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

Getting the dose right using physiologically-based pharmacokinetic modeling: dexamethasone to prevent post-extubation stridor in children as proof of concept

Introduction

Critically ill patients show large variability in drug disposition due to e.g., age, size, disease and treatment modalities. Physiologically-based pharmacokinetic (PBPK) models can be used to design individualized dosing regimens taking this into account. Dexamethasone, prescribed for the prevention post-extubation stridor (PES), is metabolized by the drug metabolizing enzyme CYP3A. As CYP3A4 undergoes major changes during childhood, we aimed to develop age-appropriate dosing recommendations for children of dexamethasone for PES, as proof of concept for PBPK modeling to individualize dosing for critically ill patients.

Methods

All simulations were conducted in Simcyp™ v21 (a population-based PBPK modeling platform), using an available dexamethasone compound model and pediatric population model in which CYP3A4 ontogeny is incorporated. Published pharmacokinetic (PK) data was used for model verification. Evidence for the dose to prevent post-extubation stridor was strongest for 2-6 year old children, hence simulated drug concentrations resulting from this dose from this age group were targeted when simulating age-appropriate doses for the whole pediatric age range.

Results

Dexamethasone plasma concentrations upon single and multiple intravenous administration were predicted adequately across the pediatric age range. Exposure-matched predictions of dexamethasone PK indicated that doses (in mg/kg) for the 2-6 years olds can be applied in 3 month-2 year old children, whereas lower doses are needed in children of other age groups (60% lower for 0-2 weeks, 40% lower for 2-4 weeks, 20% lower for 1-3 months, 20% lower for 6-12 year olds, 40% lower for 12-18 years olds).

Discussion

We show that PBPK modeling is a valuable tool that can be used to develop model-informed recommendations using dexamethasone to prevent PES in children. Based on exposure matching, the dose of dexamethasone should be reduced compared to commonly used doses, in infants <3 months and children ≥6 years, reflecting age-related variation in drug disposition. PBPK modeling is an promising tool to optimize dosing of critically ill patients.

Efficacy and Safety of Remdesivir in Hospitalized Pediatric COVID-19: A Retrospective Case-Controlled Study

Introduction

While most children experience mild coronavirus disease 2019 (COVID-19) infections, a minority of cases progress to severe or critical illness. This study aimed to assess the efficacy and safety of Remdesivir (RDV) therapy in children with moderate to severe COVID-19, enhancing clinical decision-making and expanding our understanding of antiviral treatments for pediatric patients.

Methods

The study included 60 patients, 38 receiving RDV treatment and 22 serving as the control group. Data was collected retrospectively from January 2021 to January 2022 through electronic hospital records.

Results

Regarding the main clinical symptoms reported, most patients experienced Upper Respiratory Tract Infections (93.3%), indicating respiratory involvement. Additional symptoms included Central Nervous System (11.7%) and Gastrointestinal (10.0%). Among the 38 cases in the RDV group included in the study, the adverse effects associated with using RDV: Hypoalbuminemia in 19 cases (50.0%) and anemia in 18 cases (47.4%), making them the most common adverse effects. Only one case in the RDV group experienced non-RDV-related death with a different clinical diagnosis. The results showed that RDV treatment was well-tolerated in pediatric patients, with no significant differences in hospital stay and oxygen treatment compared to the control group with P values (0.2, 0.18), respectively.

Conclusion

The outcomes indicate that Remdesivir may represent a safe and therapeutic choice for children with coronavirus disease 2019 (COVID-19).

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.

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.

Predicting the correct dose in children: Role of computational Pediatric Physiological-based pharmacokinetics modeling tools

The pharmacokinetics (PKs) and safety of medications in particular groups can be predicted using the physiologically-based pharmacokinetic (PBPK) model. Using the PBPK model may enable safe pediatric clinical trials and speed up the process of new drug research and development, especially for children, a population in which it is relatively difficult to conduct clinical trials. This review summarizes the role of pediatric PBPK (P-PBPK) modeling software in dose prediction over the past 6 years and briefly introduces the process of general P-PBPK modeling. We summarized the theories and applications of this software and discussed the application trends and future perspectives in the area. The modeling software's extensive use will undoubtedly make it easier to predict dose prediction for young patients.

A comparison of different methods for the first-in-pediatric dose selection

BACKGROUND AND AIM

To conduct a pediatric clinical trial, it is important to optimize pediatric dose as accurately as possible. This is mainly because due to ethical reasons, children cannot be given several doses to evaluate pharmacokinetics, safety, and efficacy of a drug.

METHODS

In this study, several simple methods to project a first-in-pediatric dose to initiate a clinical trial were evaluated. These methods were as follows:(1) Weight-based pediatric dose prediction (allometric scaling), (2) Salisbury rule (weight-based method), and (3) pediatric dose prediction based on predicted clearance. These methods were compared with the dose given to children in clinical practice. The methods were also compared with whole-body physiologically based pharmacokinetic (PBPK) model (n = 11). A ±30% prediction error (predicted vs. observed) was considered acceptable.

RESULTS

There were 27 drugs with 113 observations (different age groups from preterm neonates to adolescents). At least, ≤30% prediction error in pediatric dose projection was noted for more than 70% observations. The predictive performance of all the proposed methods was comparable with the whole-body PBPK.

CONCLUSIONS

The proposed methods are simple and accurate and can be developed on a spreadsheet in a very short period of time.

RELEVANCE FOR PATIENTS

The study provides an estimate of first-in-pediatric dose by simple methods to initiate pediatric clinical trials. Especially, Salisbury rule is based on body weight and is very simple and works fairly well in children >30 kg body weight and can be even used in clinical settings.

SARS-CoV-2 Associated Respiratory Failure in a Preterm Infant and the Outcome after Remdesivir Treatment

Severe coronavirus disease 2019 (COVID-19) occurs in approximately 10% of neonates infected with severe acute respiratory syndrome coronavirus 2. Guidelines for optimal management of severe COVID-19 in neonates do not exist. In this report, we describe a late-preterm neonate with severe COVID-19, requiring invasive mechanical ventilation who recovered following treatment with remdesivir and high dose dexamethasone.

Remdesivir: the first FDA-approved anti-COVID-19 Treatment for Young Children

Following the emergence of the SARS-CoV-2 pandemic, finding efficient forms of treatment is seen as a priority for both adults and children. On April 25, 2022, remdesivir has become the first United States Food and Drug Administration (FDA) approved COVID-19 treatment for young children, specifically ≥28-days-old children, weighing ≥3 kilograms, who are either hospitalized or non-hospitalized, showing a high risk for progression to severe COVID-19 (prone to hospitalization or death). This new approval, which expands its already FDA-approved use in adults to young children, is supported by the CARAVAN study (a phase 2/3 single-arm, open-label study to evaluate the safety, tolerability, pharmacokinetics, and efficacy of remdesivir (GS-5734™) in participants, from birth to < 18 years of age, with COVID-19). This study is in progress, with an estimated primary completion in February 2023. While positive effects of remdesivir have been ascertained through various studies, controversy has surrounded remdesivir since its initial FDA approval in 2020 due to the contradictory results obtained by various studies. However, many case reports state its positive effects on the outcome of the patients, encouraging an optimistic vision for the future.

COVID-19 Infection in Children and Infants: Current Status on Therapies and Vaccines

Since the beginning in December 2019, the SARS-CoV-2 outbreak appeared to affect mostly the adult population, sparing the vast majority of children who only showed mild symptoms. The purpose of this investigation is to assess the status on the mechanisms that give children and infants this variation in epidemiology compared to the adult population and its impact on therapies and vaccines that are aimed towards them. A literature review, including in vitro studies, reviews, published guidelines and clinical trials was performed. Clinical trials concerned topics that allowed a descriptive synthesis to be produced. Four underlying mechanisms were found that may play a key role in providing COVID-19 protection in babies. No guidelines are available yet for therapy due to insufficient data; support therapy remains the most used. Only two vaccines are approved by the World Health Organization to be used in children from 12 years of age, and there are currently no efficacy or safety data for children below the age of 12 years. The COVID-19 clinical frame infection is milder in children and adolescents. This section of the population can act as vectors and reservoirs and play a key role in the transmission of the infection; therefore, vaccines are paramount. More evidence is required to guide safely the vaccination campaign.

Challenges and opportunities for improving access to approved neonatal drugs and devices

Neonatal drug and device development has lagged behind other patient populations. Oftentimes, providers are using drugs and devices without adequate study of safety and efficacy. Neonates deserve dedicated drug and device development programs, which will require novel approaches and unique collaborations between multiple key stakeholders. Legislative efforts, infrastructure, clinical trial methodology, and international collaborations have all contributed to improvements in neonatal drug and device development, but more work is still needed. Leadership from neonatologists, clinical care providers, and parents is essential to implement needed changes.

COVID-19 in Children: Update on Diagnosis and Management

In December 2019, a new infectious disease called coronavirus disease 2019 (COVID-19) attributed to the new virus named severe scute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detected. The gold standard for the diagnosis of SARS-CoV-2 infection is the viral identification in nasopharyngeal swab by real-time polymerase chain reaction. Few data on the role of imaging are available in the pediatric population. Similarly, considering that symptomatic therapy is adequate in most of the pediatric patients with COVID-19, few pediatric pharmacological studies are available. The main aim of this review is to describe and discuss the scientific literature on various imaging approaches and therapeutic management in children and adolescents affected by COVID-19. Clinical manifestations of COVID-19 are less severe in children than in adults and as a consequence the radiologic findings are less marked. If imaging is needed, chest radiography is the first imaging modality of choice in the presence of moderate-to-severe symptoms. Regarding therapy, acetaminophen or ibuprofen are appropriate for the vast majority of pediatric patients. Other drugs should be prescribed following an appropriate individualized approach. Due to the characteristics of COVID-19 in pediatric age, the importance of strengthening the network between hospital and territorial pediatrics for an appropriate diagnosis and therapeutic management represents a priority.

Severe COVID-19 Complicated by Cerebral Venous Thrombosis in a Newborn Successfully Treated with Remdesivir, Glucocorticoids, and Hyperimmune Plasma

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) pandemic, affecting all age groups with a wide spectrum of clinical presentation ranging from asymptomatic to severe interstitial pneumonia, hyperinflammation, and death. Children and infants generally show a mild course of the disease, although infants have been observed to have a higher risk of hospitalization and severe outcomes. Here, we report the case of a preterm infant with a severe form of SARS-CoV-2 infection complicated by cerebral venous thrombosis successfully treated with steroids, hyperimmune plasma, and remdesivir.

Management and Outcome of Coronavirus Disease 2019 (COVID-19) in Pediatric Cancer Patients: A Single Centre Experience from a Developing Country

INTRODUCTION

Sufficient data pertaining to the impact of the Coronavirus disease 2019 (COVID-19) on pediatric cancer patients is still lacking. The aim of this prospective study was to describe clinical management and outcomes of COVID-19 in pediatric oncology patients.

PATIENTS AND METHODS

Conducted between May 1, 2020 and November 30, 2020, this study included 76 pediatric oncology patients with confirmed COVID-19. Remdesivir (RDV) was the antiviral therapy used.

RESULTS

The median age of patients was 9 years. Sixty patients were on first line treatment. Hematological malignancies constituted 86.8% of patients. Severe to critical infections were 35.4% of patients. The commonest symptom was fever (93.4%). Chemotherapy was delayed in 59.2% of patients and doses were modified in 30.2%. The 60-day overall survival (OS) stood at 86.8%, with mortalities occurring only among critical patients. Of sixteen acute leukemia patients in the first induction therapy, 13 survived and 10 achieved complete remission. A negative RT-PCR within 2 weeks and improvement of radiological findings were statistically related to disease severity (P = .008 and .002, respectively). Better OS was associated with regression of radiological findings after 30 days from infection (P = .002). Forty-five patients received RDV, 42.1% had severe and critical forms of infection compared to 25.7% in the No-RDV group and yet OS was comparable in both groups.

CONCLUSION

Most pediatric cancer patients with COVID-19 should have good clinical outcomes except for patients with critical infections. Cancer patients can tolerate chemotherapy including induction phase, alongside COVID-19 treatment. In severe and critical COVID-19, RDV might have a potential benefit.

COVID-19 Infection in Children, Infants and Pregnant Subjects: An Overview of Recent Insights and Therapies

BACKGROUND

The SARS-CoV-2 pandemic has involved a severe increase of cases worldwide in a wide range of populations. The aim of the present investigation was to evaluate recent insights about COVID-19 infection in children, infants and pregnant subjects.

METHODS

a literature overview was performed including clinical trials, in vitro studies, reviews and published guidelines regarding the present paper topic. A descriptive synthesis was performed to evaluate recent insights and the effectiveness of therapies for SARS-CoV-2 infection in children, infants and pregnant subjects.

RESULTS

Insufficient data are available regarding the relationship between COVID-19 and the clinical risk of spontaneous abortion and premature foetus death. A decrease in the incidence of COVID-19 could be correlated to a minor expression of ACE2 in childrens' lungs. At present, a modulation of the dose-effect posology for children and infants is necessary.

CONCLUSIONS

Pregnant vertical transmission has been hypothesised for SARS-CoV-2 infection. Vaccines are necessary to achieve mass immunity for children and also pregnant subjects.

Model-Informed Repurposing of Medicines for SARS-CoV-2: Extrapolation of Antiviral Activity and Dose Rationale for Paediatric Patients

Repurposing of remdesivir and other drugs with potential antiviral activity has been the basis of numerous clinical trials aimed at SARS-CoV-2 infection in adults. However, expeditiously designed trials without careful consideration of dose rationale have often resulted in treatment failure and toxicity in the target patient population, which includes not only adults but also children. Here we show how paediatric regimens can be identified using pharmacokinetic-pharmacodynamic (PKPD) principles to establish the target exposure and evaluate the implications of dose selection for early and late intervention. Using in vitro data describing the antiviral activity and published pharmacokinetic data for the agents of interest, we apply a model-based approach to assess the exposure range required for adequate viral clearance and eradication. Pharmacokinetic parameter estimates were subsequently used with clinical trial simulations to characterise the probability target attainment (PTA) associated with enhanced antiviral activity in the lungs. Our analysis shows that neither remdesivir, nor anti-malarial drugs can achieve the desirable target exposure range based on a mg/kg dosing regimen, due to a limited safety margin and high concentrations needed to ensure the required PTA. To date, there has been limited focus on suitable interventions for children affected by COVID-19. Most clinical trials have defined doses selection criteria empirically, without thorough evaluation of the PTA. The current results illustrate how model-based approaches can be used for the integration of clinical and nonclinical data, providing a robust framework for assessing the probability of pharmacological success and consequently the dose rationale for antiviral drugs for the treatment of SARS-CoV-2 infection in children.

Physiologically-Based Pharmacokinetic Modeling of Remdesivir and Its Metabolites to Support Dose Selection for the Treatment of Pediatric Patients With COVID-19

Severe coronavirus disease 2019 (COVID‐19) disease, including multisystem inflammatory syndrome, has been reported in children. This report summarizes development of a remdesivir physiologically‐based pharmacokinetic (PBPK) model that accurately describes observed adult remdesivir and metabolites exposure and predicts pediatric remdesivir and metabolites exposure. The adult PBPK model was applied to predict pediatric remdesivir and metabolites steady‐state exposures using the Pediatric Population Model in SimCYP and incorporated the relevant physiologic and mechanistic information. Model development was based on adult phase I exposure data in healthy volunteers who were administered a 200‐mg loading dose of remdesivir intravenous (IV) over 0.5 hours on Day 1, then 100‐mg daily maintenance doses of IV over 0.5 hours starting on Day 2 and continuing through Days 5 or 10. Simulations indicated that use of the adult therapeutic remdesivir dosage regimen (200‐mg loading dose on Day 1 then 100‐mg daily maintenance dose starting on Day 2) in pediatric patients ≥ 40 kg and a weight‐based remdesivir dosage regimen (5‐mg/kg loading dose on Day 1 then 2.5‐mg/kg daily maintenance dose starting on Day 2) in pediatric patients weighing 2.5 to < 40 kg is predicted to maintain therapeutic exposures of remdesivir and its metabolites. The comprehensive PBPK model described in this report supported remdesivir dosing in planned pediatric clinical studies and dosing in the emergency use authorization and pediatric compassionate use programs that were initiated to support remdesivir as a treatment option during the pandemic.

Chloroquine and hydroxychloroquine provoke arrhythmias at concentrations higher than those clinically used to treat COVID-19: A simulation study

Abstract

The risk of fatal arrhythmias is the major concern for using chloroquine (CQ) or hydroxychloroquine (HCQ) to treat coronavirus disease 2019 (COVID‐19), but the reported number of life‐threatening arrhythmic events or deaths is relatively small. The objective of this study was to assess the arrhythmogenic risk of these two drugs using a multiscale heart simulation, which allows testing even at high concentrations, including those that cause fatal arrhythmias. We measured the inhibitory action of CQ, HCQ, and HCQ with 30 μM azithromycin (AZ) on six ion currents (fast [INa] and late [INa,L] components of the sodium current, L‐type calcium current [ICa,L], rapid [IKr/hERG], and slow [IKs] components of delayed rectifier potassium, and inward rectifier potassium [IK1]) over a wide range of concentrations using the automated patch‐clamp system. Using the concentration–inhibition relationship that was thus obtained, we simulated the drug effects while increasing the concentration until the life‐threatening arrhythmia, torsade de pointes (TdP), was observed. The obtained threshold concentrations for TdP were 12.5, 35, and 22.5 μM for CQ, HCQ, and HCQ with AZ, respectively. Adding therapeutic concentrations of mexiletine or verapamil successfully prevented the occurrence of TdP, and verapamil was more effective. CQ, HCQ, and HCQ with AZ thresholds for TdP were larger than both antiviral concentrations that were reported by in vitro experiments and free plasma concentrations that were attained by the clinically used dosage. The current simulation data provided a safety margin to the currently used clinical dose for CQ and HCQ/AZ.

Physiologically based pharmacokinetic (PBPK) modeling of RNAi therapeutics: Opportunities and challenges

Physiologically based pharmacokinetic (PBPK) modeling is a powerful tool with many demonstrated applications in various phases of drug development and regulatory review. RNA interference (RNAi)-based therapeutics are a class of drugs that have unique pharmacokinetic properties and mechanisms of action. With an increasing number of RNAi therapeutics in the pipeline and reaching the market, there is a considerable amount of active research in this area requiring a multidisciplinary approach. The application of PBPK models for RNAi therapeutics is in its infancy and its utility to facilitate the development of this new class of drugs is yet to be fully evaluated. From this perspective, we briefly discuss some of the current computational modeling approaches used in support of efficient development and approval of RNAi therapeutics. Considerations for PBPK model development are highlighted both in a relative context between small molecules and large molecules such as monoclonal antibodies and as it applies to RNAi therapeutics. In addition, the prospects for drawing upon other recognized avenues of PBPK modeling and some of the foreseeable challenges in PBPK model development for these chemical modalities are briefly discussed. Finally, an exploration of the potential application of PBPK model development for RNAi therapeutics is provided. We hope these preliminary thoughts will help initiate a dialogue between scientists in the relevant sectors to examine the value of PBPK modeling for RNAi therapeutics. Such evaluations could help standardize the practice in the future and support appropriate guidance development for strengthening the RNAi therapeutics development program.

Characterising and managing paediatric SARSCoV-2 infection: Learning about the virus in a global classroom

AIM

This study is a comprehensive review with the purpose of collecting the most relevant data in several sections including current treatment guidelines in the paediatric population.

METHODS

Literature was systematically searched in different databases. Results were limited to 2019+ and English, French and Spanish language.

RESULTS

Children can exhibit mild and less severe COVID-19 disease than adults and also have asymptomatic carriage of SARS-CoV-2, while severe disease is more frequently noted during infancy (<1 year). SARS-CoV-2 binds the angiotensin-converting enzyme 2 (ACE-2) receptor; age-, racial-, and gender-specific differences in ACE-2 expression need to be elucidated in order to explain the differential clinical profiles between children and adults. Multisystem inflammatory syndrome in children (MIS-C) is an important condition to recognise in children. The decision to use antiviral or immunomodulatory therapy in a child or adolescent should be individualised based on the clinical scenario. Remdesivir is the only FDA-approved therapy available for children older than 12 years old who require hospitalisation for COVID-19.

CONCLUSION

Further studies are urgently required to address prevention and treatment in at-risk and infected children, especially with underlying comorbidities. The chapter on the overall impact of COVID-19 in children has not yet been written. Nevertheless, SARS-CoV-2 has now joined a long list of human pandemics, which may forever change the world's history.

Time-Dependent Distribution of Hydroxychloroquine in Cynomolgus Macaques Using Population Pharmacokinetic Modeling Method

To evaluate the biodistribution of hydroxychloroquine (HCQ) in cynomolgus macaques and receive dynamic quantitative relationship between plasma, blood, and lung tissue concentration using the population pharmacokinetic modeling method, seventeen cynomolgus macaques were divided into six groups according to different HCQ dosing regimens over 5 days. The monkeys were euthanized, and blood, plasma, urine, feces and ten tissues were collected. All the samples were prepared by protein precipitation and analyzed by HPLC-MS/MS detection. The population pharmacokinetics of HCQ in the plasma, red blood cells, and lung tissue was conducted and simulated via ADAPT program. Results demonstrated that the maximum concentration (C max) of HCQ was 292.33 ng/mL in blood and 36.90 ng/mL in plasma after single dose of 3 mg/kg. The value of area under curve (AUC0-∞) was determined as 5,978.94 and 363.31 h* ng/mL for the blood and plasma, respectively. The descending order of the tissue-to-plasma concentration ratio was liver > spleen > kidney > lung > heart > subcutaneous fat > brain. The tissue-to-plasma concentration ratio and the tissue-to-blood concentration ratio for lung were found to be time-dependent with 267.38 and 5.55 at 120 h postdose, respectively. A five-compartment model with first-order oral absorption and elimination best described the plasma, blood, and lung tissue pharmacokinetics. The estimated elimination rate constant (ke) for a typical monkey was 0.236 h-1. The volume of distribution in central (Vc/F) and other two peripheral compartments (Vb/F and Vl/F) were 114, 2.68, and 5.55 L, respectively. Model-based simulation with PK parameters from cynomolgus macaques showed that the ratio of the blood or plasma to lung tissue was a dynamic change course, which suggested that the rate of HCQ concentration decrease in the blood or plasma was faster than that in the lung tissue. HCQ was found to be accumulated in tissues, especially in the liver, kidney, lung, and spleen. Also, the tissue-to-plasma concentration ratio increased over time. The population pharmacokinetic model developed could allow for the assessment of pharmacokinetics-pharmacodynamics relationships, especially relevant tissue concentration-response for HCQ. Determining appropriate treatment regimens in animals allows translation of these to clinical studies.

Comparison of antiviral effect for mild-to-moderate COVID-19 cases between lopinavir/ritonavir versus hydroxychloroquine: A nationwide propensity score-matched cohort study

OBJECTIVES

We aimed to compare the antiviral effect of hydroxychloroquine (HCQ) and lopinavir/ritonavir (LPV/r) in patients with COVID-19.

METHODS

Nationwide retrospective case-control study was conducted to compare the effect of HCQ and LPV/r on viral shedding duration among patients with mild-to-moderate COVID-19 using the reimbursement data of National Health Insurance Service. After propensity score matching (PSM), multivariate analysis was conducted to determine statistically significant risk factors associated with prolonged viral shedding.

RESULTS

Overall, 4197 patients with mild-to-moderate COVID-19 were included. Patients were categorized into three groups: LPV/r (n = 1268), HCQ (n = 801), and standard care without HCQ or LPV/r (controls, n = 2128). The median viral shedding duration was 23 (IQR 17-32), 23 (IQR 16-32), and 18 (IQR 12-25) days in the LPV/r, HCQ, and control groups, respectively. Even after PSM, the viral shedding duration was not significantly different between LPV/r and HCQ groups: 23 (IQR, 17-32) days versus 23 (IQR, 16-32) days. On multivariate analysis, old age, malignancy, steroid use, and concomitant pneumonia were statistically significant risk factors for prolonged viral shedding.

CONCLUSION

The viral shedding duration was similar between HCQ and LPV/r treatment groups. There was no benefit in improving viral clearance compared to the control group.

Compassionate use of remdesivir in children with COVID-19

Children represent a minority of total COVID-19 cases, but studies have reported severe disease and death in pediatric patients. Remdesivir (RDV) has recently demonstrated promising results in adults with COVID-19, but few data have been reported to date in children.A nationwide multicenter observational study was conducted on children with confirmed SARS-CoV-2 receiving compassionate treatment with RDV in Spain. Eight patients were included in the study, four infants and four older children [median age 5 years old; IQR 4 months-11.6 years old]. Half of them had complex underlying medical conditions, and the rest were mostly infants (3/4). Six out of eight children needed Pediatric Intensive Care Unit Admission. No RDV-related adverse outcomes were observed in our patients. Seven have reached successful clinical outcome, but one patient with serious clinical status died due to complications. However, she received RDV very late after the first COVID-19 symptom.Conclusions: In our cohort, most of the patients achieved successful clinical outcome, without observing adverse events. Clinical trials of RDV therapy for children with COVID-19 are urgently needed, to assess the safety, tolerability, efficacy, and pharmacokinetics of RDV in children, as this could be an effective treatment in severe cases. What is Known: • Remdesivir has not been approved to treat COVID-19 in children under 12 years old, although the drug is currently being prescribed in critically ill children. • Remdesivir has recently demonstrated promising results in adults with COVID-19, but few data have been reported to date in paediatric population. What is New: • We report a multicentre cohort of children with confirmed SARS-CoV-2 and severe COVID-19 disease receiving remdesivir during the first month of the pandemic in Spain. • No remdesivir-related adverse outcomes were observed in most of the cases. Seven patients reached successful clinical outcome, and one died due to complications (bacterial sepsis).

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.

Repurposing Approved Drugs for Guiding COVID-19 Prophylaxis: A Systematic Review

The SARS-CoV-2 outbreak originally appeared in China in December 2019 and became a global pandemic in March 2020. This infectious disease has directly affected public health and the world economy. Several palliative therapeutic treatments and prophylaxis strategies have been used to control the progress of this viral infection, including pre-(PrEP) and post-exposure prophylaxis. On the other hand, research groups around the world are still studying novel drug prophylaxis and treatment using repurposing approaches, as well as vaccination options, which are in different pre-clinical and clinical testing phases. This systematic review evaluated 1,228 articles from the PubMed and Scopus indexing databases, following the Kitchenham bibliographic searching protocol, with the aim to list drug candidates, potentially approved to be used as new options for SARS-CoV-2 prophylaxis clinical trials and medical protocols. In searching protocol, we used the following keywords: "Covid-19 or SARS-CoV-2" or "Coronavirus or 2019 nCoV," "prophylaxis," "prophylactic," "pre-exposure," "COVID-19 or SARS-CoV-2 Chemoprophylaxis," "repurposed," "strategies," "clinical," "trials," "anti-SARS-CoV-2," "anti-covid-19," "Antiviral," "Therapy prevention in vitro," in cells "and" human testing. After all protocol steps, we selected 60 articles that included: 15 studies with clinical data, 22 studies that used in vitro experiments, seven studies using animal models, and 18 studies performed with in silico experiments. Additionally, we included more 22 compounds between FDA approved drugs and drug-like like molecules, which were tested in large-scale screenings, as well as those repurposed approved drugs with new mechanism of actions. The drugs selected in this review can assist clinical studies and medical guidelines on the rational repurposing of known antiviral drugs for COVID-19 prophylaxis.

A Narrative Review of Emerging Therapeutics for COVID-19

The novel severe acute respiratory syndrome coronavirus 2, the causal agent of coronavirus disease 2019 (COVID-19), quickly spread around the world, resulting in the most aggressive pandemic experienced in more than 100 years. Research on targeted therapies and vaccines has been initiated on an unprecedented scale and speed but will take months and even years to come to fruition. Meanwhile, the efficacy of emerging therapeutics for use in treating COVID-19 is feverishly being investigated to identify the best available treatment options for dealing with the current wave of disease. This review of publications with a "treatment" tag through June 29, 2020 in the National Library of Medicine's LitCovid literature hub, provides frontline clinicians with a pragmatic summary of the current state of the rapidly evolving evidence supporting emerging candidate therapeutics for COVID-19. Two main categories of pharmaceutical therapeutics are showing promise: those with antiviral activity directly addressing infection and those that counteract the inflammatory cytokine storm induced by severe disease. Preliminary results suggest that other approaches such as convalescent plasma therapy and lung radiation therapy may have some efficacy. The current clinical evidence for potential treatments is preliminary-often small retrospective series or early results of randomized trials-and the science is evolving rapidly. The long-term results from large, well-designed randomized controlled trials will provide definitive evidence for therapeutic effectiveness and are likely months away. The trial landscape for promising therapies is described.

Pharmacotherapy of Acute COVID-19 Infection and Multisystem Inflammatory Syndrome in Children: Current State of Knowledge

Background: The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic is a health care emergency across the world. Although mitigation measures, such as social distancing and face masks, have attempted to slow the spread of the infection, cases continue to rise. Children who are otherwise healthy tend to develop a milder acute Coronavirus disease 2019 (COVID-19) infection and have lower mortality rates compared with adults. Methods: Guidelines and current primary and secondary literature on the treatment of COVID-19 and the multisystem inflammatory syndrome in children were searched and reviewed. There are 6 published pediatric series that included 252 children with acute COVID-19 infection and describe various treatments and outcomes. Results: Guidelines recommend treating pediatric patients similarly to adult patients. Currently, no prophylactic drug therapy has been shown to reduce the spread of infection. Treatment options for acute COVID-19 are limited to remdesivir and glucocorticoids for patients who require oxygen and/or mechanical ventilation. The efficacy of hydroxychloroquine, chloroquine, and azithromycin has not been proven and their safety has been a concern. Other therapies that are being explored include interleukin (IL)-1 and IL-6 inhibitors. In children, an atypical Kawasaki-like disease emerged after recent exposure to SARS-CoV-2 and has been named Multisystem Inflammatory Syndrome in Children (MIS-C). Nine case series, including 418 pediatric patients, described pharmacotherapies used and patient outcomes. These pharmacotherapies included intravenous immune globulin and glucocorticoids and in some patients, IL-1 and IL-6 inhibitors. Conclusion: Given the paucity of data in children, this article presents currently recommended pharmacotherapies for the treatment of acute COVID-19 infection in adult patients and whenever available, in pediatric patients. Pharmacotherapies used in the treatment of MIS-C in children are also reviewed.

Challenges and stepwise fit-for-purpose optimization for bioanalyses of remdesivir metabolites nucleotide monophosphate and triphosphate in mouse tissues using LC-MS/MS

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A robust and reliable LC–MS/MS method for the quantification of RMP and RTP was optimized and validated.

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The novel method solved the major challenges of direct determination of RMP and RTP in biological matrix through improvement of LC retention, stability and recovery.

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The method was validated and successfully applied to mouse tissue distribution study.

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This method provides useful information for further study of remdesivir as well as extends the approach for phosphate determination.

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The method solved the major challenges for determining RMP and RTP in biological matrix such as LC retention, stability and recovery.

Remdesivir is a prodrug of the nucleotide analogue and used for COVID-19 treatment. However, the bioanalysis of the active metabolites remdesivir nucleotide triphosphate (RTP) and its precursor remdesivir nucleotide monophosphate (RMP) is very challenging. Herein, we established a novel method to separate RTP and RMP on a BioBasic AX column and quantified them by high-performance liquid chromatography-tandem mass spectrometry in positive electrospray ionization mode. Stepwise, we optimized chromatographic retention on an anion exchange column, improved stability in matrix through the addition of 5,5′-dithiobis-(2nitrobenzoic acid) and PhosSTOP EASYpack, and increased recovery by dissociation of tight protein binding with 2 % formic acid aqueous solution. The method allowed lower limit of quantification of 20 nM for RMP and 10 nM for RTP. Method validation demonstrated acceptable accuracy (93.6%–103% for RMP, 94.5%–107% for RTP) and precision (RSD < 11.9 % for RMP, RSD < 11.4 % for RTP), suggesting that it was sensitive and robust for simultaneous quantification of RMP and RTP. The method was successfully applied to analyze RMP and RTP in mouse tissues. In general, the developed method is suitable to monitor RMP and RTP, and provides a useful approach for exploring more detailed effects of remdesivir in treating diseases.

Treatment of children with COVID-19: position paper of the Italian Society of Pediatric Infectious Disease

A statement of consensus was formulated after reviewing available literature on pediatric treatment strategies for COVID-19 by the Steering and Scientific Committee of the Italian Society of Infectious Pediatric Diseases in connection with the Italian Society of Paediatrics.