Hydroxychloroquine for Treatment of SARS-CoV-2 Infection? Improving Our Confidence in a Model-Based Approach to Dose Selection

The In Vitro, In Vivo, and PBPK Evaluation of a Novel Lung-Targeted Cardiac-Safe Hydroxychloroquine Inhalation Aerogel

Hydroxychloroquine (HCQ) was repurposed for COVID-19 treatment. Subtherapeutic HCQ lung levels and cardiac toxicity of oral HCQ were overcome by intratracheal (IT) administration of lower HCQ doses. The crosslinker-free supercritical fluid technology (SFT) produces aerogels and impregnates them with drugs in their amorphous form with efficient controlled release. Mechanistic physiologically based pharmacokinetic (PBPK) modeling can predict the lung's epithelial lining fluid (ELF) drug levels. This study aimed to develop a novel HCQ SFT formulation for IT administration to achieve maximal ELF levels and minimal cardiac toxicity. HCQ SFT formulation was prepared and evaluated for physicochemical, in vitro release, pharmacokinetics, and cardiac toxicity. Finally, the rat HCQ ELF concentrations were predicted using PBPK modeling. HCQ was amorphous after loading into the chitosan-alginate nanoporous microparticles (22.7±7.6 μm). The formulation showed a zero-order release, with only 40% released over 30 min compared to 94% for raw HCQ. The formulation had a tapped density of 0.28 g/cm3 and a loading efficiency of 35.3±1.3%. The IT administration of SFT HCQ at 1 mg/kg resulted in 23.7-fold higher bioavailability, fourfold longer MRT, and eightfold faster absorption but lower CK-MB and LDH levels than oral raw HCQ at 4 mg/kg. The PBPK model predicted 6 h of therapeutic ELF levels for IT SFT HCQ and a 100-fold higher ELF-to-heart concentration ratio than oral HCQ. Our findings support the feasibility of lung-targeted and more effective SFT HCQ IT administration for COVID-19 compared to oral HCQ with less cardiac toxicity. Graphical abstract.

Recent Advances in Inhaled Nanoformulations of Vaccines and Therapeutics Targeting Respiratory Viral Infections

With the rapid outbreak of respiratory viral infections, various biological (e.g. vaccines, peptides, recombinant proteins, antibodies and genes) and antiviral agents (e.g. ribavirin, palivizumab and valaciclovir) have been successfully developed for the treatment of respiratory virus infections such as influenza, respiratory syncytial virus and SARS-CoV-2 infections. These therapeutics are conventionally delivered via oral, intramuscular or injection route and are associated with several adverse events due to systemic toxicity. The inherent in vivo instability of biological therapeutics may hinder them from being administered without proper formulations. Therefore, we have witnessed a boom in nanotechnology coupled with a needle-free administration approach such as the inhalation route for the delivery of complex therapeutics to treat respiratory infections. This review discussed the recent advances in the inhalation strategies of nanoformulations that target virus respiratory infections.

The investigation of the complex population-drug-drug interaction between ritonavir-boosted lopinavir and chloroquine or ivermectin using physiologically-based pharmacokinetic modeling

OBJECTIVES

Therapy failure caused by complex population-drug-drug (PDDI) interactions including CYP3A4 can be predicted using mechanistic physiologically-based pharmacokinetic (PBPK) modeling. A synergy between ritonavir-boosted lopinavir (LPVr), ivermectin, and chloroquine was suggested to improve COVID-19 treatment. This work aimed to study the PDDI of the two CYP3A4 substrates (ivermectin and chloroquine) with LPVr in mild-to-moderate COVID-19 adults, geriatrics, and pregnancy populations.

METHODS

The PDDI of LPVr with ivermectin or chloroquine was investigated. Pearson's correlations between plasma, saliva, and lung interstitial fluid (ISF) levels were evaluated. Target site (lung epithelial lining fluid [ELF]) levels of ivermectin and chloroquine were estimated.

RESULTS

Upon LPVr coadministration, while the chloroquine plasma levels were reduced by 30, 40, and 20%, the ivermectin plasma levels were increased by a minimum of 425, 234, and 453% in adults, geriatrics, and pregnancy populations, respectively. The established correlation equations can be useful in therapeutic drug monitoring (TDM) and dosing regimen optimization.

CONCLUSIONS

Neither chloroquine nor ivermectin reached therapeutic ELF levels in the presence of LPVr despite reaching toxic ivermectin plasma levels. PBPK modeling, guided with TDM in saliva, can be advantageous to evaluate the probability of reaching therapeutic ELF levels in the presence of PDDI, especially in home-treated patients.

Safety, Tolerability, and Pharmacokinetics of Nebulized Hydroxychloroquine: A Pilot Study in Healthy Volunteers

Background: Early in the coronavirus disease 2019 (COVID-19) pandemic, hydroxychloroquine (HCQ) drew substantial attention as a potential COVID-19 treatment based on its antiviral and immunomodulatory effects in vitro. However, HCQ showed a lack of efficacy in vivo, and different groups of researchers attributed this failure to the insufficient drug concentration in the lung following oral administration (HCQ is only available in the market in the tablet form). Delivering HCQ by inhalation represents a more efficient route of administration to increase HCQ exposure in the lungs while minimizing systemic toxicity. In this pilot study, the safety, tolerability, and pharmacokinetics of HCQ nebulizer solution were evaluated in healthy volunteers. Methods: Twelve healthy participants were included in this study and were administered 2 mL of HCQ01 solution (equivalent to 25 mg of HCQ sulfate) through Aerogen^® Solo, a vibrating mesh nebulizer. Local tolerability and systemic safety were assessed by forced expiratory volume in the first and second electrocardiograms, clinical laboratory results (e.g., hematology, biochemistry, and urinalysis), vital signs, and physical examinations. Thirteen blood samples were collected to determine HCQ01 systemic exposure before and until 6 hours after inhalation. Results: The inhalation of HCQ01 was well tolerated in all participants. The mean value of C_max for the 12 participants was 9.66 ng/mL. T_max occurred at around 4.8 minutes after inhalation and rapidly decreased thereafter. The reported systemic exposure was very low with a mean value of 5.28 (0.6-15.6) ng·h/mL. Conclusion: The low systemic concentrations of HCQ01 of 9.66 ng/mL reported by our study compared with 1 μg/mL previously predicted after 200 mg BID oral administration, and the safety and tolerability of HCQ01 administered as a single dose through nebulization, support the assessment of its efficacy, safety, and tolerability in further studies for the treatment of COVID-19.

Study on Hydroxychloroquinine Sulfate Being Given to the Admitted COVID -19 Positive Patients at Institute of JLNMCH, Bhagalpur, Bihar, India

Background

As the global death toll from new coronavirus illness (COVID-19) rises, the scientific community and healthcare systems are under massive pressure to manage the outbreak and develop effective medical remedies. Meanwhile, desperation has pushed practitioners, scientists, and authorities to recommend and attempt medicines with little or no proof. Despite the lack of clear and unequivocal facts supporting its efficacy and safety, hydroxychloroquine-sulfate (HCQS) has recently received substantial public and political interest in treating and prophylaxis new infectious diseases COVID-19.

Aim

To analyze the impact of HCQS in COVID-19-positive patients admitted at tertiary level government-owned Jawaharlal Nehru Medical College and Hospital (JLNMCH, Bhagalpur) Bihar.

Methods

Two hundred two RT-PCR-positive COVID-19 patients were included in this research. The study participants were randomly distributed into the intervention category and control category, each consisting of 101 study subjects. Study participants in the intervention category were administered hydroxychloroquine in 200 mg tablets. The control category was given placebo tablets that looked similar to tablets of hydroxychloroquine and were given in the same pattern. Chest X-ray PA view, 12 lead ECG, baseline hemogram including a concentration of CD4 cells, ratio between the concentration of CD8 cells and CD4 cells and concentration of CD8 cells, the concentration of C-reactive protein, RT PCR test of samples obtained from the oropharyngeal region and nasopharyngeal region nasopharyngeal for verification COVID-19 were done. These measurements were carried out in both the control and intervention categories at baseline and at the moment of obtaining a negative RT-PCR report.

Results

The confirmed cases of COVID-19 was 52.9% in the intervention category and 53.4% in the control category at the end of the administration of drugs. Symptoms related to COVID-19 were observed in 11.6% of subjects in the intervention category and 13.5% in the control category. Other new symptoms were observed in 16.8% of subjects in the intervention category and 14.5% of study subjects in the control category. One death was reported in the control category. Emergency hospitalization was required for one subject in the intervention category, while two subjects in the control category required emergency hospitalization. 12.4 days was the mean duration of recovery in the intervention category, while 13.6 days were the mean duration of recovery in the control category. The recovery duration and COVID-related symptoms were lesser in the intervention category than in the control category; however, the variation between the two categories was statistically non-significant (p˃0.01).

Conclusion

According to this research, no statistically significant difference was noticed in COVID-19 incidence between the control category and intervention category, showing that hydroxychloroquine sulfate cannot be utilized as the main curative agent in the treatment of COVID-19. However, there was a reduction in recovery days and symptoms related to COVID-19 in study subjects administered with HCQS.

Colchicine for the treatment of COVID-19 patients: efficacy, safety, and model informed dosage regimens

Colchicine is widely investigated for cardioprotection of COVID-19 patients since it can prevent the phenomenon of 'cytokine storm' and may reduce the complications arising from COVID-19. Despite the potentially beneficial effects of colchicine, there is no consensus on the appropriate dosage regimen and numerous schemes are currently used.In this study, simulations were performed to identify the ability of dosage regimens to attain plasma levels in CVOID-19 patients, known to be generally safe and efficacious. Since renal and hepatic impairment, as well as, drug-drug interactions have been identified to be the most significant factors increasing colchicine toxicity, the impact of these interactions was assessed in the simulations.Some dosage regimens lead to high colchicine concentrations, while others result in sub-therapeutic levels. Additional dosage schemes were proposed in this study aiming to be applied in patients with clearance insufficiency. Colchicine administration of 0.5 mg twice daily, can be considered safe and effective. In cases of clearance impairment, doses as low as 0.25 mg thrice or twice daily should be applied.Colchicine is a narrow therapeutic index drug and dosage regimens tailored to patients' needs should be designed.

The frequency of arrhythmias in COVID-19 patients, a study in the Shahid Mostafa Khomeini Hospital of Ilam from March to August 2020

Cardiac arrhythmias are important causes of death among populations and are always responsible for a high percentage of mortality in hospitalized patients. The aim of this descriptive analytical study was to evaluate the frequency of arrhythmias in patients with coronavirus disease 2019 (COVID-19) in the Shahid Mostafa Khomeini Hospital of Ilam from March to August 2020. All the COVID-19 patients with a cardiac condition admitted to the intensive care unit were enrolled in the study by census. Electrocardiography (ECG) and Holter monitoring were used to diagnose arrhythmias. Data analysis was performed in Microsoft Excel using descriptive statistics (frequency and percentage). The total number of eligible patients was 45, of whom 26 (57.8%) were men and 19 (42.2%) were women. The mortality rate of arrhythmias among COVID-19 patients was 17.77% (8 out of 45 patients), and the recovery rate was 82.13% (37 out of 45 patients). Tachycardia and a lack of response to heart-rate-reducing drugs were observed in patients with COVID-19. Owing to an overlap between these symptoms and those of heart diseases, there is a need to further evaluate patients with arrhythmias. Although arrhythmias are not common in COVID-19 patients, they can be fatal and have a high mortality rate, which can be prevented by early detection.

The Rise and Fall of Hydroxychloroquine and Chloroquine in COVID-19

On March 11th, the World Health Organization (WHO) announced the unprecedented outbreak of "severe acute respiratory syndrome coronavirus 2" (SARS-CoV-2) to be a pandemic. Thus far, COVID-19 has infected over 58,229,138 individuals and caused 1,382,106 deaths worldwide. This has led to the re-purposing of available drugs under "off-label" use-drugs such as hydroxychloroquine and chloroquine. Both drugs have since been evaluated for their ability to treat COVID-19. Here, we summarize recent evidence regarding the use of hydroxychloroquine and chloroquine in hospitalized patients with COVID-19. All data is current as of November 23, 2020.

Optimization of hydroxychloroquine dosing scheme based on COVID-19 patients' characteristics: a review of the literature and simulations

During the recent COVID-19 outbreak hydroxychloroquine (HCQ) has been proposed as a safe and effective therapeutic option. However, a wide variety of dosing schemes has been applied in the clinical practice and tested in clinical studies. An extended literature survey was performed investigating the pharmacokinetics, the efficacy and safety of HCQ in COVID-19 treatment. Population pharmacokinetic models were retrieved from the literature and after evaluation and assessment one was selected in order to perform simulations. The most commonly applied dosing schemes were explored for patients with different weights and different levels of HCQ clearance impairment. Model-based simulations of HCQ concentrations revealed that high initial doses followed by low and sparse doses may offer significant benefits to patients by decreasing the viral load without reaching levels considered to produce adverse effects. For instance, the dosing scheme proposed for a 70 kg adult with moderate COVID-19 symptoms would be 600 mg upon diagnosis, 400 mg after 12 h, 300 mg after 24 h, 200 mg after 36 h, followed by 200 mg BID for 4 d, followed by 200 mg OD for 5 d. Based on the results from simulations performed and the currently published knowledge regarding HCQ in COVID-19 treatment, this study provides evidence that a high loading dose followed by sparse doses could offer significant benefits to the patients.

Connecting Hydroxychloroquine In Vitro Antiviral Activity to In Vivo Concentration for Prediction of Antiviral Effect: A Critical Step in Treating Patients With Coronavirus Disease 2019

Translation of in vitro antiviral activity to the in vivo setting is crucial to identify potentially effective dosing regimens of hydroxychloroquine. In vitro 50%/90% maximal effective concentration values for hydroxychloroquine should be compared to the in vivo free extracellular tissue concentration, which is similar to the free plasma hydroxychloroquine concentration.

A Missing Link: Engagements of Dendritic Cells in the Pathogenesis of SARS-CoV-2 Infections

Dendritic cells (DC) connect the innate and adaptive arms of the immune system and carry out numerous roles that are significant in the context of viral disease. Their functions include the control of inflammatory responses, the promotion of tolerance, cross-presentation, immune cell recruitment and the production of antiviral cytokines. Based primarily on the available literature that characterizes the behaviour of many DC subsets during Severe acute respiratory syndrome (SARS) and coronavirus disease 2019 (COVID-19), we speculated possible mechanisms through which DC could contribute to COVID-19 immune responses, such as dissemination of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to lymph nodes, mounting dysfunctional inteferon responses and T cell immunity in patients. We highlighted gaps of knowledge in our understanding of DC in COVID-19 pathogenesis and discussed current pre-clinical development of therapies for COVID-19.

Hydroxychloroquine in Coronavirus Disease 2019 Patients: What Still Needs to Be Known About the Kinetics

Different dosage regimens of hydroxychloroquine are used to manage COVID-19 patients, without information on the pharmacokinetics in this population.Blood samples (n=101) were collected from 57 COVID-19 patients for 7 days and concentrations were compared with simulated kinetic profiles.Hydroxychloroquine exposure is low and cannot be predicted by other populations.

Development of a Physiologically-Based Pharmacokinetic (PBPK) Model of Nebulized Hydroxychloroquine for Pulmonary Delivery to COVID-19 Patients

Despite inconclusive evidence, chloroquine (CQ) and hydroxychloroquine (HCQ)are commonly used for the treatment of Corona virus Disease 2019(COVID-19) in critically ill patients.It was hypothesized that HCQ as an aerosol application can reach the antiviral concentration of ~1-5 μM in the alveolar cells which has been proven effective in vitro. A physiologically-based pharmacokinetic (PBPK) model of nebulized HCQ for pulmonary delivery to COVID-19 patients using the Nasal-Pulmonary Module in GastroPlus^® V9.7 simulator, in order to calculate the necessary inhalation dose regimen of HCQ, was developed. The physiological, drug disposition, and pharmacokinetic parameters were obtained from the literature and used during model building after optimization using Optimization Module, while oral data was used for validation. The 25 mg BID inhalation dosing was predicted to lead to alveolar HCQ levels of 7 µM (above EC50 of ~1-5 µM), and small plasma levels of 0.18 µM (as compared to plasma levels of 3.22 µM after 200 mg BID oral dosing). However, average contact time (>1 µM) is around 0.5 h in lung parts, suggesting indirect exposure response effect of HCQ.The developed PBPK model herein predicted HCQ levels in plasma and different lung parts of adults after multiple inhalation dosing regimens for 5 days. This in-silico work needs to be tested in vivo on healthy subjects and COVID-19 patients using 12.5 mg BID and 25 mg BID inhalation doses.

Challenges of drug development during the COVID-19 pandemic: Key considerations for clinical trial designs

There is an urgent need for targeted and effective COVID-19 treatments. Several medications, including hydroxychloroquine, remdesivir, lopinavir-ritonavir, favipiravir, tocilizumab and others have been identified as potential treatments for COVID-19. Bringing these repurposed medications to the public for COVID-19 requires robust and high-quality clinical trials that must be conducted under extremely challenging pandemic conditions. This article reviews translational science principles and strategies for conducting clinical trials in a pandemic and evaluates recent trials for different drug candidates. We hope that this knowledge will help focus efforts during this crisis and lead to the expedited development and approval of COVID-19 therapies.

A Strategy to Treat COVID-19 Disease With Targeted Delivery of Inhalable Liposomal Hydroxychloroquine: A Preclinical Pharmacokinetic Study

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is a newly identified pathogen causing the coronavirus disease 2019 (COVID‐19) pandemic. Hydroxychloroquine (HCQ), an antimalarial and anti‐inflammatory drug, has been shown to inhibit SARS‐CoV‐2 infection in vitro and tested in clinical studies. However, achievement of lung concentrations predicted to have in vivo antiviral efficacy might not be possible with the currently proposed oral dosing regimens. Further, high cumulative doses of HCQ raise concerns of systemic toxicity, including cardiotoxicity. Here, we describe a preclinical study to investigate the pharmacokinetics (PKs) of a novel formulation of liposomal HCQ administered by intratracheal (IT) instillation in Sprague‐Dawley rats. Compared with unformulated HCQ administered intravenously, liposomal HCQ showed higher (~ 30‐fold) lung exposure, longer (~ 2.5‐fold) half‐life in lungs, but lower blood exposure with ~ 20% of peak plasma concentration (C_max) and 74% of area under the curve from 0 to 72 hours (AUC_0–72) and lower heart exposure with 23% of C_max and 58% of AUC_0–24 (normalized for dose). Similar results were observed relative to IT administration of unformulated HCQ. These PKs result in an animal model that demonstrated the proof of concept that inhalable liposomal HCQ may provide clinical benefit and serve as a potential treatment for COVID‐19.

Pharmacokinetic Basis of the Hydroxychloroquine Response in COVID-19: Implications for Therapy and Prevention

BACKGROUND AND OBJECTIVES

Chloroquine/hydroxychloroquine has recently been the subject of intense debate regarding its potential antiviral activity against SARS-Cov-2, the etiologic agent of COVID-19. Some report possible curative effects; others do not. Therefore, the objective of this study was to simulate possible scenarios of response to hydroxychloroquine in COVID-19 patients using mathematical modeling.

METHODS

To shed some light on this controversial topic, we simulated hydroxychloroquine-based interventions on virus/host cell dynamics using a basic system of previously published differential equations. Mathematical modeling was implemented using Python programming language v 3.7.

RESULTS

According to mathematical modeling, hydroxychloroquine may have an impact on the amplitude of the viral load peak and viral clearance if the drug is administered early enough (i.e., when the virus is still confined within the pharyngeal cavity). The effects of chloroquine/hydroxychloroquine may be fully explained only when also considering the capacity of this drug to increase the death rate of SARS-CoV-2-infected cells, in this case by enhancing the cell-mediated immune response.

CONCLUSIONS

These considerations may not only be applied to chloroquine/hydroxychloroquine but may have more general implications for development of anti-COVID-19 combination therapies and prevention strategies through an increased death rate of the infected cells.

Effect of Combination Therapy of Hydroxychloroquine and Azithromycin on Mortality in Patients With COVID-19

Conflicting evidence regarding the use of hydroxychloroquine (HCQ) and azithromycin for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection do exist. We performed a retrospective single-center cohort study including 377 consecutive patients admitted for pneumonia related to coronavirus disease 2019 (COVID-19). Of these, 297 were in combination treatment, 17 were on HCQ alone, and 63 did not receive either of these 2 drugs because of contraindications. The primary end point was in-hospital death. Mean age was 71.8 ± 13.4 years and 34.2% were women. We recorded 146 deaths: 35 in no treatment, 7 in HCQ treatment group, and 102 in HCQ + azithromycin treatment group (log rank test for Kaplan-Meier curve P < 0.001). At multivariable Cox proportional hazard regression analysis, age (hazard ratio (HR) 1.057, 95% confidence interval (CI) 1.035-1.079, P < 0.001), mechanical ventilation/continuous positive airway pressure (HR 2.726, 95% CI 1.823-4.074, P < 0.001), and C reactive protein above the median (HR 2.191, 95% CI 1.479-3.246, P < 0.001) were directly associated with death, whereas use of HCQ + azithromycin (vs. no treatment; HR 0.265, 95% CI 0.171-0.412, P < 0.001) was inversely associated. In this study, we found a reduced in-hospital mortality in patients treated with a combination of HCQ and azithromycin after adjustment for comorbidities. A large randomized trial is necessary to confirm these findings.

Inhaled hydroxychloroquine to improve efficacy and reduce harm in the treatment of COVID-19

Current formulations and dose regimens of hydroxychloroquine (HCQ) put patients at risk of harm. An analysis of clinical trials registered on ClinicalTrials.gov revealed that this may continue as many studies combine HCQ with agents that prolong the QT interval. Further, almost all of the trials registered do not consider dosage adjustment in the elderly, a patient population most likely to require HCQ treatment. Here we describe an inhaled formulation of HCQ which has passed safety studies in clinical trials for the treatment of asthma and discuss how this approach may reduce side-effects and improve efficacy. As this simple formulation progressed to phase II studies, safety data can be used to immediately enable phase II trials in COVID-19.

Therapeutic strategies against COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus that mainly affects the upper and lower respiratory tract and is responsible for extremely different degrees of disease, ranging from flu-like symptoms to atypical pneumonia that may evolve to acute respiratory distress syndrome and, ultimately, death. No specific therapy for SARS-CoV-2 has yet been identified, but since the beginning of the outbreak, several pre-existing therapeutics have been reconsidered for the treatment of infected patients. The aim of this article is to discuss current therapeutics against SARS-CoV-2. A literature review was performed using PubMed, collecting data from English-language articles published until June 20th, 2020. Literature analysis showed that with the acquisition of more in-depth knowledge on the characteristics of SARS-CoV-2 and the pathogenesis of the different clinical manifestations, a more rationale use of available drugs has become possible. However, the road to defining which drugs are effective and which schedules of administration must be used to maximize efficacy and minimize adverse events is still very long. To date, it is only clear that no drug can alone cope with all the problems posed by SARS-CoV-2 infection and effective antivirals and inflammatory drugs must be given together to reduce COVID-19 clinical manifestations. Moreover, choice of therapy must always be tailored on clinical manifestations and, when they occur, drugs able to fight coagulopathy and venous thromboembolism that may contribute to respiratory deterioration must be prescribed.

Prospects for RNAi Therapy of COVID-19

COVID-19 caused by the SARS-CoV-2 virus is a fast emerging disease with deadly consequences. The pulmonary system and lungs in particular are most prone to damage caused by the SARS-CoV-2 infection, which leaves a destructive footprint in the lung tissue, making it incapable of conducting its respiratory functions and resulting in severe acute respiratory disease and loss of life. There were no drug treatments or vaccines approved for SARS-CoV-2 at the onset of pandemic, necessitating an urgent need to develop effective therapeutics. To this end, the innate RNA interference (RNAi) mechanism can be employed to develop front line therapies against the virus. This approach allows specific binding and silencing of therapeutic targets by using short interfering RNA (siRNA) and short hairpin RNA (shRNA) molecules. In this review, we lay out the prospect of the RNAi technology for combatting the COVID-19. We first summarize current understanding of SARS-CoV-2 virology and the host response to viral entry and duplication, with the purpose of revealing effective RNAi targets. We then summarize the past experience with nucleic acid silencers for SARS-CoV, the predecessor for current SARS-CoV-2. Efforts targeting specific protein-coding regions within the viral genome and intragenomic targets are summarized. Emphasizing non-viral delivery approaches, molecular underpinnings of design of RNAi agents are summarized with comparative analysis of various systems used in the past. Promising viral targets as well as host factors are summarized, and the possibility of modulating the immune system are presented for more effective therapies. We place special emphasis on the limitations of past studies to propel the field faster by focusing on most relevant models to translate the promising agents to a clinical setting. Given the urgency to address lung failure in COVID-19, we summarize the feasibility of delivering promising therapies by the inhalational route, with the expectation that this route will provide the most effective intervention to halt viral spread. We conclude with the authors' perspectives on the future of RNAi therapeutics for combatting SARS-CoV-2. Since time is of the essence, a strong perspective for the path to most effective therapeutic approaches are clearly articulated by the authors.

Drug targets for COVID-19 therapeutics: Ongoing global efforts

The current global pandemic COVID-19 caused by the SARS-CoV-2 virus has already inflicted insurmountable damage both to the human lives and global economy. There is an immediate need for identification of effective drugs to contain the disastrous virus outbreak. Global efforts are already underway at a war footing to identify the best drug combination to address the disease. In this review, an attempt has been made to understand the SARS-CoV-2 life cycle, and based on this information potential druggable targets against SARS-CoV-2 are summarized. Also, the strategies for ongoing and future drug discovery against the SARS-CoV-2 virus are outlined. Given the urgency to find a definitive cure, ongoing drug repurposing efforts being carried out by various organizations are also described. The unprecedented crisis requires extraordinary efforts from the scientific community to effectively address the issue and prevent further loss of human lives and health.

Impact of Disease on Plasma and Lung Exposure of Chloroquine, Hydroxychloroquine and Azithromycin: Application of PBPK Modeling

We use a mechanistic lung model to demonstrate that accumulation of chloroquine (CQ), hydroxychloroquine (HCQ), and azithromycin (AZ) in the lungs is sensitive to changes in lung pH, a parameter that can be affected in patients with coronavirus disease 2019 (COVID-19). A reduction in pH from 6.7 to 6 in the lungs, as observed in respiratory disease, led to 20-fold, 4.0-fold, and 2.7-fold increases in lung exposure of CQ, HCQ, and AZ, respectively. Simulations indicated that the relatively high concentrations of CQ and HCQ in lung tissue were sustained long after administration of the drugs had stopped. Patients with COVID-19 often present with kidney failure. Our simulations indicate that renal impairment (plus lung pH reduction) caused 30-fold, 8.0-fold, and 3.4-fold increases in lung exposures for CQ, HCQ, and AZ, respectively, with relatively small accompanying increases (20 to 30%) in systemic exposure. Although a number of different dosage regimens were assessed, the purpose of our study was not to provide recommendations for a dosing strategy, but to demonstrate the utility of a physiologically-based pharmacokinetic modeling approach to estimate lung concentrations. This, used in conjunction with robust in vitro and clinical data, can help in the assessment of COVID-19 therapeutics going forward.

In vitro activity of lopinavir/ritonavir and hydroxychloroquine against severe acute respiratory syndrome coronavirus 2 at concentrations achievable by usual doses

BACKGROUND/AIMS

As the coronavirus disease-2019 global pandemic progresses, screening of antiviral agents effective against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is urgently needed. In addition, considering the viral load kinetics of SARS-CoV-2, which peaks early in the illness, and the massive burden of the disease, which may increase in the near future, identifying well-tolerated oral antivirals becomes increasingly important. We examined the in vitro activity of lopinavir/ritonavir and hydroxychloroquine on SARS-CoV-2, at concentrations which can be used to treat coronavirus-19 patients with little concern of toxicity.

METHODS

Lopinavir/ritonavir (7/1.75 μg/mL), hydroxychloroquine base (1 or 2 μg/mL), or a combination thereof were administered 1 hour after the inoculation of SARS-CoV-2 to Vero cells at a multiplicity of infection of 0.05. We examined cytopathic effects of virus 48 hours after administration of the respective treatments and measured viral loads at three time points (0, 24, and 48 hours post-treatment) by quantitative real-time reverse-transcription polymerase chain reaction, and compared the results obtained from the different antiviral regimens tested.

RESULTS

The severity of cytopathic effects was lower in lopinavir/ritonavir-treated cells, and viral load was significantly reduced in this group compared with the control group (p < 0.001). However, hydroxychloroquine did not show significant inhibitory effects on anti-SARS-CoV-2-mediated cytotoxicity or on viral load at either concentration.

CONCLUSION

Lopinavir/ritonavir showed significant inhibitory effects on SARS-CoV-2 in vitro at its usual plasma concentration. However, the in vitro antiviral activity of hydroxychloroquine at concentrations commonly used in humans was minimal, whether used alone or in combination with lopinavir/ritonavir.

Simulated Assessment of Pharmacokinetically Guided Dosing for Investigational Treatments of Pediatric Patients With Coronavirus Disease 2019

IMPORTANCE

Children of all ages appear susceptible to severe acute respiratory syndrome coronavirus 2 infection. To support pediatric clinical studies for investigational treatments of coronavirus disease 2019 (COVID-19), pediatric-specific dosing is required.

OBJECTIVE

To define pediatric-specific dosing regimens for hydroxychloroquine and remdesivir for COVID-19 treatment.

DESIGN, SETTING, AND PARTICIPANTS

Pharmacokinetic modeling and simulation were used to extrapolate investigated adult dosages toward children (March 2020-April 2020). Physiologically based pharmacokinetic modeling was used to inform pediatric dosing for hydroxychloroquine. For remdesivir, pediatric dosages were derived using allometric-scaling with age-dependent exponents. Dosing simulations were conducted using simulated pediatric and adult participants based on the demographics of a white US population.

INTERVENTIONS

Simulated drug exposures following a 5-day course of hydroxychloroquine (400 mg every 12 hours × 2 doses followed by 200 mg every 12 hours × 8 doses) and a single 200-mg intravenous dose of remdesivir were computed for simulated adult participants. A simulation-based dose-ranging study was conducted in simulated children exploring different absolute and weight-normalized dosing strategies.

MAIN OUTCOMES AND MEASURES

The primary outcome for hydroxychloroquine was average unbound plasma concentrations for 5 treatment days. Additionally, unbound interstitial lung concentrations were simulated. For remdesivir, the primary outcome was plasma exposure (area under the curve, 0 to infinity) following single-dose administration.

RESULTS

For hydroxychloroquine, the physiologically based pharmacokinetic model analysis included 500 and 600 simulated white adult and pediatric participants, respectively, and supported weight-normalized dosing for children weighing less than 50 kg. Geometric mean-simulated average unbound plasma concentration values among children within different developmental age groups (32-35 ng/mL) were congruent to adults (32 ng/mL). Simulated unbound hydroxychloroquine concentrations in lung interstitial fluid mirrored those in unbound plasma and were notably lower than in vitro concentrations needed to mediate antiviral activity. For remdesivir, the analysis included 1000 and 6000 simulated adult and pediatric participants, respectively. The proposed pediatric dosing strategy supported weight-normalized dosing for participants weighing less than 60 kg. Geometric mean-simulated plasma area under the time curve 0 to infinity values among children within different developmental age-groups (4315-5027 ng × h/mL) were similar to adults (4398 ng × h/mL).

CONCLUSIONS AND RELEVANCE

This analysis provides pediatric-specific dosing suggestions for hydroxychloroquine and remdesivir and raises concerns regarding hydroxychloroquine use for COVID-19 treatment because concentrations were less than those needed to mediate an antiviral effect.

Hydroxychloroquine in Patients with Rheumatic Disease Complicated by COVID-19: Clarifying Target Exposures and the Need for Clinical Trials

OBJECTIVE

To characterize hydroxychloroquine (HCQ) exposure in patients with rheumatic disease receiving longterm HCQ compared to target concentrations with reported antiviral activity against the coronavirus disease 2019 caused by SARS-CoV-2 (COVID-19).

METHODS

We evaluated total HCQ concentrations in serum and plasma from published literature values, frozen serum samples from a pediatric systemic lupus erythematosus trial, and simulated concentrations using a published pharmacokinetic model during pregnancy. For each source, we compared observed or predicted HCQ concentrations to target concentrations with reported antiviral activity against SARS-CoV-2.

RESULTS

The average total serum/plasma HCQ concentrations were below the lowest SARS-CoV-2 target of 0.48 mg/l in all studies. Assuming the highest antiviral target exposure (total plasma concentration of 4.1 mg/l), all studies had about one-tenth the necessary concentration for in vitro viral inhibition. Pharmacokinetic model simulations confirmed that pregnant adults receiving common dosing for rheumatic diseases did not achieve target exposures; however, the models predict that a dosage of 600 mg once a day during pregnancy would obtain the lowest median target exposure for most patients after the first dose.

CONCLUSION

We found that the average patient receiving treatment with HCQ for rheumatic diseases, including children and non-pregnant/pregnant adults, are unlikely to achieve total serum or plasma concentrations shown to inhibit SARS-CoV-2 in vitro. Nevertheless, patients receiving HCQ long term may have tissue concentrations far exceeding that of serum/plasma. Because the therapeutic window for HCQ in the setting of SARS-CoV-2 is unknown, well-designed clinical trials that include patients with rheumatic disease are urgently needed to characterize the efficacy, safety, and target exposures for HCQ.

The deep impact of novel CoVID-19 infection in an Orthopedics and Traumatology Department: the experience of the Piacenza Hospital

Since February 21st, 2020 CoVID-19 spread throughout all Italy expanding like a "tsunami" from Codogno (Lodi, Lombardy, Northern Italy) to neighboring cities. In a few days Lodi, Piacenza, Milano, Brescia and Bergamo were forced to deal with this disaster starting the lockdown at different time. No national plan had been prepared. As result, CoVID-19 has paralyzed the Italian healthcare system. At time of writing, in Italy there are 169 323 infected patients and 22 260 deaths. Italy is fighting hard to manage CoVID-19 crisis even if most hospitals were unprepared to deal with massive influx of critically ill CoVID-19 patients. Piacenza in Emilia-Romagna region (Northern Italy) is one of the epicenters of the Italian pandemic, and the local hospital - Guglielmo da Saliceto - has quickly become a "CoVID-19 hospital" with the great effort of all the medical staff. Here we report the experience of our hospital, particularly the strategy adopted in the Orthopedics and Traumatology Department.