D-fenfluramine-evoked serotonergic responses in olanzapine-treated schizophrenic patients

Review: The biological basis of antipsychotic response in schizophrenia

Schizophrenia is a severe mental illness affecting approximately 1% of the population worldwide. Antipsychotic drugs are effective in symptom control in up to two-thirds of patients, but in at least one-third of patients the response is poor. The reason for this is not clear, but one possibility is that good and poor responders have different neurochemical pathologies, and may therefore benefit from different treatment approaches. In this selective review we summarise research findings investigating the biological differences between patients with schizophrenia who show a good or a poor response to treatment with antipsychotic drugs.

A novel antipsychotic, perospirone, has antiserotonergic and antidopaminergic effects in human brain: findings from neuroendocrine challenge tests

RATIONALE

Perospirone is a new antipsychotic drug in which dopamine D(2) antagonist and serotonin 5-HT(2) antagonist effects have been found in animal studies. It was developed by a Japanese pharmaceutical company and launched in 2001. Perospirone's receptor binding profile may resemble that of atypical antipsychotic drugs, but to date there has been no evidence relating to its receptor binding affinity in the human brain.

OBJECTIVE

The purpose of this study was to investigate the receptor binding profile of perospirone via neuroendocrine challenge tests.

METHODS

Twenty subjects (ten females and ten males) were tested on four occasions in a double-blind, cross-over design receiving: (a) placebo, (b) perospirone 4 mg, (c) paroxetine 20 mg, and (d) paroxetine 20 mg plus perospirone 4 mg, administered orally at 8.00 a.m. Plasma cortisol and prolactin levels were measured prior to administration and every hour for 6 h thereafter. In addition, psychological responses rated by visual analog scales and vital signs such as body temperature, pulse, and blood pressure were assessed in combination with blood sampling.

RESULTS

Perospirone 4 mg increased prolactin levels significantly higher than placebo, whereas paroxetine 20 mg plus perospirone 4 mg significantly attenuated cortisol responses induced by paroxetine 20 mg.

CONCLUSIONS

The present findings suggest that perospirone has the characteristics of both D(2) and 5-HT(2) antagonist in the human brain. Further PET studies in the human brain are required in order to directly investigate these effects.