title: Influence of clozapine on platelet serotonin, monoamine oxidase and plasma serotonin levels.
abstract: The purpose of this study was to investigate the influence of clozapine on plasma serotonin, platelet serotonin and monoamine oxidase (MAO) levels in schizophrenic patients and to compare their results with those of unmedicated healthy controls. Groups of 20 outpatients with schizophrenia and 20 healthy controls matched for age, sex and smoking status were recruited for the study. Psychopathology, neurocognitive functioning, plasma serotonin, platelet serotonin and MAO levels were assessed after 1-week drug free interval, and 8 weeks after initiation of clozapine treatment in an open design. The mean clozapine dose at week 8 was 382.5+/-96.4 (range: 250-600) mg/day. In the patient group, at baseline, plasma serotonin and platelet MAO levels were significantly lower, and platelet serotonin levels were significantly higher than in controls. After 8 weeks of clozapine treatment, plasma serotonin and platelet MAO levels increased significantly, while a significant decrease in platelet serotonin levels was detected compared with baseline values. Baseline platelet MAO levels explained 22% of the variance in Clinical Global Impression - Improvement (CGI-I) and improvement in attention, while baseline platelet serotonin predicted 23% of the variance in the improvement in positive symptoms during clozapine treatment. Our data indicate that clozapine may be reversing or compensating for a pre-existing alteration in serotonergic neurotransmission in schizophrenic patients. The prediction of response to clozapine through peripheral biochemical markers may have important clinical implications if repeated in larger samples.
authors.affiliation: Department of Psychiatry, Hacettepe University, Faculty of Medicine, Ankara 06100, Turkey. aertugru@hacettepe.edu.tr
authors.forename: Aygun
authors.initials: A
authors.lastname: Ertugrul
authors.forename: Gulberk
authors.initials: G
authors.lastname: Ucar
authors.forename: Koray
authors.initials: K
authors.lastname: Basar
authors.forename: Basaran
authors.initials: B
authors.lastname: Demir
authors.forename: Samiye
authors.initials: S
authors.lastname: Yabanoglu
authors.forename: Berna
authors.initials: B
authors.lastname: Ulug
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D001792:Blood Platelets / Q000187:drug effects; D003024:Clozapine / Q000009:adverse effects* / Q000627:therapeutic use; D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D008297:Male; D008995:Monoamine Oxidase / Q000097:blood / Q000378:metabolism*; D009483:Neuropsychological Tests; D012563:Schizophrenia, Paranoid / Q000097:blood* / Q000188:drug therapy* / Q000453:epidemiology; D012565:Schizophrenic Psychology; D012701:Serotonin / Q000097:blood / Q000378:metabolism*; D012720:Severity of Illness Index; D012907:Smoking / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014706:Verbal Learning; D014825:Vocabulary
chemical_list: D014150:Antipsychotic Agents; D012701:Serotonin; D008995:Monoamine Oxidase; D003024:Clozapine