Posted by conundrum on April 4, 2010, at 11:06:19
In reply to Re: Severe anhedonia...I can't live like this anym » conundrum, posted by Economist on April 3, 2010, at 19:10:35
Well prozac is a 5 HT2A/C antagonist. So it antagonizes, meaning blocks, those receptors. Normally when those receptors are activated its normal ligand, serotonin, it decreases NE and DA release. By blocking them prozac increases NE and DA release. Thats why some ppl feel more motivated on prozac than other SSRIs and why its sometimes bad for people with anxiety. Prozac does however increase serotonin which actually works in opposite effect. At lower doses not enough of the serotonin (5 HT) transporters are blocked to significantly increase serotonin, but the drug is still able to block the 5 HT2A/C receptors enough to have an effect. So at lower doses more NE and DA are released.
Brainbeard made some good posts on this in the neurotransmitter section.
http://www.dr-bob.org/babble/neuro/20091104/msgs/931609.html
However prozac does increase serotonin at this dose. I can feel it, since most serotonergics give me a headache and diarrhea and prozac still does this even at 2.5 mgs per day. So something that can block those receptors without increasing serotonin would be good. APs and TCAs do this as well as Remeron.
Pristiq only felt good in the beginning when it didn't feel like an SSRI. After the first day I felt more "color" which is something that had been gone for a long time. After a couple weeks that faded and I started to get those serotonergic headaches.
I found a study from wWeth that shows that NE increase with pristiq after the first dose then serotonin begins to increase. So right now its not helping at all really, although the headaches aren't as bad as with a straight SSRI.
This is from a study showing how Pristiq(desvenlafaxine) increases NE right away compared to serotonin. They actually had to add another drug to get it to increase serotonin.
"Effect of DVS(Pristiq) on Hypothalamic Levels of Monoamines (5-HT, NE, and DA). Acute oral administration of DVS (30 mg/kg) did not significantly [F(2,19) = 0.74, P = 0.4898] alter concentrations of 5-HT in the hypothalamus (Fig. 4A). However, pretreatment with WAY-100635 (5-HT1A antagonist, 0.3 mg/kg s.c.), which did not alter 5-HT levels on its own, resulted in a significant 78% increase in extracellular 5-HT levels [F(1,9) = 36.09, P = 0.0001] in the rat hypothalamus.
In contrast to the observations with 5-HT levels, acute administration of DVS, when given alone, produced a significant [F(2,16) = 6.11, P = 0.0107] increase in NE concentrations (Fig. 4B)."
Here is a link. The part I copied is about 2/3s down the page.
http://jpet.aspetjournals.org/content/318/2/657.full
Its interesting that it kind of reflects how I felt. So I think there might be some value in understanding the science behind the drugs.
Just curious, I guess your pdoc believes you have anhedonia, since they are willing to prescribe so many dopaminergics. Is this right?
Post-SSRI syndrome: iatrogenic anhedonia, memory and concentration problems, sexual dysfunction. [NOTE no sadness or anxiety, this is NOT depression!]
Current med: 100mg pristiq
Location: USA
poster:conundrum
thread:940577
URL: http://www.dr-bob.org/babble/20100328/msgs/942140.html