Coumadin and Herceptin

In the database of official manuals used in the service creation an interaction registered by statistical results of studies was found, which can either lead to negative consequences for the patient health or strengthen a mutual positive effect. A doctor should be consulted to address the issue of joint drug administration.

Using warfarin together with trastuzumab can cause you to bleed more easily. You may need a dose adjustment in addition to testing of your prothrombin time or International Normalized Ratio (INR). Call your doctor promptly if you have any unusual bleeding or bruising, vomiting, blood in your urine or stools, headache, dizziness, or weakness. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

MONITOR: Trastuzumab may potentiate the hypoprothrombinemic effect of warfarin, although data are limited and the mechanism is unknown. There have been isolated post-marketing case reports of patients stabilized on warfarin whose INR increased several weeks following the addition of trastuzumab, accompanied by signs of excessive anticoagulation such as epistaxis, bruisability, and prolonged bleeding from cuts. A search on a large patient database conducted by the manufacturer of trastuzumab found several bleeding events among 469 women with HER2-overexpressing metastatic breast cancer who were randomized to receive chemotherapy with or without trastuzumab. Although trastuzumab patients had a higher crude incidence of bleeding events, which were generally mild to moderate in severity (with nosebleeds being the most common), they were also seen more frequently and received treatment significantly longer than controls. After adjusting for time on study, the incidence rates were similar for both groups, with or without anticoagulants.

MANAGEMENT: Given the potential for interaction and the high degree of interpatient variability with respect to warfarin metabolism, patients should be closely monitored during concomitant therapy with trastuzumab. The INR should be checked frequently and warfarin dosage adjusted accordingly, particularly following initiation, discontinuation or change of dosage of trastuzumab in patients who are stabilized on their warfarin regimen. The same precaution may be applicable during therapy with other oral anticoagulants, although clinical data are lacking. Patients should be advised to promptly report any signs of bleeding to their physician, including pain, swelling, headache, dizziness, weakness, prolonged bleeding from cuts, increased menstrual flow, vaginal bleeding, nosebleeds, bleeding of gums from brushing, unusual bleeding or bruising, red or brown urine, or red or black stools.

Coumadin

Generic Name: warfarin

Brand name: Coumadin, Jantoven

Synonyms: n.a.

What is Coumadin?

Herceptin

Generic Name: trastuzumab

Brand name: Herceptin, Kanjinti, Ogivri

Synonyms: n.a.

What is Herceptin?