It's a pro-drug (meaning it won't be psychoactive before the body metabolizes it. In addition, the metabolites of the drug are normal amphetamine and a relatively unpopular stimulant known as theophylline (which I know next to nothing about). I understand it was used in line with tradition ADHD treatments up until the 90s when it got some huge backlash. So basically the drug here can be thought of these two drugs interacting in the body. The fact that it is a pro-drug complicates things though, as like Heroin or other pro-drugs, different rates of metabolism in different regions of the body can lead to drastically different effects. (kinda like how Heroin is incredibly more potent and effective and potent than Morphine, despite the fact that Heroin just metabolizes into Morphine before it can even work).
Looks like, in the US, it's a schedule I substance meaning "no recognized medical use." I don't think it's manufactured anymore, what what I was able to find online.