title: Is there a relationship between antipsychotic blood levels and their clinical efficacy? An analysis of studies design and methodology.
abstract: There are now more than 50 studies concerning neuroleptic blood levels and clinical outcome relationships. Haloperidol, the most studied, is the only antipsychotic permitting some conclusions. A number of authors suggest that the striking lack of agreement between different studies results from heterogeneity of their quality. Here, we have used a scoring system for assessing the quality of those studies. According to this system, none (0/14) of the studies having a score < 0.60 was able to show a therapeutic window, as compared to 53% (10/19) of those having a score > or = 0.60 (p = 0.002, Fisher exact test). Also, the studies able to identify the presence of a therapeutic window during haloperidol treatment were those having sample size > 20 (p = 0.06) and those whose patients were treated with fixed doses (p = 0.02). The diagnosis of schizophrenia in the studies seems not to be an exclusive condition, as compared with those also including schizophreniform and schizoaffective disorders (p = 0.12). Our qualitative analysis of haloperidol blood level publications seem to indicate that an upper limit may exist for haloperidol efficacy; values above this limit seem not to provide any supplementary clinical improvement and may even reduce therapeutic effect.
authors.affiliation: Department of Pharmacology and Physiology, Federal University of Bahia, Salvador-Bahia, Brazil.
authors.forename: I R
authors.initials: IR
authors.lastname: de Oliveira
authors.forename: R M
authors.initials: RM
authors.lastname: Dardennes
authors.forename: E S
authors.initials: ES
authors.lastname: Amorim
authors.forename: B
authors.initials: B
authors.lastname: Diquet
authors.forename: E P
authors.initials: EP
authors.lastname: de Sena
authors.forename: E C
authors.initials: EC
authors.lastname: Moreira
authors.forename: E J
authors.initials: EJ
authors.lastname: de Castro-e-Silva
authors.forename: C
authors.initials: C
authors.lastname: Payan
authors.forename: J
authors.initials: J
authors.lastname: Fermanian
authors.forename: C
authors.initials: C
authors.lastname: Marcílio
mesh_terms: D014150:Antipsychotic Agents / Q000097:blood* / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D006220:Haloperidol / Q000097:blood* / Q000627:therapeutic use*; D006801:Humans; D012559:Schizophrenia / Q000097:blood* / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D014150:Antipsychotic Agents; D006220:Haloperidol