The imuran is known for interacting with the warfarin, and makes the later less effective. Your doctor should have known that, however, when they were prescribed. It should just be a matter of adjusting your warfarin dose up to compensate for the Imuran.
If you continue to have problems, look to other drugs, foods, and vitamins and/or herbal supplements that might be making a mess of things. Vitamin K is commonly found in multi vitamins. Prednisone, asprin, naproxen and ibuprofen are all discouraged while taking warfarin. I know I now have to change my warfarin dose every time I go back on pred.
My doctor advised that I take a multi-vit with 100% of USRDA of vitamin K in it. At first it did not make any sense, but advised me on how taking a constant, steady supply of vit K would help me with controlling the occasional salad or other diet burst. Much less yo-yo'ing of the blood levels while taking the supplement. The warfarin is just adjusted for the small ammt in the vitamin.
So far it's working - keep trying, you will hit on your perfect combination soon enough.
