I'm allergic to colistin, but I take two other IV medications inhaled. Aztreonam and Fortaz. My insurance changed in January, so although they are covered, it does cost me $100 a month (each) to stay on them. I used to pay $50 a month, but with my new insurance came new copays for IV drugs, even though I'm not infusing them, I'm inhaling them. It's ridiculous that it costs so much more than a non formulary copay in my plan (non formulary is only $30)