As it is it is very OP, since 1 card per poison makes it easy to mill a deck to death before they even get a chance to react.
My suggestion is making curare a status on par of neurotoxin (if I undertood it right that is indeed your idea, if not please explain), but instead of discarding one card per poison, discard one card every time curare deals damage. It is still quite powerful with a bit of stall added so it should probably be something pricy.