Psychosis pimozide

Pimozide (Orap). Pimozide is probably the most potent of all antipsychotics, but it is seldom used to treat schizophrenia. Instead, pimozide is most often used to treat Tourette s syndrome. There is actually no reason why pimozide can t be used to treat psychosis and no reason why other antipsychotics are not effective in Tourette s syndrome. Pimozide was simply used first in controlled clinical trials to treat Tourette s syndrome, and the physicians who routinely treat that illness became accustomed to using it. Pimozide is only available in an oral form. The lack of an injectable form to treat agitated patients as well as the lack of availability of data from controlled trials in schizophrenia patients likely explains why it has not been used very often in the treatment of schizophrenia. 

Phencyclidine-induced psychosis is probably mediated via dopamine D2 receptors. This is consistent with the results of studies with different dopamine receptor antagonists in the treatment of this psychosis. In one study haloperidol (a predominantly D2 antagonist with noradrenergic effects) and pimozide (a predominantly D2 antagonist with no noradrenergic activity) were equally effective and both were superior to chlorpromazine (a non-selective D and D2 antagonist with noradrenergic effects) (17). 

Giannini AJ, Nageotte C, Loiselle RH, Malone DA, Price WA. Comparison of chlorpromazine, haloperidol and pimozide in the treatment of phencyclidine psychosis DA-2 receptor specificity. J Toxicol Clin Toxicol 1984-1985 22(6) 573-9. 

Sultana A, McMonagle T. Pimozide for schizophrenia and related psychosis. Cochrane Database Syst Rev 2000 3 CD001949. 

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