A study published October 3 2017 in JAMA has cautioned that physicians prescribing non vitamin K oral anticoagulants NOACs should consider the potential risks associated with concomitant use of other drugs. In the study of more than 90 000 individuals with nonvalvular atrial fibrillation the risk of major bleeding was significantly increased with concurrent use of amiodarone fluconazole rifampin or phenytoin compared with NOAC use alone.