I had to use an AI (finally!) because the patent covering tapentadol (US6248737B1 - 1-phenyl-3-dimethylaminopropane compounds with a pharmacological effects) was written using software that converts Markush structures into text. Think if it like a huge tree with branches and branches in the branches and then twigs, each ending in a leaf. In short, in the form of a text it's utterly unreadable.
But the long and the short of it is that tapentadol is the bastard child of picendaol and tramadol.
Like tramadol it's both an opioid and a monoamine modulator and like picenadol (which in fact it almost perfectly overlays) it demonstrates mixed agonism, but in the worst way.
I think it important to note that while tramadol was actually two of the four stereoisomers of the same molecule, tapentadol is just one of four possible stereoisomers and I note that an unexpectedly large number of reference standard suppliers are offering a dozen or more compounds listed as 'Tapentadol Impuity A' upto whatever letter they go to.
That's the problem with stereochemistry. While it's relatively simple to resolve the
trans pair (tramadol) and the
cis pair (waste), IF generics manufacturers are grappling with finding more efficient synthetic routes to just one of four stereoisomers, it appears that multiple routes are currently used and each one can yield certain impurities.
Now I honestly have no idea if they are toxic, I'm merely highlighting the fact that if you use Google Patents to look at the patent you will notice that 174 other patents cite it and if you scroll through the list you will note that a score of more are clearly alternative (optimized) syntheses.
So this is not intended to scare anyone, only to suggest they might do well to avoid generics produced in nations where price-point is extremely important, oversight less that perfect.
