Worse thing to do is to fast and take poisonous drugs.
Anxiety can be dealt with breathing and EFT while fasting. Dr. Fuhrman and Dr. Goldhammer wean their patients off of the drugs and then make them fast.
Good job thus far. If it is hard to bear then break your fast a day ahead of the appointment and take your meds, but eventually get off it with tapering off method and then do a liver cleanse, this will get all toxins out of your liver, then you may fast.