Depends on what your reason is for fasting and how strict you want to be.
If you are fasting for weight loss, to eat less calories in a day, a half cup of something, as long as it’s not high calorie, is going to be fine. It’s not going to mess up your weight loss, as long as you are still in a calorie deficit for the day.
If you are fasting for other reason’s, like keeping insulin from spiking, that’s different. But, if you have to eat something, make it something low on the glycemic index, like oats (not instant oatmeal). You can google and get a list of low glycemic foods.
Are you sure that the meds need to be taken first thing in the morning? I know some do. You might want to check with your doctor (unless doctor has already told you to take the meds at a certain time).
None of my meds need to be taken first thing, they just need to be taken at consistent intervals. So I just take them later than I used to.