The effect of drug interactions on bleeding risk associated with warfarin therapy in hospitalized patients.

Abstract

BACKGROUND:

Bleeding is a serious adverse drug reaction associated with warfarin therapy, often induced by interacting co-medication.

METHODS:

We investigated the frequency and clinical consequences of warfarin drug interactions utilizing medical records of 6,772 warfarin-treated in-patients of Turku University Hospital.

RESULTS:

A total of 48% of warfarin-treated in-patients were exposed to interacting co-medication. Adjusted odds ratio (OR) for bleeding was highest for cytochrome P450 2C9 (CYP2C9) inhibitors (OR 3.6; 95% confidence interval (CI) 2.4-5.6). Non-selective non-steroidal anti-inflammatory drugs (NSAID) and coxibs were associated with a bleeding risk of a similar magnitude (OR 2.6; 95% CI 1.6-4.2 and OR 3.1; 95% CI 1.4-6.7, respectively). Selective serotonin re-uptake inhibitors (SSRI) were associated with a remarkably higher bleeding risk than non-SSRIs (OR 2.6; 95% CI 1.5-4.3 and OR 1.2; 95% CI 0.3-4.3, respectively). Odds ratio for bleeding in the platelet aggregation inhibitor group was 1.6 (95% CI 0.8-3.1).

CONCLUSION:

We conclude that co-medication in warfarin-treated in-patients is common and should be carefully evaluated to decrease the bleeding risk associated with warfarin therapy.

• Authors: Milka Hauta-Aho, Tuire Tirkkonen, Tero Vahlberg, Kari Laine
• Journal: Annals of medicine (Ann Med) Vol. 41 Issue 8 Pg. 619-28 ( 2009) ISSN: 1365-2060 [Electronic] England
• PMID: 19711211 (Publication Type: Journal Article)

Chemical References

• Anti-Inflammatory Agents, Non-Steroidal
• Anticoagulants
• Antidepressive Agents
• Enzyme Inhibitors
• Platelet Aggregation Inhibitors
• Warfarin
• CYP2C9 protein, human
• Cytochrome P-450 CYP2C9
• Aryl Hydrocarbon Hydroxylases

Topics

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Anti-Inflammatory Agents, Non-Steroidal (adverse effects, pharmacology)
• Anticoagulants (adverse effects, pharmacokinetics)
• Antidepressive Agents (adverse effects, pharmacology)
• Aryl Hydrocarbon Hydroxylases (antagonists & inhibitors)
• Case-Control Studies
• Cytochrome P-450 CYP2C9
• Databases, Factual
• Drug Interactions
• Enzyme Inhibitors (adverse effects, pharmacology)
• Female
• Finland
• Hemorrhage (chemically induced)
• Hospitalization
• Hospitals, University
• Humans
• Male
• Middle Aged
• Platelet Aggregation Inhibitors (adverse effects, pharmacology)
• Warfarin (adverse effects, pharmacokinetics)
• Young Adult