RE: Routine clozapine assay monitoring to improve the management of treatment-resistant schizophrenia

Abstract

Routine clozapine assay monitoring should start during initial titration of clozapine dosages Kitchen and colleagues have published a very clinically relevant paper highlighting the importance of routine clozapine assays.1 We would support their conclusion of increased use of routine monitoring using clozapine assays. However, it is difficult to fathom why routine therapeutic drug monitoring (TDM) is still not considered justifiable in clinical practice. Clozapine fulfils the criteria for TDM as it has a narrow therapeutic index, substantial inter-individual variations in daily dose and plasma concentration relationship, and complex metabolism. We suggest that TDM should start during the initial titration to determine the target dose, rather than being restricted to annual monitoring