I just finished watching five years of Breaking Bad in one week. I also take Concerta, which I read is methylphenidate HCl. Perhaps those two sentences are related…
I have bounced around the amphetamine articles in Wiki and assimilating each cross-ref leaves me more confused and lost in chirality. (Good story title.)
I know the result will be kind of silly, but can anyone listicate or summarize just a one-on-one comparison of the two drugs for a non-chemist?
Methamphetamine: N-methyl-1-phenylpropan-2-amine
Methylphenidate: methyl phenyl(piperidin-2-yl)acetate
And now perhaps can we get the explanation for a non-chemist, like the OP asked?
Czarcasm is a funny guy. I’m presuming he is being true to his name.
It’s easy. They’re spelled different. 
Just a placeholder. I’m reading up on the two here, and here. There seem to be major differences in what parts of the brain they effect, their safety, their contraindications and their side effects.
They’re both related, only one is a meth.
Two related drugs may affect the nervous system using the same neurotransmitters, primarily dopamine, but one can have more affinity and be more “willing” to bind with your receptors. Also the mechanisms are different; seems Concerta blocks reuptake while meth I believe “dumps” dopamine into the synapse. Also, I see that Concerta has a 2-3 hour half-life; meth is 9-12 hours. The effects potency and risk for addiction is affected by that.
That’s similar to why Prozac might not work for someone, but closely related Paxil will work (especially if you complaint is a too-high sex drive). They both affect primarily serotonin, but will have different effects on you, and maybe opposite ones on someone else.
Here is the molecular structure of Methamphetamine (Corners represent carbon atoms; the squiggly bit represents the actual methyl group, CH3.)
Here is that of Methylphenidate (I think, in this case, the vertical straight line at the top left represents the methyl group.)
They are quite different, you see. This makes them different substances with different biological activities. The similarity of the beginning of their names does not signify much of relevance to their properties as drugs.
One of the biggest tasks in Pharmaceutical chemistry is taking something that is effective to some degree and making it work better. The chemists that do this play with the basic structure of a chemical, modifying so it binds to receptors longer, does not break down in the body so fast, targets more specific receptors better. Often, this involves adding things like fluorine atoms or methyl/ethyl groups, changing ring structures and twisting shapes to stabilise activity (or to control chirality). It is as much art as chemistry (as the complexity of the modelling is still far ahead of computed solutions to the problem), and then there is the actual chemical synthesis of the target molecule.
So while Methamphetamine may have provided pointers to treatments for ADHD, this has provided a framework for more focused and better drugs with a reduced risk of abuse.
IANAChemist (but I did study Chemistry a long time ago):
So they are both Phenyl rings (6-carbon rings with alternating double and single bonds).
Methamphetamine has a 3-carbon chain hanging off, with an amine group and a short 1 carbon (methyl) group hanging off. I guessing that that group can rotate, making the structure fairly flexible. The amine affects solubility and polarity, too.
Methylphenidate has a linked piperidine (carbon ring with a nitrogen, no alternating bonds) and an acetyl group with a methyl group. This is bigger, and the piperidine is a zigzaggy chair structure (not flat like the phenyl group). This certainly affects the way the molecule behaves. Also, the acetyl group has different consequences for solubility and polarity, and may influence the ability of the piperidine to rotate. However, piperidine is used in organic synthesis, so it may be secondary to the therapeutic effects.
I’ve been on virtually every stimulant drug in the PDR including pharm grade meth and subjectively I can tell you that there is a huge difference just between individual enantiomers of a given drug. For example I currently take dexmethylphenidate which is the single isomer version of racemic Ritalin and there is a huge difference in therapeutic effects. I don’t get anywhere near the side effects such as the mood swings, rapid heart rate and other issues that I had with ritalin, meth, adderall and their ilk - at least not with the timed release version which unfortunately is still under patent. If I have any complain with it at all it’s that it works too well, but that’s another story.
The point is that people can have highly specific responses to drugs, especially psychotropics. So it matters less what the specific chemical differences are and more how they will affect you in any given dose.
