sounds like it should able to help existing addict to wean off addiction as well. good news indeed.

does it work for someone who is already addicted?

Probably because the actual pain relieving properties of morphine and its ilk are negligible. I found that out when I broke my knee.
You can still feel everything, it's just kind of "over there somewhere" because you're so disoriented by the drug. Purple haze, indeed!
In my experience, Ibuprofin (Advil Liqui-Gels) was way better than morphine.

But will it get Darvon N100 (Propoxyphene Napsylate) back on the market? That was an inexpensive yet powerful pain medication.
Napsylate was added to make it insoluble in water and nearly impossible to convert into an injectable form as can be done with Propoxyphene Hydrochloride.
There's two reasons it got pulled. For one it was long off-patent and cheap. The second was because it's an opioid and practically since it was first developed some nuts have been hollering that some people might get addicted to it. Some of those nuts want all opioids banned simply because they are partially chemically similar to opium. (The pharmacology version of the anti-nuclear, anything "nuke" is bad sort of person.)
If a person does manage to get addicted to Darvon, quitting it "cold turkey" works quickly, with the drug being flushed from the body within hours.
Don't confuse it with Darvocet (Dextropropoxyphene Paracetamol). If you can't take Tylenol (paracetamol AKA acetaminophen) you can't take Darvocet.
It's possible to overdose and have bad effects from just about any drug, even aspirin. It's not the pills' fault if someone does that.
The VA prescribed Darvon N100 to my father for many years. One or two pills a day worked great on his back pain. In recent years the VA kept trying to switch his prescription to Darvocet and he kept having to get them to not do that because he cannot take Tylenol. He can't take codeine either. Once one of the VA docs told Dad he had to be careful with Darvon because he could get addicted to it. Dad replied "Are you addicted if you forget to take it?"
Since 2007 most formulations of Darvon and Darvocet have been off the market. The people determined to keep an affordable and very effective medication for severe pain off the market have won. :P

Blocking dopamine, I wonder if this could make the patient more prone to depression?

Maybe we will now be able to get real pain control.

I am not a doctor and know nothing about drugs but this report reminded me of an article I read years ago in a newspaper about an Isreali surgeon, Dr Andre Waismann, who spends his life curing drug addicts by just this technique i.e. washing out opiates from the receptors in the brain ( which causes the cravings ) whilst the patient is under general anesthesia . After waking up, the addict just needs to take a medication that "keeps the receptors in the brain blocked to any effect by narcotics.” Its a purely medical/mechanical approach inspired by his experience of wounded soldiers that had became hooked on morphine whilst in hospital. Seems to have worked since 1993. It would be great if Adelaide Uni & Uni of Colorado could link their research with Dr Waismann to bring this approach up for International study and acknowledgement. Anything that works, for whatever reason , is far better than all the expensive and regression prone "treatments" tried around the world today. My best wishes to the success of this line of research to speedily bring about a new life to all those stuck in a nightmare existence.

Its somewhat unclear in this article what specificaly this does. It really only mentions that this drug, which btw has been on the market for ALONG time and has been used for people with drug addictions for awhile, only affects "cravings" which is only one part of addiction, does it just stop cravings or does it stop/disrupt the physical addiction/withdrawal cycle.
This also isnt the first time drugs like this have been used in this manner, that is combining them with the opiate of choice to mediate the physical dependancy, if indeed that is what its doing. They've used another drug, naltrexone in very small dosages combined with oxycodone, aswell as a morphine/naltrexone by the name of Embeda. Naltrexone and naloxone are both similar although different enough to have different classifications, but are both used in the same manner.
I am glad to see research is being done in this area as current treatments for addictions is woefully inadequate and we need to learn and understand all the underlying mechanisms that cause addiction so that they can be circumvented without stopping the pain-killing and other effects(including euphoria). Addiction isnt simple the fact that you feel good or it provides something good so thats its only normal that you will at some point have to "pay" for that through negative effects, all of the good things can be kept while eliminated the negative effects as they are related indirectly but can be seperated with proper scientific understanding. Its not a matter of if, but how long it takes to get to that point in my humble opinion.

Opioid addiction is a terrible side effect for people suffering from chronic pain. It would be nothing short of amazing if this one simple change, merely to co-formulate morphine with 1970's (+)-naloxone, is all that was necessary to prevent the addiction.
Because the suffering of addiction must be nearly as bad as the suffering due to chronic pain.

One of the very worst parts of being on opiate therapy is the fear that is always in the back of one's mind...what if, for some reason, I can't get my scrip filled next month! It's totally valid. Withdrawal is a major event. BUT, I need the pain relief. It DOES work for me. I would LOVE to try this. The peace of mind would be worth the world to me. I could live with no pain relief for a few days if I HAD to. Not sure I would live through withdrawals. So, if this is all it's advertised to be...addiction cured, pain relief intact, sign me up. I'm going to ask my doctor about this ASAP. (I've been on opiate therapy for nearly 10 years now.)