Potential drug-drug interaction between duloxetine and acenocoumarol in a patient with Alzheimer's disease.
BACKGROUND
Recent evidence suggests that duloxetine may increase the effect of warfarin, thereby increasing the possibility of bleeding. However, a MEDLINE search for articles published between 1980 and May 2007 (terms: duloxetine, anticoagulants, acenocoumarol, and interaction; no language restriction) did not yield any reports of an interaction between concomitant use of duloxetine and acenocoumarol.


OBJECTIVE
The aim of this study was to describe a potential drug-drug interaction between duloxetine and acenocoumarol in a patient with Alzheimer's disease. The possible mechanism of this potential interaction is examined.


METHODS
This report presents the case of a 63-year-old white female patient weighing 64 kg receiving oral treatment with the synthetic coumarin anticoagulant acenocoumarol (mean dosage, 9 mg/wk) for 8 years who experienced a persistent (3-week) decrease in international normalized ratio (INR) to 1.49 after taking a single 60-mg dose of duloxetine. Three weeks after discontinuation of duloxetine, the INR returned to the previous baseline level (2.58).


CONCLUSIONS
This case report suggests a possible drug-drug interaction between duloxetine and acenocoumarol. Duloxetine should be administered with caution in patients receiving acenocoumarol therapy.
Monastero
Roberto
R
Laboratory of Epidemiology and Psychology of Aging and Dementia, Department of Clinical Neuroscience, University of Palermo, Palermo, Italy. roberto.monastero@unipa.it
Camarda
Rosolino
R
Camarda
Cecilia
C
D000074:Acenocoumarol / Q000008:administration & dosage / Q000009:adverse effects*; D000544:Alzheimer Disease / Q000188:drug therapy; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects*; D004347:Drug Interactions; D000068736:Duloxetine Hydrochloride; D005260:Female; D006801:Humans; D019934:International Normalized Ratio; D008875:Middle Aged; D017367:Selective Serotonin Reuptake Inhibitors / Q000008:administration & dosage / Q000009:adverse effects*; D013876:Thiophenes / Q000008:administration & dosage / Q000009:adverse effects*
D000074:Acenocoumarol; D000925:Anticoagulants; D000068736:Duloxetine Hydrochloride; D017367:Selective Serotonin Reuptake Inhibitors; D013876:Thiophenes