Great for you!

A couple keys about doing extended fasting. Keep electrolytes up. Specifically salt, magnesium and potassium. Realyte makes some packages of unflavored electrolyte mix that can be mixed in water. How you break the fast is just as important as the length of the fast. Don't pig out when breaking the fast. Eat a small amount then wait a couple hours before eating a full meal. Some protein and fat while avoiding sugary stuff and heavy high carb foods like potatoes. Bone broth to sip on at the end of an extended fast would be a good first consumption.

Just what the big boys tell me. I'm certainly no doctor so don't take that as any medical or nutritional advice. It is just what I have heard from some internet guys. May or may not be correct.

I don't know what if any interaction with the drug you are taking the fasting will manifest. Just be aware of it and might be worth discussing with the doctor who prescribed the drug.