I take fast acting aderall 10mg 2x's a day but I try to not take it everyday or the whole 20 mgs's becaseu I find that after taking it for several days in a row it is not as effective and I really don't want to up the dose. I think it only last about 4 hrs for me and when I have taken the er version it lasts maybe 8 hrs. I'be not tryed vynasse mainly because I can get addrall generic and it's cheaper for me. I hate how insurance determines what we will take but we have to pay our other bills and I have 2 boys on ADHD meds too.
It does make me not so hungry and I like that side effect but when I come off of it I am very hungry so I tend to eat more in the evening which I'm sure isn't good either. Have you taken it very long? Maybe you need to up the dose a bit or try another stimulant that your insurance pays for. Adderall seems to work best for me of the meds that I have tried.