7 replies to this topic

[Furniture]

It seems that this topic died down a long time ago. I haven't seen a thread about KOR antagonists on this forum for many years...but I'm wondering if anyone in 2026 knows of a legitimate vendor or other source that offers a selective KOR (Kappa Opioid Receptor) antagonist?

 

Basically, I'm talking about either JDTic, Norbinaltorphimine (nor-BNI) or Aticaprant.

 

There have been lots of other KOR antagonists thrown around on this forum but most of these aren't what I'm looking for. For example Amentoflavone's action on KOR is weak and others (like Buprenorphine & Naltrexone) aren't selective for KOR and are actually much more active at the MOR, which is an undesirable effect for what I'm looking for.

 

However, if you know of another KOR antagonist (apart from the 3 I mentioned) that is selective and strong-acting... feel free to mention it. 

 

I do know of pglchem as a source for nor-BNI. However, that's the only one I've found and I'd like to explore alternate options if they are ones. As of yet, I do not know of a vendor that offers JDTic or Aticaprant. 

 

Feel free to send me a DM if you'd rather communicate that way. 

 

 

[Galaxyshock]

What is your goal with kappa-antagonists, decrease in fear/anxiety responses or dysphoria? I'm kinda interested in kappa-antagonists too. I've used Naltrexone, Apigenin and Ginseng which show some kappa-antagonist activity but of course aren't particularly strong or selective but I've still benefited from them.

 

I would be careful with strong antagonists though, the kappa-opioid receptor isn't there just to do harm as the endogenous ligand dynorphin is 10 times stronger analgesic than morphine.

[Furniture]

What is your goal with kappa-antagonists, decrease in fear/anxiety responses or dysphoria? I'm kinda interested in kappa-antagonists too. I've used Naltrexone, Apigenin and Ginseng which show some kappa-antagonist activity but of course aren't particularly strong or selective but I've still benefited from them.

 

I would be careful with strong antagonists though, the kappa-opioid receptor isn't there just to do harm as the endogenous ligand dynorphin is 10 times stronger analgesic than morphine.

 

Goal would be a decrease in anhedonia. 

I wound up testing nor-BNI (aka Norbinaltorphimine) in the time since I posted this. I ended up just going with Pglchem. I couldn't find any additional vendors offering nor-BNI (or any vendors at all offering JDTic or Aticaprant). They're a chemical supplier based in Ukraine (https://pglchem.com/...inaltorphimine/) and they provide mass-spec & proton NMR data for it (on this page --> https://pglchem.com/...naltorphimine), so I felt somewhat comfortable purchasing it from them. I did not have it third-party tested. 

I only trialed a single 200mcg dose and the effect was the opposite of what I expected. That single dose was enough to produce a mild to moderate dysphoria. And this lasted for several days, give or take. I observed no other effects, positive or negative, apart from the dysphoria. No changes in pain, cognition, wakefulness, etc. 

I can't say for certain why this happened. A "nocebo" effect could explain it, considering the single small dose. It could also be that blocking KOR just isn't compatible with my specific neurobiology. 

However, I do have to say that the dysphoric sensation felt almost identical to my past experiences with Naltrexone. Perhaps the nor-BNI that I received from pglchem was not authentic or was not pure. Maybe it contained Naltrexone or some other related analogue with MOR-blocking effects (which would explain the dysphoria). For what it's worth, nor-BNI is very structurally similar to Naltrexone, so maybe something went wrong during synthesis? I don't know...

I do plan on trialing it again in the future, just to confirm how it affects me. But because of the possibility of multiple day dysphoria following administration, I'll need to plan accordingly. The last time it had a negative impact on my work performance. 


 

[Galaxyshock]

Thanks for sharing your experience @Furniture.

 

I think with opioid antagonists you have to look at the compensatory mechanisms that the body produces in response to the receptor binding. Naltrexone for example causes rapid increase in beta-endorphin and cortisol. Perhaps selective kappa-antagonists cause surge of dynorphin or some other neurochemical that kinda overrides the effects? I think it's possible.

 

There was also an anecdote of JDTic causing derealization to someone, another example that you can't simply "antagonize bad brain activity" without consequences. The human brain is kinda crafted towards survival by evolution, and the drive away from pain tends to be stronger than the drive towards pleasure - when it comes to things like anhedonia. If I have learned anything in these years, things tend to get very complicated when it comes to brain meds. 

 

 

[Furniture]


Is this something you believe only when it comes to modulating pleasure circuits? Or are you saying that the direct antagonism of brain receptors of any kind will always produce compensatory effects?

If it is the former, I would agree. The homeostatic mechanisms underlying pleasure & reward circuits are the most difficult of all to overcome (and probably in our best interest). But if it's the latter, I have to disagree. 

 

There are several clinically-approved medications (ones intended to be used daily/long-term) that directly antagonize or negatively modulate specific brain receptors which do not produce negative compensatory effects. I, for one, have been taking Fycompa (Perampanel) off-label for several years without any change in efficacy, or anything resembling a compensatory effect, in that entire time. And Fycompa is a centrally-acting, selective AMPA-glutamate receptor antagonist. 

Edited by Furniture, 12 June 2026 - 12:57 AM.

[Galaxyshock]


Is this something you believe only when it comes to modulating pleasure circuits? Or are you saying that the direct antagonism of brain receptors of any kind will always produce compensatory effects?

If it is the former, I would agree. The homeostatic mechanisms underlying pleasure & reward circuits are the most difficult of all to overcome (and probably in our best interest). But if it's the latter, I have to disagree. 

 

There are several clinically-approved medications (ones intended to be used daily/long-term) that directly antagonize or negatively modulate specific brain receptors which do not produce negative compensatory effects. I, for one, have been taking Fycompa (Perampanel) off-label for several years without any change in efficacy, or anything resembling a compensatory effect, in that entire time. And Fycompa is a centrally-acting, selective AMPA-glutamate receptor antagonist. 

 

It's my own speculation, but some kind of neuroadaptations tend to always happen - but not always enough to overcome or "neutralize" the effects of whatever substance you are introducing to the system. There's also case of paradoxical effect and also sometimes the human body starts rejecting a drug - despite it having therapeutic effects. But yeah if AMPA-antagonist works for you without side effects, I wouldn't be worried that you suddenly have some kind of glutamate storm or something hehe. 

 

Anyways, like I said things get very complex when it comes to brain chemistry, and I think we are still long way from figuring out the whole picture. I do have heard that with the help of AI and Quantum Computers we are starting to be able to "map" the human body and start producing more targeted drugs. But I think it will take time before we have decent medications instead of the old SSRIs and such.  I do remain optimistic that there's interest in pharmaceutical research in neuroactive medications, why wouldn't there be since there's money to be made and the current options leave much to be desired. 

Edited by Galaxyshock, 12 June 2026 - 02:27 AM.

[Mind_Activation]

What is your goal with kappa-antagonists, decrease in fear/anxiety responses or dysphoria? I'm kinda interested in kappa-antagonists too. I've used Naltrexone, Apigenin and Ginseng which show some kappa-antagonist activity but of course aren't particularly strong or selective but I've still benefited from them.

 

I would be careful with strong antagonists though, the kappa-opioid receptor isn't there just to do harm as the endogenous ligand dynorphin is 10 times stronger analgesic than morphine.

 

There are indeed several serious side-effects of Kappa-antagonism, that we have only recently elucidated on. The permanent ones, like JDTic of course has cardio-vascular ones, but even the non-permanent ones, like CERC-501/Aticaprant, have potentially serious long-term ones. (they're not immediately evident)

 

There are compensatory mechanisms that are triggered by Kappa Antagonism, one being the activation/promotion of Microglia* in the brain - these then release large amounts of pro-inflammatory cytokines like IL-1b and IL-6 - this is probably the source of the declining effect of Kappa antagonism on mood. (hence the failed depression-trials)

 

Another one, possibly even more serious, is the fact that blockade of Kappa-receptors in peripheral tissue may be linked to the growth of certain forms of cancer, since it blocks cytokines needed to kickstart the anti-cancer processes... This one has me currently quite worried, as it is harder to counter-act than the microglial effects.

 

I'm currently very interested in restarting exploration of Kappa antagonism as well, but I see these side-effects as something that we need to analyse deeper.

 

 

*(specialised immune-cells, that are modified brain-cells - needed since the blood-brain-barrier blocks normal immune-cells)

 

 

Ref:

----------------------------

"Blockade of kappa-opioid receptors amplifies microglia-mediated inflammatory responses"

https://www.scienced...091305721002008

 

"Microglia in depression: an overview of microglia in the pathogenesis and treatment of depression"

https://link.springe...974-022-02492-0

(microglia and their role in all sorts of neurological phenomena is an absolutely fascinating subject btw, and something I recommend everyone take a closer look at)

 

"More than analgesia: evidence for metabolic regulation by the kappa opioid receptor in triple-negative breast cancer"

https://www.scienced...007091225006440

 

 

 

Edited by Mind_Paralysis, 17 July 2026 - 04:09 PM.

[Galaxyshock]

Nice to see you back @Mind_Activation!

 

Interesting about the anti-cancer properties of kappa opioid activation. So it kinda triggers the "death drive" to cancer cells. Whereas mu-opioid activation can trigger cancer growth "life drive" and mu-antagonists such as Naltrexone have shown anti-cancer properties through this antagonistic mechanism. Hell, maybe the whole pathophysiology of cancer stems from the opioid network triggering "unwanted growth".