Neuroleptic-induced decrease in plasma homovanillic acid and antipsychotic activity in schizophrenic patients

David Pickar, Rodrigo Labarca, Markku Linnoila, Alec Roy, Daniel Hommer, Donald Everett, Steven M. Paul

Research output: Contribution to journalArticlepeer-review

207 Scopus citations


Plasma-free homovanillic acid, a major metabolite of dopamine, was measured in chronically ill schizophrenic patients both before and during treatment with the antipsychotic phenothiazine, fluphenazine. Neuroleptic treatment was associated with a significant time-dependent decrease in plasma homovanillic acid from pretreatment values, which were significantly elevated when compared with those of age- and sex-matched healthy control subjects. Further, both the absolute concentrations as well as the neuroleptic-induced reductions in plasma homovanillic acid determined over 5 weeks ofneuroleptic treatment were statistically significantly correlated with ratings of psychosis and improvement in psychosis, respectively. These findings suggest that the delayed effects of neuroleptic agents on presynaptic dopamine activity may more closely parallel their therapeutic actions than do their immediate effects in blocking postsynaptic dopamine receptors and that a decrease in dopamine "turnover" may be responsible for their antipsychotic effects.

Original languageEnglish
Pages (from-to)954-957
Number of pages4
Issue number4665
StatePublished - 1984


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