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standards of non-Merck sources.
Medication Safety Issues
Sound-alike/look-alike issues:
Lactulose may be confused with lactose
Pronunciation
(LAK tyoo lose)
U.S. Brand Names
Generic Available
Yes
Canadian Brand Names
Pharmacologic Category
Pharmacologic Category Synonyms
Use
Adjunct in the prevention and treatment of portal-systemic encephalopathy; treatment of chronic constipation
Pregnancy Risk Factor
B
Lactation
Excretion in breast milk unknown
Contraindications
Hypersensitivity to lactulose or any component of the formulation; galactosemia (or 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).
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.
Adverse Reactions
Frequency not defined: Gastrointestinal: Flatulence, diarrhea (excessive dose), abdominal discomfort, nausea, vomiting, cramping
Drug Interactions
Decreased effect: Oral neomycin, laxatives, antacids
Storage
Keep solution at room temperature to reduce viscosity. Discard solution if cloudy or very dark.
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
Pharmacodynamics/Kinetics
Absorption: Not appreciable
Metabolism: Via colonic flora to lactic acid and acetic acid; requires colonic flora for drug activation
Excretion: Primarily feces and urine (?3%)
Dosage
Diarrhea may indicate overdosage and responds to dose reduction
Prevention of portal systemic encephalopathy (PSE): Oral:
Infants: 2.5-10 mL/day divided 3-4 times/day; adjust dosage to produce 2-3 stools/day
Older Children: Daily dose of 40-90 mL divided 3-4 times/day; if initial dose causes diarrhea, then reduce it immediately; adjust dosage to produce 2-3 stools/day
Constipation: Oral:
Children: 5 g/day (7.5 mL) after breakfast
Adults: 15-30 mL/day increased to 60 mL/day in 1-2 divided doses if necessary
Acute PSE: Adults:
Oral: 20-30 g (30-45 mL) every 1-2 hours to induce rapid laxation; adjust dosage daily to produce 2-3 soft stools; doses of 30-45 mL may be given hourly to cause rapid laxation, then reduce to recommended dose; usual daily dose: 60-100 g (90-150 mL) daily
Rectal administration: 200 g (300 mL) diluted with 700 mL of H2O or NS; administer rectally via rectal balloon catheter and retain 30-60 minutes every 4-6 hours
Administration: Oral
Dilute lactulose in water, usually 60-120 mL, prior to administering through a gastric or feeding tube.
Administration: Other
Syrup formulation has been used in preparation of rectal solution.
Monitoring Parameters
Blood pressure, standing/supine; serum potassium, bowel movement patterns, fluid status, serum ammonia
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 as directed, 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. Increased fiber, fluids, and exercise may also help reduce constipation. Do not use if experiencing abdominal pain, nausea, or vomiting. Diarrhea may indicate overdose. May cause flatulence, belching, or abdominal cramping. Report persistent or severe diarrhea or abdominal cramping. Breast-feeding precaution: Consult prescriber if breast-feeding.
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
None reported
Nursing: Physical Assessment/Monitoring
Assess results of laboratory tests, therapeutic effectiveness (soft formed stools or resolution of CNS status in PSE), and adverse response (eg, CHF). Monitor frequency/consistency of stools; diarrhea may indicate overdose. Teach patient proper use, possible side effects/appropriate interventions, and adverse symptoms to report.
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)
Syrup: 10 g/15 mL (15 mL, 30 mL, 237 mL, 473 mL, 946 mL, 1890 mL)
Constulose: 10 g/15 mL (240 mL, 960 mL)
Enulose: 10 g/15 mL (480 mL)
Generlac: 10 g/15 mL (480 mL, 1920 mL)
Pricing: U.S. (www.drugstore.com)
Pack (Kristalose)
10 g (30): $42.99
20 g (30): $61.99
Solution (Enulose)
10 g/15 mL (480): $19.97
Solution (Lactulose)
10 g/15 mL (473): $20.01
References
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 May 2008
Content last modified May 2008
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