Evidence suggests that clozapine plasma levels of at least 250-350 mcg/L are required for optimal clinical response.
Our recommended therapeutic range (Clozapine levels 350-600 mcg/L) follows the consensus guidelines published in psychopharmacology in 2018 (1). Only about 1/3 of patients show drug levels within that range. Some patients will require higher clozapine concentrations of up to 800 mcg/L for disease control without increased levels of side effects.
Hiemke C, et al. Consensus Guidelines for Therapeutic Drug Monitoring in Neuropsychopharmacology: Update 2017. Pharmacopsychiatry. 2018 Jan;51(1-02):e1. doi: 10.1055/s-0037-1600991. Epub 2018 Feb 1.
Clozapine Assay performed by Alfred Pathology Service from 14 Jan 2020