^^^ It is cool stuff, but I have to disagree with a couple of things.
Opioids on there own is still the most effective single agent, that is why they are prescribed besides the risk. I also know many pain patients personally(also my own pain issues, though I was addicted before that, which makes me biased, not to mention hyperalgesia). But NSAIDS and gabapentin didn't do a damn thing once the pain was severe.
(Note that many of these people ended up becoming "addicted" in the psychological sense and abusing they're medication, but not all).
And for analgesia, opioids eventually reach a kind of ceiling, in regards to tolerance, so that, assuming the pain doesn't increase, the patient eventually reaches a dose that works indefinitely. This is part of the rationale with both methadone and the rare heroin assisted clinics; tolerance to opioids only develops rapidly if the opioids are abused. With proper use they remain effective as analgesics for an extended period.
Caffeine is also only suitable for certain types of pain, and even then it is only suitable for acute use(though in fairness, the doses used as a co-analgesic are fairly low).
I do agree 100% with co-analgesics, but calling opioids "not effective" would imply every other analgesic useless, especially seeing as opioids ate the only analgesic with no know ceiling effect(for they're analgesia).
You're absolutely right about methadone, it is well known as an amazing analgesic, but tram and similar drugs have a ceiling effect and unique side effects limiting use.(don't much about tapentadol)l, but it's mechanism of action is similar)
As for morphine, there is a reason it is the gold standard: it has stronger PNS effects than comparable opioids, and a multitude of other advantages. It's side effects can be pretty rough, though, and with it's slow onset one can only wonder why diamorphine is not utilized in the states, especially since both cocaine and meth are Schedule II!
Oxycodone IV should also be utilized in the states, for reasons I've brought up before. One more thing, studies have shown that multiple opioids(including IV morphine/oxycodone together) are more effective than a single agent, despite the WHO's recommendation of using a single opioid.
(The oxy/morphine combo was not only more effective than an equivelant dose of either, but also carried less side effects, particularly in comparison to morphine alone)
