lactulose (Enulose, Kristalose, Constulose, Generlac)
Classes: Laxatives, Osmotic; Ammonium Detoxicants
Dosing and uses of Enulose, Kristalose (lactulose)
Adult dosage forms and strengths
oral/rectal solution
- 10g/15mL
packet
- 10g
- 20g
Constipation
Solution: 15-30 mL (10-20 g) PO once daily; may be increased to 60 mL (40 g) once daily
Crystals: 10-20 g PO qDay; may increase to 40 g/day
Portal Systemic Encephalopathy
Prophylaxis
30-45 mL (20-30 g) PO q6-8hr, adjusted until 2-3 soft stools/day; if acute, may be given q1-2hr until 2-3 soft stools/day
Treatment
20-30 g (30-45 mL) PO q1hr to induce rapid defecation; reduced to 20-30 g q6-8hr after defecation achieved; titrated to produce 2-3 soft stools/day
300 mL (200 g) PR with 700 mL water or NS, retained for 30-60 minutes; may be repeated q4-6hr; transition to oral treatment before discontinuance of rectal administration
Pediatric dosage forms and strengths
oral/rectal solution
- 10g/15mL
packet
- 10g
- 20g
Constipation
0.7-2 g/kg/day (1-3 mL/kg/day) PO in divided doses; not to exceed 40 g/day (60 mL/day)
Portal Systemic Encephalopathy
Prophylaxis
Infants: 2.5-10 mL/day (1.7-6.67 g/day) PO in divided doses; titrated to produce 2-3 soft stools/day
Children and adolescents: 40-90 mL/day (26.7-60 g/day) PO in divided doses; titrated to produce 2-3 soft stools/day
Enulose, Kristalose (lactulose) adverse (side) effects
Frequency not defined
Dehydration
Diarrhea
Excessive bowel activity
Hypernatremia
Hypokalemia
Nausea
Vomiting
Abdominal cramping
Abdominal distention
Belching
Flatulence
Warnings
Contraindications
Galactosemia (patients require low-galactose diet)
Cautions
Diabetes (preparation contains lactose and galactose)
Monitor for electrolyte imbalance when drug is used for >6 months or in patients predisposed to electrolyte abnormalities
Avoid using other laxatives concomitantly
Inadequate response possible when taken concomitantly with anti-infective
Pregnancy and lactation
Pregnancy category: B
Lactation: Unknown whether drug is distributed into milk; use with caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Enulose, Kristalose (lactulose)
Mechanism of action
Constipation: Hyperosmotic agent increases stool water contents, softens stool, promotes peristalsis, and reduces blood ammonia concentration
Portal systemic encephalopathy: Breakdown of lactulose to organic acids by colonic bacteria acidifies colonic contents, thereby subsequently inhibiting diffusion of ammonia back to blood; agent also enhances diffusion of NH3 from blood into gut, where it is converted to NH4+
Absorption
Bioavailability: <3% absorbed
Onset: 24-48 hr
Metabolism
Absorbed lactulose is not metabolized; unabsorbed lactulose is extensively metabolized to organic acids by colonic bacteria
Metabolites: Lactic acid (main), formic acid, acetic acid (all active)
Elimination
Excretion: Urine (absorbed lactulose), feces and bile (unabsorbed lactulose and metabolites; minimal)