Does anyone know a good poison or drug that paralyses...?

Pancuronium bromide is one of the chemicals used in the lethal injection. it causes paralysis in under 1 minute. there is one problem however and that is that it would have to be injected rather than drunk. however from a literative point of view if the character is going to point a gun at the person whois poisoned then they might as well just prik the person with a ring or something filled with the poison which would only require a few drops.