It’s weird drugs for the rest of the week!
Salvia probably means one of two things, if anything, to most people: a houseplant (for which purpose it is ubiquitous) or a recreational drug that you can still get your hands on legally (for which purpose it is ubiquitous). It is funny to flip back and forth between pages where people are trying to figure out exactly the best way to get this stuff in your body and pages where people are trying to figure out which plant will go best with those azaleas and think that everyone’s talking about the same thing. Plants are funny that way, I guess.
Of course, we’re interested in the first group of people. Salvinorin A is a psychoactive component in salvia, that binds to a subset of opioid receptors (but not the subclass we’re mostly hitting with painkillers).
Part of what makes salvinorin so unusual is that it is completely lacking in nitrogen atoms. Many drugs have a nitrogen-containing functionality (which, in amines, can ionize, allowing it to sometimes carry a charge, and sometimes not carry a charge). As far as I know, all the opioids that lack one are just research curiosities for the time being (or odd one-off nonmedical compounds like salvinorin). See, for example, morphine, codeine, heroin, naloxone, buprenorphine, methadone, hydrocodone…you get the idea.