Drug-induced transcendence? That's a new one on me. But generally no. I believe that the brain is a highly tuned organ, and pissing around with it chemically, make its do stupid things, which at the time, might seem reasonable within your conciousness, but ultimately don't tend to hold much worth. Sure, you can come to meaningful conclusions, but I think that if someone should be able to come to those conclusions without the use of drugs.
Nitrous is the best example. I don't know if this is universal, but all of my friends, during a nitrous high, feel they understand the universe, that they have solved some deep spiritual unknown problem. When they come to, they can't remember it, and its because it doesn't make sense, its not that they answered a question, its that they had the feeling of solution. There is no question to answer, so one can't solve it.
Equally, I don't really believe in Nootropics. Sure, certain drugs can increase short term memory, and maybe long term, but there will be a cost, whether it's increased seizure risk, quicker loss of memories, lower concentration. And I also don't think that really makes you any 'smarter'.