ABSTRACT
Introduction Safety studies have shown that COVID-19 vaccinations can provoke inflammatory processes in patients. The subsequent release of cytokines is accompanied by an increased inflammatory marker, C-reactive protein (CRP) [1]. For some antipsychotic drugs, inflammatory processes have been associated with increased drug levels, even above therapeutically approved ranges [2] [3]. It is not clear, whether this holds also true for COVID-19 vaccinations. Methods We present a case series comprising of 10 inpatients at the CIMH treated with an antipsychotic drug. Patients received a first, second or third dose of the COVID-vaccination Comirnaty in the morning. Blood samples were taken directly before the injection and were followed on day 1 and 4 while constant dosing. Blood testing included drug levels, safety laboratory, and CRP. Results CRP levels were elevated in nine patients;four of those also presented an increase in antipsychotic drug levels within a few days after COVID-19 vaccination. Blood level changes were i)+0%,+24%,+125%,+116% in quetiapine-, ii)+0%,+0%,+100% in olanzapine-, iii)+0,+42% in clozapine-treated patients, and iv)+205% in one risperidone-treated patient. As a result, three patients had drug levels above the therapeutically recommended range. Conclusion We present a series of patients with increased antipsychotic drug levels after COVID-19 vaccinations mediated via inflammatory processes. The intensity of inflammatory reactions strongly varies across patients. Hence, COVID-19 vaccinations may constitute an unpredictable risk factor for increased drug levels. Therapeutic drug monitoring can help to prevent safety risks in those patients with supra-therapeutic drug levels.