Undetectable or subtherapeutic serum levels of antipsychotic drugs preceding switch to clozapine.

ABSTRACT: Adequate antipsychotic treatment intensity is required for defining treatment-resistant schizophrenia (TRS) and justifying clozapine treatment. We investigated the occurrence of undetectable or subtherapeutic serum levels of oral antipsychotics preceding switch to clozapine as an endpoint of TRS. For patients starting clozapine, 12-month retrospective reviews of antipsychotic serum concentration measurements were performed in a Norwegian therapeutic drug monitoring (TDM) database from 2005 to 2017. Undetectable levels in high-sensitive analytical assays defined 'no drug use', while levels <50% of the lower reference range defined 'subtherapeutic use'. Similar data were collected for patients switching to long-acting injectable (LAI) antipsychotics, as a reference of 'no or subtherapeutic d

SUBMITTER: Kylleso L 

PROVIDER: S-EPMC7367852 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature