title: The relationship between the plasma concentration of blonanserin, and its plasma anti-serotonin 5-HT(2A) activity/anti-dopamine D₂ activity ratio and drug-induced extrapyramidal symptoms.
abstract: OBJECTIVE
  Blonanserin is a second-generation antipsychotic that was developed in Japan. We investigated the relationships between plasma concentration, the plasma anti-5-HT(2A) activity/anti-D₂ activity (S/D) ratio and extrapyramidal symptoms (EPS) in blonanserin dosing.
  
  
  METHODS
  The subjects were 29 outpatients with schizophrenia. We assessed EPS using the Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). The plasma concentrations were measured by high performance liquid chromatography, and the plasma anti-D₂ and anti-5-HT(2A) activities were measured by [³H]-spiperone and [³H]-ketanserin radioreceptor assays.
  
  
  RESULTS
  The results revealed that there were significant correlations between both the plasma concentration and the DIEPSS total score (P<0.05). A negative correlative tendency was found between the S/D ratio and the DIEPSS total score. Furthermore, the plasma concentrations were divided into a low plasma concentration group and a high plasma concentration group, and the S/D ratios were divided into a low S/D ratio group and a high S/D ratio group. We then compared each group based on the DIEPSS total scores. The score in the high plasma concentration-low S/D ratio group was significantly higher than in the high plasma concentration-high S/D ratio, low plasma concentration-high S/D ratio and low plasma concentration-low S/D ratio groups (P<0.05 for all).
  
  
  CONCLUSIONS
  These findings indicate that the incidence of EPS during treatment with blonanserin is mainly determined by plasma concentration, but the incidence of EPS may be inhibited when anti-5HT(2A) activity is predominant over anti-D₂ activity.
authors.affiliation: Department of Psychiatry, Tanzawa Hospital, Hadano Department of Psychiatry, Seimo Hospital, Gunma, Japan. suzuhide@red.livedoor.com
authors.forename: Hidenobu
authors.initials: H
authors.lastname: Suzuki
authors.forename: Keishi
authors.initials: K
authors.lastname: Gen
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000009:adverse effects* / Q000097:blood* / Q000627:therapeutic use; D004409:Dyskinesia, Drug-Induced / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000009:adverse effects* / Q000097:blood* / Q000627:therapeutic use; D010880:Piperidines / Q000009:adverse effects* / Q000097:blood* / Q000627:therapeutic use; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D044348:Receptors, Serotonin, 5-HT2 / Q000378:metabolism; D012559:Schizophrenia / Q000097:blood / Q000188:drug therapy*
chemical_list: D014150:Antipsychotic Agents; D010879:Piperazines; D010880:Piperidines; D017448:Receptors, Dopamine D2; D044348:Receptors, Serotonin, 5-HT2; C079310:blonanserin