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 (Ref).
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 (Ref).
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 (Ref).
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 (Ref).
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 (Ref).
The renal dosing recommendations are based upon the best available evidence and clinical expertise. Senior Editorial Team: Bruce Mueller, PharmD, FCCP, FASN, FNKF; Jason A. Roberts, PhD, BPharm (Hons), B App Sc, FSHP, FISAC; Michael Heung, MD, MS.
Altered kidney function: No dosage adjustment necessary for any degree of kidney impairment (systemic absorption limited) (Ref).
Hemodialysis, intermittent (thrice weekly): No supplemental dose or dosage adjustment necessary (systemic absorption limited) (Ref).
Peritoneal dialysis: No dosage adjustment necessary (systemic absorption limited) (Ref).
CRRT: No dosage adjustment necessary (systemic absorption limited) (Ref).
PIRRT (eg, sustained, low-efficiency diafiltration): No dosage adjustment necessary (systemic absorption limited) (Ref).
There are no dosage adjustments provided in the manufacturer's labeling.
(For additional information see "Lactulose: Pediatric drug information")
Note: Doses in pediatric patients may be expressed in volume (mL) or weight (g); use extra caution. Oral solution contains 10 g lactulose per 15 mL; packets contain 10 g or 20 g per packet.
Constipation: Limited data available: Infants, Children, and Adolescents: Oral solution (10 g per 15 mL): Oral: 0.667 to 2 g/kg/day (1 to 3 mL/kg/day) divided once or twice daily; maximum daily dose: 60 g/day (90 mL/day) (Ref).
Constipation, palliative care: Limited data available: Children and Adolescents: Oral solution (10 g per 15 mL): 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 (Ref).
Portal systemic encephalopathy, prevention (PSE): Oral solution (10 g per 15 mL):
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.
Refer to adult dosing.
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, 237 mL, 473 mL, 480 mL [DSC], 946 mL); 20 g/30 mL (30 mL)
Yes
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.
Oral:
Oral solution: May mix with fruit juice, water, or milk.
Crystals for oral solution: Dissolve contents of packet in 120 mL water.
Constipation (Constulose, Kristalose): Treatment of constipation.
Hepatic encephalopathy (Enulose, Generlac): Treatment and prevention of recurrence of hepatic encephalopathy.
Lactulose may be confused with lactose
The following adverse drug reactions are derived from product labeling unless otherwise specified.
Postmarketing: Gastrointestinal: Abdominal cramps (Passmore 1993), abdominal distention (Barish 2010), abdominal distress, abdominal pain (Barish 2010), anorexia (Passmore 1993), bloating (Hudson 2019), diarrhea (Hudson 2019), eructation, flatulence (Kang 2021), nausea (Kang 2021), vomiting (Barish 2010)
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.
Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the Lexicomp drug interactions program by clicking on the “Launch drug interactions program” link above.
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
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).
It is not known if lactulose is present in breast milk; however, lactulose is poorly absorbed following oral administration.
The manufacturer recommends that caution be exercised when administering lactulose to nursing women.
Contraindicated in patients on galactose-restricted diet.
BP, standing/supine; serum electrolytes; bowel movement frequency; fluid status; serum ammonia.
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%)
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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