lactulose (Enulose, Kristalose, Constulose, Generlac)

Dosing and uses of Enulose, Kristalose (lactulose)

• Adult
• Pediatric

 

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)