Antiviral Prodrugs Research Articles

Ultrasensitive turn-off fluorescent sensor for estimation of the new influenza antiviral prodrug baloxavir marboxil in its pharmaceutical formulation.

Carbon quantum dots (CQDs) are a recently developed class of fluorescent nanoparticles made from carbon. Co-doping with heteroatoms such as nitrogen and sulfur improved the properties and generated a high quantum yield. In the proposed study, we utilized a simple, cost-effective, single-stage hydrothermal approach to produce extreme photoluminescence co-doped, nitrogen and sulfur, CQDs (N,S-CODs). Thiosemicarbazide was used as a nitrogen and sulfur source, while citric acid was used as a carbon source to produce fluorescent probes. The prepared N,S-CQDs were subjected to extensive characterization. The generated N,S-CQDs yielded strong fluorescence emission at λ em 430.0 nm after excitation at λ ex 360.0 nm, with a relatively high quantum yield of 41.3% utilizing quinine sulfate as a reference fluorescent compound. These N,S-CQDs were applied as fluorescent nanosensors for the ultrasensitive spectrofluorimetric determination of baloxavir marboxil (BXM) directly without pre-derivatization for the first time. BXM effectively quenches the native fluorescence of N,S-CQDs. Considering the optimal conditions, the fluorescence intensity reduction of N,S-CQDs exhibited a 'turn-off' response to BXM at concentrations of 10.0-100.0 ng ml-1, with detection limits of 1.88 ng ml-1 and quantitation limits of 5.69 ng ml-1, respectively. The proposed method determined BXM successfully in its tablet dosage form and further expanded to confirm the content uniformity of the tablet units in agreement with USP guidelines.

The Antiviral and Antimalarial Prodrug Artemisinin from the Artemisia Species: A Review.

Artemisinin is a truly fascinating drug in many ways. Since the unrestrained procedure of its detection, as an antimalarial drug, artemisinin has received a great deal of consideration. Recently, application of artemisinin-based combination therapy has been broadly applied for treating numerous ailments. Moreover, as an antimalarial compound, artemisinin and its associated compounds have abundant healing efficacy and can be repurposed for additional symptoms, like autoimmune infections, cancer, and viral contaminations. Recently a number of studies have highlighted the significance of the artemisinin-related compounds in SARS-CoV-2 treatment. The current review purposes to present a concise account of the history of the antiviral and antimalarial prodrugs-Artemisinin, from the Artemisia species. It is followed by its antiviral, antimalarial prospective, chemical nature and extraction procedure, photochemistry, mechanism of action, and its clinical trials and patents, and accentuates the significance of the mechanistic studies concerned for therapeutic results, both in viral and malarial circumstances.

Glyoxal Caging of Nucleoside Antivirals toward Self-Activating, Extended-Release Prodrugs.

Nucleoside antivirals are a leading class of compounds prescribed as a first-line treatment for viral infections. However, inherent limitations such as low solubility and circulation lifetime can necessitate multi-intraday dosing. Here, we deploy the 1,2-dialdehyde glyoxal to generate antiviral nucleoside prodrugs with enhanced pharmacokinetic properties and extended-release activity to combat poor patient adherence. The near-quantitative reaction of glyoxal with acyclovir (ACV) drastically improves ACV solubility and enables subsequent drug release with a half-life of 1.9 h under physiological conditions. Further, glyoxal caging thermoreversibly disrupts ACV activity against HIV-1 reverse transcription in vitro and HSV-1 pathology in cellulo. Finally, the amenability of a panel of nucleoside reverse transcriptase inhibitors to glyoxal caging showcases the potential of this highly versatile method for achieving timed-release activation of a clinically important class of antiviral therapeutics.

Safety, tolerability and pharmacokinetics of ASC10, a novel oral double prodrug of a broad-spectrum antiviral agent, β-d-N4-hydroxycytidine: results from a randomized, double-blind, placebo-controlled phase 1 study in Chinese healthy subjects

ABSTRACT Background Considering the rise of new SARS-CoV-2 variants that have reduced the efficacy of COVID-19 vaccines, the development of new antiviral medications for the disease has become increasingly necessary. In this study, ASC10, a novel antiviral prodrug, was studied in a phase 1 trial in healthy Chinese participants. Research design and methods Part 1 involved 60 participants, receiving 50–800 mg ASC10 or placebo twice daily for 5.5 days. Part 2, with 12 participants, explored ASC10 dosing in the fed/fasting states. Results ASC10-A, the main pharmacologically active metabolite, rapidly appeared in plasma (Tmax: 1.00–2.00 h) and decreased (t1/2: 1.10–3.04 h) without accumulation. The Cmax and area under the plasma concentration – time curve (AUC) of ASC10-A increased dose-dependently (50–800 mg BID) over 5.5 days, with no accumulation. The Tmax was slightly delayed in the fed state; however, the Cmax and AUC were similar between the fed and fasting states. Adverse events (AEs) were comparable (ASC10/placebo, 66.7%) and mostly mild (95%). Conclusion ASC10 was demonstrated to be safe and well tolerated and exhibited dose-proportional exposure and minimal food effects. Clinical trial registration www.clinicaltrials.gov identifier is NCT05523141.

Experimental and theoretical study of the Favipiravir association in water solvent

Favipiravir, also known as T-705, is an antiviral prodrug that was first developed against the influenza virus and was later found to be effective against other RNA viruses, including arenaviruses, bunyaviruses, Zika, Ebola, Lassa, and COVID-19 viruses, in addition to influenza A and B. Due to the global prevalence of SARS-COV-2 in 2019, Favipiravir was used as an antiviral drug for treating COVID-19, but the challenges facing it, including its solubility, tablet ability, and bioavailability, remain. It is critical and challenging to develop a drug with appropriate bioavailability, improved oral absorption, and increased solubility without interfering with other functions and preventing the consumption of high daily doses. For this purpose, in the present study, the interactions of Favipiravir-Favipiravir and Favipiravir-H2O and the association of the Favipiravir molecules were investigated experimentally and theoretically. The theoretical results showed that under normal conditions, all structures were stable, but the most stable structure based on calculations of electronic energy, Gibbs, and solvation Gibbs free energies (minimum value), both in the gas phase and in the aqueous phase, is related to the B-enol isomer. Also, the change in dipole moment in the solvation process for this isomer was less than others. Also, the intense intermolecular hydrogen bonds O-H…O and N-H…O between the Favipiravir and water molecules showed that Favipiravir…Favipiravir interactions are stronger than Favipiravir…H2O interactions in aqueous solutions. These interactions indicate that Favipiravir can participate in the aggregation phenomena in high concentrations. Also, Stokeʼs shift values slightly increased with the decreasing the drug concentration in water (intramolecular charge transfer phenomenon).

Antiviral drug recognition and elevator-type transport motions of CNT3.

Nucleoside analogs have broad clinical utility as antiviral drugs. Key to their systemic distribution and cellular entry are human nucleoside transporters. Here, we establish that the human concentrative nucleoside transporter 3 (CNT3) interacts with antiviral drugs used in the treatment of coronavirus infections. We report high-resolution single-particle cryo-electron microscopy structures of bovine CNT3 complexed with antiviral nucleosides N4-hydroxycytidine, PSI-6206, GS-441524 and ribavirin, all in inward-facing states. Notably, we found that the orally bioavailable antiviral molnupiravir arrests CNT3 in four distinct conformations, allowing us to capture cryo-electron microscopy structures of drug-loaded outward-facing and drug-loaded intermediate states. Our studies uncover the conformational trajectory of CNT3 during membrane transport of a nucleoside analog antiviral drug, yield new insights into the role of interactions between the transport and the scaffold domains in elevator-like domain movements during drug translocation, and provide insights into the design of nucleoside analog antiviral prodrugs with improved oral bioavailability.

Molnupiravir, a ribonucleoside antiviral prodrug against SARS-CoV-2, alters the voltage-gated sodium current and causes adverse events

Molnupiravir (MOL) is a ribonucleoside prodrug for oral treatment of COVID-19. Common adverse effects of MOL are headache, diarrhea, and nausea, which may be associated with altered sodium channel function. Here, we investigated the effect of MOL on voltage-gated Na+ current (INa) in pituitary GH3 cells. We show that MOL had distinct effects on transient and late INa, in combination with decreased time constant in the slow component of INa inactivation. The 50% inhibitory concentration (IC50) values of MOL for suppressing transient and late INa were 26.1 and 6.3 μM, respectively. The overall steady-state current-voltage relationship of INa remained unchanged upon MOL exposure. MOL-induced alteration of INa may lead to changes in physiological function through sodium channels. Apart from its effect on inhibiting RNA virus replication, MOL exerts inhibitory effects on plasmalemma INa, which might constitute an additional yet crucial underlying mechanism of its pharmacological activity or adverse events.

Cell-Dependent Activation of ProTide Prodrugs and Its Implications in Antiviral Studies.

The ProTide prodrug design is a powerful tool to improve cell permeability and enhance the intracellular activation of nucleotide antiviral analogues. Previous in vitro studies showed that the activation of ProTide prodrugs varied in different cell lines. In the present study, we investigated the activation profiles of two antiviral prodrugs tenofovir alafenamide (TAF) and sofosbuvir (SOF) in five cell lines commonly used in antiviral research, namely, Vero E6, Huh-7, Calu-3, A549, and Caco-2. We found that TAF and SOF were activated in a cell-dependent manner with Vero E6 being the least efficient and Huh-7 being the most efficient cell line for activating the prodrugs. We also demonstrated that TAF was activated at a significantly higher rate than SOF. We further analyzed the protein expressions of the activating enzymes carboxylesterase 1, cathepsin A, histidine triad nucleotide-binding protein 1, and the relevant drug transporters P-glycoprotein and organic anion-transporting polypeptides 1B1 and 1B3 in the cell lines using the proteomics data extracted from the literature and proteome database. The results revealed significant differences in the expression patterns of the enzymes and transporters among the cell lines, which might partially contribute to the observed cell-dependent activation of TAF and SOF. These findings highlight the variability of the abundance of activating enzymes and transporters between cell lines and emphasize the importance of selecting appropriate cell lines for assessing the antiviral efficacy of nucleoside/nucleotide prodrugs.

ANTIVIRAL DRUGS IN THE TREATMENT FOR COVID-19

Introduction. Covid-19 is an infectious contagious disease of viral etiology caused by SARS-COv-2.
 Covid-19 is a highly infectious viral disease caused by SARS-CoV-2. The management of Covid-19 presents significant challenges, and the decision regarding the level of medical care provided, whether in outpatient or hospital settings, relies primarily on the clinical assessment of the patient's condition.
 The aim of this paper is to review and analyze the pharmacological properties of antiviral drugs used in the treatment regimens for Covid-19.
 Materials and Methods: In this research, internet resources such as PubMed, Google Scholar, and CrossRef were utilized. The focus was on providing an up-to-date review of the pharmacokinetic and pharmacodynamic characteristics of antiviral drugs used in the treatment of Covid-19.
 Monlupiravir is an antiviral prodrug with activity against SARS-CoV-2. It is prescribed for patients with mild to moderate Covid-19 who are at high risk of developing severe forms of the disease or death. Ribavirin is a nucleoside analogue with broad-spectrum antiviral activity. Remdesivir is a direct-acting antiviral drug that inhibits the RNA-dependent RNA polymerase, and it is indicated for seriously ill Covid-19 patients with pneumonia requiring oxygen therapy, as well as for patients with comorbidities such as diabetes mellitus, respiratory and cardiovascular diseases, immunosuppressive conditions, and renal failure.
 Favipiravin is a direct-acting synthetic antiviral drug, selective RNA polymerase inhibitor, which is indicated for the treatment of moderate and severe COVID-19, pandemic infections caused by influenza virus, and also when other drugs are ineffective.
 Lopinavir/ritonavir is a combination drug, a protease inhibitor, which is used in the treatment charts for seriously ill patients with COVID-19.
 Conclusion. The search for effective etiotropic drugs for treatment of patients with COVID-19 is still continuing. Monlupiravir, ribavirin, remdesivir, favipiravin, plitidepsin, lopinavir / ritonavir are used for treatment. Mechanism of drugs’ action, peculiarities of their pharmacokinetics and pharmacodynamics, possible side effects, dosage forms are required for the choice of the drug.
 Favipiravir is a synthetic antiviral drug that acts as a selective RNA polymerase inhibitor. It is indicated for the treatment of moderate to severe Covid-19, as well as for pandemic influenza infections when other drugs are ineffective. Lopinavir/ritonavir is a combination drug and a protease inhibitor used in the treatment of severely ill patients with Covid-19.

Sustainable Stability-Indicating spectra manipulations for the concurrent quantification of a novel Anti-COVID-19 drug and its active Metabolite: Green profile assessment

Millions of individuals have lost their lives and changed their routines as a direct consequence of exposure to the coronavirus (Covid-19). Molnupiravir (MOL) is an orally bioavailable tiny molecule antiviral prodrug that is effective for curing the coronavirus that produces serious acute respiratory disorder (SARS-CoV-2). Fully green-assessed stability-indicating simple spectrophotometric methods have been developed and fully validated as per ICH criteria. The potential impact of degradation products of drug components on the safety and efficacy of a medication's shelf life is likely to be negligible. The field of pharmaceutical analysis necessitates various stability testing under different conditions. The conduct of such inquiries affords the prospect of predicting the most probable routes of degradation and ascertaining the inherent stability characteristics of the active drugs. Consequently, a surge in demand arose for the creation of an analytical methodology that could consistently measure the degradation products and/or impurities that may be present in pharmaceuticals. Herein, five smart and simple spectrophotometric data manipulation techniques have been produced for the concurrent estimation of MOL and its active metabolite as its possible acid degradation product namely; N-hydroxycytidine (NHC). Structure confirmation of NHC build-up through IR, MS and NMR analyses. All current techniques verified linearity ranging from 10 to 150 μg/ml and 10–60 μg/ml for MOL and NHC, respectively. The limit of quantitation (LOQ) values were in the range of 4.21–9.59 μg/ml, while the limit of detection (LOD) values were ranging from 1.38 − 3.16 μg/ml. The current methods were evaluated in terms of greenness by four assessing methods and confirmed to be green. The significant novelty of these methods depends on their being the first environmentally soundness stability-indicating spectrophotometric approaches for the concurrent estimation of MOL and its active metabolite, NHC. Also, the preparation of purified NHC delivers significant cost savings, instead of purchasing an expensive ingredient. These smart methods were utilized for analyzing the pharmaceutical dosage form which may be of great benefit to the pharmaceutical market.

Ecofriendly stability-indicating UHPLC-PDA method for determination of the new influenza antiviral prodrug Baloxavir Marboxil; application to degradation kinetic studies and structure elucidation of the major degradation products using LC-MS

Implementation of green chemistry principles in analytical procedures is of great importance. Green analytical chemistry minimizes the dangerous impact on human beings and the environment that is the primary objective nowadays. In the proposed work, a well-developed, fully validated and ecofriendly stability indicating UHPLC coupled with photodiode array detector (PDA) method was established for the determination of Baloxavir Marboxil (BXM), a novel antiviral drug for the treatment of influenza A and B, in raw materials and pharmaceutical formulations. The method employed Inertsil ODS-3 C18 column to separate BXM from its forced degradation products using a mobile phase composed of 0.1% citric acid (pH 2.5 ± 0.05)-methanol (50:50, v/v), at a flow rate of 0.8 mL/min in an isocratic separation mode. BXM was monitored using diode array detector at 260.0 nm. BXM stability was inspected using various stress conditions as per ICH recommendations. The impact of acid, base hydrolysis, and oxidative stress conditions was greater on BXM in comparison to photo and thermal hydrolysis. The formed degradation products were injected into the mass spectrometer (MS) to elucidate their structures. The suggested pathways for degradation mechanisms were presented. Moreover, the proposed method was effectively utilized to study the degradation kinetics of acid, base and oxidative degradation of BXM. Additionally, four assessment tools were employed to evaluate the greenness of the developed method, namely; the National Environmental Method Index, the Analytical Eco-scale, Green Analytical Procedure tool, and the Analytical Greenness metric. Moreover, a comparative study of the method's greenness was conducted with the reported HPLC method and the results confirming that the suggested method is superior regarding the guidelines and principles of green chemistry. In addition to, having higher qualitative and quantitative scores in comparison to the reported method, and providing reliable and precise results of the method greenness.

Drugs That Mimic Hypoxia Selectively Target EBV-Positive Gastric Cancer Cells.

Latent infection of Epstein-Barr virus (EBV) is associated with lymphoid and epithelial cell cancers, including 10% of gastric carcinomas. We previously reported that hypoxia inducible factor-1α (HIF-1α) induces EBV's latent-to-lytic switch and identified several HIF-1α-stabilizing drugs that induce this viral reactivation. Here, we tested three classes of these drugs for preferential killing of the EBV-positive gastric cancer AGS-Akata cell line compared to its matched EBV-negative AGS control. We observed preferential killing with iron chelators [Deferoxamine (DFO); Deferasirox (DFX)] and a prolyl hydroxylase inhibitor (BAY 85-3934 (Molidustat)), but not with a neddylation inhibitor [MLN4924 (Pevonedistat)]. DFO and DFX also induced preferential killing of the EBV-positive gastric cancer AGS-BDneo and SNU-719 cell lines. Preferential killing was enhanced when low-dose DFX (10 μM) was combined with the antiviral prodrug ganciclovir. DFO and DFX induced lytic EBV reactivation in approximately 10% of SNU-719 and 20-30% of AGS-Akata and AGS-BDneo cells. However, neither DFO nor DFX significantly induced synthesis of lytic EBV proteins in xenografts grown in NSG mice from AGS-Akata cells above the level observed in control-treated mice. Therefore, these FDA-approved iron chelators are less effective than gemcitabine at promoting EBV reactivation in vivo despite their high specificity and efficiency in vitro.

Earth-friendly-assessed silver-nanoparticles spectrophotometric method for rapid and sensitive analysis of Molnupiravir, an FDA-approved candidate for COVID-19: application on pharmaceutical formulation and dissolution test

Molnupiravir is the first oral direct-acting antiviral prodrug recently approved for the COVID-19 pandemic. Here and for the first time, we present a novel, sensitive, robust, and simple silver-nanoparticles spectrophotometric technique for molnupiravir analysis in its capsules and dissolution media. This spectrophotometric technique involved silver-nanoparticles synthesis through a redox reaction between the reducing agent (molnupiravir) and the oxidizing agent (silver nitrate) in presence of polyvinylpyrrolidone as a stabilizing agent. The produced silver-nanoparticles have an intense surface plasmon resonance peak at 416 nm where the measured absorbance values were utilized for the quantitative analysis of molnupiravir. The produced silver-nanoparticles were recognized by using the transmission electron microscope. Under optimal conditions, a good linear rapport was accomplished between molnupiravir concentrations and the corresponding absorbance values in a range of (100–2000) ng/mL with a detection limit of 30 ng/mL. Greenness assessment was implemented using eco-scale scoring and GAPI disclosing the excellent greenness of the suggested technique. The suggested silver-nanoparticles technique was authenticated according to recommendations of the ICH and statistically assessed with the reported liquid chromatographic method without significant differences regarding accuracy or precision. Accordingly, the suggested technique is deemed a green and cheap alternative for assaying molnupiravir due to its reliance primarily on water. Furthermore, the suggested technique’s high sensitivity can be employed for investigating molnupiravir bioequivalence in future studies.Graphical

Real-time monitoring of enzyme-catalyzed phosphoribosylation of anti-influenza prodrug favipiravir by time-lapse nuclear magnetic resonance spectroscopy.

Favipiravir (brand name Avigan), a widely known anti-influenza prodrug, is metabolized by endogenous enzymes of host cells to generate the active form, which exerts inhibition of viral RNA-dependent RNA polymerase activity; first, favipiravir is converted to its phosphoribosylated form, favipiravir-ribofuranosyl-5'-monophosphate (favipiravir-RMP), by hypoxanthine-guanine phosphoribosyltransferase (HGPRT). Because this phosphoribosylation reaction is the rate-determining step in the generation of the active metabolite, quantitative and real-time monitoring of the HGPRT-catalyzed reaction is essential to understanding the pharmacokinetics of favipiravir. However, assay methods enabling such monitoring have not been established. 19 F- or 31 P-based nuclear magnetic resonance (NMR) are powerful techniques for observation of intermolecular interactions, chemical reactions, and metabolism of molecules of interest, given that NMR signals of the heteronuclei sensitively reflect changes in the chemical environment of these moieties. Here, we demonstrated direct, sensitive, target-selective, nondestructive, and real-time observation of HGPRT-catalyzed conversion of favipiravir to favipiravir-RMP by performing time-lapse 19 F-NMR monitoring of the fluorine atom of favipiravir. In addition, we showed that 31 P-NMR can be used for real-time observation of the identical reaction by monitoring phosphorus atoms of the phosphoribosyl group of favipiravir-RMP and of the pyrophosphate product of that reaction. Furthermore, we demonstrated that NMR approaches permit the determination of general parameters of enzymatic activity such as Vmax and Km . This method not only can be widely employed in enzyme assays, but also may be of use in the screening and development of new favipiravir-analog antiviral prodrugs that can be phosphoribosylated more efficiently by HGPRT, which would increase the intracellular concentration of the drug's active form. The techniques demonstrated in this study would allow more detailed investigation of the pharmacokinetics of fluorinated drugs, and might significantly contribute to opening new avenues for widespread pharmaceutical studies.

LC-MS/MS-based metabolite quantitation of the antiviral prodrug baloxavir marboxil, a new therapy for acute uncomplicated influenza, in human plasma: Application to a human pharmacokinetic study

Baloxavir marboxil (BXM) is a novel orally administrated prodrug for the treatment of acute uncomplicated influenza. In the present study, a bioanalytical LC-MS/MS method was developed and validated for the quantification of baloxavir acid (BXA), the active form of baloxavir marboxil in plasma of healthy volunteers using dolutegravir as an internal standard (IS) following plasma protein precipitation with acetonitrile. BXA and the internal standard were chromatographically separated using Waters Xterra® MS C8 column (5 µm, 4.6 × 50 mm) and a mobile phase comprised of 10.0 mM ammonium formate pH 3.5 and acetonitrile (80:20, v/v) delivered at a flow rate of 0.6 mL/min. The transitions of m/z 484.00 → 247.0 and 420.30 → 277.1 for BXA and IS, respectively in multiple reaction monitoring (MRM) mode in a positive ESI interface were used for quantitation through triple-quad mass spectrometry, API 4000. The method linearity was proven across the concentration range of 0.5–200.0 ng/mL, adjusted, and validated completely in accordance with the bioanalytical guidelines of the United States-FDA. Finally, the present method was effectively applied for the pharmacokinetic study of BXA in healthy human volunteers with accepted reproducibility and ruggedness.

Reshaping the Binding Pocket of the Neurotransmitter:Solute Symporter (NSS) Family Transporter SLC6A14 (ATB0,+) Selectively Reduces Access for Cationic Amino Acids and Derivatives.

SLC6A14 (ATB0,+) is unique among SLC proteins in its ability to transport 18 of the 20 proteinogenic (dipolar and cationic) amino acids and naturally occurring and synthetic analogues (including anti-viral prodrugs and nitric oxide synthase (NOS) inhibitors). SLC6A14 mediates amino acid uptake in multiple cell types where increased expression is associated with pathophysiological conditions including some cancers. Here, we investigated how a key position within the core LeuT-fold structure of SLC6A14 influences substrate specificity. Homology modelling and sequence analysis identified the transmembrane domain 3 residue V128 as equivalent to a position known to influence substrate specificity in distantly related SLC36 and SLC38 amino acid transporters. SLC6A14, with and without V128 mutations, was heterologously expressed and function determined by radiotracer solute uptake and electrophysiological measurement of transporter-associated current. Substituting the amino acid residue occupying the SLC6A14 128 position modified the binding pocket environment and selectively disrupted transport of cationic (but not dipolar) amino acids and related NOS inhibitors. By understanding the molecular basis of amino acid transporter substrate specificity we can improve knowledge of how this multi-functional transporter can be targeted and how the LeuT-fold facilitates such diversity in function among the SLC6 family and other SLC amino acid transporters.

Biology of Peptide Transporter 2 in Mammals: New Insights into Its Function, Structure and Regulation.

Peptide transporter 2 (PepT2) in mammals plays essential roles in the reabsorption and conservation of peptide-bound amino acids in the kidney and in maintaining neuropeptide homeostasis in the brain. It is also of significant medical and pharmacological significance in the absorption and disposing of peptide-like drugs, including angiotensin-converting enzyme inhibitors, β-lactam antibiotics and antiviral prodrugs. Understanding the structure, function and regulation of PepT2 is of emerging interest in nutrition, medical and pharmacological research. In this review, we provide a comprehensive overview of the structure, substrate preferences and localization of PepT2 in mammals. As PepT2 is expressed in various organs, its function in the liver, kidney, brain, heart, lung and mammary gland has also been addressed. Finally, the regulatory factors that affect the expression and function of PepT2, such as transcriptional activation and posttranslational modification, are also discussed.

The first Chinese oral anti-COVID-19 drug Azvudine launched

The first Chinese oral anti-COVID-19 drug Azvudine launched

In vitro evaluation of the impact of Covid-19 therapeutic agents on the hydrolysis of the antiviral prodrug remdesivir

Remdesivir (RDV, Veklury®) is an FDA-approved prodrug for the treatment of hospitalized patients with COVID-19. Recent in vitro studies have indicated that human carboxylesterase 1 (CES1) is the major metabolic enzyme catalyzing RDV activation. COVID-19 treatment for hospitalized patients typically also involves a number of antibiotics and anti-inflammatory drugs. Further, individuals who are carriers of a CES1 variant (polymorphism in exon 4 codon 143 [G143E]) may experience impairment in their ability to metabolize therapeutic agents which are CES1 substrates. The present study assessed the potential influence of nine therapeutic agents (hydroxychloroquine, ivermectin, erythromycin, clarithromycin, roxithromycin, trimethoprim, ciprofloxacin, vancomycin, and dexamethasone) commonly used in treating COVID-19 and 5 known CES1 inhibitors on the metabolism of RDV. Additionally, we further analyzed the mechanism of inhibition of cannabidiol (CBD), as well as the impact of the G143E polymorphism on RDV metabolism. An in vitro S9 fraction incubation method and in vitro to in vivo pharmacokinetic scaling were utilized. None of the nine therapeutic agents evaluated produced significant inhibition of RDV hydrolysis; CBD was found to inhibit RDV hydrolysis by a mixed type of competitive and noncompetitive partial inhibition mechanism. In vitro to in vivo modeling suggested a possible reduction of RDV clearance and increase of AUC when coadministration with CBD. The same scaling method also suggested a potentially lower clearance and higher AUC in the presence of the G143E variant. In conclusion, a potential CES1-mediated DDI between RDV and the nine assessed medications appears unlikely. However, a potential CES1-mediated DDI between RDV and CBD may be possible with sufficient exposure to the cannabinoid. Patients carrying the CES1 G143E variant may exhibit a slower biotransformation and clearance of RDV. Further clinical studies would be required to evaluate and characterize the clinical significance of a CBD-RDV interaction.

A validated LC-MS/MS method for determination of antiviral prodrug molnupiravir in human plasma and its application for a pharmacokinetic modeling study in healthy Egyptian volunteers

A fully validated, simple, rapid and reproducible liquid chromatography-tandem mass spectrometry method was developed to determine NHC (N-hydroxycytidine), the active metabolite of Molnupiravir (MOL) in human plasma; one of the limited treatment options for SARS-CoV-2 in plasma of healthy volunteers. The internal standard (IS) used was ribavirin. The extraction of analyte and IS from plasma was performed using acetonitrile as a solvent for protein precipitation. Agilent Zorbax Eclipse plus C18, 4.6 × 150 mm, (5 µm) was used for chromatographic separation using a mixture of methanol0.2 % acetic acid (5:95, v/v) as a mobile phase that was pumped at a flow rate of 0.9 mL/min. Detection was performed on a triple quadrupole mass spectrometer operating in multiple reaction monitoring (MRM) employing positive ESI interface using API4500 triple quadrupole tandem mass spectrometer system, with the transitions set at m/z 260.10 → 128.10 and 245.10 → 113.20 for NHC and IS respectively. Method validation was performed in accordance with United States FDA bioanalytical guidance. The concentration range of 20.0–10000.0 ng/mL was used to establish linearity via weighted linear regression approach (1/x2). Moreover, the analyzed pharmacokinetic data from twelve Egyptian healthy volunteers were used to develop a population pharmacokinetic model for NHC. The developed model was used to perform simulations and evaluate the current MOL dosing recommendations through calculating the maximum concentration (Cmax) “the safety metric” and area under the curve (AUC0-12 h) “the efficacy metric” for 1000 virtual subjects. Geometric mean ratios (GMR) with their associated 90% confidence intervals (CI) compared to literature values were computed. Geometric means of simulation-based Cmax and AUC0-12 were 3827 ng/mL (GMR = 1.05; 90% CI = 0.96–1.15) and 9320 ng.h/mL (GMR = 1.04; 90% CI = 0.97–1.11), respectively indicating that current MOL dosage can achieve the therapeutic targets and dose adjustment may not be required for the Egyptian population. The developed model could be used in the future to refine MOL dosage once further therapeutic targets are identified.