CONSTULOSE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CONSTULOSE (CONSTULOSE).
Lactulose is a synthetic disaccharide that is not absorbed in the small intestine. In the colon, it is metabolized by bacteria to short-chain fatty acids, leading to an osmotic effect that draws water into the bowel, thereby softening stools and increasing bowel motility. In hepatic encephalopathy, lactulose acidifies the colonic environment, promoting the conversion of ammonia (NH3) to ammonium (NH4+), which is trapped and excreted in feces.
| Metabolism | Not absorbed systemically; metabolized by colonic bacteria (e.g., Lactobacillus, Bacteroides) to lactic acid, acetic acid, and other short-chain fatty acids. |
| Excretion | Primarily fecal (unchanged); minimal systemic absorption (<3%), thus negligible renal excretion. |
| Half-life | Not applicable due to minimal systemic absorption; local action in colon. In cases of systemic absorption, half-life is not clinically relevant. |
| Protein binding | <1%, primarily to albumin if absorbed, but negligible due to low systemic bioavailability. |
| Volume of Distribution | Not applicable due to minimal systemic absorption; predominantly confined to gastrointestinal lumen. |
| Bioavailability | Oral: <3% systemic absorption; Rectal: minimal systemic absorption (<5%). |
| Onset of Action | Oral: 24-48 hours for laxative effect; Rectal: 15-30 minutes for bowel evacuation. |
| Duration of Action | Oral: 24-48 hours; Rectal: 1-2 hours. Effects may persist up to 72 hours after oral administration. |
10-20 g (15-30 mL) orally once daily, increased to 30-45 g (45-60 mL) if needed; or 30-45 g (45-60 mL) orally every 6-8 hours for hepatic encephalopathy.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment required; lactulose is minimally absorbed and primarily acts locally. Use with caution in severe renal impairment due to risk of electrolyte disturbances. |
| Liver impairment | No dose adjustment for mild to moderate hepatic impairment; for severe hepatic impairment (e.g., Child-Pugh C) monitor for electrolyte imbalances and adjust dose as needed. |
| Pediatric use | Infants: 2.5-10 g (3.75-15 mL) daily in divided doses. Children: 5-15 g (7.5-22.5 mL) daily. Adolescents: 15-30 g (22.5-45 mL) daily. Dose may be increased to achieve 2-3 soft stools daily. |
| Geriatric use | Initiate at lower end of adult dosing (10-15 g orally once daily) and titrate slowly to avoid excessive diarrhea and electrolyte imbalance. Monitor renal function and electrolytes. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for CONSTULOSE (CONSTULOSE).
| Breastfeeding | Lactulose is not absorbed and is not excreted into breast milk in significant amounts. M/P ratio is not available due to lack of absorption. Considered compatible with breastfeeding. |
| Teratogenic Risk | Constulose (lactulose) is not absorbed systemically, so teratogenic risk is minimal. No fetal risks are expected during any trimester. Animal reproduction studies have not been conducted, but based on pharmacokinetics, no harm is anticipated. |
| Fetal Monitoring |
■ FDA Black Box Warning
No FDA black box warning.
| Serious Effects |
["Patients with galactosemia (lactulose contains galactose)","Bowel obstruction","Intestinal perforation"]
| Precautions | ["May cause electrolyte disturbances (e.g., hypernatremia, hypokalemia) with prolonged use","Use with caution in patients with diabetes mellitus (contains galactose and lactose)","Monitor for excessive diarrhea or dehydration"] |
Loading safety data…
| No specific fetal monitoring is required. Monitor maternal fluid and electrolyte balance with prolonged use due to potential diarrhea. |
| Fertility Effects | No known effects on human fertility. Animal studies have not been conducted, but systemic absorption is negligible. |