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lactulose (Chronulac, Cephulac)

Tradenames: Chronulac, Cephulac. Indications: 1) constipation: 30 mL PO QHS. 2) hepatic encephalopathy: 30-45 mL PO TID/QID. Contraindications: pregnancy-category B safety in lactation ? Dosage: May be taken as is or diluted with water or fruit juice Liquid: 10 g/15 mL (240, 480, 1920 mL). Pharmacokinetics: 1) onset of bowel relief occurs within 24-48 hours 2) < 3% of dose is absorbed 3) unabsorbed lactulose reaches the colon to form lactic acid & small amounts of acetic & formic acid Adverse effects: 1) common (> 10%) - flatulence, diarrhea (with excessive dose) 2) less common (1-10%) - abodominal discomfort, nausea/vomiting 3) 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: 1) decreases blood NH3 concentration 2) breakdown of lactulose to organic acids by saccharolytic colonic bacteria acidifies colonic contents 3) acidification of colon inhibits diffusion of NH3 from the colon to the blood (trapped as NH4+) 5) osmotic laxative Notes: - milk & milk products may contain significant amounts of lactulose

General

disaccharide laxative

Database Correlations

PUBCHEM correlations

References

  1. The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
  2. 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
  3. Kaiser Permanente Northern California Regional Drug Formulary, 1998
  4. PubMed Search PubMed search: lactulose

Component-of

Duphalac