title: Treatment resistant or resistant to treatment? Antipsychotic plasma levels in patients with poorly controlled psychotic symptoms.
abstract: A large proportion of individuals with schizophrenia show an inadequate response to treatment with antipsychotics. It can be unclear whether this is secondary to subtherapeutic antipsychotic plasma levels or to medication ineffectiveness. The purpose of the present study was to determine the extent of subtherapeutic antipsychotic plasma levels in a group of patients clinically identified as treatment-resistant. In addition we investigated the frequency of antipsychotic plasma level monitoring in standard clinical practice. Antipsychotic plasma levels were measured in 36 patients identified as having treatment-resistant schizophrenia by their treating clinicians. Sixteen (44%) patients showed either undetectable (19%) or subtherapeutic levels (25%), and 20 (56%) patients had levels in the therapeutic range. Subtherapeutic plasma levels were significantly associated with black ethnicity, shorter duration of current treatment and antipsychotics other than olanzapine and amisulpride. Antipsychotic plasma levels had been measured in only one patient in the year prior to our study. We found over one-third of patients identified as treatment-resistant have subtherapeutic antipsychotic levels. This indicates that they may be under-treated rather than treatment-resistant, and thus should receive different management. Currently the measurement of antipsychotic levels may be under-utilised.
authors: Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK robert.mccutcheon@kcl.ac.uk.
authors: Robert
authors: R
authors: McCutcheon
authors: Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
authors: Katherine
authors: K
authors: Beck
authors: Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK Psychiatric Imaging, MRC Clinical Sciences Centre, Hammersmith Hospital, London, UK.
authors: Michael A P
authors: MA
authors: Bloomfield
authors: Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
authors: Tiago R
authors: TR
authors: Marques
authors: Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
authors: Maria
authors: M
authors: Rogdaki
authors: Department of Psychosis Studies, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK Psychiatric Imaging, MRC Clinical Sciences Centre, Hammersmith Hospital, London, UK.
authors: Oliver D
authors: OD
authors: Howes
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage* / Q000097:blood*; D004351:Drug Resistance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012559:Schizophrenia / Q000097:blood* / Q000188:drug therapy*
chemical_list: D014150:Antipsychotic Agents
keywords: Schizophrenia; adherence; antipsychotics; therapeutic drug monitoring; treatment resistant