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Understanding the relationship between cross-dependence and cross tolerance?

candidsurprise

Bluelighter
Joined
Oct 18, 2017
Messages
134
I made an account just for this question!

From what I understand, cross tolerance is simply the accumulation of tolerance to a specific drug through the build up of tolerance to a different but related drug that acts on the same receptors . Cross dependence is the process whereby taking different but related drugs contributes the development of the same physical dependence. For instance, using a moderate dose of ambien one night to sleep, temazepam the next day and klonopin the day after that would lead to dependence. Even though using each individual drug once every three/four days in the same way, but without using the other drugs, would likely lead to no dependence. Those substances would be cross dependent. So really I have two questions:

1) What confuses me is to what extent can substances be considered cross tolerant but not cross dependent? What I mean by that is substances seem to be able to share cross tolerances, yet do not perpetuate the dependence of the other. For instance, during my GBL withdrawal period I used baclofen and phenibut to completely eliminate withdrawal symptoms and emerge from the other side basically experiencing no withdrawal at all. But if I had used GBL for the 2 weeks that I used its 'cross tolerant' substances (i.e. baclofen and phenibut) and instead of them, obviously I would have have had to emerge from those two weeks looking forward to a week plus of shakes, no sleep and the whole schabang. So why do these substances get me through withdrawal scot-free when they directly ramp up tolerance to the drug that I'm withdrawing from? Shouldn't they just prolong withdrawal as would happen if I just took GBL instead, given that they act on identical receptors?

2) More importantly, what are the implications of this when it comes to developing dependency? I was under the impression that alternating or rotating between two drugs that hit the same receptors would contribute to a 'GABA B' dependence if we were to use the example of rotating GBL, phenibut and baclofen on different days PRIOR to the development of dependency to any one of those drugs. Is this not the case? If it is not the case, how is that reconciled with the fact that, for example, alternating between different benzos will definitely lead to a singular dependency on benzos? Is it because all benzos act on the same receptor in the same way, whilst GBL, phenibut and baclofen act on the same receptor in different ways?

Or am I missing something more obvious here?

TLDR: why does phenibut get me out of GBL withdrawal without having to go through more withdrawals even though it acts on the same receptors, and does this have implications when it comes to alternating drugs that act on the same receptor before getting dependent on any one of those particular drugs?
 
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The likely reason you didn't experience the same level of WD when you stopped phenibut/baclofen is because of their long half-lives compared to the ultra-short hl of GHB. I see no other possibility, because both baclofen and phenibut work on GABA-B, same as GHB, and that's the reason they helped with the WD in the first place.

Drugs that work on the same receptor should be both cross-tolerant and cross-dependent.
 
The likely reason you didn't experience the same level of WD when you stopped phenibut/baclofen is because of their long half-lives compared to the ultra-short hl of GHB. I see no other possibility, because both baclofen and phenibut work on GABA-B, same as GHB, and that's the reason they helped with the WD in the first place.

Drugs that work on the same receptor should be both cross-tolerant and cross-dependent.

But surely I would have experienced something after finishing baclofen? The GBL withdrawals started so I took phenibut for about 4 days and then i switched to baclofen for about 7 days on the advice of some research into the subject. After I came off the baclofen I felt practically nothing. So basically those drugs eliminated the withdrawals that I should have had from GBL and didn't 'continue' the withdrawals which were due to GABA-B downregulation in the first place. It just strikes me as strange since I was under the impression that the GBL withdrawals are consequential on GABA-B downregulation. And I also thought phenibut and baclofen both cause further GABA-B downregulation by agonising GABA-B just like GBL. Unless I'm totally wrong about either of those things or being overly simplistic? I guess what I'm trying to get at is working out how dependence works between different drugs that act on the same receptor given my experience here.
 
Even within the same class of receptor, there are many different isoforms expressed in different parts of the brain, and often times, different drugs will have different affinities for different isoforms. That's one reason why you can often minimize withdrawals by switching to a different drug with a linger half life that still hits the same class of receptor
 
Even within the same class of receptor, there are many different isoforms expressed in different parts of the brain, and often times, different drugs will have different affinities for different isoforms. That's one reason why you can often minimize withdrawals by switching to a different drug with a linger half life that still hits the same class of receptor

Would you be able to expand a bit on this please? In terms of how exactly having different affinities for different isoforms results in 'masking' withdrawals without prolonging them, despite acting on the same receptor. Also do you know anything about how this interacts with cross dependence? What I mean by that is would the same mechanism you describe result in a much lower degree of cross dependence between drugs that act on the same receptor, versus taking a single drug in that category? Thanks.
 
But surely I would have experienced something after finishing baclofen? The GBL withdrawals started so I took phenibut for about 4 days and then i switched to baclofen for about 7 days on the advice of some research into the subject. After I came off the baclofen I felt practically nothing. So basically those drugs eliminated the withdrawals that I should have had from GBL and didn't 'continue' the withdrawals which were due to GABA-B downregulation in the first place. It just strikes me as strange since I was under the impression that the GBL withdrawals are consequential on GABA-B downregulation. And I also thought phenibut and baclofen both cause further GABA-B downregulation by agonising GABA-B just like GBL. Unless I'm totally wrong about either of those things or being overly simplistic? I guess what I'm trying to get at is working out how dependence works between different drugs that act on the same receptor given my experience here.

Phenibut isn't a selective GABA-B agonist. In fact, it has a few times stronger affinity for voltage-dependent calcium channcels (VDCC) than it has for GABA-B, effectively making its action more akin to classical selective VDCC blocker gabapentinoids such as gabapentin and pregabalin, with a hint of GABA-B agonism if you like. Baclofen, on the other hand, has negligible VDCC blockage at doses used due to its 100-fold higher GABA-B affinity than phenibut, so that one is more GABA-B in nature. Still, if you used only phenibut for first 7 days, it could have masked the withdrawals through VDCC as well, because VDCC blockers are used for many types of withdrawal with considerable success.

7 days of low-level agonism compared to hardcore agonism of GHB is plenty time to upregulate GABA-B so that long half-life baclofen can act as a taper afterwards.

Well, that's how I would explain it with my knowledge. Some more knowledgeable people may know better.
 
Phenibut isn't a selective GABA-B agonist. In fact, it has a few times stronger affinity for voltage-dependent calcium channcels (VDCC) than it has for GABA-B, effectively making its action more akin to classical selective VDCC blocker gabapentinoids such as gabapentin and pregabalin, with a hint of GABA-B agonism if you like. Baclofen, on the other hand, has negligible VDCC blockage at doses used due to its 100-fold higher GABA-B affinity than phenibut, so that one is more GABA-B in nature. Still, if you used only phenibut for first 7 days, it could have masked the withdrawals through VDCC as well, because VDCC blockers are used for many types of withdrawal with considerable success.

7 days of low-level agonism compared to hardcore agonism of GHB is plenty time to upregulate GABA-B so that long half-life baclofen can act as a taper afterwards.

Well, that's how I would explain it with my knowledge. Some more knowledgeable people may know better.

Thank you, this is very informative. I will reply in a little bit. If anyone else has any info please throw it out there!
 
Even within the same class of receptor, there are many different isoforms expressed in different parts of the brain, and often times, different drugs will have different affinities for different isoforms. That's one reason why you can often minimize withdrawals by switching to a different drug with a linger half life that still hits the same class of receptor

Well said.

Pharmacokinetics are confusing

Indeed, but so much fun! %)

Phenibut isn't a selective GABA-B agonist. In fact, it has a few times stronger affinity for voltage-dependent calcium channcels (VDCC) than it has for GABA-B, effectively making its action more akin to classical selective VDCC blocker gabapentinoids such as gabapentin and pregabalin, with a hint of GABA-B agonism if you like. Baclofen, on the other hand, has negligible VDCC blockage at doses used due to its 100-fold higher GABA-B affinity than phenibut, so that one is more GABA-B in nature. Still, if you used only phenibut for first 7 days, it could have masked the withdrawals through VDCC as well, because VDCC blockers are used for many types of withdrawal with considerable success.

7 days of low-level agonism compared to hardcore agonism of GHB is plenty time to upregulate GABA-B so that long half-life baclofen can act as a taper afterwards.

Well, that's how I would explain it with my knowledge. Some more knowledgeable people may know better.

I’d agree with this.
 
I'll elaborate for you when I get a chance to think about how to explain it.

Belligerent drunk brings up a very good point along with nicely detailed information :)
 
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