Reuptake inhibitors block the activity of releasing agents, aren't they?
*facepalm* I didn't even think about that. I've heard that low doses of methylphenidate with amphetamine (or was it the other way around?) have a synergistic effect, but this would leave a 1:1 ratio, so it wouldn't work. I also realized that if the leucine is cleaved from the methylphenidate, it would become ritalinic acid, which apparently is an inactive metabolite. So back to the drawing board...
So I'm trying to think of another way to link the two maybe, or maybe find another drug to link to amphetamine. What could be some other linker molecules that would make it to the liver other than amino acids (perhaps with structures similar to amino acids)? Could an analog of leucine be able to be cleaved like lysine is cleaved from amphetamine in Vyvanse? If so, I figured I could try linking amphetamine and modafinil with a leucine analog.
I figured it would automatically be a prolonged release prodrug, and also since modafinil has a lower abuse potential, it might be an ideal drug with a lower recreational value than even Vyvanse. Even though modafinil acts as a DRI, I have read that low doses of modafinil with amphetamine are synergistic. If there's a 1:1 ratio of amphetamine and modafinil, then it would be like 30mg of amphetamine with 30mg of modafinil, which doesn't seem like it would be a high enough dose of modafinil to "cancel out" the amphetamine.
If modafinil is not an ideal drug to link, what other stimulants would work (with a primary amine)? I've looked through many of the PIHKAL phenethylamine derivatives on wikipedia but it seems that most of them have hallucinogenic effects like MDMA. I'm still looking for some with mostly stimulant effects. Also, most of the other stimulants I've found are DRIs, which would not be ideal. I've also looked through substituted amphetamines on wikipedia, but it's hard to tell which ones are better.
You all have no idea how much appreciate all the help and feedback you all have given so far.
I owe you guys big time, hahaha.