Posted by Cam W. on December 27, 2001, at 23:14:49
In reply to Re: Cam:antipsychotic question » Cam W., posted by Chloe on December 27, 2001, at 21:11:32
Chloe - Yes, unfortunately the damage is done. The good news is that it is highly unlikely that Seroquel will add any more problems. It is thought that the loose binding of dopamine-D2 receptors by the atypical antipsychotics (like Seroquel), rather than the irreversible binding of dopamine-D2 receptors to the traditional antipsychotics (like Mellaril) helps to avoid EPS and TD.
With the atypicals, at any one time the D2 receptors are less than 79% blocked. Above this level is when one starts seeing EPS symptoms (and ultimately TD symptoms). I think that I read somewhere that with most of the atypicals you can obtain greater than 80% blockage of D2 receptors if you raise the dose high enough (Risperdal™ [risperidone] >6mg; Zyprexa™ [olanzapine] >35mg - approximately), except with Clozaril™ (clozapine) and Seroquel. I am fairly sure that they have tried, but have been unable to get Seroquel to block the D2 receptors at a level greater than 80%.
Yeah, SSRIs do seem to exacerbate TD and can even cause EPS in a minority of people. I don't really know why. It could be because when you increase serotonergic tone, you (in a roundabout way) decrease dopaminergic transmission. This is just a guess, though.
As for the use of Clozaril, has your doc ever considered a rechallenge, with a close watch on your blood cells? I have seen a few rechallenges where the second time around there has been no blood problems (so far). The downside to the cases that I know about is that the docs are a little jumpy about Clozaril rechallenges and keep the people on weekly blood tests forever (so far). That can be a real pain (where I wouldn't put a window).
- Cam
poster:Cam W.
thread:87920
URL: http://www.dr-bob.org/babble/20011222/msgs/88002.html