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- Title
Treatment response to olanzapine and haloperidol and its association with dopamine D receptor occupancy in first-episode psychosis.
- Authors
Zipursky, Robert B.; Christensen, Bruce K.; Daskalakis, Zafiris; Epstein, Irvin; Roy, Paul; Furimsky, Ivana; Sanger, Todd; Kapur, Shitij
- Abstract
<bold>Objective: </bold>Response to typical antipsychotic medication has been associated with achieving a level of striatal dopamine D2 receptor occupancy in the range of 65% to 70%. We undertook this study to determine whether response to the atypical antipsychotic olanzapine occurs at lower levels of D2 receptor occupancy. <bold>Method: </bold>Eighteen patients who presented with a first episode of psychosis were randomized to receive olanzapine 5 mg daily or haloperidol 2 mg daily in a double-blind design. We acquired positron emission tomography (PET) scans using the D2 ligand [11C]raclopride within the first 15 days of treatment to determine the percentage of D2 receptors occupied by the medication. According to response, dosage was then adjusted to a maximum dosage of 20 mg daily of either drug. PET scans were repeated after 10 to 12 weeks of treatment. <bold>Results: </bold>At the first PET scan, the 8 olanzapine-treated patients had significantly lower D2 receptor occupancies (mean 63.4%, SD 7.3) than those observed in the 10 patients treated with haloperidol (mean 73.0%, SD 6.1). When patients were rescanned following dosage adjustment, mean D2 receptor occupancies were greater than 70% in both groups. D2 receptor occupancies did not differ significantly between the olanzapine-treated group (mean 72.0%, SD 5.7) and the haloperidol-treated group (mean 78.7%, SD 7.6). <bold>Conclusions: </bold>These results suggest that, in patients being treated for a first episode of psychosis, olanzapine has its antipsychotic effect at approximately the same levels of D2 receptor occupancy as are achieved with low dosages of haloperidol.
- Subjects
DOPAMINE antagonists; ANTIPSYCHOTIC agents; SEROTONIN antagonists; NEUROTRANSMITTERS; DRUG therapy for psychoses; DRUG therapy for schizophrenia; BASAL ganglia; BENZAMIDE; BENZODIAZEPINES; CELL receptors; COMPARATIVE studies; DOSE-effect relationship in pharmacology; RESEARCH methodology; MEDICAL cooperation; PSYCHOLOGY; PSYCHOSES; RESEARCH; SCHIZOPHRENIA; POSITRON emission tomography; TRANQUILIZING drugs; EVALUATION research; RANDOMIZED controlled trials; TREATMENT effectiveness; BLIND experiment; ACUTE diseases; HALOPERIDOL; PSYCHOLOGICAL factors
- Publication
Canadian Journal of Psychiatry, 2005, Vol 50, Issue 8, p462
- ISSN
0706-7437
- Publication type
journal article
- DOI
10.1177/070674370505000806