Inhibition of cloned hERG potassium channels by risperidone and paliperidone

Assessment of Risperidone Toxicity in Zebrafish (Danio rerio) Embryos

Risperidone is an antipsychotic medication used in the treatment of conditions like autism and schizophrenia. The goal of the current study was to examine the effects of risperidone in zebrafish embryos ( Danio rerio ) with regard to survival, development, and cardiac and neural systems. The results showed that concentrations above 100 μM were associated with deaths, teratogenic effects, and cardiotoxic and neurotoxic effects. The findings support the utility of zebrafish for toxicological screening studies.

Sudden unexplained death in schizophrenia patients: An autopsy-based comparative study from China

Explainable sudden deaths in schizophrenia patients due to both cardiac (SCD) and non-cardiac causes (SNCD) have been extensively documented. However, sudden unexplained death (SUD) in this cohort remains to be elucidated. This study retrospectively analyzed 18 SUD cases that underwent systematic autopsy at our institutes during the period 2010-2022. The etiological, demographic, and autopsy features of the SUD cases were then compared with 37 year-matched sudden explainable deaths (23 SCD cases and 14 SNCD cases). Our results showed that the average age of the SUD was 39.0 ( ± 8.4) years, with the disease duration of 11.8 ( ± 8.1) years and a male/female ratio of 11:7. Most cases occurred during daytime (72.2%) and outside of hospital (77.8%). A large proportion of the SUD cases (77.8%) had persistent psychiatric episodes before death. Clozapine was found to be the most commonly used antipsychotic (33.3%), followed by Olanzapine (27.8%), Risperidone (27.8%) and Chlorpromazine (27.8%) in the SUD cases. When compared among groups, the SUD cases showed significantly younger ages (p = 0.035), lower heart weight (p = 0.004) and lower proportion of Clozapine use (p = 0.045). The presence of persistent psychiatric episodes was significantly higher in the SUD group than in any explainable deaths (p = 0.018) and was an independent risk factor for SUD (OR = 4.205, p = 0.040). This is the first autopsy-based study of SUD cases from China. We conclude that a stable mental state maintained by antipsychotics (i.e., Clozapine) is vital to schizophrenia patients.

Effects of iloperidone on hERG 1A/3.1 heterotetrameric channels

OBJECTIVES

Iloperidone is an atypical antipsychotic drug that is widely used for the treatment of schizophrenia. hERG 3.1, alternatively spliced form of hERG 1A, is considered a potential target for an antipsychotic drug. The present study was designed to study the effects of iloperidone on hERG 1A/3.1 heterotetrameric channels.

METHODS

The interactions of iloperidone with hERG 1A/3.1 heterotetrameric channels stably expressed in HEK cells were investigated using the whole-cell patch-clamp technique and western blot analysis.

RESULTS

Iloperidone inhibited the hERG 1A/3.1 tail currents at -50 mV in a concentration-dependent manner with an IC50 value of 0.44 μM. The block of hERG 1A/3.1 currents by iloperidone was voltage-dependent and increased over a range of voltage for channel activation. However, the block by iloperidone was voltage-independent at more depolarized potentials where the channels were fully activated. A fast application of iloperidone inhibited the hERG 1A/3.1 current elicited by a 5-s depolarizing pulse to +60 mV to fully inactivate the hERG 1A/3.1 currents. Iloperidone also induced a rapid and reversible inhibition of hERG 1A/3.1 tail currents during repolarization. However, iloperidone had no effect on either hERG 1A or hERG 1A/3.1 channel trafficking to the cell membrane.

CONCLUSIONS

Our results indicated that iloperidone concentration-dependently inhibited hERG 1A/3.1 currents by preferentially interacting with the open states of channels, but not by the disruption of membrane trafficking or surface membrane expression of hERG 1A and hERG 1A/3.1 channel proteins.

Antipsychotics cardiotoxicity: What's known and what's next

Chronic use of antipsychotic medications entails a dilemma between the benefit of alleviating psychotic symptoms and the risk of troubling, sometimes life-shortening adverse effects. Antipsychotic-induced cardiotoxicity is one of the most life-threatening adverse effects that raises widespread concerns. These cardiotoxic effects range from arrhythmia to heart failure in the clinic, with myocarditis/cardiomyopathy, ischemic injuries, and unexplained cardiac lesions as the pathological bases. Multiple mechanisms have been proposed to underlie antipsychotic cardiotoxicity. This review aims to summarize the clinical signs and pathological changes of antipsychotic cardiotoxicity and introduce recent progress in understanding the underlying mechanisms at both the subcellular organelle level and the molecular level. We also provide an up-to-date perspective on future clinical monitoring and therapeutic strategies for antipsychotic cardiotoxicity. We propose that third-generation antipsychotics or drug adjuvant therapy, such as cannabinoid receptor modulators that confer dual benefits — i.e., alleviating cardiotoxicity and improving metabolic disorders — deserve further clinical evaluation and marketing.