Yeah that's the thing it's all about the time release. Correct me if I'm wrong but vyvance big thing is that it.... fuck I forgot it the most of it but it slowly release through the liver because of a extra molecule on the drug. This makes it that your body only sucks it up as needed. When blood levels drop. So allegedly its damn hard to overdose on vyvance. The larger doses are only for how long of a day last for. 40mg 8hrs 60mg 10hrs etc.