Sith poison doesn't work like that.
Sith poison was a biological toxin, and a product of
Sith alchemy, that when absorbed in sufficient quantity, multiplied the rage felt by a person. In action it was more of a disease, taking up residence in the victim's body and setting off chemical reactions that rapidly diminished the victim's ability to resist the pull of the
dark side of
the Force. The poison could be fatal unless counteracted by strong
Jedi powers, and even then its effects were likely to remain.
After being introduced to the body, the poison is absorbed on a molecular level, feeding on the individual's anger and drawing them closer to the
dark side. The individual's judgment becomes less rational, and they eventually become so enraged that they begin to lash out involuntarily with the dark side.
So yeah --- can't just focus it to one person... it makes you irrational.
