Electrophysiological Profile of Different Antiviral Therapies in a Rabbit Whole-Heart Model.

Antiviral therapies for treatment of COVID-19 may be associated with significant proarrhythmic potential. In the present study, the potential cardiotoxic side effects of these therapies were evaluated using a Langendorff model of the isolated rabbit heart. 51 hearts of female rabbits were retrogradely perfused, employing a Langendorff-setup. Eight catheters were placed endo- and epicardially to perform an electrophysiology study, thus obtaining cycle length-dependent action potential duration at 90% of repolarization (APD90), QT intervals and dispersion of repolarization. After generating baseline data, the hearts were assigned to four groups: In group 1 (HXC), hearts were treated with 1 µM hydroxychloroquine. Thereafter, 3 µM hydroxychloroquine were infused additionally. Group 2 (HXC + AZI) was perfused with 3 µM hydroxychloroquine followed by 150 µM azithromycin. In group 3 (LOP) the hearts were perfused with 3 µM lopinavir followed by 5 µM and 10 µM lopinavir. Group 4 (REM) was perfused with 1 µM remdesivir followed by 5 µM and 10 µM remdesivir. Hydroxychloroquine- and azithromycin-based therapies have a significant proarrhythmic potential mediated by action potential prolongation and an increase in dispersion. Lopinavir and remdesivir showed overall significantly less pronounced changes in electrophysiology. In accordance with the reported bradycardic events under remdesivir, it significantly reduced the rate of the ventricular escape rhythm.

Preimplantation development of in vitro-produced bovine embryos treated with hydroxychloroquine.

Hydroxychloroquine (HCQ) is a safe antimalarial drug but its overdosage or inappropriate use, such as during the pandemic, may cause adverse effects once this drug is considered a potent inhibitor of autophagy. Information about HCQ's effects on the reproductive field, including gametes and initial embryos, is limited. In this study, we evaluated the effect of HCQ (1, 6, 12, and 24 µM) on pre-implantation embryo development, autophagy, and apoptosis of bovine embryos produced in vitro. A dose-response experiment showed a reduction (p < 0.05) in cleavage only at the highest concentration. Blastocyst rate was gradually reduced (p < 0.05) with the increase of HCQ dosage starting at 6 µM, with no embryo formation occurring at 24 µM. Further analysis showed that embryos treated with 12 µM of HCQ had a higher (p < 0.05) accumulation of acidic autophagic vesicles on Days 5 and 7 of development and a higher (p < 0.01) apoptotic index on Day 7. To our knowledge, this is the first study to evaluate the effects of HCQ on embryo pre-implantation development in mammals. The results contribute with more information related to the study of autophagy in embryology as well as add some discussion on HCQ toxicology and its effects on reproductive cells.

Evaluation of weak genotoxicity of hydroxychloroquine in human TK6 cells.

Hydroxychloroquine (HCQ), a derivative of chloroquine (CQ), is an antimalarial and antirheumatic drug. Since there is limited data available on the genotoxicity of HCQ, in the current study, we used a battery of in vitro assays to systematically examine the genotoxicity of HCQ in human lymphoblastoid TK6 cells. We first showed that HCQ is not mutagenic in TK6 cells up to 80 µM with or without exogenous metabolic activation. Subsequently, we found that short-term (3-4 h) HCQ treatment did not cause DNA strand breakage as measured by the comet assay and the phosphorylation of histone H2A.X (γH2A.X), and did not induce chromosomal damage as determined by the micronucleus (MN) assay. However, after 24-h treatment, both CQ and HCQ induced comparable and weak DNA damage and MN formation in TK6 cells; upregulated p53 and p53-mediated DNA damage responsive genes; and triggered apoptosis and mitochondrial damage that may partially contribute to the observed MN formation. Using a benchmark dose (BMD) modeling analysis, the lower 95% confidence limit of BMD50 values (BMDL50) for MN induction in TK6 cells were about 19.7 µM for CQ and 16.3 µM for HCQ. These results provide additional information for quantitative genotoxic risk assessment of these drugs.

Accelerated hydroxychloroquine toxic retinopathy.

PURPOSE: To report a case series of patients with retinal toxicity due to hydroxychloroquine (HCQ) within a short span of treatment. METHODS: A retrospective review of case records of patients with accelerated HCQ toxicity within 1 year of starting the treatment was done. Systemic co-morbidities, details of HCQ treatment, details of ocular examination, and results of multimodal investigations were noted. RESULTS: Nine patients (1 male, 8 females) with age ranging from 40 to 73 years (mean 54.2 ± 13.4 years) who showed accelerated HCQ toxicity were included. None had systemic conditions or drug history predisposing to early HCQ toxicity. The treatment duration ranged from 2 to 11 months and the cumulative HCQ dose ranged from 18 to 120 g (mean 45.0 ± 33.0 g). The visual acuity was normal in 8 (88.9%) patients and retinal evaluation was normal in 4 (44.4%). Optical coherence tomography was abnormal in 4 (44.4%). Six (66.6%) cases had reduced sensitivity in the parafoveal point on visual field testing. All 9 cases had multifocal electroretinographic changes diagnostic of HCQ toxicity. The HCQ treatment was stopped in 8 and continued with reduced dose in 1 patient. The mean duration of follow-up was 11.2 ± 9.6 months during which 5 patients showed improved mfERG and 1 patient had a stable mfERG. Visual fields improvement was noted in 2 cases. CONCLUSIONS: Patients on HCQ need to be kept on regular monitoring with more frequent follow-ups to detect signs of early onset toxicity and prevent permanent visual impairment. mfERG is an important diagnostic tool for HCQ toxicity.

Hydroxychloroquine Toxicity in the Vital Organs of the Body: In Vivo Study.

BACKGROUND: Hydroxychloroquine (HCQ) toxicity can adversely affect vital organs, cause pathologic ocular damage, and can have direct cardiovascular effects. This study aims to identify the biochemical, hematological, and histological alterations of the vital organs associated with the effects of HCQ. METHODS: Male albino rats were exposed to the equivalent of HCQ therapeutic doses given to human patients being affected by malaria, lupus erythematosus, and COVID-19. The animal blood samples were subjected to hematological analysis, biochemical analysis, liver function tests, kidney function tests, and cardiac biomarkers. Liver, kidney, heart, spleen, and testis biopsies were subjected to histological examination. RESULTS: HCQ significantly lowered the values of erythrocytes, hemoglobin, hematocrit, platelets, leucocytes, and lymphocytes but significantly increased the values of aspartate aminotransferase (AST), alanine aminotransferase (ALT), amylase, alkaline phosphatase, lactate dehydrogenase, cholesterol, and chlorine ions. The renal tissues of HCQ-treated animals demonstrated glomerular fragmentation, partial atrophy degeneration, renal tubules hydropic degeneration, hyaline cast formation, and interstitial edema formation. Additionally, the heart exhibited myofiber necrosis, myolysis, wavy appearance, disorganization, and disarray. The testicular tissues also demonstrated spermatocyte degeneration, spermatogenic cell sloughing, testicular interstitial edema, and occasional spermatogenic arrest. Additionally, the spleen showed a decrease in the number and size of the white pulp follicles, a decrease in the number of apoptotic activity, and a decline in the number of T-rich cells. However, the red pulp demonstrated a diffuse decline in B rich-lymphocytes and macrophages. The liver was also the least affected but showed Kupffer cell hyperplasia and occasional hepatocyte dysplasia. CONCLUSIONS: The results indicate that chronic exposure to HCQ could alter the structures and functions of the vital organs.

Vinpocetine protects against chloroquine-induced cardiotoxicity by mitigating oxidative stress.

Chloroquine (CQ) and hydroxychloroquine (HCQ) are classical antimalarial drugs, and recently have been used for other applications including coronavirus disease 2019 (COVID-19). Although they are considered safe, cardiomyopathy may associate CQ and HCQ applications particularly at overdoses. The goal of the present study was to evaluate the potential protective effect of the nootropic agent vinpocetine against CQ and HCQ adverse effects with a specific focus on the heart. For this purpose, a mouse model of CQ (0.5 up to 2.5 g/kg)/HCQ (1 up to 2 g/kg) toxicity was used, and the effect of vinpocetine was evaluated by survival, biochemical, as well as histopathological analyses. Survival analysis revealed that CQ and HCQ caused dose-dependent lethality, which was prevented by co-treatment with vinpocetine (100 mg/kg, oral or intraperitoneal). To gain deeper understanding, a dose of 1 g/kg CQ-which did not cause death within the first 24 h after administration-was applied with and without vinpocetine administration (100 mg/kg, intraperitoneal). The CQ vehicle group showed marked cardiotoxicity as evidenced by significant alterations of blood biomarkers including troponione-1, creatine phosphokinase (CPK), creatine kinase-myocardial band (CK-MB), ferritin, and potassium levels. This was confirmed at the tissue level by massive alteration of the heart tissue morphology and coincided with massive oxidative stress. Interestingly, co-administration of vinpocetine strongly ameliorated CQ-induced alterations and restored the antioxidant-defense system of the heart. These data suggest that vinpocetine could be used as an adjuvant therapy together with CQ/HCQ applications.

Cardiotoxicity of chloroquine and hydroxychloroquine through mitochondrial pathway.

BACKGROUND: Medical therapies can cause cardiotoxicity. Chloroquine (QC) and hydroxychloroquine (HQC) are drugs used in the treatment of malaria and skin and rheumatic disorders. These drugs were considered to help treatment of coronavirus disease (COVID-19) in 2019. Despite the low cost and availability of QC and HQC, reports indicate that this class of drugs can cause cardiotoxicity. The mechanism of this event is not well known, but evidence shows that QC and HQC can cause cardiotoxicity by affecting mitochondria and lysosomes. METHODS: Therefore, our study was designed to investigate the effects of QC and HQC on heart mitochondria. In order to achieve this aim, mitochondrial function, reactive oxygen species (ROS) level, mitochondrial membrane disruption, and cytochrome c release in heart mitochondria were evaluated. Statistical significance was determined using the one-way and two-way analysis of variance (ANOVA) followed by post hoc Tukey to evaluate mitochondrial succinate dehydrogenase (SDH) activity and cytochrome c release, and Bonferroni test to evaluate the ROS level, mitochondrial membrane potential (MMP) collapse, and mitochondrial swelling. RESULTS: Based on ANOVA analysis (one-way), the results of mitochondrial SDH activity showed that the IC50 concentration for CQ is 20 µM and for HCQ is 50 µM. Based on two-way ANOVA analysis, the highest effect of CQ and HCQ on the generation of ROS, collapse in the MMP, and mitochondrial swelling were observed at 40 µM and 100 µM concentrations, respectively (p < 0.05). Also, the highest effect of these two drugs has been observed in 60 min (p < 0.05). The statistical results showed that compared to CQ, HCQ is able to cause the release of cytochrome c from mitochondria in all applied concentrations (p < 0.05). CONCLUSIONS: The results suggest that QC and HQC can cause cardiotoxicity which can lead to heart disorders through oxidative stress and disfunction of heart mitochondria.

Quantitative analysis of optical coherence tomography imaging in patients with different severities of hydroxychloroquine toxicity.

PURPOSE: To determine the diagnostic validity of quantitative measures derived from optical coherence tomography (OCT) images in their ability to discriminate between cohorts of eyes unaffected by hydroxychloroquine (HCQ) and those with a range of toxicity severities, including mild toxicity. METHODS: Prospective, single-centre, case-control study conducted between August 2010 and May 2017. Participants were exposed to HCQ for at least 5 years (mean±SD =14±7.2 years) and classified into affected and unaffected cohorts based on the American Academy of Ophthalmology's 2016 recommendations. For affected eyes, severity (groups 1-4) was assigned based on the extent of ellipsoid zone loss. For all eyes, spectral domain-OCT scans were analysed quantitatively to compute inner retinal thickness (IRT), outer retinal thickness (ORT), and minimum signal intensity (MI) and compared across toxicity groups. RESULTS: Of the 85 participants (mean age 59±12 years, 93% female), 30 had retinal toxicity. Significant differences in ORT and MI were observed between each affected severity group and unaffected eyes. Significant differences in IRT were observed for groups 3-4 but not groups 1-2. ORT and MI were each able to discriminate between unaffected and group 1 eyes with the highest discrimination at the inner subfields (areas under the curve, AUC=0.96 for ORT and AUC=0.93 for MI). CONCLUSIONS: Quantitative analysis of OCT scans revealed significant differences between eyes with and without toxicity in two different measures. Each individual metric could discriminate between the unaffected and the lowest severity category, suggesting their potential utility in screening for HCQ toxicity in patients at risk.

Effect of hydroxychloroquine or chloroquine and short wavelength light on in vivo retinal function and structure in mouse eyes.

CLINICAL RELEVANCE: The use of chloroquine or hydroxychloroquine can lead to both acute and chronic changes to both retinal structure and function. BACKGROUND: Chloroquine (CQ) and hydroxychloroquine (HCQ) have the potential for retina toxicity. The acute impact of short-term drug exposure (2-4 weeks) on in vivo retinal structure and function and assess whether short wavelength light exposure further exacerbates any structural and functional changes was assessed in a murine model. METHODS: Adult C57BL/6 J mice received intraperitoneal injection of vehicle or hydroxychloroquine (10 mg/kg) 3 times per week for 2 or 4 weeks, or chloroquine for 4 weeks (10 mg/kg). Over this period, animals were exposed to room light (8 hours) or short-wavelength light 4 hours per day (4 hours of normal room light) for 5 days each week. Retinal changes were assessed using electroretinography (ERG), in vivo optical coherence tomography (OCT) imaging. RESULTS: Short-term low-dose HCQ and CQ treatment led to RPE thickening and elongation of photoreceptors. These structural changes were associated with a no dysfunction in the case of HCQ treatments and widespread functional changes (photoreceptor sensitivity, bipolar cell amplitude and oscillatory potential amplitude) in the case of CQ treatment. Exposure to low intensity short-wavelength light does not appear to alter the effect of HCQ or CQ. CONCLUSIONS: HCQ and CQ treatment has acute effects on both retinal structure and function, effects that were not exacerbated by short wavelength light exposure. Whether chronic short wavelength light exposure exacerbates these changes require further study.

"En Face" Spectral-Domain Optical Coherence Tomography versus Multifocal Electroretinogram in Hydroxychloroquine Retinopathy Screening.

INTRODUCTION: The performance of "en face" optical coherence tomography (OCT) in screening for chloroquine (CQ) or hydroxychloroquine (HCQ) retinopathy has not been largely explored. The aim of this study was to determine the concordance of "en face" OCT with multifocal electroretinography (mfERG) in screening for CQ/HCQ retinopathy. METHODS: This is a prospective cohort study conducted at the Rothschild Foundation Hospital, Paris, between August 2016 and February 2021. Patients taking HCQ were followed up over 2 consecutive years and received an "en face" OCT and a mfERG on each visit. RESULTS: A total of 91 patients (182 eyes) were analyzed. mfERG and "en face" OCT were concordant in 147 eyes (86.3%). Cohen's kappa coefficient for concordance between mfERG and "en face" OCT was considered weak with a value 0.61 (95% CI: 0.50-0.72). The sensitivity and specificity of "en face" OCT were 70% (95% CI: 59-79%) and 91% (95% CI: 83-96%), respectively, relatively to mfERG. Proportion of abnormal R2/R5 and R3/R5 ratios did not differ between patients with normal and abnormal "en face" OCT (p = 0.2). DISCUSSION: "En face" OCT and mfERG have low concordance and cannot be used interchangeably as each investigation evaluates a different facet of CQ/HCQ retinopathy. "En face" OCT could be used as a complement in screening for CQ/HCQ retinal toxicity if the anomalies detected on "en face" OCT are confirmed by B-scan OCT sections.

Toxicology evaluation of overdose hydroxychloroquine on zebrafish (Danio rerio) embryos.

Potential risks of treatment with hydroxychloroquine (HCQ) include QT interval prolongation, hypoglycemia, a wide range of neuropsychiatric manifestations, hematotoxicity, and potential genetic defects. HCQ is extremely toxic when used in overdose and can lead to tachycardia, hypotension, known central nervous system, transmission defects, hypokalemia and other manifestations in individuals. The mechanism of excessive HCQ leading to these manifestations is still unclear. In this paper, overdose HCQ at different concentrations was used to treat zebrafish embryos, and the phenomena like human beings were obtained, such as increased heart rate and nervous system inhibition. With the increase of concentration to 100 µM, embryo mortality and malformation rate increased and hatching rate decreased, in situ hybridization showed abnormal differentiation of embryo germ layers and formation of vital organs. We selected embryos treated with 50 µM HCQ, in which concentration the mortality rate, hatching rate and malformation rate of the embryos were like those of the control group, for transcriptome analysis. Although the above indexes did not change significantly, the molecular changes related to the development of the heart, eye, nerve and other important organs were significant. This study provides useful information for further research on the toxicity mechanism of HCQ overdose, and provides some insight that can guide future studies in humans.

Machine Learning-Based Automated Detection of Hydroxychloroquine Toxicity and Prediction of Future Toxicity Using Higher-Order OCT Biomarkers.

OBJECTIVE: Despite guidelines for hydroxychloroquine (HCQ) toxicity screening, there are clear challenges to accurate detection and interpretation. In the current report, the feasibility of automated machine learning (ML)-based detection of HCQ retinopathy and prediction of progression to toxicity in eyes without preexisting toxicity has been described. DESIGN: Retrospective, longitudinal cohort study. SUBJECTS: Subjects on HCQ therapy. METHODS: This was an institutional review board-approved, retrospective, longitudinal image analysis of 388 subjects on HCQ. Multilayer, compartmental, retinal segmentation with ellipsoid zone (EZ) mapping was used to harvest quantitative spectral-domain (SD)-OCT biomarkers. Using a combination of clinical features (i.e., cumulative HCQ dose and the duration of therapy) and quantitative imaging biomarkers (e.g., volumetric EZ integrity and compartmental measurements), ML models were created to detect toxicity and predict progression based on ground-truth OCT-based toxicity readings by 2 masked retina specialists. Furthermore, 10-fold cross-validation was performed. MAIN OUTCOME MEASURES: The model performance was visualized using receiver operator curves and calculating the area under the curve (AUC). The corresponding sensitivity and specificity values were evaluated for the feasibility of HCQ toxicity screening and prediction. RESULTS: The prevalence of HCQ toxicity in this cohort of 388 patients was 9.8% (n = 38). Twenty-one eyes progressed to toxicity during follow-up. OCT-based features (i.e., partial EZ attenuation, EZ volume, outer nuclear layer volume, and compartmental thicknesses) and clinical features (i.e., HCQ daily dose, HCQ cumulative dose, and duration of therapy) showed significant differences between the toxic and nontoxic groups. Percentage area with partial EZ attenuation (i.e., percentage of the macula with an EZ-retinal pigment epithelium thickness of ≤ 20 µm) was the most discriminating single feature (toxic, 35.7 ± 46.5%; nontoxic, 1.8 ± 4.4%; P < 0.0001). Using a random forest model, high-performance, automated toxicity detection was achieved, with a mean AUC of 0.97, sensitivity of 95%, and specificity of 91%. Furthermore, the toxicity progression prediction model had a mean AUC of 0.89, with a sensitivity and specificity of 90% and 80%, respectively. CONCLUSIONS: This report described the feasibility of high-performance automated classification models that used a combination of clinical and quantitative SD-OCT biomarkers to detect HCQ retinal toxicity and predict progression to toxicity in cases without toxicity. Future work is needed to validate these findings in an independent dataset.

Pulmonary Delivery of Aerosolized Chloroquine and Hydroxychloroquine to Treat COVID-19: In Vitro Experimentation to Human Dosing Predictions.

In vitro screening for pharmacological activity of existing drugs showed chloroquine and hydroxychloroquine to be effective against severe acute respiratory syndrome coronavirus 2. Oral administration of these compounds to obtain desired pulmonary exposures resulted in dose-limiting systemic toxicity in humans. However, pulmonary drug delivery enables direct and rapid administration to obtain higher local tissue concentrations in target tissue. In this work, inhalable formulations for thermal aerosolization of chloroquine and hydroxychloroquine were developed, and their physicochemical properties were characterized. Thermal aerosolization of 40 mg/mL chloroquine and 100 mg/mL hydroxychloroquine formulations delivered respirable aerosol particle sizes with 0.15 and 0.33 mg per 55 mL puff, respectively. In vitro toxicity was evaluated by exposing primary human bronchial epithelial cells to aerosol generated from Vitrocell. An in vitro exposure to 7.24 µg of chloroquine or 7.99 µg hydroxychloroquine showed no significant changes in cilia beating, transepithelial electrical resistance, and cell viability. The pharmacokinetics of inhaled aerosols was predicted by developing a physiologically based pharmacokinetic model that included a detailed species-specific respiratory tract physiology and lysosomal trapping. Based on the model predictions, inhaling emitted doses comprising 1.5 mg of chloroquine or 3.3 mg hydroxychloroquine three times a day may yield therapeutically effective concentrations in the lung. Inhalation of higher doses further increased effective concentrations in the lung while maintaining lower systemic concentrations. Given the theoretically favorable risk/benefit ratio, the clinical significance for pulmonary delivery of aerosolized chloroquine and hydroxychloroquine to treat COVID-19 needs to be established in rigorous safety and efficacy studies. Graphical abstract.

Acute and subacute oral toxicity of artemisinin-hydroxychloroquine sulfate tablets in rats.

Artemisinin-hydroxychloroquine sulfate tablets (AH) are considered a relatively inexpensive and novel combination therapy for treating all forms of malaria, especially aminoquinoline drugs-resistant strains of P.falciparum. We aim to carry out acute and subacute oral toxicity studies in rats to acquire preclinical data on the safety of AH. Acute toxicity was evaluated in Sprague-Dawley (SD) rats at a single dose of 1980, 2970, 4450, 6670, and 10000 mg/kg. A 14-days subacute toxicity was assessed in SD rats at doses of 0, 146, 219, 328, and 429 mg/kg. The median lethal dose (LD50) of acute oral administration of AH in rats is found to be 3119 mg/kg, and toxic symptoms include decreased spontaneous activity, dyspnea, bristling, soft feces, spasticity, and convulsion. Repeated doses of AH have toxic effects on the nervous system, skin, blood system, liver, kidney, and spleen in rats. The main toxic reactions include epilation, emaciation, mental irritability, decreased body weight gain and food consumption, changes in the hematological and biochemical parameters, especially pathological lesions in the liver, kidney, and spleen. The no-observed-adverse-effect level (NOAEL) and lowest-observed-adverse-effect level (LOAEL) of AH are considered to be 219 mg/kg and 328 mg/kg, respectively.

New insights in pathogenic mechanism of hydroxychloroquine retinal toxicity through optical coherence tomography angiography analysis.

INTRODUCTION: There is only a unique report with a small sample size studying hydroxychloroquine (HCQ) retinal toxicity with swept-source (SS) optical coherence tomography angiography (OCTA). The aim of this study was to quantify OCTA quantitative parameters in patients who underwent HCQ therapy. METHODS: We conducted a retrospective study. The study included 43 eyes of 22 patients taking HCQ for more than 5 years (high-risk group), 57 eyes of 29 patients taking HCQ for 5 years or less (low-risk group) and 25 eyes of 50 age-matched healthy controls. OCTA quantitative parameters (vessel density (VD) and foveal avascular zone (FAZ) area in superficial capillary plexus (SCP), middle capillary plexus (MCP), deep capillary plexus (DCP), total capillary plexus (TCP), and choriocapillaris (CC)) were recorded. RESULTS: In the low-risk group, VD in the SCP and MCP was increased compared to control group (p value <.05). In the high-risk group, VD in the SCP, MCP and TCP was increased (p value <.05). The subgroup analysis revealed an increased VD at SCP in systemic lupus erythematosus (SLE) high-risk patients, an increased VD at TCP and CC in rheumatoid arthritis (RA) high-risk subjects, and a decreased VD at CC level in the high-risk group patients with Sjögren's syndrome (SS) and connective tissue disease (CTD) (p value <.05). Furthermore, we demonstrated a significant enlargement of FAZ area at MCP level in the high-risk group patients with SS and CTD (p value <.05). CONCLUSION: We demonstrated an increase of VD in patients who underwent HCQ treatment, so we suggest that HCQ retinal toxicity is not vascular mediated.

A novel 5-ring multifocal electroretinography stimulus for detecting hydroxychloroquine retinal toxicity.

PURPOSE: Multifocal electroretinogram (mfERG) shows great utility as a screening tool to detect early hydroxychloroquine (HCQ) retinopathy, but its widespread use is limited by the lack of accessibility and long test duration. In this study, we evaluated a novel concentric 5-ring mfERG stimulus to provide a simplified and rapid protocol for screening HCQ toxicity. METHODS: Patients referred for HCQ retinopathy screening were consented to this observational cross-sectional study. Patients with amblyopia, high refractive error (more than 8 diopters), other retinal diseases precluding appropriate evaluation or history of retinal surgery were excluded. The data were collected from patients undergoing HCQ screening at a single center from July 2019 to March 2020. Patients were tested with the new concentric 5-ring mfERG stimulus, standard 61-hexagon mfERG stimulus, spectral domain optical coherence tomography and automated 10-2 visual fields. For the main outcome, the 5-ring mfERG was compared to 61-hexagon stimulus to determine the time-to-test completion and assess the association between ring (R1-R5) amplitude and ring ratio compared against cumulative dose, dose by real body weight and duration of therapy using Pearson correlation. RESULTS: In total, 52 patients (104 eyes; 5 males and 47 females) were recruited with a mean age of 59 years (range 23-85 years). The 5-ring protocol was markedly quicker to perform (1.3 ± 0.2 min; mean (SD)) compared to the 61-hexagon protocol (5.2 ± 0.6 min), p < 0.0001; n = 10 patients. The new R2/R5 ring ratio showed a moderate correlation with daily dose (r = - 0.640), cumulative dose (r = - 0.581) and duration of therapy (r = - 0.417). Similar correlations were observed with the new R2/R4 ring ratio which were not significantly different from the new R2/R5 correlation coefficients. The new R2/R5 ring ratio demonstrated a stronger correlation with daily (p = 0.002) and cumulative dose (p = 0.0001) compared to the 61-hexagon stimulus. CONCLUSIONS: In this exploratory study, our novel 5-ring mfERG protocol significantly shortened data acquisition time while providing comparable results to the standard 61-hexagon stimulus for detecting HCQ-induced electrophysiological changes that are correlated with HCQ dosages and treatment duration. Our protocol has the potential to be more clinically practical by simplifying routine screening.

Synthesis and evaluation of enantiomers of hydroxychloroquine against SARS-CoV-2 in vitro.

Since the end of 2019, the outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has evolved into a global pandemic. There is an urgent need for effective and low-toxic antiviral drugs to remedy Remdesivir's limitation. Hydroxychloroquine, a broad spectrum anti-viral drug, showed inhibitory activity against SARS-CoV-2 in some studies. Thus, we adopted a drug repurposing strategy, and further investigated hydroxychloroquine. We obtained different configurations of hydroxychloroquine side chains by using chiral resolution technique, and successfully furnished R-/S-hydroxychloroquine sulfate through chemical synthesis. The R configuration of hydroxychloroquine was found to exhibit higher antiviral activity (EC50 = 3.05 µM) and lower toxicity in vivo. Therefore, R-HCQ is a promising lead compound against SARS-CoV-2. Our research provides new strategy for the subsequent research on small molecule inhibitors against SARS-CoV-2.

Ameliorating hydroxychloroquine induced retinal toxicity through cerium oxide nanoparticle treatments.

The present study investigated the potential protective effects of cerium oxide nanoparticles (CNP) on human retinal pigment epithelium (ARPE-19) cells damaged by hydroxychloroquine (HCQ). Toxicity of HCQ on the ARPE-19 cells was explored with a dose response trial. CNP rescue both a pre-treatment protocol, where CNP were applied 24 hours prior to HCQ application and a simultaneous treatment protocol where both CNP and HCQ were applied together, were used. In the dose response trial, 250 µM HCQ showed 51.84% cell viability after 24 hours and 32.75% after 48 hours time period. This was selected as model HCQ dose for rescue trials. The simultaneous treatment trials did not show a significant increase in viability compared to model toxic dose. The CNP pre-treatment trials showed a significant increase in cellular viability compared to model toxic dose with 68.03% ± 3.27 viability (p = 4.56E-05) at 24 hours and 51.85% ± 4.96 (p = 1.18E-05) at 48 hours time period. CNP pre-treatment showed significant protection of cells from HCQ induced toxicity. The difference in efficacy of simultaneous and pre-treatment is hypothesized to lie in the cellular localization of CNP. Furthermore, including the reactive oxygen species (ROS) scavenging properties of CNP seems to be responsible for protection, the effect of CNP on autophagosome and lysosome colocalization are also hypothesized to play a significant role.

Impact of Structural Changes on Multifocal Electroretinography in Patients With Use of Hydroxychloroquine.

Purpose: To investigate the relationship between retinal structure and macular function in eyes screened for hydroxychloroquine (HCQ) toxicity. Methods: Participants referred for hydroxychloroquine retinopathy screening with spectral domain optical coherence tomography (SD-OCT) and multifocal electroretinogram (mfERG) testing were included in the analysis. Amplitude and implicit time of mfERG N1 and P1 responses were included in the analysis. Ring ratios were computed for amplitude values as the ratio of rings 1-3:5 (R1-3:R5). A control group of healthy participants was included for comparison of SD-OCT metrics. Results: Sixty-three eyes screened for HCQ retinopathy and 30 control eyes were analyzed. The outer nuclear layer (ONL) was significantly thinner in HCQ patients in the foveal (P = 0.008), parafoveal (P < 0.0001), and perifoveal (P < 0.0001) regions. The HCQ cohort was further divided into two subgroups according to the presence of structural clinically detectable retinopathy (i.e., structural damage as detected by multimodal imaging). HCQ eyes without retinopathy had a thinner ONL thickness in the foveal (P = 0.032), parafoveal (P < 0.0001), and perifoveal (P < 0.0001) regions and a thinner inner nuclear layer (INL) in the parafoveal region (P = 0.045 versus controls). Structural changes in HCQ patients without retinopathy were significantly associated with macular function as R2:R5 ring ratio of mfERG P1 amplitude was associated with INL (P = 0.002) and ONL (P = 0.044) thicknesses, and R3:R5 ring ratio of P1 amplitude was associated with ONL thickness (P = 0.004). Conclusions: Our results suggest that structural alterations secondary to HCQ toxicity may occur in the absence of clinically detectable retinopathy, and this may reflect in an impaired macular function.