![[dr. bob]](/dr-bob-sm.gif)
Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 14 of 14. This is the beginning of the thread.
Posted by Amigan on September 16, 2007, at 12:15:19
Greetings everyone.
I decided to register to this forum after i stumbled on it, while i was searching the net for informations on psychiatric medications and saw how informative it is. Very nice forum, although its layout seems a bit bizzare. :-P
My native language is not english, so you'll have to excuse any errors i will possibly make.Anyway, on the purpose of this thread:
I read from several, different sources that fluoxetine (prozac) is the most CNS stimulating SSRI. I don't doubt it, i just don't understand it..
It would be more logical to me to assume that sertaline, (zoloft) (and possibly duloxetine?) are more potent stimulants than fluoxetine, since they both possesses a weak inhibitory action in the reuptake of dopamine, while fluoxetine doesn't seem to have this property.
I'm sure that most of you know that inhibition in the reuptake of dopamine causes stimulation and that's what makes me to become confused about it.
What i would like, is a simple pharmacological explanation on why fluoxetine is the most stimulating SSRI.Thank you.
Posted by Jamal Spelling on September 16, 2007, at 12:18:43
In reply to Ok, Fluoxetine is the most stimulating SSRI..., posted by Amigan on September 16, 2007, at 12:15:19
Posted by linkadge on September 16, 2007, at 12:19:02
In reply to Ok, Fluoxetine is the most stimulating SSRI..., posted by Amigan on September 16, 2007, at 12:15:19
Fluoxetine does have some affinity for norepinephrine and dopamine reuptake pumps. Less than sertraline but still present.
Some of fluoxetine's metabolites also have effects on other neurotransmitter systems.
Fluoxetine is also a 5-ht2c antagonist. 5-ht2c antagonists have locomotor stimulant like properties.
Linkadge
Posted by 6 underground on September 16, 2007, at 12:43:03
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by linkadge on September 16, 2007, at 12:19:02
yes prozac is stimulating, it wakes me up in the mornings. Not like a stimulant, but its so, its hard to explain that this medication has, really changed my life patterns. I do more things, im more with it.
But at higher doses such as 60mg is i think is more sedating.
Posted by Phillipa on September 16, 2007, at 12:43:41
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by linkadge on September 16, 2007, at 12:19:02
Link is an expert not me but I know how I felt on prozac by day three in constant panic and didn't have anxiety before trying it. Now this was when it first came out many moons ago so the dose was 20mg. First day I accomplished so much then downhill and ditched it after three days. But to me it is very stimulating even with benzos. Phillipa
Posted by Amigan on September 16, 2007, at 12:52:55
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by linkadge on September 16, 2007, at 12:19:02
Thank you for your replies.
It's strange that both of you are suggesting an action on the reuptake of norepinephrine, because i have browsed many sites (like rxlist, wikipedie) and non mentions of a significant NE reuptake inhibition. It's not that i don't believe you. (LOL) Perhaps it's something that is not well documented.> Fluoxetine does have some affinity for norepinephrine and dopamine reuptake pumps. Less than sertraline but still present.
Exactly. LESS than sertaline.
Furthermore, i have read many studies suggesting that fluoxetine , among other SSRIs, can even cause a decrease on the amount of dopamine in the synapses. According to these studies, some rare advert effects like akathisia and EPS are attributed to this action.> Some of fluoxetine's metabolites also have effects on other neurotransmitter systems.
Ok.
> Fluoxetine is also a 5-ht2c antagonist. 5-ht2c antagonists have locomotor stimulant like properties.I see. There so many different 5-ht receptors. It's difficult for me to keep track of them all. :D
Posted by Amigan on September 16, 2007, at 13:03:08
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by Phillipa on September 16, 2007, at 12:43:41
> Link is an expert not me but I know how I felt on prozac by day three in constant panic and didn't have anxiety before trying it. Now this was when it first came out many moons ago so the dose was 20mg. First day I accomplished so much then downhill and ditched it after three days. But to me it is very stimulating even with benzos. Phillipa
Yes. Increased anxiety is very common at the first week(s) of treatment with most SSRIs. After this period, anxiety is expected to subside and you start to notice the therapeutic effects of the drug. Or so they say. :D
Posted by Jamal Spelling on September 16, 2007, at 14:46:22
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by Amigan on September 16, 2007, at 12:52:55
> Thank you for your replies.
> It's strange that both of you are suggesting an action on the reuptake of norepinephrine, because i have browsed many sites (like rxlist, wikipedie) and non mentions of a significant NE reuptake inhibition. It's not that i don't believe you. (LOL) Perhaps it's something that is not well documented.Hi Amigan
See for example http://www.preskorn.com/books/ssri_s3.html for more information on this.
Jamal
Posted by linkadge on September 16, 2007, at 15:07:23
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by Amigan on September 16, 2007, at 12:52:55
>Thank you for your replies.
>It's strange that both of you are suggesting an >action on the reuptake of norepinephrine, >because i have browsed many sites (like rxlist, >wikipedie) and non mentions of a significant NE >reuptake inhibition.Thats because they may have a different concept of significant. Even though floxetine was supposedly the first marketed SSRI, it is dirty compared to other SSRI's.
You may want to check out this website:
You can do seaches on compounds for receptor affities and the like. Wikipedia and rxlist are unlikely to contain specific receptor affinities.
>Exactly. LESS than sertaline.
>Furthermore, i have read many studies suggesting >that fluoxetine , among other SSRIs, can even >cause a decrease on the amount of dopamine in >the synapses.All SSRI's can cause a decrease in dopaminergic function. Even sertraline is still many many times more potent an SSRI than it is a dopamine reuptake inhibitor. Some people do not find fluoxetine stimulating. I found it sedating, just less sedating than other SSRI's.
>According to these studies, some rare advert >effects like akathisia and EPS are attributed to >this action.
All of the SSRI's can cause akathesia. Citalopram gave me terrable akathesia. Another consideration is floxetine's long half life. A shorter acting SSRI would allow dopamine to surge back after concentrations drop, but because fluoxetine has such a long half life it may supress dopamine more.
Fluoxetine is a stronger 5-ht2c antagonist than it is a 5-ht reuptake inhibitor. Blocking 5-ht2c receptors allows serotonin and norepinephrine to be released in the frontal cortex. Fluoxetine is atypical in this regard.
Linkadge
Posted by Amigan on September 16, 2007, at 15:19:54
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by Jamal Spelling on September 16, 2007, at 14:46:22
> > Thank you for your replies.
> > It's strange that both of you are suggesting an action on the reuptake of norepinephrine, because i have browsed many sites (like rxlist, wikipedie) and non mentions of a significant NE reuptake inhibition. It's not that i don't believe you. (LOL) Perhaps it's something that is not well documented.
>
> Hi Amigan
>
> See for example http://www.preskorn.com/books/ssri_s3.html for more information on this.I see. Thanks!
One last question about this subject, please:
Is effexor (which is a SNRI) more CNS stimulative than fluoxetine?
The reason that i'm asking this, is that my doctor has prescribe a combination of lexotanil (bromazepam) with prozac, because of an anxiety/panic disorder i have, and lexotanil makes me drowsy.
Lowering the dose is not an option for me because it makes the anxiety to reoccur.
IF efexor is indeed more potent in that direction, i could persuade my doctor to prescribe me this med instead of prozac. I believe that this would help me fight the disorder and the fatigue.
Posted by Jamal Spelling on September 16, 2007, at 16:09:42
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI... » Jamal Spelling, posted by Amigan on September 16, 2007, at 15:19:54
> One last question about this subject, please:
> Is effexor (which is a SNRI) more CNS stimulative than fluoxetine?On average, yes. But your mileage may vary. Some people find Effexor sedating.
> The reason that i'm asking this, is that my doctor has prescribe a combination of lexotanil (bromazepam) with prozac, because of an anxiety/panic disorder i have, and lexotanil makes me drowsy.
> Lowering the dose is not an option for me because it makes the anxiety to reoccur.
> IF efexor is indeed more potent in that direction, i could persuade my doctor to prescribe me this med instead of prozac. I believe that this would help me fight the disorder and the fatigue.I rather doubt that benzodiazepine sedation could be counteracted with an SSRI or SNRI. Perhaps try a less sedating benzodiazepine instead. As time passes and you become tolerant to the effects of bromazepam, it may also become less sedating. Moreover, SSRIs / SNRIs may actually aggrevate anxiety, so possibly you might try a less stimulating SSRI.
Jamal
Posted by Happyflower 1 :-) on September 16, 2007, at 21:25:26
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by Jamal Spelling on September 16, 2007, at 16:09:42
Wow, thanks for this info on the drug I am using. I find I was irritable for a couple days, like week 3 of trying it, but it has gone away, and i feel much better. Didn't know it could be stimulating, maybe that explains why it says you should take it in the morning? I do have more energy, I just thought it was a symptom of depression, and the drugs just started to help with the depression. I didn't know the drug itself could be stimulating. Just what I love a cup of coffee, my allergy meds and now prozac to add! yeah!
Posted by Amigan on September 17, 2007, at 6:14:48
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by Happyflower 1 :-) on September 16, 2007, at 21:25:26
Just wanted to thank you all for your feedback.
@Linkage
I saw your post after i replied to jamal spelling. Very useful link.
Posted by marcus75 on September 22, 2007, at 14:58:05
In reply to Re: Ok, Fluoxetine is the most stimulating SSRI..., posted by Amigan on September 16, 2007, at 12:52:55
In my view it is the most stimulating because of its low affinity for the alpha-1 receptor (equilibrium dissociation costant is 5900). Fluvoxamine Ki is even higher, 7500, but it more sedating because it has higher affinity for H1.
This is the end of the thread.
Psycho-Babble Medication | Extras | FAQ
Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.org
Script revised: February 4, 2008
URL: http://www.dr-bob.org/cgi-bin/pb/mget.pl
Copyright 2006-17 Robert Hsiung.
Owned and operated by Dr. Bob LLC and not the University of Chicago.