I had the same thoughts and asked the same question. Had a liver transplant 2.5 years ago and it is better to be lucky than good but I have not missed an am nor pm dose in that time. But being paranoid I asked both Mayo and my local DR. and both said missing just one dose was not a big deal. But I assume two would be. Can't confirm but someone once told me that TAC stays in your system for 72 hrs.. Not sure if that is true or what its half life would be. Have had surgeries and blood tests where I could not take my meds till hours later than my normal range and the DRs. involved always told me np. I would not worry. Hang in there. (---: