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Suggest dosage for Warfarin in an elderly person

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Posted on Tue, 19 Jul 2016
Question: Hi, My husband ( 73 y.o. white) has a St. XXXXXXX mechanical aortic heart valve. He takes warfarin to keep his blood thin to keep it from clotting. He has had the valve for about 27 years. He hasn't had any problems until recently. He was taking about 5 mg 4 times a week and 7.5 mg 3 times a week..keeping his INR between 2.5 to 3.5 But over the last couple of years his doctor has had to increase his warfarin to keep it in range. but for the last 9 month or so the warfarin is not working. His doseage has increased dramaticly. His present dose is 20 mg daily except M.. W.. F is 25mg. and his INR is 1.0 . In the last 6 months he has only been in range maybe 2 or 3 times. He has been getting his blood tested every week. He has type 2 DM and he has HEP C which has been treated 2 times without success. He recently was treated with Harvoni. After about 18 weeks the virus still is present. I am very concerned about the INR as the dr. that treats him. We certainly don't want him to develop a clot. Can you suggest any reasons for the warfarin not working? What should we do? Thank you for your expertise.
Betty
doctor
Answered by Dr. Lilit Baghdasaryan (52 minutes later)
Brief Answer:
Warfarin effectivity is altered from many factors

Detailed Answer:
Dear Betty,

Warfarin is a very sensitive medication, and it's effectivity is altered by food, many other medications and patient's organism condition.
Sometimes we have temporary decrease of effectivity, but 9 months and 20 mg warfarinare too much.
Unfortunately there is no other medication proved for prosthetic valves.
There are new medications, which can be prescribed in stead of warfarin in some of diseases but not in prosthetic valves. From these medications Dabigatran is contraindicated, as there was a study which failed to prove it's effectivity in such patients.
There is another medication Rivaroxaban. And there is ongoing study with Rivaroxaban in such patients, but we don't have results yet.
Anyway, if warfarin will not work at all, if your husband's INR remains around 1, maybe your doctors think about Rivaroxaban. Maybe it is better to go with a medication, that we are not sure if it works or not, than with a medication, that we know surely, is not working at all.

Hope this information is helpful for you

Wishing a good health to your husband

Regards,
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar
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Answered by
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Dr. Lilit Baghdasaryan

Cardiologist

Practicing since :2007

Answered : 1536 Questions

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Suggest dosage for Warfarin in an elderly person

Brief Answer: Warfarin effectivity is altered from many factors Detailed Answer: Dear Betty, Warfarin is a very sensitive medication, and it's effectivity is altered by food, many other medications and patient's organism condition. Sometimes we have temporary decrease of effectivity, but 9 months and 20 mg warfarinare too much. Unfortunately there is no other medication proved for prosthetic valves. There are new medications, which can be prescribed in stead of warfarin in some of diseases but not in prosthetic valves. From these medications Dabigatran is contraindicated, as there was a study which failed to prove it's effectivity in such patients. There is another medication Rivaroxaban. And there is ongoing study with Rivaroxaban in such patients, but we don't have results yet. Anyway, if warfarin will not work at all, if your husband's INR remains around 1, maybe your doctors think about Rivaroxaban. Maybe it is better to go with a medication, that we are not sure if it works or not, than with a medication, that we know surely, is not working at all. Hope this information is helpful for you Wishing a good health to your husband Regards,