Time release medications in general are fascinating. There's another ADHD medicine, Vyvanse, that has a really interesting mechanism. The (dextro)amphetamine molecule is chemically binded to l-lysine-- a common amino acid. This makes it inactive, so one can't just snort it. It must be ingested, where in the digestive tract it meets protelytic enzymes that break down the bonds of amino acids. So it detaches the l-lysine molecules and then amphetamine molecules-- but only at a set rate. See, because there's only a finite amount of proteolytic enzymes in the gut this breakdown occurs at a predictable rate. It's so simple yet so complex at the same time, really is a brilliant time release mechanism