lactulose (Chronulac, Cephulac)
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Introduction
Tradenames: Chronulac, Cephulac.
Indications
- constipation: 30 mL PO QHS.
- hepatic encephalopathy: 30-45 mL PO TID/QID.
Contraindications
Dosage
May be taken as is or diluted with water or fruit juice
Liquid: 10 g/15 mL (240, 480, 1920 mL).
Pharmacokinetics
- onset of bowel relief occurs within 24-48 hours
- < 3% of dose is absorbed
- unabsorbed lactulose reaches the colon to form lactic acid & small amounts of acetic & formic acid
Adverse effects
- common (> 10%)
- flatulence, diarrhea (with excessive dose)
- less common (1-10%)
- other
- gaseous distension
- cramping
- belching
Drug interactions
- other laxatives should not be used in combination when treating hepatic encephalopathy, because loose stools may be falsely interpreted as adequate doses of lactulose
Mechanism of action
- decreases blood NH3 concentration
- breakdown of lactulose to organic acids by saccharolytic colonic bacteria acidifies colonic contents
- acidification of colon inhibits diffusion of NH3 from the colon to the blood (trapped as NH4+)
- osmotic laxative
Notes
- milk & milk products may contain significant amounts of lactulose
More general terms
Component of
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998 Department of Veterans Affairs, VA National Formulary
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ PubMed Search PubMed search: lactulose