Chloroquine kills hair cells in zebrafish lateral line and murine cochlear cultures: Implications for ototoxicity

Preliminary insight on diarylpentanoids as potential antimalarials: In silico, in vitro pLDH and in vivo zebrafish toxicity assessment

Malaria remains a major public health problem worldwide, including in Southeast Asia. Chemotherapeutic agents such as chloroquine (CQ) are effective, but problems with drug resistance and toxicity have necessitated a continuous search for new effective antimalarial agents. Here we report on a virtual screening of ∼300 diarylpentanoids and derivatives, in search of potential Plasmodium falciparum lactate dehydrogenase (PfLDH) inhibitors with acceptable drug-like properties. Several molecules with binding affinities comparable to CQ were chosen for in vitro validation of antimalarial efficacy. Among them, MS33A, MS33C and MS34C are the most promising against CQ-sensitive (3D7) with EC50 values of 1.6, 2.5 and 3.1 μM, respectively. Meanwhile, MS87 (EC50 of 1.85 μM) shown the most active against the CQ-resistant Gombak A strain, and MS33A and MS33C the most effective P. knowlesi inhibitors (EC50 of 3.6 and 5.1 μM, respectively). The in vitro cytotoxicity of selected diarylpentanoids (MS33A, MS33C, MS34C and MS87) was tested on Vero mammalian cells to evaluate parasite selectivity (SI), showing moderate to low cytotoxicity (CC50 > 82 μM). In addition, MS87 exhibited a high SI and the lowest resistance index (RI), suggesting that MS87 may exert effective parasite inhibition with low resistance potential in the CQ-resistant P. falciparum strain. Furthermore, the in vivo toxicity of the molecules on early embryonic development, the cardiovascular system, heart rate, motor activity and apoptosis were assessed in a zebrafish animal model. The overall results indicate the preliminary potential of diarylpentanoids, which need further investigation for their development as new antimalarial agents.

A Box-Behnken design-based chemometric approach to optimize the sono-photodegradation of hydroxychloroquine in water media using the Fe(0)/S2O82-/UV system

The huge utilization of hydroxychloroquine in autoimmune infections led to an abnormal increment in its concentration in wastewater, which can pose a real risk to the environment, necessitating the development of a pretreatment technique. To do this, we are interested in researching how hydroxychloroquine degrades in contaminated water. The main goal of this investigation is to optimize the operating conditions for the sono-photodegradation of hydroxychloroquine in water using an ultrasound-assisted Fe(0)/S 2 O 8 2 - /UV system. To get adequate removal of HCQ, a chemometric method based on the Box-Behnken design was applied to optimize the influence of the empirical parameters selected, including Fe(0) dose,S 2 O 8 2 - concentration, pH, and initial HCQ concentration. The quadratic regression model representing the HCQ removal rate (η(%)) was evolved and validated by ANOVA. The optimal conditions as a result of the above-mentioned trade-off between the four input variables, with η(%) as the dependent output variable, were captured using RSM methodology and the composite desirability function approach. For HCQ full decomposition, the optimal values of the operating factors are as follows:S 2 O 8 2 - dose, 194.309 mg/L; Fe(0) quantity, 198.83 mg/L; pH = 2.017, and HCQ initial dose of 296.406 mg/L. Under these conditions, the HCQ removal rate, achieved after 60 min of reaction, attained 98.95%.

Zebrafish neuromast sensory system: Is it an emerging target to assess environmental pollution impacts?

Environmental pollution poses risks to ecosystems. Among these risks, one finds neurotoxicity and damage to the lateral line structures of fish, such as the neuromast and its hair cells. Zebrafish (Danio rerio) is recommended as model species to be used in ecotoxicological studies and environmental biomonitoring programs aimed at assessing several biomarkers, such as ototoxicity. However, little is known about the history of and knowledge gaps on zebrafish ototoxicity. Thus, the aim of the current study is to review data available in the scientific literature about using zebrafish as animal model to assess neuromast toxicity. It must be done by analyzing the history and publication category, world production, experimental design, developmental stages, chemical classes, neuromasts and hair cell visualization methods, and zebrafish strains. Based on the results, number, survival and fluorescence intensity of neuromasts, and their hair cells, were the parameters oftentimes used to assess ototoxicity in zebrafish. The wild AB strain was the most used one, and it was followed by Tübingen and transgenic strains with GFP markers. DASPEI was the fluorescent dye most often applied as method to visualize neuromasts, and it was followed by Yo-Pro-1 and GFP transgenic lines. Antibiotics, antitumorals, metals, nanoparticles and plant extracts were the most frequent classes of chemicals used in the analyzed studies. Overall, pollutants can harm zebrafish's mechanosensory system, as well as affect their behavior and survival. Results have shown that zebrafish is a suitable model system to assess ototoxicity induced by environmental pollution.

Multisensory strategies for postural compensation after lateral line loss

To control elevation underwater, aquatic vertebrates integrate multisensory information (e.g., vestibular, visual, proprioceptive) to guide posture and swim kinematics. Here we characterized how larval zebrafish changed posture and locomotive strategies after imposed instability (decreased buoyancy) in the presence and absence of visual cues. We discovered that larvae sank more after acute loss of lateral line (flow-sensing) hair cells. In response, larvae engaged different compensatory strategies, depending on whether they were in the light or dark. In the dark, larvae swam more frequently, engaging their trunk to steer their nose up and climb more effectively. However, in the light, larvae climbed more often, engaging both pectoral fins and trunk to elevate. We conclude that larvae sense instability and use vestibular and visual information as available to control posture and trajectory. Our work is a step towards understanding the multisensory neural computations responsible for control strategies that allow orientation and navigation in depth.

N-(coumarin-3-yl)cinnamamide Promotes Immunomodulatory, Neuroprotective, and Lung Function-Preserving Effects during Severe Malaria

Plasmodium berghei ANKA (PbA) infection in mice resembles several aspects of severe malaria in humans, such as cerebral malaria and acute respiratory distress syndrome. Herein, the effects of N-(coumarin-3-yl)cinnamamide (M220) against severe experimental malaria have been investigated. Treatment with M220 proved to protect cognitive abilities and lung function in PbA-infected mice, observed by an object recognition test and spirometry, respectively. In addition, treated mice demonstrated decreased levels of brain and lung inflammation. The production and accumulation of microglia, and immune cells that produce the inflammatory cytokines TNF and IFN-γ, decreased, while the production of the anti-inflammatory cytokine IL-10 by innate and adaptive immune cells was enhanced. Treatment with M220 promotes immunomodulatory, neuroprotective, and lung function-preserving effects during experimental severe malaria. Therefore, it may be an interesting therapeutic candidate to treat severe malaria effects.

Acute and Longer-Term Effects of COVID-19 on Auditory and Vestibular Symptoms

OBJECTIVE

To evaluate long-term effects of COVID-19 on auditory and vestibular symptoms in a diverse cohort impacted by the initial 2020 COVID-19 infection in the pandemic's epicenter, before vaccine availability.

STUDY DESIGN

Cohort study of individuals with confirmed COVID-19 infection, diagnosed in the March-May 2020 infection wave. A randomized, retrospective chart review of 1,352 individuals was performed to identify those with documented new or worsening auditory (aural fullness, tinnitus, hyperacusis, hearing loss) or vestibular (dizziness, vertigo) symptoms. Those with documented symptoms (613 of the 1,352 initial cohort) were contacted for a follow-up telephone survey in 2021-2022 to obtain self-report of aforementioned symptoms.

SETTING

Academic tertiary hospital system in Bronx, NY.

PATIENTS

Adults 18 to 99 years old with confirmed COVID-19 infection, alive at time of review. One hundred forty-eight charts were excluded for restricted access, incomplete data, no COVID-19 swab, or deceased at time of review.

INTERVENTION

Confirmed COVID-19 infection, March to May 2020.

MAIN OUTCOMES MEASURES

Auditory and vestibular symptoms documented in 2020 medical records and by self-report on 2021 to 2022 survey.

RESULTS

Among the 74 individuals with documented symptoms during the first 2020 COVID-19 wave who participated in the 2021 to 2022 follow-up survey, 58% had documented vestibular symptoms initially in 2020, whereas 43% reported vestibular symptoms on the 2021 to 2022 survey ( p = 0.10). In contrast, 9% had documented auditory symptoms initially in 2020 and 55% reported auditory symptoms on the 2021 to 2022 survey ( p < 0.01).

CONCLUSIONS

COVID-19 may impact vestibular symptoms early and persistently, whereas auditory effects may have more pronounced long-term impact, suggesting the importance of continually assessing COVID-19 patients.

Diclofenac, ibuprofen, and paracetamol biodegradation: overconsumed non-steroidal anti-inflammatories drugs at COVID-19 pandemic

The consumption of non-steroidal anti-inflammatory drugs (NSAIDs) have increased significantly in the last years (2020-2022), especially for patients in COVID-19 treatment. NSAIDs such as diclofenac, ibuprofen, and paracetamol are often available without restrictions, being employed without medical supervision for basic symptoms of inflammatory processes. Furthermore, these compounds are increasingly present in nature constituting complex mixtures discarded at domestic and hospital sewage/wastewater. Therefore, this review emphasizes the biodegradation of diclofenac, ibuprofen, and paracetamol by pure cultures or consortia of fungi and bacteria at in vitro, in situ, and ex situ processes. Considering the influence of different factors (inoculum dose, pH, temperature, co-factors, reaction time, and microbial isolation medium) relevant for the identification of highly efficient alternatives for pharmaceuticals decontamination, since biologically active micropollutants became a worldwide issue that should be carefully addressed. In addition, we present a quantitative bibliometric survey, which reinforces that the consumption of these drugs and consequently their impact on the environment goes beyond the epidemiological control of COVID-19.

Toxicological effects of hydroxychloroquine sulfate and chloroquine diphosphate substances on the early-life stages of fish in the COVID-19 pandemic context

Hydroxychloroquine sulfate (HCQ) and chloroquine diphosphate (CQ) have been used at increased rates to treat COVID-19 but can constitute a potential environmental risk. The objective was to evaluate the toxicity of sublethal concentrations of HCQ and CQ in zebrafish embryos/larvae. The 50% lethal concentrations (LC50) of HCQ and CQ at 96 h post-fertilization (hpf) were calculated by testing various concentrations on 2,160 embryos. The LC50 obtained were 560 and 800 µM for HCQ and CQ, respectively. Next, the embryotoxicity assay was performed, where 1,200 embryos were subjected to sublethal concentrations of HCQ and CQ. The hatching and heart rates were recorded. After euthanasia, photomicrographs of all larvae were taken to measure the total length, pericardial and yolk sac areas. The embryos exposed to sublethal concentrations of HCQ and CQ showed delayed hatching at 72 hpf, as well as an increase in the heart rate, larger pericardial and yolk sac areas, and body malformations at 96 hpf. The findings show that HCQ and CQ are toxic to fish in the early development phases. Understanding the mechanisms of toxicity will help extrapolate the effects of 4-aminoquinoline derivatives when they reach the aquatic environment in the context of the COVID-19 pandemic.

Hair cell toxicology: With the help of a little fish

Hearing or balance loss are disabling conditions that have a serious impact in those suffering them, especially when they appear in children. Their ultimate cause is frequently the loss of function of mechanosensory hair cells in the inner ear. Hair cells can be damaged by environmental insults, like noise or chemical agents, known as ototoxins. Two of the most common ototoxins are life-saving medications: cisplatin against solid tumors, and aminoglycoside antibiotics to treat infections. However, due to their localization inside the temporal bone, hair cells are difficult to study in mammals. As an alternative animal model, zebrafish larvae have hair cells similar to those in mammals, some of which are located in a fish specific organ on the surface of the skin, the lateral line. This makes them easy to observe in vivo and readily accessible for ototoxins or otoprotective substances. These features have made possible advances in the study of the mechanisms mediating ototoxicity or identifying new potential ototoxins. Most importantly, the small size of the zebrafish larvae has allowed screening thousands of molecules searching for otoprotective agents in a scale that would be highly impractical in rodent models. The positive hits found can then start the long road to reach clinical settings to prevent hearing or balance loss.

Slight High-Frequency Hearing Loss, Effect of COVID-19 or Hydroxychloroquine Usage?

BACKGROUND AND OBJECTIVES

Concerns about ototoxic and vestibulotoxic effects have been raised with the use of antiviruses in the treatment of COVID-19. This study aimed to determine the effect of hydroxychloroquine (HCQ) and examine the auditory system and its associated auditory and vestibular symptoms in patients with COVID-19.

STUDY DESIGN

Prospective study.

PATIENTS

Thirty patients with a history of HCQ (HCQ+) and 30 patients without drug use (HCQ-), and 30 healthy adults as the control group participated.

MAIN OUTCOME MEASURES

Audiological assessments and evaluation of audio-vestibular symptoms. Evaluations were also repeated 1 month later.

RESULTS

Both HCQ+ and HCQ- groups showed poor pure-tone audiometry (PTA) thresholds and decreased transient evoked otoacoustic emission amplitudes at high frequencies in comparison to the healthy group. Despite the lack of significant differences in PTA between the two groups of patients, the differences in transient evoked otoacoustic emission amplitudes were significant. PTA thresholds and otoacoustic emission showed improvement after 1 month. Dizziness was the most common symptom that was reduced after 1 month.

CONCLUSION

Slight hearing loss was seen in patients with COVID-19 with or without HCQ. Also, hearing thresholds in the HCQ+ group did not show a significant difference compared with the HCQ- group. Nevertheless, it seems that more damage is done to the hair cells of patients with HCQ intake than in other patients. Hence, the ototoxicity effect of high doses of HCQ use in the COVID-19 patients should be considered. A relative improvement in the hearing was seen over time in both patient groups.

The Pathological Mechanisms of Hearing Loss Caused by KCNQ1 and KCNQ4 Variants

Deafness-associated genes KCNQ1 (also associated with heart diseases) and KCNQ4 (only associated with hearing loss) encode the homotetrameric voltage-gated potassium ion channels Kv7.1 and Kv7.4, respectively. To date, over 700 KCNQ1 and over 70 KCNQ4 variants have been identified in patients. The vast majority of these variants are inherited dominantly, and their pathogenicity is often explained by dominant-negative inhibition or haploinsufficiency. Our recent study unexpectedly identified cell-death-inducing cytotoxicity in several Kv7.1 and Kv7.4 variants. Elucidation of this cytotoxicity mechanism and identification of its modifiers (drugs) have great potential for aiding the development of a novel pharmacological strategy against many pathogenic KCNQ variants. The purpose of this review is to disseminate this emerging pathological role of Kv7 variants and to underscore the importance of experimentally characterizing disease-associated variants.

Putative COVID-19 therapies imatinib, lopinavir, ritonavir, and ivermectin cause hair cell damage: A targeted screen in the zebrafish lateral line

The biomedical community is rapidly developing COVID-19 drugs to bring much-need therapies to market, with over 900 drugs and drug combinations currently in clinical trials. While this pace of drug development is necessary, the risk of producing therapies with significant side-effects is also increased. One likely side-effect of some COVID-19 drugs is hearing loss, yet hearing is not assessed during preclinical development or clinical trials. We used the zebrafish lateral line, an established model for drug-induced sensory hair cell damage, to assess the ototoxic potential of seven drugs in clinical trials for treatment of COVID-19. We found that ivermectin, lopinavir, imatinib, and ritonavir were significantly toxic to lateral line hair cells. By contrast, the approved COVID-19 therapies dexamethasone and remdesivir did not cause damage. We also did not observe damage from the antibiotic azithromycin. Neither lopinavir nor ritonavir altered the number of pre-synaptic ribbons per surviving hair cell, while there was an increase in ribbons following imatinib or ivermectin exposure. Damage from lopinavir, imatinib, and ivermectin was specific to hair cells, with no overall cytotoxicity noted following TUNEL labeling. Ritonavir may be generally cytotoxic, as determined by an increase in the number of TUNEL-positive non-hair cells following ritonavir exposure. Pharmacological inhibition of the mechanotransduction (MET) channel attenuated damage caused by lopinavir and ritonavir but did not alter imatinib or ivermectin toxicity. These results suggest that lopinavir and ritonavir may enter hair cells through the MET channel, similar to known ototoxins such as aminoglycoside antibiotics. Finally, we asked if ivermectin was ototoxic to rats in vivo. While ivermectin is not recommended by the FDA for treating COVID-19, many people have chosen to take ivermectin without a doctor’s guidance, often with serious side-effects. Rats received daily subcutaneous injections for 10 days with a clinically relevant ivermectin dose (0.2 mg/kg). In contrast to our zebrafish assays, ivermectin did not cause ototoxicity in rats. Our research suggests that some drugs in clinical trials for COVID-19 may be ototoxic. This work can help identify drugs with the fewest side-effects and determine which therapies warrant audiometric monitoring.

Identifying targets to prevent aminoglycoside ototoxicity

Aminoglycosides are potent antibiotics that are commonly prescribed worldwide. Their use carries significant risks of ototoxicity by directly causing inner ear hair cell degeneration. Despite their ototoxic side effects, there are currently no approved antidotes. Here we review recent advances in our understanding of aminoglycoside ototoxicity, mechanisms of drug transport, and promising sites for intervention to prevent ototoxicity.

Progress in using zebrafish as a toxicological model for traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) has been applied for more than 2000 years. However, modern basic research on the safety of TCMs is limited. Establishing safety evaluation technology in line with the characteristics of TCM and conducting large-scale basic toxicity research are keys to comprehensively understand the toxicity of TCMs. In recent years, zebrafish has been used as a model organism for toxicity assessment and is increasingly utilized for toxicity research of TCMs. Yet, a comprehensive review in using zebrafish as a toxicological model for TCMs is lacked.

AIM OF THE STUDY

We aim to summarize the progress and limitation in toxicity evaluation of TCMs using zebrafish and put forward the future research ideas.

MATERIALS AND METHODS

The scientific databases, including Springer, Science Direct, Wiley, Pubmed and China Knowledge Resource Integrated (CNKI) were searched using the key words of zebrafish, toxicology, traditional Chinese medicine, acute toxicity, liver injury, cardiotoxicity, kidney toxicity, developmental toxicity, neurotoxicity, gastrointestinal irritation, immunotoxicity, ototoxicity, and osteotoxicity.

RESULTS

Zebrafish assays are low experimental cost and short cycle, easily achieving high-throughput toxicity screening, and exemption from ethical legislation up to 5 dpf. It has been widely used to evaluate the acute toxicity, liver toxicity, cardiotoxicity, nephrotoxicity, developmental toxicity, neurotoxicity, gastrointestinal irritation, immunotoxicity, and ototoxicity caused by TCMs, although some physiological difference limited its application.

CONCLUSIONS

Zebrafish is a powerful model for TCMs toxicity evaluation, but it is not flawless. The toxicity testing criterion and high throughput assays are urgent to be established. This review provides references for future studies.

Cell death-inducing cytotoxicity in truncated KCNQ4 variants associated with DFNA2 hearing loss

KCNQ4 encodes the homotetrameric voltage-dependent potassium ion channel Kv7.4, and is the causative gene for autosomal dominant nonsyndromic sensorineural hearing loss, DFNA2. Dominant-negative inhibition accounts for the observed dominant inheritance of many DFNA2-associated KCNQ4 variants. In addition, haploinsufficiency has been presumed as the pathological mechanism for truncated Kv7.4 variants lacking the C-terminal tetramerization region, as they are unlikely to exert a dominant-negative inhibitory effect. Such truncated Kv7.4 variants should result in relatively mild hearing loss when heterozygous; however, this is not always the case. In this study, we characterized Kv7.4^Q71fs (c.211delC), Kv7.4^W242X (c.725G>A) and Kv7.4^A349fs (c.1044_1051del8) in heterologous expression systems and found that expression of these truncated Kv7.4 variants induced cell death. We also found similar cell death-inducing cytotoxic effects in truncated Kv7.1 (KCNQ1) variants, suggesting that the generality of our findings could account for the dominant inheritance of many, if not most, truncated Kv7 variants. Moreover, we found that the application of autophagy inducers can ameliorate the cytotoxicity, providing a novel insight for the development of alternative therapeutic strategies for Kv7.4 variants.

Summary: Expression of truncated KCNQ4 variants lacking the C-terminal tetramerization domain results in cell-death inducing cytotoxicity, providing novel insight into the development of alternative therapeutic strategies for DFNA2 hearing loss.

Candidate antiviral drugs for COVID-19 and their environmental implications: a comprehensive analysis

Emerging from Wuhan, China, SARS-CoV-2 is the new global threat that killed millions of people, and many are still suffering. This pandemic has not only affected people but also caused economic crisis throughout the world. Researchers have shown good progress in revealing the molecular insights of SARS-CoV-2 pathogenesis and developing vaccines, but effective treatment against SARS-CoV-2-infected patients are yet to be found. Several vaccines are available and used in many countries, while many others are still in clinical or preclinical studies. However, this involves a long-term process, considering the safety procedures and requirements and their long-term protection capacity and in different age groups are still questionable. Therefore, at present, the drug repurposing of the existing therapeutics previously designed against other viral diseases seems to be the only practical approach to mitigate the current situation. The safety of most of these therapeutic agents has already been tested. Recent clinical reports revealed promising therapeutic efficiency of several drugs such as remdesivir, tenofovir disoproxil fumarate, azithromycin, lopinavir/ritonavir, chloroquine, baricitinib, and cepharanthine. Besides, plasma therapies were used to treat patients and prevent fatal outcomes. Thus, in this article, we have summarized the epidemiological and clinical data from several clinical trials conducted since the beginning of the pandemic, emphasizing the efficiency of the known agents against SARS-CoV-2 and their harmful side effects on the human body as well as their environmental implications. This review shows a clear overview of the current pharmaceutical perspective on COVID-19 treatment.

Environmental impacts of COVID-19 treatment: Toxicological evaluation of azithromycin and hydroxychloroquine in adult zebrafish

One of the most impact issues in recent years refers to the COVID-19 pandemic, the consequences of which thousands of deaths recorded worldwide, are still inferior understood. Its impacts on the environment and aquatic biota constitute a fertile field of investigation. Thus, to predict the impact of the indiscriminate use of azithromycin (AZT) and hydroxychloroquine (HCQ) in this pandemic context, we aim to assess their toxicological risks when isolated or in combination, using zebrafish (Danio rerio) as a model system. In summary, we observed that 72 h of exposure to AZT and HCQ (alone or in binary combination, both at 2.5 μg/L) induced the reduction of total protein levels, accompanied by increased levels of thiobarbituric acid reactive substances, hydrogen peroxide, reactive oxygen species and nitrite, suggesting a REDOX imbalance and possible oxidative stress. Molecular docking analysis further supported this data by demonstrating a strong affinity of AZT and HCQ with their potential antioxidant targets (catalase and superoxide dismutase). In the protein-protein interaction network analysis, AZT showed a putative interaction with different cytochrome P450 molecules, while HCQ demonstrated interaction with caspase-3. The functional enrichment analysis also demonstrated diverse biological processes and molecular mechanisms related to the maintenance of REDOX homeostasis. Moreover, we also demonstrated an increase in the AChE activity followed by a reduction in the neuromasts of the head when zebrafish were exposed to the mixture AZT + HCQ. These data suggest a neurotoxic effect of the drugs. Altogether, our study demonstrated that short exposure to AZT, HCQ or their mixture induced physiological alterations in adult zebrafish. These effects can compromise the health of these animals, suggesting that the increase of AZT and HCQ due to COVID-19 pandemic can negatively impact freshwater ecosystems.

Detecting Novel Ototoxins and Potentiation of Ototoxicity by Disease Settings

Over 100 drugs and chemicals are associated with permanent hearing loss, tinnitus, and vestibular deficits, collectively known as ototoxicity. The ototoxic potential of drugs is rarely assessed in pre-clinical drug development or during clinical trials, so this debilitating side-effect is often discovered as patients begin to report hearing loss. Furthermore, drug-induced ototoxicity in adults, and particularly in elderly patients, may go unrecognized due to hearing loss from a variety of etiologies because of a lack of baseline assessments immediately prior to novel therapeutic treatment. During the current pandemic, there is an intense effort to identify new drugs or repurpose FDA-approved drugs to treat COVID-19. Several potential COVID-19 therapeutics are known ototoxins, including chloroquine (CQ) and lopinavir-ritonavir, demonstrating the necessity to identify ototoxic potential in existing and novel medicines. Furthermore, several factors are emerging as potentiators of ototoxicity, such as inflammation (a hallmark of COVID-19), genetic polymorphisms, and ototoxic synergy with co-therapeutics, increasing the necessity to evaluate a drug's potential to induce ototoxicity under varying conditions. Here, we review the potential of COVID-19 therapies to induce ototoxicity and factors that may compound their ototoxic effects. We then discuss two models for rapidly detecting the potential for ototoxicity: mammalian auditory cell lines and the larval zebrafish lateral line. These models offer considerable value for pre-clinical drug development, including development of COVID-19 therapies. Finally, we show the validity of in silico screening for ototoxic potential using a computational model that compares structural similarity of compounds of interest with a database of known ototoxins and non-ototoxins. Preclinical screening at in silico, in vitro, and in vivo levels can provide an earlier indication of the potential for ototoxicity and identify the subset of candidate therapeutics for treating COVID-19 that need to be monitored for ototoxicity as for other widely-used clinical therapeutics, like aminoglycosides and cisplatin.

Hydroxychloroquine in COVID-19: therapeutic promises, current status, and environmental implications

The outbreak of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected the entire world with its infectious spread and mortality rate. The severe cases of coronavirus disease 2019 (COVID-19) are characterized by hypoxia and acute respiratory distress syndrome. In the absence of any specific treatment, just the preventive and supportive care options are available. Therefore, much focus is given to assess the available therapeutic options not only to avoid acute respiratory failure and hypoxia but also to reduce the viral load to control the severity of the disease. The antimalarial drug hydroxychloroquine (HCQ) is among the much-discussed drugs for the treatment and management of COVID-19 patients. This article reviews the therapeutic potential of HCQ in the treatment of COVID-19 based on the available in vitro and clinical evidence, current status of registered HCQ-based clinical trials investigating therapeutic options for COVID-19, and environmental implications of HCQ.

The Ototoxicity of Antimalarial Drugs-A State of the Art Review

This review summarizes current knowledge about the occurrence of hearing and balance disorders after antimalarial drugs treatment. It also examines the clinical applications of antimalarials, their mechanisms behind this ototoxicity and how it can be monitored. It includes studies with larger numbers of patients and those in which auditory function was assessed using audiological tests. Some antimalarials have been repurposed for other conditions like autoimmune disorders, rheumatic diseases, some viral diseases and cancers. While old antimalarial drugs, such as quinoline derivatives, are known to demonstrate ototoxicity, a number of new synthetic antimalarial agents particularly artemisinin derivatives, demonstrate unknown ototoxicity. Adverse audiovestibular effects vary depending on the medication itself, its dose and route of administration, as well as the drug combination, treated disease and individual predispositions of the patient. Dizziness was commonly reported, while vestibular symptoms, hearing loss and tinnitus were observed much less frequently, and most of these symptoms were reversible. As early identification of ototoxic hearing loss is critical to introducing possible alternative treatments with less ototoxic medications, therefore monitoring systems of those drugs ototoxic side effects are much needed.