title: Optimal Dosing of Risperidone and Olanzapine in the Maintenance Treatment for Patients With Schizophrenia and Related Psychotic Disorders: A Retrospective Multicenter Study.
abstract: OBJECTIVE
  This study aims to determine the optimal tolerability dose ranges of risperidone (RIS) and olanzapine (OLZ) administered during schizophrenia maintenance phase.
  
  
  METHODS
  Two-year continuation rates of prescription at discharge were examined using a retrospective cohort study method. Adult patients with schizophrenia and related psychotic disorders, receiving antipsychotic monotherapy with RIS or OLZ at discharge, were included. The primary outcome measures were the time to treatment discontinuation and 2-year continuation rates at 4 modal dose ranges of each drug. We estimated the optimal tolerability dose ranges by comparing the continuation rates at various modal doses.
  
  
  RESULTS
  Of 648 patients, 344 received RIS and 304 received OLZ. The RIS 2-year continuation rates at 4 daily modal dose ranges were significantly different (0.5-2.5 mg: 46.0%, 3.0-5.0 mg: 40.0%, 5.5-7.5 mg: 30.0%, and 8.0-10.0 mg: 28.0%), with the difference favoring RIS at lower doses (0.5-5.0 mg) more than higher doses (5.5-10.0 mg). In contrast, there were no significant differences among OLZ 4 modal dose ranges (2.5-7.5 mg: 49.1%, 10.0-15.0 mg: 42.6%, 17.5-22.5 mg: 40.9%, and 25.0-30.0 mg: 39.0%). The time to treatment discontinuation significantly favored OLZ over RIS. However, it did not significantly differ between RIS and OLZ at lower doses.
  
  
  CONCLUSIONS
  It is suggested that the optimal tolerability dose range during maintenance treatment is 0.5 to 5.0 mg/d for RIS and 2.5 to 30 mg/d for OLZ, and that RIS at lower doses is comparable with OLZ at lower doses.
authors.affiliation: From the *Department of Psychiatry, Kawasaki Medical Graduate School, Kurashiki; †Zikei Hospital; ‡Okayama Psychiatric Medical Center, Okayama; §Taiyo Hills Hospital, Takahashi; and ∥Momonosato Hospital, Kasaoka, Japan.
authors.forename: Yusaku
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Takeda
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Kishi
authors.forename: Toshiki
authors.initials: T
authors.lastname: Harada
authors.forename: Akira
authors.initials: A
authors.lastname: Nomura
authors.forename: Kenji
authors.initials: K
authors.lastname: Washida
authors.forename: Bunta
authors.initials: B
authors.lastname: Yoshimura
authors.forename: Kojiro
authors.initials: K
authors.lastname: Sato
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yada
authors.forename: Shozo
authors.initials: S
authors.lastname: Aoki
mesh_terms: D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage* / Q000494:pharmacology; D001569:Benzodiazepines / Q000008:administration & dosage* / Q000494:pharmacology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D000077152:Olanzapine; D017063:Outcome Assessment, Health Care; D011618:Psychotic Disorders / Q000188:drug therapy*; D012189:Retrospective Studies; D018967:Risperidone / Q000008:administration & dosage* / Q000494:pharmacology; D012559:Schizophrenia / Q000188:drug therapy*; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D001569:Benzodiazepines; D018967:Risperidone; D000077152:Olanzapine