Posted by psychobot5000 on May 29, 2012, at 1:22:22
In reply to Pristiq or Effex: How are they different or alike, posted by Laney on May 26, 2012, at 11:28:06
> I might be trying one or the other?
>
> I know pristiq is more expensive but is it superior? What are your thoughts? Is withdrawl from pristiq the same as effexor??
>
> Can't take abilify right now! Too expensive!!!
>
> Thanks! LaneyHi Laney,
I haven't done specific research on these drugs, so don't take this as gospel, but I can probably help answer your question. Apologies if I'm covering material you already know.
Effexor (venlafaxine) is almost the same molecule as Pristiq (desvenlafaxine). The difference is that effexor is the racemic mixture of the molecule. Here's what that means. Many molecules, including drugs, have a mirror image that also exists, and tends to be formed at the same time. So Effexor is actually two extremely similar molecules mixed together: the right (r) isomer, and the left (s, for sinister, (which means left) I assume) isomer. Pristiq, in contrast, is just the r-isomer.
Why split up the drug? Sometimes there are legitimate reasons, such as when the second isomer causes unwanted side-effects (this may be the case with provigil (a racemic mixture) and nuvigil, which some say causes less stomach trouble.
However, usually creating a new drug like pristiq is simply an excuse for a drug company to take a successful drug whose patent has run out, and repatent the active isomer, so they can charge a great deal, again. I've always assumed that was the case with Pristiq, though I haven't actually researched it. I see some company publicity labeling pristiq as the 'active' isomer. That's fine, but if the other isomer is inactive, it probably just means you need to take twice the dose of effexor as you do of pristiq, and you'll get the same effect. Were I you, I wouldn't pay the extra money for the new drug, but that's just a hunch.
Best,
pb5000
poster:psychobot5000
thread:1018716
URL: http://www.dr-bob.org/babble/20120522/msgs/1018813.html