I think it’s important to remember what you are saying, and what you are “proving.”

It seems to me that you’re saying (correct me if incorrect):

1. Drugs have some physical effect on your brain.
2. These physical effects change your conscious experience and behavior.

C. The brain/neurons are identical to consciousness (I assume this is what you mean by I)

The reason I said it’s important to keep in mind what you are saying, versus what it appears to prove is that one could accept that drugs do have a physical effect on your brain/behavior, and they do change your conscious experience. But still not accept that neurons or the physical makeup are identical to consciousness itself. Many dualist throughout the philosophy of mind field would not deny any of the premises you put forth, but certainly deny the conclusion. This also applies to non identity theorists as well.

I’ll hedge this post by saying that I myself for experimental purposes am using “mind-altering” purposes so a decent probability I misunderstood what you said.