Lactulose (Duphalac)Classification: Laxative

Action: Causes an influx of fluid in the intestinal tract by increasing the osmotic pressure within the intestinal lumen. Bacterial metabolism of the drug to lactate and other acids which are only partially absorbed in the distal ileum and colon augments the osmotic effect of lactulose. The distention of the colon due to increased fluid enhances intestinal motility and secretion. These result to the passage of soft stools. Decrease in the lumenal pH (due to bacterial metabolism) further increase motility and secretion. Lactulose also lowers intestinal absorption of ammonia presumably due to increased utilization of ammonia by intestinal bacteria.

Indication: Constipation, salmonellosis. Treatment of hepatic encephalopathy.

Adverse Reactions: Abdominal discomfort associated with flatulence and intestinal cramps. Nausea, vomiting, diarrhea on prolonged used.

Nursing Considerations


  • Assess patient’s condition before therapy and reassess regularly thereafter to monitor drug’s effectiveness. Identify cause of constipation: Assess lifestyle in relation to fluids, bulk and exercise
  • For patient with hepatic encephalopathy, regularly assess mental condition (clearing of confusion, lethargy, restlessness, irritability) and ammonia level (30-70 mg/100 mL).
  • Monitor for possibleĀ adverseĀ GI reaction: nausea, vomiting, abdominal cramps, belching, diarrhea, flatulence and distension.
  • Monitor fluid and electrolyte status: urine output, input-output ratio to identify fluid loss, hypokalemia and hypernatremia.
  • Monitor for increased glucose levels in diabetic patients.
  • Assess patient’s and family’s knowledge of drug therapy.

Nursing Diagnoses

  • Constipation related to underlying condition
  • Diarrhea related to adverse drug reaction
  • Fluid and electrolyte imbalance related to adverse GI reaction
  • Knowledge-deficit related to drug therapy
  • Noncompliance


  • Oral route
    • Give with full glass of fruit juice, water, milk to increase palatability of oral form; increase fluids by 2 L/day; do not give with other laxatives; if diarrhea occurs, reduce dosage.
  • Rectal route
    • Administer retention enema by diluting 300 mL of lactulose/700 mL of water or 0.9% NaCl; administer by rectal balloon catheter; retain for 30-60 minutes; repeat if evacuated too quickly.


  • Advice patient to dilute drug with juice or water or take with food to improve taste
  • Teach patient that normal bowel movements do not always occur daily and that adequate fluid consumption is necessary
  • Inform patient of possible adverse effects and the need to notify physician immediately if these occurs. Remind patient not to use in presence of abdominal pain, nausea and vomiting.
  • Instruct patient to notify physician if constipation is unrelieved or symptoms of electrolyte imbalance occur; muscle cramps, pain, weakness, dizziness and excessive thirst
  • Inform patient that bowel tone may be lost if used as laxative for long term therapy. Do not give at bedtime because it may interfere with sleep.
  • Inform patient that diarrhea may indicate over dosage.


  • Relief of constipation
  • Decreased blood ammonia level and clearing of mental state
  • Patient and family state understanding of drug therapy