Posted by Keith Talent on April 22, 2004, at 23:48:22
In reply to Re: mode of action of Seroquel (+ other antipsycs) » Geoffrey Ruch, posted by katia on April 20, 2004, at 2:18:03
The old antipsychotics worked by antagonising dopamine 2 receptors. Haloperidol is much cleaner than things like chlorpromazine, which is very dirty, in that it has anticholinergic and antihistaminergic effects as well (and probably others too) which cause bad side effects. The newer antipsychotics block dopamine 2, but also serotonin 2 receptors, which greatly relieves anxiety. It may also be why the newer drugs don't seem to cause movement disorders (tardive dyskinesia) with long-term use. Aripiprazole (Abilify) is, I understand, unique in that it is a dopamine receptor partial agonist - so if there is hardly any dopamine being released into the synapse, the drug will provide a certain amount of stimulation. If there's a lot of dopamine, trying to stimulate the dopamine receptors, the Abilify will kind of put an upper limit to how much the dopamine can bind to, and agonise, the dopamine receptors. This is important because it is believed that in schizophrenia, there are brain regions with too little dopaminergic activity (associated with negative symptoms) and regions with overactivity (associated with positive symptoms). I don't know anything about Seroquel specifically.