A 2016 review article in Neuroplasticity comprehensively lists drugs for ADHD and focus enhancement, detailing their status, effects, and drawbacks.

“there's an excellent review article that I can refer you to it's by Ahn et al, AHN it was published in 2016 so it's a little bit behind the times, although it's surprisingly comprehensive given that, which lines up all the various drugs that I've discussed, Racetams., and Adderall and Ritalin, and various forms of dopaminergic agents and cholinergic agents spells out whether or not they are sold over the counter by prescription, and really lines them up in all their effects, their drawbacks, et cetera.”