Wouldn't it be possible to offer kits or services for chemical manufacturers, to test the level of binding of their chemicals, and define that above a certain level of binding , you're chemical have to be regulated in some way?
I think. My understanding of the legal changes may be lacking here.
This is essentially the 'drug-discovery pipeline' that big pharma spends hundreds of millions on when developing new medications.
But if metabolism can transform said chemical , then sure, you've got to take it into account. But many of those drugs can be detected by pre-metabolism binding, i think.
This matters because it's not really appropriate to schedule chemicals which happen to trigger a response in a test-kit, but are not plausibly drugs of abuse due to side-effects, or lack of any reasonable mechanism of getting to the sites where they'd be active.
The "intended for consumption" is a convenient fiction for the head-shops and dodgy websites that sell such things, but actually having to test things which aren't intended for use in certain ways would be a massive imposition on, well, everything that uses chemicals[2].
There are heuristics that cover a lot of ground, and that's basically what the Analog Act tries to preempt, but there are still huge numbers of potentially active compounds we have no idea about. In-vitro binding studies are perhaps the next filtering step, but you still ought to have to demonstrate actual demonstrable plausibility of action for it to be a crime[3]. In addition, if you have something that feels like cocaine, but rapidly metabolises into a lethal neurotoxin or whatever in the same dose, it's not going to be a drug of abuse, except perhaps in suicides.
In terms of banning/restricting sale of things, maybe binding data would be sufficient, but I'm not sure just what the implications for testing & compliance for everyone involved would be.
[1] https://en.wikipedia.org/wiki/Prodrug
[2] Despite some TV adverts to the contrary, this would be everything.
[3] Leading to (IMO) the utterly bizarre world of fakes/illegal placebos, for which in many places you can be convicted for the same degree crime as the drug you purported to be selling, rather than say, fraud.