The relationship of LAI paliperidone and LAI aripiprazole plasma levels to their efficacy and tolerability: data from EULAST

OBJECTIVE: Poor adherence in schizophrenia is often solved by long-acting injectable (LAI) medication. Even LAIs need to be individualised through dosing adjustments to ensure efficacy and safety. It can be achieved by implementing therapeutic drug monitoring (TDM). That's why we decided to analyse data from the EULAST study. METHODS: Data from 180 patients who were randomised to one of the LAI groups were used in this study. Their plasma levels at the beginning, throughout and at the end of the study were analysed, and their relationships with efficacy, extrapyramidal side effects, functional status and quality of life were assessed. RESULTS: At the beginning, a significant number (56.1%) of all patients had subtherapeutic plasma levels, during the study 41% of patients had subtherapeutic plasma levels, and at the end, 26.7%. Only a minimum of patients had supratherapeutic plasma levels. No substantial evidence for the relationship between LAI type, plasma level range and treatment outcomes, including efficacy, side effects, functional status and quality of life, was found. CONCLUSIONS: Our data did not confirm the impact of LAIs' plasma levels on treatment outcomes. It seems beneficial to revise and reconsider the therapeutic reference range for LAIs; however, further studies are needed.