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Pronunciation
(LAK tyoo lose)
Generic Available (U.S.)
Yes: Excludes crystals for solution
U.S. Brand Names
Canadian Brand Names
Pharmacologic Category
Pharmacologic Category Synonyms
Use: Labeled Indications
Prevention and treatment of portal-systemic encephalopathy (including hepatic precoma and coma); treatment of constipation
Pregnancy Risk Factor
B
Lactation
Excretion in breast milk unknown/use caution
Contraindications
Use in patients requiring a low galactose diet
Warnings/Precautions
Concerns related to adverse effects:
• Electrolyte imbalance: Monitor periodically for electrolyte imbalance when lactulose is used >6 months or in patients predisposed to electrolyte abnormalities (eg, elderly). Hepatic disease may predispose patients to electrolyte imbalance. Infants receiving lactulose may develop hyponatremia and dehydration.
Disease-related concerns:
• Diabetes: Use with caution in patients with diabetes mellitus; solution contains galactose and lactose.
Concurrent drug therapy issues:
• Anti-infectives (oral): Patients receiving lactulose and an oral anti-infective agent should be monitored for possible inadequate response to lactulose.
Other warnings/precautions:
• Electrocautery procedures: During proctoscopy or colonoscopy procedures involving electrocautery, a theoretical risk of reaction between H2 gas accumulation and electrical spark may exist; thorough bowel cleansing with a nonfermentable solution is recommended.
Adverse Reactions
Frequency not defined.
Endocrine & metabolic: Dehydration, hypernatremia, hypokalemia
Gastrointestinal: Abdominal discomfort, abdominal distention, belching, cramping, diarrhea (excessive dose), flatulence, nausea, vomiting
Drug Interactions
There are no known significant interactions.
Storage
Store at room temperature; do not freeze. Protect from light. Discard solution if cloudy or very dark. Prolonged exposure to cold temperatures will cause thickening which will return to normal upon warming to room temperature.
Mechanism of Action
The bacterial degradation of lactulose resulting in an acidic pH inhibits the diffusion of NH3 into the blood by causing the conversion of NH3 to NH4+; also enhances the diffusion of NH3 from the blood into the gut where conversion to NH4+ occurs; produces an osmotic effect in the colon with resultant distention promoting peristalsis; reduces blood ammonia concentration to reduce the degree of portal systemic encephalopathy
Pharmacodynamics/Kinetics
Onset:
Constipation: Up to 24-48 hours to produce a normal bowel movement
Encephalopathy: At least 24-48 hours
Absorption: Not appreciable
Metabolism: Via colonic flora to lactic acid and acetic acid; requires colonic flora for drug activation
Excretion: Primarily feces; urine (≤3%)
Dosage
Constipation: Oral:
Children (unlabeled use): 0.7-2 g/kg/day (1-3 mL/kg/day) in divided doses, maximum 40 g/day (60 mL/day) (NASPGHAN, 2006)
Adults: 10-20 g (15-30 mL) daily; may increase to 40 g (60 mL) daily if necessary
Prevention of portal systemic encephalopathy (PSE): Oral:
Infants: 1.7-6.7 g/day (2.5-10 mL/day) in divided doses; adjust dosage to produce 2-3 stools/day
Children: 26.7-60 g/day (40-90 mL/day) in divided doses; adjust dosage to produce 2-3 stools/day
Adults: 20-30 g (30-45 mL) 3-4 times/day; adjust dose every 1-2 days to produce 2-3 soft stools/day
Treatment of acute PSE: Adults:
Oral: 20-30 g (30-45 mL) every 1 hour to induce rapid laxation; reduce to 20-30 g (30-45 mL) 3-4 times/day after laxation is achieved titrate to produce 2-3 soft stools/day
Rectal administration (retention enema): 200 g (300 mL) diluted with 700 mL of water or NS via rectal balloon catheter; retain for 30-60 minutes; may repeat every 4-6 hours; transition to oral treatment prior to discontinuing rectal administration
Administration: Oral
Oral solution: May mix with fruit juice, water, or milk.
Crystals for oral solution: Dissolve contents of packet in 120 mL water.
Administration: Other
Rectal: Mix with water or normal saline; administer as retention enema using a rectal balloon catheter; retain for 30-60 minutes. Transition to oral lactulose when appropriate (able to take oral medication and no longer a risk for aspiration) prior to discontinuing rectal administration.
Monitoring Parameters
Blood pressure, standing/supine; serum electrolytes, serum ammonia; bowel movement patterns, fluid status
Dietary Considerations
Contraindicated in patients on galactose-restricted diet; may be mixed with fruit juice, milk, water, or citrus-flavored carbonated beverages.
Patient Education
Not for long-term use. Take alone or diluted with water, juice or milk, or take with food. Laxative results may not occur for 24-48 hours; do not take more often than recommended or for a longer time than recommended. Do not use any other laxatives while taking lactulose. Do not use if experiencing abdominal pain, nausea, or vomiting. Diarrhea may indicate need to decrease dose. May cause flatulence, belching, or abdominal cramping. Report persistent or severe diarrhea or abdominal cramping.
Geriatric Considerations
Elderly are more likely to show CNS signs of dehydration and electrolyte loss than younger adults. Therefore, monitor closely for fluid and electrolyte loss with chronic use. Sorbitol is equally effective as a laxative and less expensive. However, sorbitol cannot be substituted in the treatment of hepatic encephalopathy.
Dental Health: Effects on Dental Treatment
No significant effects or complications reported
Dental Health: Vasoconstrictor/Local Anesthetic Precautions
No information available to require special precautions
Mental Health: Effects on Mental Status
None reported
Mental Health: Effects on Psychiatric Treatment
The therapeutic GI effect of laxation is desired; however, concomitant use with SSRIs, carbamazepine, valproic acid, and lithium may produce additive GI side effects
Nursing: Physical Assessment/Monitoring
Assess therapeutic effectiveness (soft formed stools or resolution of CNS status). Monitor frequency/consistency of stools. May need to adjust dose for severe diarrhea.
Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Crystals for solution, oral:
Kristalose®: 10 g/packet (30s); 20 g/packet (30s)
Solution, oral: 10 g/15 mL (15 mL, 30 mL, 237 mL, 473 mL, 500 mL, 946 mL, 1892 mL)
Constulose: 10 g/15 mL (237 mL, 946 mL)
Enulose: 10 g/15 mL (473 mL)
Solution, oral/rectal: 10 g/15 mL (237 mL, 473 mL, 946 mL)
Generlac: 10 g/15 mL (473 mL, 1892 mL)
Pricing: U.S. (www.drugstore.com)
Pack (Kristalose)
10 g (30): $57.57
20 g (30): $79.86
Solution (Enulose)
10 g/15 mL (473): $25.97
Solution (Lactulose Encephalopathy)
10 g/15 mL (473): $19.98
References
“Evaluation and Treatment of Constipation in Infants and Children: Recommendations of the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition,” J Pediatr Gastroenterol Nutr, 2006, 43(3):e1-13.
Lederle FA, Busch DL, Mattox KM, et al, “Cost-Effective Treatment of Constipation in the Elderly: A Randomized Double-Blind Comparison of Sorbitol and Lactulose,” Am J Med, 1990, 89(5):597-601.
International Brand Names
Lexi-Comp.com
Last full review/revision April 2011
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