Sorafenib Warfarin

Sorafenib levels may be reduced by inhibitors of CYP3A4. Antacids may reduce the absorption of sorafenib. Siorafenib may increase docetaxel and doxorubicin levels. Isolated cases of raised ENRs and bleeding have been reported in patients taking warfarin with sorafenib. 

A study in patients given sorafenib and taking warfarin found that the INR did not differ between those patients taking sorafenib and those not taking sorafenib, despite previous in vitro evidence that sorafenib inhibits the cytochrome P450 isoenzyme CYP2C9, the main isoenzyme involved in the metabolism of warfarin. 

Sorafenib A possible interaction of sorafe-nib with warfarin has been reported [14 ]. 

A 70-year-old man with hypertension, congestive heart failure, atrial fibrillation, gastroesophageal refiux disease, chronic obstructive pulmonary disease, and chronic hepatitis C infection was stabilized on warfarin 36 mg/ week. He developed a hepatocellular carcinoma and started to take sorafenib 200 mg/ day. After 1 month his prothrombin time had risen to 85 s and his INR was 40. Sorafenib and warfarin were withdrawn, and after reintroduction of warfarin his INR stabilized on a dosage of 36 mg/week. Sorafenib 200 mg/ day was again introduced, and about 2 weeks later the INR rose to 4.7. Sorafenib was withdrawn permanently. 

Moretti LV, Montalvo RO. Elevated International Normalized Ratio associated with concurrent use of sorafenib and warfarin. Am J Health Syst Pharm 2009 66(23) 2123-5. 

INR during warfarin therapy when sorafenib 200 mg/day was added [53 ]. 

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