Lactulose

ADMINISTRATION ROUTES:

PO, NG

ALTERNATIVE NAMES:

Duphalac

ICU INDICATIONS:

1. Constipation
2. Hepatic encephalopathy

PRESENTATION AND ADMINISTRATION:

PO/NG:

Duphalac 10g/15 mL

Store at room temperature

DOSAGE:

PO:

Constipation

10-20 mL BD or OD

Hepatic Coma

Initally 30-45 mL hourly until bowel cleared

Reduce to 30-45 mL QID or TDS once achieved

Coma from portal-systemic encephalopathy should be treated aggressively with frequent dosing, reducing when constant watery diarrhoea is produced. Continuous long-term therapy is indicated to lessen severity and prevent recurrence of portal-systemic encephalopathy. The dose for this purpose is the same as the reduced dose above, with an aim of 2-3 loose soft bowel motions per day

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose as in normal renal function

DOSAGE IN PAEDIATRICS:

PO:

Constipation

0.5 mg/kg BD or OD

Hepatic coma

1 mg/kg hourly until bowel cleared

Reduce to 1 mg/kg QID or TDS

CLINICAL PHARMACOLOGY:

Lactulose is a synthetic disaccharide in solution form for enteral administration. It is a colonic acidifier that promotes laxation. Lactulose causes a decrease in blood ammonia concentration and reduces the degree of portal systemic encephalopathy. These actions are due to the following process:

• Bacterial degradation of lactulose in the colon acidifies colonic contents
• Acidification of colonic contents results in the retention of ammonia in the colon as the ammonium ion
• Colonic contents is now more acidic than blood so ammonia migrates from blood into the colon
• The acidic colonic contents converts ammonia (NH₃) to ammonium ion (NH₄⁺), trapping it and preventing its absorption
• The laxative action of the metabolites of lactulose expels the trapped ammonium ion from the colon

CONTRAINDICATIONS:

1. Mechanical bowel obstruction
2. Since lactulose contains galactose, it is contraindicated in patients who require a low galactose diet

WARNINGS:

Infants receiving lactulose may develop hyponatraemia and dehydration

PRECAUTIONS:

General:

See WARNINGS and CONTRAINDICATIONS

Laboratory Tests:

No tests in addition to routine ICU tests are required but electrolytes should be monitored closely, particularly in children

Drug/Laboratory Test Interactions:

None known

IMPORTANT DRUG INTERACTIONS IN ICU:

Other laxatives should not be used, especially during the initial phase of therapy for portal-systemic encephalopathy, because the loose stools resulting from their use may falsely suggest that adequate lactulose dosage has been achieved.

ADVERSE REACTIONS:

Gastrointestinal:

Diarrhoea, nausea and vomiting, gaseous distention with flatulence or belching, abdominal discomfort

Metabolic:

Dehydration, hypokalaemia, hypernatraemia