Elevated Clozapine Blood Concentrations After Second COVID-19 Vaccination With Spikevax (COVID-19 Vaccine Moderna)

When, Why and How to Re-challenge Clozapine in Schizophrenia Following Myocarditis

Clozapine-induced myocarditis (CIM) is among the most important adverse events limiting the use of clozapine as the most effective treatment for schizophrenia. CIM necessitates the immediate termination of clozapine, often resulting in its permanent discontinuation with considerable detrimental effects on patients' psychopathology and long-term outcome. Consequently, a clozapine re-challenge after CIM is increasingly regarded as a viable alternative, with published reports indicating a success rate of approximately 60%. However, published cases of re-challenges after CIM remain limited. Here, we provide a narrative review of the current state of research regarding the epidemiology, pathophysiology, risk factors, diagnosis and clinical management of CIM as well as a synthesis of current recommendations for re-challenging patients after CIM. This includes a step-by-step guide for this crucial procedure based on the current evidence regarding the pathophysiology and risk factors for CIM. Slow dose titration regimes and addressing risk factors including concomitant valproate and olanzapine are crucial both to prevent CIM and to ensure a safe and successful re-challenge. Furthermore, we discuss the utility of C-reactive protein, troponin, N-terminal-pro hormone and brain natriuretic peptide, therapeutic drug-monitoring and cardiac magnetic resonance imaging for CIM screening and diagnosis as well as for post-CIM re-challenges.

A Rapid Review of the Effects of the COVID-19 Vaccine Among Individuals Taking Clozapine

BACKGROUND

The COVID-19 pandemic prompted the rapid development of vaccines to combat the virus. Several COVID-19 vaccines have proven effective in preventing infection, hospitalization, and death. Vaccination has been especially recommended for vulnerable populations, such as individuals with psychiatric illnesses who face increased risks due to comorbidities and socioeconomic factors. This rapid review identifies and analyzes the effects of COVID-19 vaccines among individuals taking clozapine.

METHODS

The review included articles from PubMed, OVID, Clinical Key, Web of Science, and Google Scholar, published between September 2020 and December 2023. Inclusion criteria were peer-reviewed journals, English language, patients on clozapine receiving a COVID-19 vaccine, and documented vaccine-related adverse effects.

RESULTS

Twelve articles were included, consisting of 8 case reports, 1 cross-sectional study, and 3 prospective observational studies, involving 298 subjects, with 9 subjects from case reports. After the first vaccine dose, 27 of 248 subjects experienced adverse effects, with 1 case report advising a temporary halt and dose reduction of clozapine. The subject in this case was admitted in a delirious state 4 days after vaccination with repeated falls and urinary incontinence; active infectious and neurologic etiologies were ruled out. Second dose data were available for 261 subjects, with 31 reporting adverse effects. Adverse effects included hematological changes, delirious state, seizures, and fever.

CONCLUSIONS

The review suggests that individuals on clozapine receiving COVID-19 vaccines may experience adverse effects. Clozapine levels and immune system interactions should be monitored in these cases.

Vaccination and clozapine use: a systematic review and an analysis of the VAERS database

In the context of COVID-19 concerns related to the potential interactions between clozapine and vaccination arose. With the ultimate goal of deriving recommendations for clinical practice, we systematically reviewed the current evidence regarding altered vaccine effectiveness in clozapine-treated patients and safety aspects of vaccination, such as haematological changes and the impact of vaccines on clozapine blood levels, in clozapine-treated patients. A systematic PRISMA-conform literature search of four databases (PubMed, PsycINFO, EMBASE and Cochrane Library) complemented by a case-by-case analysis of the Vaccine Adverse Event Reporting System (VAERS) database was performed. We then systematically appraised the joint evidence and tried to derive recommendations for clinical practice. 14 records were included in this analysis. These records consisted of 5 original articles and 9 case reports. Among the original articles, two studies provided data on the association between clozapine use and antibody responses to vaccination, both indicating that clozapine use in schizophrenia may be associated with reduced levels of immunoglobulins. Additionally, three studies examined vaccine safety in clozapine-treated patients, with no clinically significant adverse effects directly attributable to the interplay between vaccinations and clozapine. VAERS Analysis encompassed 137 reports and showed no consistent evidence of an increased risk for clozapine blood level increases or adverse events. We found no evidence indicating that clozapine impairs the effectiveness of vaccines. Moreover, no serious safety concerns seem to apply when patients on clozapine are receiving vaccines. However, it is crucial to acknowledge that data on the interaction between clozapine and vaccines remain limited.

Pharmacomicrobiomics and Drug-Infection Interactions: The Impact of Commensal, Symbiotic and Pathogenic Microorganisms on a Host Response to Drug Therapy

Microorganisms have a close relationship with humans, whether it is commensal, symbiotic, or pathogenic. Recently, it has been documented that microorganisms may influence the response to drug therapy. Pharmacomicrobiomics is an emerging field that focuses on the study of how variations in the microbiome affect the disposition, action, and toxicity of drugs. Two additional sciences have been added to complement pharmacomicrobiomics, namely toxicomicrobiomics, which explores how the microbiome influences drug metabolism and toxicity, and pharmacoecology, which refers to modifications in the microbiome as a result of drug administration. In this context, we introduce the concept of "drug-infection interaction" to describe the influence of pathogenic microorganisms on drug response. This review analyzes the current state of knowledge regarding the relevance of microorganisms in the host's response to drugs. It also highlights promising areas for future research and proposes the term "drug-infection interaction" as an extension of pharmacomicrobiomics.

Changes in Psychotropic Drug Blood Levels After SARS-CoV-2 Vaccination: A Two-Center Cohort Study

BACKGROUND

Limited evidence from case reports suggests that coronavirus disease 2019 (COVID-19) vaccination may interact with the treatment outcomes of psychiatric medications. Apart from clozapine, reports on the effect of COVID-19 vaccination on other psychotropic agents are scarce. This study aimed to investigate the impact of COVID-19 vaccination on the plasma levels of different psychotropic drugs using therapeutic drug monitoring.

METHODS

Plasma levels of psychotropic agents, including agomelatine, amisulpride, amitriptyline, escitalopram, fluoxetine, lamotrigine, mirtazapine, olanzapine, quetiapine, sertraline, trazodone, and venlafaxine, from inpatients with a broad spectrum of psychiatric diseases receiving COVID-19 vaccinations were collected at 2 medical centers between 08/2021 and 02/2022 under steady-state conditions before and after vaccination. Postvaccination changes were estimated as a percentage of baseline.

RESULTS

Data from 16 patients who received COVID-19 vaccination were included. The largest changes in plasma levels were reported for quetiapine (+101.2%) and trazodone (-38.5%) in 1 and 3 patients, respectively, 1 day postvaccination compared with baseline levels. One week postvaccination, the plasma levels of fluoxetine (active moiety) and escitalopram increased by 31% and 24.9%, respectively.

CONCLUSIONS

This study provides the first evidence of major changes in the plasma levels of escitalopram, fluoxetine, trazodone, and quetiapine after COVID-19 vaccination. When planning COVID-19 vaccination for patients treated with these medications, clinicians should monitor rapid changes in bioavailability and consider short-term dose adjustments to ensure safety.