Posted by Elizabeth on November 30, 2001, at 15:37:45
In reply to Re: SSRIs and MAOIs for SP, posted by PaulB on November 30, 2001, at 12:36:54
> You know SSRI's exert their antidepressant effect differently to MAOIs.
Yes. The two classes of drugs both increase the amount of serotonin available, but they do so by different mechanisms, and MAOIs have other effects too (because the enzyme, MAO, metabolizes other neurotransmitters besides serotonin). Inhibition of MAO probably increases serotonin concentrations to a greater degree than serotonin reuptake blockade does: metabolism of serotonin by MAO accounts for a lot more of the "cleanup" of stray serotonin than does reuptake into cells.
> MAOI antidepressants in general may be more potent antidepressants for they are prescribed when other antidepressants do not work or people have relapsed on them.
That's right, although it's a misuse of the word "potent." "Potency" just refers to the amount of a drug needed to achieve a particular effect -- thus we could say that Parnate is a slightly more potent MAO inhibitor than Nardil is (you can take a smaller dose of Parnate and achieve the same percent MAO inhibition, although the dose difference is small), or that Prozac, Paxil, and Celexa are more potent serotonin reuptake inhibitors than Zoloft and Luvox are (the first three drugs are generally clinically effective in doses ranging from 20-80 mg or so, while the effective daily dose of Zoloft will be more like 50-200 mg and most people who take Luvox need 100-300 mg/day). But saying that Parnate is a more potent antidepressant than Prozac is really doesn't make sense since they don't do the same thing.
> The reason I would prefer to take a SSRI than a MAOI is because of their selectivity which allows them to work for longer.
Allows them to work for longer? I'm not sure how you came to this conclusion. ???
> I have recurrant bouts of depression and with Paroxetine I found that the effect lasted much longer than Venlafaxine which is not selective.
There are a lot of things we don't understand about these drugs (that's what makes them so interesting, IMO), but your experience probably did not have anything to do with the selectivity of Paxil. (You're right that while Paxil is a selective serotonin reuptake inhibitor, Effexor is a nonselective monoamine reuptake inhibitor, blocking the uptake of serotonin, norepinephrine, and (at very high doses) dopamine.)
-elizabeth
poster:Elizabeth
thread:85575
URL: http://www.dr-bob.org/babble/20011123/msgs/85648.html