This unusual dose-dependent reversal from agonism to antagonism relates to amisulpride's activation of the presynaptic autoreceptors:
I found
this paper:
You might also like to read the article
Amisulpride, the Wonder Drug from France! which I posted in the very low dose amisulpride thread. That also talks about the different effects of the very low-dose, low-dose and normal-dose regimens.
I believe that this also applies to Abilify (but I am not entirely sure now, as I cannot seem to find a paper that indicates the reversal of effects at different dose levels).
This paper says:
There are indeed significant risks involved in normal-dose antipsychotics, such as the developments of extrapyramidal symptoms. And even for low-dose amisulpride, which you might expect would be largely exempt from these risks, there was
one case report of a patient given low-dose amisulpride (100 mg daily) for depression developing extrapyramidal symptoms.
However, I am taking not the low-dose regimen, but the very low-dose regimen (I take just 12.5 mg of amisulpride daily).
Note that antipsychotics are not the only class of drugs acting on the brain that have significant and permanent side effects. Lots of antidepressants, but especially SSRIs, are known to cause
permanent sexual and emotional dysfunction, that remains even after stopping the drugs. See post-SSRI sexual dysfunction, which
one study found occurred in 70% of patients taking SSRIs or SNRIs.
I feel safer taking very low-dose amisulpride than I would taking an SSRI.