Wondering if the many pill bottles that I have accumulated of Jantoven (generic for Coumadin) which are quite full might be slowly going bad. I have several bottles as I was previously on prescription for 5mg daily and 2 mg twice a week. Well the way the prescription was always written was always for the max number of pills for both doses. So I would amass a lot of extra of the smaller dose. Ive always kept them on hand figuring it would be my emergency stash. Wondering how long those pills are good for? They're kept in my kitchen cabinet in a climate controlled house, they're even in the dark. Any reason to think they would go bad or expire?