Posted by Christ_empowered on September 6, 2011, at 11:54:46
In reply to Re: weight gain, posted by jono_in_adelaide on September 5, 2011, at 22:18:01
OK, from what I read, when the atypicals first came out they noticed less EPS and less TD, at least in animal studies. Now, it turns out that part of the problem was that docs tended to use excessively high doses of high potency, harsh drugs (especially Haldol for some reason), particularly in the US (in Europe, they apparently haven't been as heavy-handed with antipsychotics). It wasn't uncommon for people to be given 10-20 milligrams of Haldol, for instance; modern brain imaging studies have shown that you can get sufficient D2 blockade out of 2-5 milligrams daily.
With a lot of the atypicals, if you ramp the dose up enough, they start acting more like the old drugs--EPS, TD, dysphoria, cognitive dulling, that sort of thing. With the older drugs, if you keep the dose low enough, you can get improvement in positive symptoms w/o EPS or cognitive problems or drug-induced dysphoria/depression. Of course, nobody's backing the old drugs anymore, so docs (especially in the US) tend to Rx the newer ones right off the bat and switch people to the newer ones if they're on the older ones.
To be fair, Zyprexa did have a slight edge over both perphenazine and the other atypicals in the CATIE study. It also tended to cause lots of weight gain and metabolic problems.
The only truly novel antipsychotic on the market in the US right now is Abilify, which functions as a partial agonist at D2 receptors (and elsewhere, I think). This doesn't seem to translate into anything particularly amazing, at least not for me; all I've noticed with Abilify is symptom control w/o EPS or significant cognitive dulling. People still report feeling slowed down/zombie-fied at higher doses, it can still cause NMS, EPS, and TD in some people, and it has its own problems (akathisia, lack of sedation, etc.).
A lot of the switch to atypicals was done because of marketing, honestly.