I guess you didn't actually read it (or comprehend). Cocaine has an extremely high risk of addicition and would therefore fall under that prohibition.
Secondly, here you go again with the "just" a venial sin garbage. Nobody's advocating venial sin. Jone says that it's venial if there's no proportionate justification, but no sin at all if there's proportioniate justification. So, if you could take cocaine without the risk of addiction (not possible, from what I understand), and it didn't compromise your reason, and you needed it to get your work done, yes, it would be justifiable ... and NO sin at all (not "just" venial sin).
Given the examples Jone gives where there would be no sin to take narcotics occasionally, I have to wonder what else could be considered "proportionate justification". It seems a bit too easy to claim "proportionate justification".
I wouldn't want to make that judgment without consulting a good and holy Catholic priest.
ETA: It looks like you are copying and pasting Jone. Do you have an online version? I have the book, but it sure would be nice to access it online.