>Sure you can. Desoxyn, Ritalin, and all the others work about the same, and have largely the same side effects. The only reason Methamphetamine is preferred over Amphetamine (i.e. Adderall) for recreational use is that Methamphetamine is much easier for an illicit drug kitchen to cook up from extracted ephedrine.
Perhaps op was suggesting that, generally speaking, regulated sellers don't call those drugs speed. I would argue that because 'the dose makes the poison' is probably the biggest factor here, buying from a regulated seller is a really good idea, and is probably going to make more difference than which particular drug in this class you choose, just because my perception is that the quality control of unregulated sellers is such that the actual amount of the drug you are getting is going to vary a lot, which makes maintaining a therapeutic dose rather difficult.
Also, while they are all broadly similar drugs, little changes in chemical structure can make a rather large difference when trying for cognitive enhancement. This is a very complex thing. I mean, these are all in the same class of drugs, sure, they are broadly similar, but they are not the same. methamphetamine metabolizes to amphetamine, for example. From talking to both patients and doctors, at least for the treatment of ADHD? it is quite common for one of those drugs to work, while the others don't help a particular patient at all. In my own case, methylphenidate seems to work at child-sized dosages, while amphetamine doesn't seem to help focus much at all.
>Addicts can't tell the difference between the various drugs in this class. (http://theinfluence.org/neuroscientist-meth-is-virtually-ide...)
First, the link claims to have tested methamphetamine vs amphetamine; it did not claim to test methylphenidate.
(as a side note, my own experiences line up with the conventional medical wisdom that methylphenidate is significantly less euphoric than amphetamine. I haven't tried methamphetamine) - next, the 'addicts choice' test might go to addictiveness, but even if they are similarly addictive, it doesn't at all address the concerns about neurotoxicity.
Now, I'm no doctor; I don't know if the claims of methamphetamine neurotoxicity are true or not, or if they are true or not at dosages one might reasonably use to enhance cognitive function (which is a rather different question) but... the neurotoxicity concerns are one of the larger differences between amphetamine and methamphetamine, and in my mind, one of the stronger reasons to choose the former over the latter.