
Adult: Initially 15–30 mL daily in 1 or 2 doses. Doses up to 90 mL daily may be used if necessary. Maintenance, 10–
25 mL daily.
Child: 6–12 years, 15 mL daily. 1–5 years, 5–10 mL daily. <12 months, 3–5 mL daily.
Hepatic encephalopathy
Adult: Oral/nasogastric tube, 30–45 mL every 1–2 hours to induce rapid laxative effect. Reduce to 30–45 mL 3–4 times daily when laxative effect has been achieved. The dose is subsequently adjusted to produce 2–3 soft stools per day.
Rectal (if the oral route is unavailable), dilute 300 mL of lactulose oral liquid with 700 mL water or sodium
chloride 0.9%; retain enema for 30–60 minutes and repeat every 4–6 hours until the person is able to take orally.
Child: Oral/nasogastric tube, 1 mL/kg (up to adult dose) every 1–2 hours until desired response, then every 6 hours.
Counselling
This medicine tastes very sweet, it may help to mix it with fruit juice, water or milk
Practice points
onset of action is 1–3 days
a systematic review concluded there was not enough evidence to determine whether lactulose benefited
patients with hepatic encephalopathy
Products
LACTULOSE SYRUP 10 GM/15ML 100-300 ML BOTTLE (EZILAX®, LACTULOSE®, LACTUVER®,
LAXODAD®, RAMLAC®, RIALAC®)