I'd be surprised if most people who advocate that drugs be tested on consenting adult humans would themselves give consent... especially to drugs which weren't already shown to be safe when tested on animals.

It would be interesting if every citizen was required to act as a research subject every year, to more equitably distribute human testing.

But of course most people would freak out if such a requirement was ever seriously floated, as they want drugs tested on others not on them, so it would never happen.

I think there's an argument to be made that informed consent can't be given by someone who doesn't understand the underlying science, which is virtually everyone.

What if those people are people who can be exploited and coerced into "giving consent" because they are poor, and need the money?

What if the human dies in 10% of experiments? What if it's 90%?

I think you're going to have trouble finding adult humans that are willing to infect themselves with, e.g., vibrio cholera to test new vaccines (or, for that matter, to have their guts biopsied for immunological assays).