title: Dopamine D2 receptor occupancy by risperidone: implications for the timing and magnitude of clinical response.
abstract: The objective of the study is to investigate whether dopamine D2 receptor occupancy by risperidone and plasma levels over time can account for therapeutic efficacy and the latency period to response. Thirty-eight examinations with (123)I-IBZM single photon emission computed tomography were performed on 22 patients with schizophrenia, at diagnosis, 48 h after starting risperidone treatment and at a stable dose. Risperidone plasma levels were determined and psychopathologic evaluations (Brief Psychiatric Rating Scale, Positive and Negative Syndrome Scale) were carried out. No differences in the striatal/occipital (S/O) ratio or plasma levels were found between examinations at the 48-h time point and when a stable dose level had been established, so these parameters could not account for the latency period required for clinical response. D2 receptor occupancy at 48 h correlated positively with clinical improvement after 2 weeks of treatment. Therefore, if these results are confirmed, D2 receptor occupancy at the beginning of treatment with risperidone may be a predictor of subsequent clinical response.
authors.affiliation: Department of Nuclear Medicine, St Pau Hospital, U.A.B. (Autónoma University from Barcelona), Barcelona, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Catafau
authors.forename: Iluminada
authors.initials: I
authors.lastname: Corripio
authors.forename: Victor
authors.initials: V
authors.lastname: Pérez
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Martin
authors.forename: Alain
authors.initials: A
authors.lastname: Schotte
authors.forename: Ignasi
authors.initials: I
authors.lastname: Carrió
authors.forename: Enric
authors.initials: E
authors.lastname: Alvarez
mesh_terms: D000293:Adolescent; D000328:Adult; D014150:Antipsychotic Agents / Q000493:pharmacokinetics* / Q000627:therapeutic use; D001549:Benzamides; D010054:Brief Psychiatric Rating Scale; D003342:Corpus Striatum / Q000000981:diagnostic imaging*; D004292:Dominance, Cerebral / Q000502:physiology; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009778:Occipital Lobe / Q000000981:diagnostic imaging*; D011618:Psychotic Disorders / Q000097:blood / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D018967:Risperidone / Q000493:pharmacokinetics* / Q000627:therapeutic use; D012559:Schizophrenia / Q000097:blood / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D015899:Tomography, Emission-Computed, Single-Photon; D016896:Treatment Outcome
chemical_list: D014150:Antipsychotic Agents; D001549:Benzamides; D011759:Pyrrolidines; D017448:Receptors, Dopamine D2; C055743:3-iodo-2-hydroxy-6-methoxy-N-((1-ethyl-2-pyrrolidinyl)methyl)benzamide; D018967:Risperidone