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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 19 of 19. This is the beginning of the thread.
Posted by crazyjoe on February 25, 2012, at 14:01:27
how does cymbalta compare to ssri's in its affinity for serotonin
Posted by SLS on February 25, 2012, at 14:36:05
In reply to med strongest on serotonin, posted by crazyjoe on February 25, 2012, at 14:01:27
> how does cymbalta compare to ssri's in its affinity for serotonin
Paxil (paroxetine) is the most potent SSRI ligand to bind to the serotonin transporter.
- Scott
Posted by Phillipa on February 25, 2012, at 18:24:18
In reply to Re: med strongest on serotonin » crazyjoe, posted by SLS on February 25, 2012, at 14:36:05
Wonder if that is why it worked for me that one time? Phillipa
Posted by SLS on February 25, 2012, at 20:46:25
In reply to Re: med strongest on serotonin » crazyjoe, posted by SLS on February 25, 2012, at 14:36:05
> > how does cymbalta compare to ssri's in its affinity for serotonin
>
> Paxil (paroxetine) is the most potent SSRI ligand to bind to the serotonin transporter.
>
>
> - Scott
Sorry, I guess I didn't really answer your question. Cymbalta (duloxetine) is more potent than Effexor (venlafaxine). Paxil is more potent than Cymbalta.
- Scott
Posted by Raisinb on February 26, 2012, at 0:25:34
In reply to med strongest on serotonin, posted by crazyjoe on February 25, 2012, at 14:01:27
Yes, Paxil is the strongest SSRI I have taken. Cymbalta has a dual effect, I think.
Posted by Laney on February 26, 2012, at 12:05:57
In reply to Re: med strongest on serotonin, posted by Raisinb on February 26, 2012, at 0:25:34
Could it be said that the stronger the SSRI, the worse the Withdrawl? Think about it Paxil, Effexor Cybalta all typically have a bad withdrawl associated with them.
Laney
Posted by SLS on February 26, 2012, at 12:55:35
In reply to Re: med strongest on serotonin, posted by Laney on February 26, 2012, at 12:05:57
> Could it be said that the stronger the SSRI, the worse the Withdrawl? Think about it Paxil, Effexor Cybalta all typically have a bad withdrawl associated with them.
>
> Laney
That's great thinking.:-)
I really don't know.
Effexor is not nearly as potent as Paxil or Cymbalta at the serotonin transporter. You've got me curious now. I had thought that perhaps having a short half-life was contributory to a drug having a more severe withdrawal syndrome. I'm thinking that there should be more to it than that. Maybe NE or ACh? But, then you would think that clomipramine (Anafranil) would be just as bad as Paxil. It isn't.
I bet Linkadge could figure it out.
- Scott
Posted by Phillipa on February 26, 2012, at 18:39:13
In reply to Re: med strongest on serotonin » Laney, posted by SLS on February 26, 2012, at 12:55:35
Then wouldn't that explain why I could withdraw easily from paxil, but be hooked for life on luvox. Doesn't it have the shortest half-life of all the SSRI's? Phillipa
Posted by SLS on February 26, 2012, at 19:48:08
In reply to Re: med strongest on serotonin » SLS, posted by Phillipa on February 26, 2012, at 18:39:13
> Then wouldn't that explain why I could withdraw easily from paxil, but be hooked for life on luvox. Doesn't it have the shortest half-life of all the SSRI's? Phillipa
Paxil has a shorter half-life than Luvox.
- Scott
Posted by linkadge on February 26, 2012, at 19:54:38
In reply to Re: med strongest on serotonin » SLS, posted by Phillipa on February 26, 2012, at 18:39:13
The degree of serotonin reuptake inhibition is also a function of the dose. Paxil may have the highest affinity for the serotonin transporter (on a mg / mg basis), but some of the SSRIs (i.e. zoloft) are dosed higher.
It is thought that paxil and effexor have the greatest withdraw due to short half life. Perhaps (as mentioned) paxil and effexor produce more anticholingeric (hence rem supression). I'm not sure how the withdrawl for paxil compares with luvox.
Linkadge
Posted by Phillipa on February 26, 2012, at 21:06:10
In reply to Re: med strongest on serotonin, posted by linkadge on February 26, 2012, at 19:54:38
How does one research this? And Scott I always thought it was luvox. Interesting. Phillipa
Posted by ed_uk2010 on February 27, 2012, at 1:32:14
In reply to Re: med strongest on serotonin » Laney, posted by SLS on February 26, 2012, at 12:55:35
>Effexor is not nearly as potent as Paxil or Cymbalta at the serotonin transporter.
In terms of affinity, yes, but Effexor is presumably a potent SRI clinically because the concentration of drug reached at the site of action is very high. Affinity is only one part of the equation, drug concentration at the active site being the other major player.
>I had thought that perhaps having a short half-life was contributory to a drug having a more severe withdrawal syndrome.
It's certainly a very major factor.
>you would think that clomipramine (Anafranil) would be just as bad as Paxil.
Although I suspect that if Anafranil was as widely used as Paxil and Effexor we would hear a lot more complaints about Anafranil withdrawal!
Posted by ed_uk2010 on February 27, 2012, at 1:41:04
In reply to Re: med strongest on serotonin, posted by linkadge on February 26, 2012, at 19:54:38
> The degree of serotonin reuptake inhibition is also a function of the dose. Paxil may have the highest affinity for the serotonin transporter (on a mg / mg basis), but some of the SSRIs (i.e. zoloft) are dosed higher.
The dose is one factor, but the various SSRIs have different pharmacokinetics eg. absorption and distribution into tissues. Drug concentrations in the brain therefore differ.
Looking at Ki data is isolation is very misleading. As a non-SSRI example, the high Ki's of Seroquel might lead you to believe that it would not be an effective antipsychotic, but the dose and drug concentrations in the brain are high (making it active), and if you compare the Ki's for different receptors you see the expected pattern - more potent at 5-HT2 than D2.
Posted by Shes_InItForTheMoney on February 29, 2012, at 1:16:20
In reply to Re: med strongest on serotonin » Laney, posted by SLS on February 26, 2012, at 12:55:35
from wikipedia: "escitalopram has the highest affinity for the human serotonin transporter (SERT)"
Posted by SLS on February 29, 2012, at 6:10:05
In reply to Re: med strongest on serotonin..lexapro » SLS, posted by Shes_InItForTheMoney on February 29, 2012, at 1:16:20
> from wikipedia: "escitalopram has the highest affinity for the human serotonin transporter (SERT)"
This is inaccurate.
I understand that Wikipedia is written by anyone who takes it upon themselves to act as an expert. Things seen in Wikipedia must be scrutinized with that in mind.
Citalopram and escitalopram are the most SELECTIVE SSRIs. Paroxetine has the highest AFFINITY.
You can check binding affinities here:
http://pdsp.med.unc.edu/pdsp.php
Paroxetine is at least 100 times more potent than escitalopram.
- Scott
Posted by Phillipa on February 29, 2012, at 18:18:04
In reply to Re: med strongest on serotonin..lexapro » Shes_InItForTheMoney, posted by SLS on February 29, 2012, at 6:10:05
Scott nothing showed up on the study? Phillipa
Posted by SLS on February 29, 2012, at 19:48:19
In reply to Re: med strongest on serotonin..lexapro » SLS, posted by Phillipa on February 29, 2012, at 18:18:04
http://www.ncbi.nlm.nih.gov/pubmed/17286545
"Paroxetine is the most potent inhibitor of the reuptake of serotonin among the available SSRIs."
"Paroxetine is a potent and selective inhibitor of serotonin uptake into neurons."
http://www.ncbi.nlm.nih.gov/pubmed/15131491"Escitalopram is the most selective SSRI yet developed"
- Scott
Posted by SLS on February 29, 2012, at 19:51:56
In reply to Re: med strongest on serotonin..lexapro, posted by SLS on February 29, 2012, at 19:48:19
Please disregard the second citation. It is irrelevant.
- Scott
Posted by Phillipa on March 1, 2012, at 18:15:34
In reply to Re: med strongest on serotonin..lexapro, posted by SLS on February 29, 2012, at 19:51:56
Thanks I wonder why had diarrhea on paxil l0mg? First ad ever took if constipating? I'm wierd. Phillipa
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