This was the story with heroin, oxymorphone, codeine... Practically every generation was in theory safer and actually turned out to be much worse.

Turned out to be much worse based on what evidence? All three of your examples have been in use for over a century and there have been dozens of pain killers invented since then that are much better at targeting specific pain receptors without the addiction.

I should clarify I'm supposing that by opioid they mean morphine based opioids.

You should probably read the article. It's not morphine based.

It is targeting mu opioid receptors, mentioned in the article as "morphine receptor."

It may not contain morphine, chemically, but neither does oxymorphone, it's only similar.. the only drug mentioned that actually contains morphine, ie. is morphine based is heroin. But having side chains and other additions can totally change a drugs' effects. Morphine-based is a poor distinction.

This is interesting, but doesn't get me too excited. Respiratory depression, whilst a perpetual issue in the the medical use of opioids, isn't necessarily a problem at the lower doses that the evidence suggests actually works. It's a problem at high doses, but those high doses don't provide significant benefits over smaller doses and are associated with hyper-sensitivity to pain and opioid tolerance.

Don't get me wrong though, respiratory depression and arrest is a real thing. I deliberately induce it as part of an anaesthetic every day.

Wow, it would be nice if this one pans out. A friend of mine had open heart surgery, and he never once complained about pain in his chest or his leg or the fact that he couldn't push down and couldn't walk far or any of the other stuff that goes along with it.

But the side effects from the opioids were driving him crazy. After a few days he stopped taking them because the pain was easier to deal with.

This is what Purdue Pharmaceuticals said about Oxycontin

The headline, yes. But if you read the actual article, it seems it's working with the same endorphin receptors without the dangerous side-effects; further, the article hedges its bets by explaining that this is purely in mice so far, and this drug candidate has a long way to go, but as it's a novel opioid that isn't derived from morphine, there is reason for very cautious optimism.

Numerous other novel opioids that aren't morphine derived have shown that it is possible to come close to the pain relief offered, while mitigating the negative side-effects. This is not impossible, I believe, but it'll be interesting to see whether PZM21 is 'the one'.

Could we now please get a move on and use the same trick to develop new antibiotics?

Roger, it's not the opiates, it's the trick:

"An international team of researchers — . . . Their secret? Starting from scratch — with computational techniques that let them explore more than four trillion different chemical interactions."

This was exactly my idea back in the mid-'70's when I thought of one of the ways computer science could be applied to drug development. Of course all we had were mainframes, but so did the drug companies.

Then, my first employment was with a pharmaceutical producer, I got the impression they were actually further away from this compared to starting a whole new drug company from scratch itself.

Until new antibiotics come along, when necessary you might want to investigate older, more well-established germ-killers like colloidal silver. The real thing is hard to beat, but it is outnumbered by quack versions and get-rich-quick schemers.

I wonder if the cost of this research is greater than the cost for lobbyists to legalize medical marijuana.

The problem with medical marijuana is that it doesn't relieve severe pain and it gets you stoned which not everybody wants.

Not to mention that smoking a plant isn't an efficient or specific drug delivery vehicle.

Patients often use liquid tinctures.

How is that actually a problem?

High CBD variants relieve pain without psychoactive effects. THC is not the only cannabinoid.

Not true. I've used high CBD strains lab tested from Washington and they still caused minor paranoia. And the level mecessary for the same pain relief as tramadol, tapentadol, or morphine sulfate, makes a person dumb as a brick and unable to do what they originally wanted to. Pipedreams are nice. Marijuana is not a supplement to opiates except in corner cases. Really depends on the person and level of pain. I have chronic pain and marijuana was not conducive for a productive lifestyle while opiates are.

Don't sell either effort short, do both.