Note: Doses in pediatric patients may be expressed in volume (mL) or weight (g); use extra precaution.
Constipation; chronic: Limited data available: Infants, Children, and Adolescents: Oral: 1 to 2 g/kg/day (1.5 to 3 mL/kg/day) divided once or twice daily (NASPGHAN [Tabbers 2014]); maximum daily dose: 60 mL/day in adults.
Constipation, palliative care: Limited data available: Children and Adolescents: Oral: 2 to 30 mL every 6 to 24 hours (Johnston 2005), others have suggested 5 to 10 mL every 2 hours until bowel movement (Kliegman 2020).
Fecal impaction, slow disimpaction: Limited data available: Infants, Children, and Adolescents: Oral: 1.33 g/kg/dose (2 mL/kg) twice daily for 7 days (Pashankar 2005; Wyllie 2011).
Portal systemic encephalopathy, prevention (PSE): Oral liquid:
Infants: Oral: 1.7 to 6.7 g/day (2.5 to 10 mL/day) in divided doses; adjust dosage to produce 2 to 3 stools/day.
Children and Adolescents: Oral: 26.7 to 60 g/day (40 to 90 mL/day) in divided doses; adjust dosage to produce 2 to 3 stools/day.
There are no dosage adjustments provided in manufacturer's labeling.
There are no dosage adjustments provided in manufacturer's labeling.
(For additional information see "Lactulose: Drug information")
Constipation: Oral: 10 to 20 g (15 to 30 mL or 1 to 2 packets) daily; may increase to 40 g (60 mL or 2 to 4 packets) daily if necessary.
Hepatic encephalopathy, treatment or prevention:
Prevention:
Note: May consider as chronic therapy for the prevention of recurrent hepatic encephalopathy with or without other therapies (AASLD [Vilstrup 2014]).
Oral: 20 to 30 g (30 to 45 mL) 2 to 4 times daily; may adjust dose every 1 to 2 days to achieve 2 to 3 soft stools/day (Agrawal 2012; manufacturer's labeling).
Treatment:
Note: Identify and treat precipitating factors. May use as monotherapy for initial treatment or in combination with other therapies when initial monotherapy is unsuccessful. Not recommended for routine treatment of minimal hepatic encephalopathy; may consider on a case-by-case basis in patients with decreased quality of life (AASLD [Vilstrup 2014]; Prasad 2007).
Oral: Initial: 20 to 30 g (30 to 45 mL) every 1 to 2 hours to induce ~2 soft stools/day, then reduce to 20 to 30 g (30 to 45 mL) 2 to 4 times daily; may adjust dose every 1 to 2 days to achieve 2 to 3 soft stools/day (AASLD [Vilstrup 2014]; Ferenci 2021; manufacturer's labeling).
Rectal (alternative route): Retention enema: 200 g (300 mL) in 700 mL NS or water, retain for 30 to 60 minutes; may repeat every 4 to 8 hours based on responsiveness to therapy. Note: Once patient can tolerate oral administration, consider transition to oral formulation (Uribe 1987; manufacturer's labeling).
There are no dosage adjustments provided in the manufacturer’s labeling.
There are no dosage adjustments provided in the manufacturer’s labeling.
Excipient information presented when available (limited, particularly for generics); consult specific product labeling. [DSC] = Discontinued product
Packet, Oral:
Kristalose: 10 g (30 ea); 20 g (30 ea)
Generic: 10 g (15 ea)
Solution, Oral:
Constulose: 10 g/15 mL (237 mL, 946 mL) [unflavored flavor]
Enulose: 10 g/15 mL (473 mL) [unflavored flavor]
Generlac: 10 g/15 mL (473 mL, 1892 mL) [unflavored flavor]
Generic: 10 g/15 mL (15 mL, 30 mL, 236 mL [DSC], 237 mL, 473 mL, 480 mL [DSC], 946 mL, 1892 mL [DSC]); 20 g/30 mL (30 mL)
Yes
Oral:
Oral solution: May mix with fruit juice, water, or milk.
Crystals for oral solution: Dissolve contents of packet in 120 mL water.
Oral solution: May mix with fruit juice, water or milk.
Crystals for oral solution: Dissolve contents of packet in 120 mL water.
Rectal: Dilute with 700 mL of water or NS; administer as retention enema using a rectal balloon catheter; retain for 30 to 60 minutes. May repeat enema immediately if inadvertently evacuated too promptly. Cleansing enemas containing soapsuds or other alkaline agents should not be used.
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.
Prevention and treatment of portal-systemic encephalopathy (PSE) (Enulose: FDA approved in infants, children, adolescents, and adults); treatment of constipation (FDA approved in adults).
Lactulose may be confused with lactose
The following adverse drug reactions and incidences are derived from product labeling unless otherwise specified. Frequency not defined.
Endocrine & metabolic: Dehydration, hypernatremia, hypokalemia
Gastrointestinal: Abdominal cramps, abdominal distention, abdominal distress, diarrhea (excessive dose), eructation, flatulence, nausea, vomiting
Patients requiring a low galactose diet
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, debilitated patients). 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.
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.
Electrolyte imbalances may occur with chronic use or in patients predisposed to electrolyte imbalances including infants; infants may also develop dehydration with hyponatremia.
None known.
Dichlorphenamide: Laxatives may enhance the hypokalemic effect of Dichlorphenamide. Risk C: Monitor therapy
Glutamine: May diminish the therapeutic effect of Lactulose. Specifically, glutamine may diminish the ammonia-lowering effects of lactulose. Risk C: Monitor therapy
Vitamin K Antagonists (eg, warfarin): Lactulose may enhance the anticoagulant effect of Vitamin K Antagonists. Risk C: Monitor therapy
Contraindicated in patients on galactose-restricted diet.
Lactulose is poorly absorbed following oral administration. Treatment of constipation in pregnant women is similar to that of nonpregnant patients and medications may be used when diet and lifestyle modifications are not effective. Lactulose may be used when an osmotic laxative is needed (Body 2016; Gomes 2018; Shin 2015).
Serum ammonia, serum electrolytes, fluid status, stool output.
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
Onset:
Constipation: Up to 24 to 48 hours to produce a normal bowel movement
Encephalopathy: At least 24 to 48 hours
Absorption: Poor
Metabolism: Via colonic flora to lactic acid and acetic acid; requires colonic flora for drug activation
Excretion: Primarily feces; urine (≤3%)
Upon discontinuation of therapy, allow 24 to 48 hours for resumption of normal bowel movements.
Pack (Kristalose Oral)
10 g (per each): $10.47
20 g (per each): $10.85
Pack (Lactulose Oral)
10 g (per each): $59.92
Solution (Lactulose Encephalopathy Oral)
10 g/15 mL (per mL): $0.08
Solution (Lactulose Oral)
10 g/15 mL (per mL): $0.03 - $0.10
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