Where I'm from out here in flyover country there are an awful lot of people stuck in dead end jobs that would literally jump at a drug like that if its effect was dramatic enough.
Getting that GED in a weekend? You better believe there are a lot of people out here in trailer park and opioid land who would be all over that. Doesn't mean much to us, but the GED opens up raises at their current jobs, and even jobs that they currently are not able to get. That's not even counting the waitress types trying to get through college at night without waking up their kid. Those single mom types would definitely take it. It wouldn't even be a question for them.
Only way an illicit drug like that would not be consumed around where I live, is if the people around here couldn't find out about it. (Even that though would be hard, because I'm sure we have drug dealers around here who are probably pretty good at marketing stuff like that.)
physical enhancers I can think of: Steroids, Viagra
mental enhancers I can think of: Modafinal (and similar, mainly, can also argue it is a physical enhancer), psychological drugs focused on better focus etc.
half and half - amphetamines. you can stay up to study but you don't pay attention so you could also stay up to party.
physical enhancers I can think of offhand: drug makes you beautiful, drug makes you physically tough, sharpshooter drug etc. etc.
mental enhancers I can think of: increase short term memory, photographic memory, increase reading speed, language processing improvements.
I guess I see that passing the GED drug mentioned in the other comment but intelligence is as a general rule not something people aspire to in this society (IMHO) therefore I would expect intelligence altering drugs would not receive as much funding as drugs that effect the things that society values, and those things tend to be physical.
Or to paraphrase Idiocracy the best minds would be devoted to enlarging penis size not making people smarter.