Many drug interactions with Warfarin are well documented in the literature, including interactions with a variety of antibiotics. However,in mamy cases it is difficult to predict when the interaction remains theoretical and when it becomes clinically significant and will be reflected in the individual patient. This study's aim is to identify and characterize related conditions (including comorbidities, laboratory test results and other parameters related to the patient)that might be predictors for drug interactions turning from theoretical to clinically significant.

Inclusion Criteria:

• Patients aged 18 and over
• Patients treated with a combination of Warfarin and Cephalosporins
• Patients who were hospitalized in the department of internal medicine
• Patients who were treated with Warfarin without Cefalosporins

Exclusion Criteria:

• Patients on Warfarin who did not actually receive the drug during their hospitalization
• Patients whose medical records were not accessible or didn't contain full data

Warfarin-treated patients who were hospitalized for any reason in the department of internal medicine and were treated with antibiotics from the Cephalosporins group during their hospitalization.