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Abstract

Spanish

French

OBJECTIVE:

To report two cases of enhanced oral anticoagulant effect induced by doxycycline coadministration.

DESIGN:

Case report.

SETTING:

University teaching hospital.

PATIENTS:

Two patients on chronic oral anticoagulation therapy who presented with severe bleeding and marked impairment in blood coagulation tests shortly after the initiation of doxycycline therapy.

DISCUSSION:

The literature concerning the possible effects of tetracyclines on hemostasis with or without antecedent anticoagulation therapy is reviewed and the speculated mechanisms for such an interaction are discussed.

CONCLUSIONS:

The administration of tetracyclines such as doxycycline to patients on chronic oral anticoagulation therapy may be associated with a marked enhancement in anticoagulant effect. In such patients the prothrombin ratio should be closely monitored and the anticoagulant dosage adjusted accordingly.

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Enhanced Anticoagulant Effect of Coumarin Derivatives Induced by Doxycycline Coadministration