Gastrointestinal bleeding due to warfarin drug interactions with ciprofloxacin

The authors document case history of an 81 years old male patient suffering from chronic bronchitis, diabetes mellitus of 2nd type and

chronic coronary artery disease who was taking warfarin because of chronic atrial fibrillation. The patient was using 3 different types

of antibiotics during the hospitalization, the last one was ciprofloxacin. On the 4th day of using of ciprofloxacin the patient started to

suffer from the extreme elevation of INR with bleeding to gastrointestinal tract. The bleeding was cured non-invasively; the treatment

of oral anticoagulation was stopped. After an exclusion of other possible causes the authors explain the developed status by a drug

interaction between warfarin and ciprofloxacin. During the hospitalization the patient took a lot of drugs with risk of drug interaction

with warfarin. The authors suppose that the prevention of thromboembolic complications by low molecular weight heparin is safer than

the prevention with warfarin in case of a polymorbid senior with fluctuant clinical status requiring a frequent change of the medication

when the avoidance of drugs with drug interaction with warfarin is impossible.

Keywords: warfarin, ciprofloxacin, drug interaction, inhibition, INR