(I'm aware of the sarcasm tag). Technically that 100% should be 99.999%. Not all drugs are found in nature. Technetium, a man-made compound, is used in some radiology.
https://go.drugbank.com/categories/DBCAT001978
No, technetium is still a natural product, it just takes a little processing. An organic miner dug up some raw uranium ore, then someone refined it, irradiated it, and isolated the resulting molybdenum-99, and finally a radiologist extracts the all-natural technetium from the decay process of that molybdenum.
Natural = found in nature.
You can argue that, and I might agree with it, but it's not regulated as such.
It is found in nature, it just has a slightly different number of protons when it's raw.
I know what you mean, but it's just the definition of natural at least on our "earth". If you find some technetium somewhere let me know.