Posted by Ritch on August 20, 2002, at 9:37:03
In reply to Citalopram pharmacology - Mitch, posted by dr. dave on August 20, 2002, at 5:21:03
> 'Celexa' 20mg is 10mg s-isomer and 10 mg r-isomer. The r-isomer is effectively inert as an SSRI or anything else. Celexa only works because of the 10mg s-isomer in it. 'Lexapro' is the 10mg s-isomer on its own. It's pretty hard and expensive to produce separately, and it's a funny thing to do when the r-isomer has virtually no pharmacological action at all.
>
> Lexapro 10mg is Celexa 20mg with 10 mg of an inert substance expensively removed.
<from other post>
We know it doesn't affect the pharmacokinetics of s-citalopram and we know that it has about 1/30th the affinity for the serotonin reuptake transporter of s-citalopram so it can't be competing at the binding site.
Thanks for those added tidbits of information! I knew that r-citalopram had less affinity for the serotonin reuptake transporter, but not 1/30th... Then, the only thing left to consider is the notion of r-citalopram *causing* side-effects (commonly associated with SSRI's) with little affinity for the serotonin reuptake transporter.Mitch
poster:Ritch
thread:109458
URL: http://www.dr-bob.org/babble/20020814/msgs/117078.html