Lactulose

Pronunciation

Pronunciation: LAK-tyoo-lohs
Class: Hyperosmotic agent

Trade Names

Cephulac
- Solution 10 g lactulose/15 mL (less than 1.6 g galactose, less than 1.2 g galactose, and up to 1.2 g of other sugars)

Chronulac
- Solution 10 g lactulose/15 mL (less than 1.6 g galactose, less than 1.2 g galactose, and up to 1.2 g of other sugars)

Constilac
- Solution 10 g lactulose/15 mL (less than 1.6 g galactose, less than 1.2 g galactose, and up to 1.2 g of other sugars)

Constulose
- Solution 10 g lactulose/15mL (less than 1.6 g galactose, less than 1.2 g galactose, and up to 1.2 g of other sugars)

Duphalac
- Solution 10 g lactulose/15 mL (less than 1.6 g galactose, less than 1.2 g galactose up to 1.2 g of other sugars)

Enulose
- Solution 10 g lactulose per 15 mL (less than 1.6 g galactose, less than 1.2 g galactose, and up to 1.2 g of other sugars)

Apo-Lactulose (Canada)
PMS-Lactulose (Canada)
ratio-Lactulose (Canada)

Pharmacology

Produces increased osmotic pressure within colon and acidifies its contents, resulting in increased stool water content and stool softening. Causes migration of ammonia from blood into colon, where it is converted to ammonium ion and expelled through laxative action.

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Pharmacokinetics

Absorption

Poorly absorbed from the GI tract when given PO and PR (no enzyme capable of hydrolysis of lactulose is present in GI tissue).

Metabolism

In the colon, lactulose is broken down primarily to lactic acid. Metabolized in the colon by bacteria.

Elimination

Less than 3% is excreted in the urine. Doses reach the colon virtually unchanged.

Onset

24 to 48 h.

Indications and Usage

Treatment of constipation; prevention and treatment of portal-systemic encephalopathy, including stages of hepatic precoma and coma.

Contraindications

Use in patients who require low-galactose diet.

Dosage and Administration

Constipation (Chronulac, Constilac, Duphalac)
Adults

PO 15 to 30 mL (10 to 20 g lactulose) daily; may increase to 60 mL/day.

Portal-Systemic Encephalopathy (Cephulac, Cholac, Enulose)
Adults

PO 30 to 45 mL 3 to 4 times daily. Adjust dosage to produce 2 to 3 soft stools/day. Hourly doses of 30 to 45 mL may be used for rapid laxation initially; once achieved, reduce to recommended daily dose. PR 300 mL with 700 mL water or physiologic saline solution via rectal balloon catheter; retain for 30 to 60 min. May repeat every 4 to 6 h.

Older Children and Adolescents

PO 40 to 90 mL/day in divided doses to produce 2 to 3 soft stools/day.

Infants

PO 2.5 to 10 mL/day in divided doses to produce 2 to 3 soft stools/day.

General Advice

Mix with fruit juice, water, or milk to make oral solution more palatable.

Storage/Stability

Store at room temperature (below 86°F). Do not freeze.

Drug Interactions

Neomycin, other anti-infectives

May interfere with desired degradation of lactulose and prevent acidification of colonic contents.

Nonabsorbable antacids

May inhibit colonic acidification.

Laboratory Test Interactions

None well documented.

Adverse Reactions

GI

Gaseous distention with flatulence or belching, abdominal discomfort and cramping; diarrhea; nausea; vomiting.

Precautions

Pregnancy

Category B .

Lactation

Undetermined.

Children

Safety and efficacy not established. Administer with caution. Infants receiving lactulose may develop hyponatremia and dehydration.

Elderly

With long-term therapy (more than 6 mo) at increased risk of dehydration and electrolyte imbalance.

Concomitant laxative use

Do not use other laxatives, especially during initial phase of therapy. Resultant loose stools may falsely suggest adequate lactulose dosage.

Debilitated patients

With long-term therapy (more than 6 mo) at increased risk of dehydration and electrolyte imbalance.

Diabetic patients

Lactulose syrup contains galactose and lactose. Use with caution.

Electrocautery procedures

Although not reported for lactulose, theoretical hazard exists for patients being treated with lactulose who may undergo electrocautery procedures during proctoscopy or colonoscopy. Accumulation of hydrogen gas in presence of electrical spark may result in explosion. Therefore patients should have thorough bowel cleansing with nonfermentable solution before undergoing such procedures.

Overdosage

Symptoms

Diarrhea, abdominal cramps.

Patient Information

  • Advise patient that drug can be mixed with fruit juice, water, or milk to make it more palatable.
  • Inform patient that drug may cause belching, flatulence, or abdominal cramps. Instruct patient to notify health care provider if these symptoms become bothersome or if diarrhea occurs.
  • Instruct patient not to take other laxatives while receiving lactulose therapy.
  • Encourage patient to increase dietary fiber and fluid intake and participate in regular exercise.

Copyright © 2009 Wolters Kluwer Health.

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