Posted by SLS on November 25, 2000, at 9:20:28
In reply to Re: Risperdal Zyprexa questions.Andrew,Cam,SLS,anyone, posted by anita on November 24, 2000, at 22:29:17
Dear Anita,
How are things going with Risperdal? Is 0.25mg. giving you a robust, steady improvement?I have decided to begin Risperdal tonight. I only have 1.0mg. tablets, so I guess I'll have to cut them. I'd like to start off at no higher than 0.5mg.
Zyprexa seems to display a therapeutic window for me. When I began at 2.5mg., I began to respond, but not robustly. When I first raised the dosage to 5.0mg., I obtained a moderate improvement. It didn't last. In fact, I just didn't like the way I was beginning to feel. I felt like I was in a bit of a fog and lost some of my "core" vigilant self. Perhaps this would have dissipated given more time, but without a return of a hint of antidepressant effect, I thought it best to switch to Risperdal so as to go in to my doctor supplied with the information of a comparison of the two, which was the goal set at my last visit.
A year ago, I asked my old doctor if there was a therapeutic window for Zyprexa when used for depression. He just smiled and looked away. Coming from him, this smile was an affirmation of the likelihood of such. I met a young woman in his waiting room who had been taking Zyprexa as monotherapy. She said that it worked great for 5 or 6 days, whereupon the improvement began to wane.
Anita to JohnL:
> Hi John,
> You forgot to ask me! ;-) I have looked everywhere for this type of information and have come up with nothing. Personally, I do think that very low doses of these atypical antipsychotics do in fact have a paradoxical effect, i.e. raise D2 levels in the mesolimbic pathway, in some way, tho I don't know if they would also antagonise the 5HT2 receptor. See my posts under Q. for Risperidal users.
> For me at least, my response to Risperdal .25mg./day is quite similar to the response I had with low-dose amisulpride. If amisulpride worked for you, I would give very low dose Risperdal or Zyprexa a try -- really.
> I have been searching everywhere for information on Risperdal and Zyprexa. It is well documented that Amisulpride blocks presynaptic D2...
and D3
> ...at low doses, and post synaptic at higher doses. I am trying to find similar information for Risperdal and Zyprexa.
Me:Zyprexa, and to a lesser degree, Risperdal, have extremely low affinities to D2 receptors when compared to the typical neuroleptics. Presynaptic autoreceptors tend to be "stickier" to begin with. At low concentrations, I can imagine how the ratio of presynaptic to postsynaptic occupancy might be quite high. Perhaps this provides a mild functional pro-dopaminergic condition similar to sulpiride and amisulpride. This type of thing would occur selectively in the limbic system and prefronal cortical areas. Perhaps there is a synergism between low-dosage pro-dopaminergic low-affinity D2 antagonism and the pro-dopaminergic effects in these same structures secondary to high-affinity 5-HT2a antagonism.
Just another uneducated guess...
- Scott
poster:SLS
thread:49296
URL: http://www.dr-bob.org/babble/20001115/msgs/49393.html