Pharmacopsychiatry 2024; 57(02): 92
DOI: 10.1055/s-0044-1779578
Abstracts │ XVth Symposium of the Task Force Therapeutic Drug Monitoring of the AGNP
Poster Abstracts

PET-derived modelling of D2-receptor occupancy of antipsychotic polypharmacy in patients with schizophrenia

M. Spangemacher
1   Department of Molecular Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
2   Central Institute of Mental Health, Department of Psychiatry, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
,
C. Schmitz
1   Department of Molecular Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
2   Central Institute of Mental Health, Department of Psychiatry, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
,
L. V. Färber
1   Department of Molecular Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
,
X. M. Hart
1   Department of Molecular Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
3   Department of Neuropsychiatry, Keio University School of Medicine, Tokyo, Japan
,
G. Gründer
1   Department of Molecular Neuroimaging, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
› Author Affiliations
 

Treatment with combinations of antipsychotics is common clinical practice. Approximately 20 – 30 % of all patients treated with antipsychotics take two or more antipsychotic substances simultaneously. The evidence supporting the benefit of antipsychotic combination treatment is limited.

There are almost no positron emission tomography (PET)-imaging studies that explored the effect of antipsychotic combination treatment on striatal D2-dopamine receptor occupancy. However, D2-receptor occupancy for most antipsychotics can be predicted from a single antipsychotic plasma level.

We present a new developed model for calculating receptor occupancy during antipsychotic polypharmacy (APP).

The receptor occupancy of a single psychopharmacological agent can be derived from the serum concentration C based on the law of mass action:

With this study, we outline a modelling approach that derives the striatal D2-dopamine receptor occupancy of antipsychotic combination treatment from experimental PET data. Under the premise of this modelling approach, we show that most antipsychotic combinations might exceed the 65 – 80 % window of D2-dopamine receptor occupancy in the clinical practice.

Our model reveals that treatment with antipsychotic combination has to be clinically evaluated. Consequently, when using antipsychotic polypharmacy, reference ranges should be adjusted and lower dosages used.



Publication History

Article published online:
12 March 2024

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