Earlier quoted context omitted.
Adding on: the problem with vyvanse is that there's no way to mess around with the dosage to get it "just right." It's like a more strict version of extended release (EX) and timed release formulations (there's a difference!). Vyvanse is metabolized to d-amphetamine in your blood cells (the specific mechanism escapes me right now), unlike the regular non-prodrug versions which get "metabolized" first in your stomach…
Yep. It's why I switched from Vyvanse (lisdexamfetamine - basically just d-amp bound to lysine which is then metabolized into d-amp during digestion) to IR generic Adderall (a mix of d-amp and l-amp). Any unwanted effects (insomnia if I take it too late, etc) are almost entirely due to the l-amp, but the slow release of Vyvanse made it essentially impossible to titrate and my options were either to take a dose so low…
In my experience, I've had to run the gamut on all the "other" ADHD drugs (ritalin, adderall, d-amphetamine ER, etc.) and then prove they weren't effective, for my insurance to finally approve it. I've heard of some people even going so far as to get prescription meth (desoxyn) because nothing else would work! Strange world.
I've stopped taking meds entirely. I don't know if it's because I'm getting old, and even a "low" dosage (5-10mg) makes me feel very uncomfortable, or if it's because I've used a lot of different slavic nootropics and neuro-regenerative peptides (e.g. semax/NASA, BPC-500, etc.), but I just do not have any tolerance for it anymore.
Fortunately, this loss of tolerance coincided with the ability for me to function very well on simple caffeine alone.