DUPHALAC
Clinical safety rating: caution
Comprehensive clinical and safety monograph for DUPHALAC (DUPHALAC).
Duphalac (lactulose) is a synthetic disaccharide that is not absorbed in the gastrointestinal tract. It is metabolized by colonic bacteria to short-chain fatty acids (e.g., acetic, lactic, formic acids), which lower colonic pH. This acidic environment favors the conversion of ammonia (NH3) to ammonium (NH4+), which is trapped in the colon and excreted in feces, thereby reducing systemic ammonia absorption. Additionally, the osmotic effect of lactulose and its metabolites draws water into the colon, producing a laxative effect.
| Metabolism | Lactulose is not metabolized by human enzymes. It is metabolized by colonic bacteria (e.g., Lactobacillus, Bacteroides) to short-chain fatty acids (acetic, lactic, formic acids) and gases (hydrogen, carbon dioxide). |
| Excretion | Lactulose is not absorbed from the gastrointestinal tract; it is excreted unchanged in feces (>99%). |
| Half-life | Not applicable; systemic exposure is negligible. Orally administered lactulose acts locally in the colon. |
| Protein binding | Not applicable; negligible systemic absorption, so no protein binding. |
| Volume of Distribution | Not applicable; acts locally in the gut, not distributed systemically. |
| Bioavailability | Oral: <0.3% systemic absorption; essentially unabsorbed. |
| Onset of Action | Lactulose (oral): 24-48 hours for laxative effect; for hepatic encephalopathy, onset is typically 24-48 hours. |
| Duration of Action | Laxative effect: 24-48 hours after a single dose; continuous use maintains effect. For hepatic encephalopathy, chronic dosing maintains reduction in blood ammonia. |
Oral: 15-30 mL once daily, may increase to 30-45 mL twice daily if needed. Rectal (enema): 150-300 mL as a single dose.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | Infants: 2.5-10 mL/day orally; Children (1-6 years): 5-10 mL/day; Children (7-14 years): 10-15 mL/day; Adolescents: 15-30 mL/day. All doses may be adjusted based on response. |
| Geriatric use | Use lower initial doses (15 mL daily) due to increased risk of electrolyte imbalance and dehydration. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for DUPHALAC (DUPHALAC).
| Breastfeeding | Lactulose is minimally absorbed; no known adverse effects in breastfed infants. M/P ratio: Not applicable due to negligible systemic absorption. Considered compatible with breastfeeding. |
| Teratogenic Risk | Lactulose is not absorbed systemically; no known teratogenic effects. No increased risk of major birth defects reported. First trimester: No evidence of fetal harm. Second/Third trimester: No known risks; use with caution if excessive diarrhea or electrolyte imbalance occurs. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Common Effects | Abdominal pain Nausea Vomiting Diarrhea |
| Serious Effects |
["Hypersensitivity to lactulose or any component of the formulation.","Patients on a low-galactose diet (e.g., galactosemia).","Intestinal obstruction (complete or partial).","Acute inflammatory bowel disease (e.g., Crohn's disease, ulcerative colitis) - relative caution."]
| Precautions | ["Gastric retention or intestinal obstruction: Do not use in patients with suspected obstruction.","Electrolyte disturbances: Prolonged use may cause diarrhea leading to fluid and electrolyte imbalance (e.g., hypernatremia, hypokalemia).","Galactosemia: Use with caution in patients with galactose intolerance or lactose intolerance due to small amounts of galactose and lactose present.","Diabetes mellitus: May affect blood glucose levels in high doses due to galactose content.","Abdominal discomfort: Flatulence, bloating, and cramps are common, especially at initiation."] |
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| Monitor serum electrolytes (sodium, potassium, chloride, bicarbonate) and fluid balance during prolonged use, especially if diarrhea occurs. Assess for abdominal distension or pain. Fetal monitoring not specifically required. |
| Fertility Effects | No known adverse effects on fertility. Lactulose does not affect reproductive hormones or gamete function. |