Comment by netizen-936824

That "not working" part has some nuance to it as well. How well do we predict ADME? Is there binding with some off target protein that makes it terrible? Maybe it just doesn't bind to the desired target at all.

Toxins don't have those constraints, its not even about regulation. Making something that's safe is way harder than making something that is not safe, purely because of the complexity involved in making the thing safe.