title: Prediction of an Optimal Dose of Aripiprazole in the Treatment of Schizophrenia From Plasma Concentrations of Aripiprazole Plus Its Active Metabolite Dehydroaripiprazole at Week 1.
abstract: It has been suggested that a plasma trough concentration of aripiprazole plus its active metabolite, dehydroaripiprazole of 225 ng/mL is a threshold for a good therapeutic response in the treatment of acutely exacerbated patients with schizophrenia. The present study investigated whether or not an optimal dose of aripiprazole could be predicted from these concentrations at week 1.
  
  
  
  The subjects were 26 inpatients with schizophrenia, who received aripiprazole once a day for 3 weeks. The daily doses were 12 mg for the first week and 24 mg for the next 2 weeks. No other drugs except biperiden and flunitrazepam were coadministered. Blood samples were taken at weeks 1 and 3 after the treatment. Plasma concentrations of aripiprazole and dehydroaripiprazole were measured using liquid chromatography with mass-spectrometric detection.
  
  
  
  There was a significant linear relationship between the plasma concentrations of aripiprazole plus dehydroaripiprazole at weeks 1 (x) and 3 (y) (P < 0.001). Regression equation was y = 2.580x + 34.86 (R = 0.698). Based on the equation, a nomogram to estimate an optimal dose of aripiprazole could be constructed.
  
  
  
  The present study suggests that an optimal dose of aripiprazole for the treatment of patients with schizophrenia can be predicted from the plasma concentrations of the sum of the 2 compounds at week 1.
authors.affiliation: Departments of *Neuropsychiatry and †Hospital Pharmacy, Graduate School of Medicine, University of the Ryukyus, Nishihara, Okinawa, Japan.
authors.forename: Goyo
authors.initials: G
authors.lastname: Nagai
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mihara
authors.forename: Akifumi
authors.initials: A
authors.lastname: Nakamura
authors.forename: Kenji
authors.initials: K
authors.lastname: Nemoto
authors.forename: Shoko
authors.initials: S
authors.lastname: Kagawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suzuki
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kondo
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics; D000068180:Aripiprazole / Q000008:administration & dosage* / Q000493:pharmacokinetics; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D049451:Nomograms; D010879:Piperazines / Q000493:pharmacokinetics*; D015363:Quinolones / Q000493:pharmacokinetics*; D012559:Schizophrenia / Q000188:drug therapy*; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D010879:Piperazines; D015363:Quinolones; C517414:dehydroaripiprazole; D000068180:Aripiprazole