title: Overanticoagulation associated with combined use of lactulose and acenocoumarol or phenprocoumon.
abstract: Some medical textbooks on drug interactions take note of the potential interaction between laxatives and coumarin anticoagulants, but epidemiological evidence that this interaction is of practical importance is lacking. We conducted a follow-up study in a large population-based cohort to investigate which laxatives are associated with overanticoagulation during therapy with coumarins. Of the 1124 patients in the cohort, 351 developed an International Normalized Ratio > or = 6.0. The only laxative with a moderate but significantly increased relative risk of overanticoagulation was lactulose (relative risk 3.4, 95% confidence interval 2.2, 5.3). In view of the widespread use of lactulose, especially among the elderly, awareness of this potential drug interaction is required.
authors.affiliation: Pharmaco-epidemiology Unit, Departments of Internal Medicine and Epidemiology & Biostatistics, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Loes E
authors.initials: LE
authors.lastname: Visser
authors.forename: Fernie J A
authors.initials: FJ
authors.lastname: Penning-van Beest
authors.forename: J H P
authors.initials: JH
authors.lastname: Wilson
authors.forename: Arnold G
authors.initials: AG
authors.lastname: Vulto
authors.forename: A A Harrie
authors.initials: AA
authors.lastname: Kasbergen
authors.forename: Peter A G M
authors.initials: PA
authors.lastname: De Smet
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.forename: Bruno H Ch
authors.initials: BH
authors.lastname: Stricker
mesh_terms: D000074:Acenocoumarol / Q000009:adverse effects*; D000925:Anticoagulants / Q000009:adverse effects*; D002400:Cathartics / Q000009:adverse effects*; D015331:Cohort Studies; D004347:Drug Interactions; D005260:Female; D006470:Hemorrhage / Q000139:chemically induced*; D006801:Humans; D019934:International Normalized Ratio; D007792:Lactulose / Q000009:adverse effects*; D008297:Male; D010644:Phenprocoumon / Q000009:adverse effects*; D012307:Risk Factors
chemical_list: D000925:Anticoagulants; D002400:Cathartics; D007792:Lactulose; D000074:Acenocoumarol; D010644:Phenprocoumon