Androids can't be poisoned, quite simply.

[quote]but would anyone actually know how to calculate the force of a punch?[/quote]

For a (very very) rough Fermi estimation, treat a punch, like an arm held straight and then swung rotationally. Divide the arm into hand, forearm, and upper arm. Determine average distance from shoulder for each, and time it takes to connect fist with target from inline with shoulders to straight in front of him. Pi/2 (quarter circle, but I gave you radius not diameter) times distance from the shoulder of hand, forearm, and upper arm, then divided by the time to connecting, and multiplied by the the masses. Should look something like hand mass times hand velocity plus forearm mass times forearm velocity plus upper arm mass times upper arm velocity.