Overanticoagulation associated with combined use of lactulose and acenocoumarol or phenprocoumon.
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.
Visser
Loes E
LE
Pharmaco-epidemiology Unit, Departments of Internal Medicine and Epidemiology & Biostatistics, Erasmus MC, Rotterdam, The Netherlands.
Penning-van Beest
Fernie J A
FJ
Wilson
J H P
JH
Vulto
Arnold G
AG
Kasbergen
A A Harrie
AA
De Smet
Peter A G M
PA
Hofman
Albert
A
Stricker
Bruno H Ch
BH
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
D000925:Anticoagulants; D002400:Cathartics; D007792:Lactulose; D000074:Acenocoumarol; D010644:Phenprocoumon