title: Evaluation of Defined Daily Dose, percentage of British National Formulary maximum and chlorpromazine equivalents in antipsychotic drug utilization.
abstract: OBJECTIVE
  The present study was carried out to investigate and compare the three methods for calculating total antipsychotic dose among outpatients with schizophrenia attending primary psychiatric health care centers. The three methods were: Defined Daily Doses (DDDs), chlorpromazine equivalents (CPZeq) and percentages of the British National Formulary (BNF) maximum.
  
  
  METHODS
  Antipsychotic drug dosing data for 250 patients with schizophrenia were investigated by calculating Spearman's rank correlation coefficients. Factors associated with antipsychotic dose, expressed as DDDs, CPZeq and percentages of the BNF maximum recommended daily dose, were investigated by means of linear regression analysis.
  
  
  RESULTS
  Spearman's correlation showed that there is a significant relationship between all pairs of the three dosing methods. In all three methods, coherence was strongest when dealing with first generation antipsychotics (FGA). Linear regression analyses showed a high degree of coherence between antipsychotic doses expressed as DDDs, CPZeq and percentages of the BNF maximum recommended daily dose.
  
  
  CONCLUSIONS
  All three tested methods are reliable and coherent for calculating antipsychotic dosing.
authors.affiliation: College of Medicine and Health Sciences, Department of Pharmacology/Toxicology, An-Najah National University, Nablus, Palestine.
authors.forename: Waleed M
authors.initials: WM
authors.lastname: Sweileh
authors.affiliation: College of Medicine and Health Sciences, Department of Pharmacology/Toxicology, An-Najah National University, Nablus, Palestine.
authors.forename: Jihad Bani
authors.initials: JB
authors.lastname: Odeh
authors.affiliation: College of Medicine and Health Sciences, Department of Pharmacology/Toxicology, An-Najah National University, Nablus, Palestine.
authors.forename: Naser Y
authors.initials: NY
authors.lastname: Shraim
authors.affiliation: College of Medicine and Health Sciences, Department of Pharmacology/Toxicology, An-Najah National University, Nablus, Palestine.
authors.forename: Sa'ed H
authors.initials: SH
authors.lastname: Zyoud
authors.affiliation: College of Medicine and Health Sciences, Department of Pharmacology/Toxicology, An-Najah National University, Nablus, Palestine.
authors.forename: Ansam F
authors.initials: AF
authors.lastname: Sawalha
authors.affiliation: College of Medicine and Health Sciences, Department of Pharmacology/Toxicology, An-Najah National University, Nablus, Palestine.
authors.forename: Samah W
authors.initials: SW
authors.lastname: Al-Jabi
keywords: %BNFmax, percentage of British National Formulary maximum; Antipsychotics; CPZeq, chlorpromazine equivalents; Chlorpromazine equivalents; DDD, Defined Daily Dose (DDD); Defined Daily Doses; FGA, first generation antipsychotics; SGA, second generation antipsychotics; Schizophrenia