Posted by Elizabeth on August 2, 2001, at 8:01:48
In reply to Q for JohnL: So...why's Prozac so different?, posted by pellmell on July 30, 2001, at 11:44:08
Here's my $0.02 (I hope you don't mind):
The main advantages of Prozac, IMO, involve its pharmacokinetic profile. The active metabolite norfluoxetine is both more selective for the serotonin transporter and more potent than is fluoxetine. At steady state, the plasma concentration of norfluoxetine exceeds that of fluoxetine in normal metabolisers (if I'm remembering correctly: it's been a while since I studied this stuff). Fluoxetine has a long elimination half-life (about 2-4 days), and norfluoxetine is extremely long-lived (its elimination half-life can be as long as two weeks), so Prozac tends to be smoother and missing a dose is less problematic compared with other SSRIs (Paxil in particular seems to cause problems for a lot of people).
That Prozac and its metabolite are so long-lived is a mixed blessing. In particular, there is a high potential for pharmacodynamic and pharmacokinetic interactions, and this persists for several weeks after discontinuing Prozac. As a result, adding or switching to tricyclic antidepressants should be done cautiously, and MAOIs should not be taken for at least five weeks after discontinuing Prozac.
At present, little is known about possible pharmacodynamic effects of fluoxetine or norfluoxetine other than monoamine reuptake inhibition.
Hope this helps.
-elizabeth
P.S. John, I do think that you've been going beyond describing your personal experience: you tell people that they "should" (your word) try certain drugs before considering other options, presumably because those drugs work for you and perhaps you have a general impressionistic sense that they work best for other people. Obviously, readers have the choice of ignoring you, but that doesn't mean that it's reasonable or honest of you to make the suggestion that a particular group of drugs should always be tried first, apparently without even any regard to what condition is being treated.
poster:Elizabeth
thread:72515
URL: http://www.dr-bob.org/babble/20010731/msgs/73073.html