Accelerated stability study of the ester prodrug remdesivir: Recently FDA-approved Covid-19 antiviral using reversed-phase-HPLC with fluorimetric and diode array detection

Favipiravir, remdesivir, and lopinavir: metabolites, degradation products and their analytical methods

Severe acute respiratory syndrome 2 (SARS-CoV-2) caused the emergence of the COVID-19 pandemic all over the world. Several studies have suggested that antiviral drugs such as favipiravir (FAV), remdesivir (RDV), and lopinavir (LPV) may potentially prevent the spread of the virus in the host cells and person-to-person transmission. Simultaneously with the widespread use of these drugs, their stability and action mechanism studies have also attracted the attention of many researchers. This review focuses on the action mechanism, metabolites and degradation products of these antiviral drugs (FAV, RDV and LPV) and demonstrates various methods for their quantification and discrimination in the different biological samples. Herein, the instrumental methods for analysis of the main form of drugs or their metabolite and degradation products are classified into two types: optical and chromatography methods which the last one in combination with various detectors provides a powerful method for routine and stability analyses. Some representative studies are reported in this review and the details of them are carefully explained. It is hoped that this review will be a good guideline study and provide a better understanding of these drugs from the aspects investigated in this study.

A validated eco-friendly HPLC-FLD for analysis of the first approved antiviral remdesivir with other potential add-on therapies for COVID-19 in human plasma and pharmaceuticals

It is crucial to have a reliable and sensitive method for separating common drugs used in SARS-CoV-2 pneumonia treatment protocols for ongoing treatment and upcoming investigations. This study presents an HPLC-FLD approach to analyze three co-administered medicines - remdesivir (RDV), hydroxychloroquine sulphate (HCQ), and levofloxacin hemihydrate (LVX) - in their pure forms, pharmaceutical preparations, and spiked human plasma. The HPLC-FLD analysis was conducted using a Symmetry® C18 column (100 mm × 4.6 mm ID, 3.5 μm particle size) at 40 °C, with (A) an aqueous mixture of 0.02 M phosphate buffer and 0.2% heptane-1-sulphonic acid sodium solutions (50 : 50) adjusted to pH 3, (B) acetonitrile, and (C) methanol as the mobile phase. The injection volume was 10 μL, and the flow rate was 1.5 mL min-1. The detection was done using a multi-wavelength excitation and emission fluorescence detector, with individual optimization for each drug. The drug separation time was less than 10 minutes, and the method showed sensitive and wide linearity ranges for all medicines, with r2 values of more than 0.999. The impact of the mobile phase pH and flow rate on suitability parameters (retention time and number of theoretical plates) was studied. The method was found to be environmentally friendly based on GAPI and AGREE metrics. The validity of the method was evaluated following ICH and FDA guidelines.

Determination of remdesivir in human plasma using (deep eutectic solvent-ionic liquid) ferrofluid microextraction combined with liquid chromatography

A microextraction technique based on ferrofluids was developed for the preconcentration and quantification of Remdesivir in human plasma samples. This method utilized a new type of magnetic colloids created by combining silica-coated magnetic particles with modified ionic liquid and natural hydrophobic deep eutectic solvent as the carrier liquid. The efficiency of the sorption and desorption steps was optimized using a chemometrics approach. Under the optimized conditions, the calibration curve exhibited linearity in the concentration range of 0.5 to 500.0 μg L-1, with a limit of detection and quantification of 0.2 and 0.5 μg L-1, respectively. The method precision was evaluated by assessing intra- and interday precision at three different analyte concentrations, yielding values of 8.9% and 16.8%, respectively. Moreover, the method accuracy fell within the range of 90.9% to 107.5%. This proposed method offers a green and environmentally friendly sample preparation technique for conducting pharmacodynamic, pharmacokinetic, and therapeutic drug monitoring studies of Remdesivir in biological fluids. Importantly, this technique eliminates the need for external energy sources or the use of dispersive solvents, providing a more efficient and sustainable approach.

Quantification of GS-441524 concentration in feline plasma using high performance liquid chromatography with fluorescence detection

The adenosine analogue GS-441524 has demonstrated efficacy in treatment of feline infectious peritonitis (FIP). With no commercially registered formulations of GS-441524 available, global focus shifted to its pro-drug remdesivir, as it became more accessible throughout the COVID-19 pandemic. This study developed and validated a simple liquid chromatography equipped with a fluorescence detector to quantify plasma concentrations of GS-441524 applicable for routine therapeutic monitoring of remdesivir or GS-441524 therapy for FIP infected cats. A Waters X-Bridge C18, 5 µm, 150 × 4.6 mm, column was used and mixtures of 20 mM ammonium acetate (pH 4.5) with acetonitrile of 5% and 70% were prepared for gradient mobile phase. With a simple protein precipitation using methanol to clean plasma sample, GS-441524 was monitored at excitation and emission wavelengths of 250 nm and 475 nm, respectively. Using an external standard, the lowest and highest limits of quantification were 19.5 ng/mL to 10,000 ng/mL, respectively. The intra- and inter day trueness of the quality controls (QCs) were within 10% of their nominal concentrations and intra- and inter day precision of the QCs (expressed as the coefficient of variation) ranged from 1.7 to 5.7%, This assay was able to quantify plasma trough levels of GS-441524 (23.7-190.1 ng/mL) after the administration of remdesivir (9.9-15.0 mg/kg BW, IV or SC) in FIP cats (n = 12). Accordingly, this study generated an alternative and cost-effective way to quantify GS-441524 in feline biological fluids at least up to 24 hr after administrations of remdesivir.

Determination of anti-SARS-CoV-2 virustatic pharmaceuticals in the aquatic environment using high-performance liquid chromatography high-resolution mass spectrometry

The Covid-19 pandemic has affected the global population since 2019. The rapid development and approval of vaccines has brought relief. Yet, effective cures are still being researched. Even if the pandemic situation may end, SARS-CoV-2 will remain and, thus, continued application of the drugs will lead to emissions of the active ingredients into the aquatic environment, as with other anthropogenic micropollutants. However, a general method for trace analysis of antiviral drugs is still missing. To this purpose, favipiravir, remdesivir, its active metabolite GS-441524, molnupiravir and its active metabolite EIDD-1931 were selected as representative analytes. A method was developed based on solid phase extraction and high-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight high-resolution mass spectrometry. Optimization comprised the choice of chromatographic columns, elution gradient, mass spectrometry and tandem mass spectrometry parameters. Solid phase extraction proved suitable for increase in limits of detection and quantitation. amelioration of the limits of detection and quantitation. Matrix effects were investigated applying the optimized method to a wastewater sample with added virustatics. All five compounds could be separated with reversed phase chromatography, whereas EIDD-1931 profited from hydrophilic interaction liquid chromatography. The optimized method yielded limits of detection and quantification of 2.1·10-1, 6.9·10-1 µg·L-1 for favipiravir, 1.8·10-3, 5.5·10-3 µg·L-1 for remdesivir, 1.9·10-3, 7.6·10-3 µg·L-1 for GS-441524, 2.9·10-3, 8.7·10-3 µg·L-1 for molnupiravir, and 1.3·10-1, 3.8·10-1 µg·L-1 for EIDD 1931. The method was first applied to compound stability testing at pH 2.8 and 9.7. At pH 2.8, remdesivir, GS-441524 and molnupiravir proved stable, whereas about 14% of EIDD-1931 and favipiravir were degraded. All five antiviral compounds were almost completely decomposed at pH 9.7. The application of the method was further demonstrated for potential transformation product detection on favipiravir ozonation monitoring.

Quantitative analysis of two COVID-19 antiviral agents, favipiravir and remdesivir, in spiked human plasma using spectrophotometric methods; greenness evaluation

Favipiravir and remdesivir have been included in the COVID-19 treatment guidelines panel of several countries. The main objective of the current work is to develop the first validated green spectrophotometric methods for the determination of favipiravir and remdesivir in spiked human plasma. The UV absorption spectra of favipiravir and remdesivir have shown some overlap, making simultaneous determination difficult. Due to the considerable overlap, two ratio spectra manipulating spectrophotometric methods, namely, ratio difference and the first derivative of ratio spectra, enabled the determination of favipiravir and remdesivir in their pure forms and spiked plasma. The ratio spectra of favipiravir and remdesivir were derived by dividing the spectra of each drug by the suitable spectrum of another drug as a divisor to get the ratio spectra. Favipiravir was determined by calculating the difference between 222 and 256 nm of the derived ratio spectra, while calculating the difference between 247 and 271 nm of the derived ratio spectra enabled the determination of remdesivir. Moreover, the ratio spectra of every drug were transformed to the first order derivative using ∆λ = 4 and a scaling factor of 100. The first-order derivative amplitude values at 228 and 251.20 nm enabled the determination of favipiravir and remdesivir, respectively. Regarding the pharmacokinetic profile of favipiravir (C_max 4.43 µg/mL) and remdesivir (C_max 3027 ng/mL), the proposed methods have been successfully applied to the spectrophotometric determination of favipiravir and remdesivir in plasma matrix. Additionally, the greenness of the described methods was evaluated using three metrics systems: the national environmental method index, the analytical eco-scale, and the analytical greenness metric. The results demonstrated that the described models were in accordance with the environmental characteristics.

Synthesis of the first remdesivir cocrystal: design, characterization, and therapeutic potential for pulmonary delivery

While cocrystal engineering is an emerging formulation strategy to overcome drug delivery challenges, its therapeutic potential in non-oral applications remains not thoroughly explored. We herein report for the first time the successful synthesis of a cocrystal for remdesivir (RDV), an antiviral drug with broad-spectrum activities against RNA viruses. The RDV cocrystal was prepared with salicylic acid (SA) via combined liquid-assisted grinding (LAG) and thermal annealing. Formation of RDV-SA was found to be a thermally activated process, where annealing at high temperature after grinding was a prerequisite to facilitate the cocrystal growth from an amorphous intermediate, rendering it elusive under ambient preparing conditions. Through powder X-ray analysis with Rietveld refinement, the three-dimensional molecular structure of RDV-SA was resolved. The thermally annealed RDV-SA produced by LAG crystalized in a non-centrosymmetric monoclinic space group P2₁ with a unit cell volume of 1826.53(17) ų, accommodating one pair of RDV and SA molecules in the asymmetric unit. The cocrystal formation was also characterized by differential scanning calorimetry, solid-state nuclear magnetic resonance, and Fourier-transform infrared spectroscopy. RDV-SA was further developed as inhaled dry powders by spray drying for potential COVID-19 therapy. The optimized RDV-SA dry powders exhibited a mass median aerodynamic diameter of 4.33 ± 0.2 μm and fine particle fraction of 41.39 ± 4.25 %, indicating the suitability for pulmonary delivery. Compared with the raw RDV, RDV-SA displayed a 15.43-fold higher fraction of release in simulated lung fluid at 120 min (p =0.0003). RDV-SA was safe in A549 cells without any in vitro cytotoxicity observed in the RDV concentration from 0.05 to 10 µM.

Recent analytical methodologies for the determination of anti-covid-19 drug therapies in various matrices: a critical review

Since the discovery of the first case infected with severe acute respiratory syndrome coronavirus-2 (SARS CoV-2) in Wuhan, China in December 2019, it has turned into a global pandemic. According to the World Health Organization (WHO) statistics, about 603.7 million confirmed coronavirus cases and 6.4 million deaths have been reported. Remdesivir (RMD) was the first U.S. Food and Drug Administration (FDA) approved antiviral drug for the treatment of coronavirus in pediatrics and adults with different disease severities, ranging from mild to severe, in both hospitalized and non-hospitalized patients. Various drug regimens are used in Covid-19 treatment, all of which rely on the use of antiviral agents including ritonavir (RTN)/nirmatrelvir (NTV) combination, molnupiravir (MLP) and favipiravir (FVP). Optimizing analytical methods for the selective and sensitive quantification of the above-mentioned drugs in pharmaceutical dosage forms and biological matrices is a must in the current pandemic. Several analytical techniques were reported for estimation of antivirals used in Covid-19 therapy. Chromatographic methods include Thin Layer Chromatography (TLC) densitometry, High Performance Thin Layer Chromatography (HPTLC), Reversed Phase-High Performance Liquid Chromatography (RP-HPLC), High Performance Liquid Chromatography Tandem Mass Spectrometry (HPLC-MS/MS) or Ultraviolet detectors (HPLC-UV), Ultra High-Performance Liquid Chromatography (UHPLC-MS/MS) or (UPLC-UV) and Micellar Liquid Chromatography (MLC). In addition to other spectroscopic methods including Paper Spray Mass Spectrometry (PS-MS), UV-Visible Spectrophotometry, and Spectrofluorimetry. Herein, we will focus on the clarification of trendy, simple, rapid, accurate, precise, sensitive, selective, and eco-friendly analytical methods used for the analysis of anti-Covid-19 drugs in dosage forms as well as biological matrices.

Development of UPLC method for simultaneous assay of some COVID-19 drugs utilizing novel instrumental standard addition and factorial design

A green, rapid, and simple RP-UPLC method was developed and optimized by full factorial design for the simultaneous separation of oseltamivir phosphate, daclatasivir dihydrochloride, and remdesivir, with dexamethasone as a co-administered drug. The separation was established on a UPLC column BEH C₁₈ 1.7 µm (2.1 × 100.0 mm) connected with a UPLC pre-column BEH 1.7 µm (2.1 × 5.0 mm) at 25 °C with an injection volume of 10 µL. The detector (PDA) was set at 239 nm. The mobile phase consisted of methanol and ammonium acetate (8.1818 mM) in a ratio of 75.7: 24.3 (v/v). The flow rate was set at 0.048 mL min^-1. The overall separation time was 9.5 min. The retention times of oseltamivir phosphate, dexamethasone, daclatasivir dihydrochloride, and remdesivir were 6.323 ± 0.145, 7.166 ± 0.036, 8.078 ± 0.124, and 8.572 ± 0.166 min (eight replicates), respectively. The proposed method demonstrated linearity in the ranges of 10.0-500.0 (ng mL^-1) and 0.5-30.0 (µg mL^-1) for oseltamivir phosphate, 50.0-5000.0 (ng mL^-1) for dexamethasone, 25.0-1000.0 (ng mL^-1) and 0.5-25.0 (µg mL^-1) for daclatasvir dihydrochlorde, and 10.0-500.0 (ng mL^-1) and 0.5-30.0 (µg mL^-1) for remdesivir. The coefficients of determination (R²) were greater than 0.9999, with percentage recoveries greater than 99.5% for each drug. The limits of quantitation were 6.4, 1.8, 7.8, and 1.6 ng mL^-1, and the limits of detection were 1.9, 0.5, 2.0, and 0.5 ng mL^-1 for oseltamivir phosphate, dexamethasone, daclatasivir dihydrochloride, and remdesivir, respectively. The proposed method was highly precise, as indicated by the low percentage of relative standard deviation values of less than 1.2% for each drug. The average content and uniformity of dosage units in the studied drugs' dosage forms were determined. The average contents of oseltamivir phosphate, dexamethasone, daclatasivir dihydrochloride, and remdesivir were nearly 93%, 102%, 99%, and 95%, respectively, while the uniformity of dosage unit values were nearly 92%, 102%, 101%, and 97%. Two novel methods were established in this work. The first method was used to assess the stability of standard solutions. This novel method was based on the slope of regression equations. The second was to evaluate the excipient's interference using an innovative instrumental standard addition method. The novel instrumental standard addition method was performed using the UPLC instrument program. It was more accurate, sensitive, time-saving, economical, and eco-friendly than the classic standard addition method. The results showed that the proposed method can estimate the tested drugs' concentrations without interference from their dosage form excipients. According to the Eco-score (more than 75), the Green Analytical Procedure Index (GAPI), and the AGREE criteria (total score of 0.77), the suggested method was considered eco-friendly.

Cosmeceutical formulations of pro-vitamin E phosphate: In-vitro release testing and dermal penetration into excised human skin

Long-term exposure to solar radiation can lead to skin damage such as photoageing, and photocarcinogenesis. This can be prevented by topically applying α-tocopherol phosphate (α-TP). The major challenge is that a significant amount of α-TP needs to reach viable skin layers for effective photoprotection. This study aims to develop candidate formulations of α-TP (gel-like, solution, lotion, and gel), and investigate formulation characteristics' effect on membrane diffusion and human skin permeation. All the formulations developed in the study had an appealing appearance and no signs of separation. All formulations had low viscosity and high spreadability except the gel. The flux of α-TP through the polyethersulfone membrane was the highest for lotion (6.63 ± 0.86 mg/cm²/h), followed by control gel-like (6.14 ± 1.76 mg/cm²/h), solution (4.65 ± 0.86 mg/cm²/h), and gel (1.02 ± 0.22 mg/cm²/h). The flux of α-TP through the human skin membrane was numerically higher for lotion compared to the gel-like (328.6 vs.175.2 µg/cm²/h). The lotion delivered 3-fold and 5-fold higher α-TP in viable skin layers at 3 h and 24 h, respectively, compared to that of the gel-like. The low skin membrane penetration rate and deposition of α-TP in viable skin layers were observed for the solution and gel. Our study demonstrated that dermal penetration of α-TP was influenced by characteristics of formulation such as formulation type, pH, and viscosity. The α-TP in the lotion scavenged higher DPPH free radicals compared to that of gel-like (almost 73% vs. 46%). The IC₅₀ of α-TP in lotion was significantly lower than that of gel-like (397.2 vs. 626.0 µg/mL). The preservative challenge test specifications were fulfilled by Geogard 221 and suggested that the combination of benzyl alcohol and Dehydroacetic Acid effectively preserved 2% α-TP lotion. This result confirms the suitability of the α-TP cosmeceutical lotion formulation employed in the present work for effective photoprotection.

Eco-friendly spectrophotometric methods for determination of remdesivir and favipiravir; the recently approved antivirals for COVID-19 treatment

Remdesivir (REM) and Favipiravir (FAV) are recently approved antivirals prescribed in severely ill COVID-19 patients. Therefore, development of new, simple, rapid, sensitive, and selective methods for analysis of such drugs in their pharmaceutical formulations will be highly advantageous. Herein, we have developed different spectrophotometric methods for analysis of the studied analytes. Method I is based on direct spectrophotometric analysis of REM and FAV in ethanol at λ_max 244 and 323 nm, respectively. For simultaneous quantitation of REM and FAV, methods II-V were followed. Method II is based on derivative spectrophotometry in which REM was determined in second-order derivative spectra at 248 nm (the zero-crossing wavelength for FAV), while FAV was measured in first-order derivative spectra at 337 nm (the zero-crossing point for REM). Method III is the dual-wavelength method in which spectral intensities were subtracted at 244-207 nm for REM and at 330-400 nm for FAV. Method IV is the ratio subtraction in which ratio spectra were obtained by a suitable divisor followed by subtraction of intensities at 272-340 nm and 335-222 nm for REM and FAV, respectively. Method V is the derivative ratio method in which the obtained ratio spectra in method IV were converted to first-order derivative and then REM and FAV were recorded at 280 and 340 nm, respectively. Calibration graphs were linear in the ranges of 1-10 µg/mL for REM through all methods and 1-20 µg/mL for FAV in methods I and II, and 2-20 µg/mL by the other methods. The evolved methods were applied to pharmaceutical dosage forms of REM and FAV. All the proposed methods were further applied to human plasma samples containing both drugs with acceptable mean recoveries.

Simultaneous spectrofluorimetic determination of remdesivir and simeprevir in human plasma

As new infectious mutations of SARS-CoV-2 emerged throughout the world, innovative therapies to counter the virus-altered drug sensitivities were urgently needed. Several antiviral options have been in clinical trials or in compassionate use for the treatment of SARS-CoV-2 infections in an attempt to minimize both clinical severity and viral shedding. Recent research indicated that simeprevir acts synergistically with remdesivir, allowing for a multiple-fold decrease in its effective dose when used at physiologically acceptable concentrations. The goal of this work is to develop a sensitive synchronous spectrofluorimetric approach to simultaneously quantify the two drugs in biological fluids. Using this method, remdesivir and simeprevir could be measured spectrofluorimetrically at 283 and 341 nm, respectively, without interference from each other using Δλ of 90 nm. The effect of various experimental parameters on the fluorescence intensity of the two drugs was extensively explored and optimized. For each of remdesivir and simeprevir, the method exhibited a linearity range of 0.10-1.10 μg/mL, with lower detection limits of 0.01 and 0.02 μg/mL and quantification limits of 0.03 and 0.05 μg/mL, respectively. The high sensitivity of the developed method permitted the simultaneous determination of both drugs in spiked plasma samples with % recoveries ranging from 95.0 to 103.25 with acceptable standard deviation values of 1.92 and 3.04 for remdesivir and simeprevir, respectively. The validation of the approach was approved by the International Council of Harmonization (ICH) guidelines.

Spectrofluorimetric quantitative analysis of favipiravir, remdesivir and hydroxychloroquine in spiked human plasma

Favipiravir, remdesivir and hydroxychloroquine have been suggested in COVID-19 Treatment Guidelines Panel of many countries. Synchronous spectrofluorometric measurement provides sensitive tool for resolving the overlapped spectra of multicomponent drugs through converting the wider spectra to narrower sharp spectra. This work introduces the first fluorescence spectroscopic method for quantitative analysis of favipiravir, remdesivir and hydroxychloroquine in spiked human plasma. Testing the fluorescence spectra of favipiravir, remdesivir and hydroxychloroquine shows severe overlap, which hinders the direct quantification of the cited drugs. To overcome the overlapping issue, the drugs under the study have been measured in the synchronous mode at Δλ = 60 nm. Favipiravir could be measured directly at 423 nm without interference of remdesivir or hydroxychloroquine. Synchronous measuring the cited drugs at Δλ = 130 nm with mathematical transforming to the first order derivative spectra allowing remdesivir and hydroxychloroquine at 384 nm and 394 nm, respectively without interference from favipiravir. Different factors affecting the spectrofluorometric measurement process have been verified. The drugs under the study have been successfully quantitatively analyzed in the spiked plasma using the proposed method.

Eco-friendly stability-indicating HPTLC micro-determination of the first FDA approved SARS-CoV-2 antiviral prodrug Remdesivir: Study of degradation kinetics and structural elucidation of the degradants using HPTLC-MS

The worldwide spread coronavirus (covid-19) pandemic caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents a global health crisis. The world was forced to face a great challenge to control and overcome this health disaster through various containment measures including efficient vaccination side by side with effective medication. Remdesivir (RMD) is the first FDA approved antiviral agent for treatment of covid-19 pandemic and hence regarded as the first-in-class medication of this highly contagious respiratory disease. The current study represents the first stability indicating HPTLC method for the estimation of RMD in bulk form and pharmaceutical formulation. The method employed TLC silica gel aluminum plates 60 F₂₅₄ as stationary phase and green mobile phase composed of ethyl acetate and ethanol (96: 4, v/v) with densitometric detection at 245 nm. Comprehensive validation of the adopted method was accomplished according to the ICH guidelines regarding linearity, ranges, detection and quantification limits, precision, accuracy and robustness. The developed method offered a neat separation of the drug in presence of pharmaceutical excipients as well as in presence of acidic, alkaline, neutral hydrolytic, oxidative and photolytic degradants. Additionally, structural elucidation of alkaline and hydrolytic oxidation degradation products was carried out using HPTLC-MS. Furthermore, for the first time the acidic and alkaline degradation kinetics of RMD were studied and its degradation rate constants and half-lives were calculated. Moreover, greenness appraisal of the developed method as well as comparison with previously published stability indicating HPLC methods were performed using analytical Eco-scale, GAPI and AGREE metrics.

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.

Nanomaterials for Photocatalytic Degradations of Analgesic, Mucolytic and Anti-Biotic/Viral/Inflammatory Drugs Widely Used in Controlling SARS-CoV-2

The COVID-19 pandemic has been transformed into one of the main worldwide challenges, in recent years. For controlling symptoms that are caused by this disease (e.g., chills or fever, shortness of breath and/or difficulty in breathing, cough, sore throat, fatigue, headache, muscle aches, the new loss of tastes and/or smells, congestion or runny nose, nausea, vomiting and/or diarrhea), lots of medicines including analgesics, mucolytics, and anti-biotic/viral/inflammatory drugs have been frequently prescribed. As these medicines finally contaminate terrestrial and aquatic habitats by entering surface waterways through pharmaceutical production and excreting trace amounts of waste after human usage, they have negative impacts on wildlife’s health and ecosystem. Residual drugs in water have the potential to harm aquatic creatures and disrupt their food chain as well as the breeding cycle. Therefore, proper degradation of these broadly used medicines is highly crucial. In this work, the use of nanomaterials applicable in photocatalytic degradations of analgesics (e.g., acetaminophen, aspirin, ibuprofen, and naproxen), mucolytics (e.g., ambroxol), antibiotics (e.g., azithromycin and quinolones including hydroxychloroquine and chloroquine phosphate), anti-inflammatory glucocorticoids (e.g., dexamethasone and cortisone acetate), antihistamines (e.g., diphenhydramine), H2 blockers (e.g., famotidine), anthelmintics (e.g., praziquantel), and finally antivirals (e.g., ivermectin, acyclovir, lopinavir/ritonavir, favipiravir, nitazoxanide, and remdesivir) which widely used in controlling/treating the coronavirus have been reviewed and discussed.

Comparative Greenness Metric Estimates for Content Uniformity Testing of Anti-Cov-2, GS-5734 in Commercial Vials: Validated Micellar Electrokinetic Chromatographic Assay

Background

The antiviral drug GS-5734 remdesivir is a new phosphoramidate prodrug developed initially as a treatment for Ebola virus which then proved to have antiviral properties against other viruses. After clinical trials, it was the first antiviral to be approved by the U.S. Food and Drug Administration in 2020 to treat severe coronavirus (COVID-19) cases. The widespread current pandemic gave an urge to its fast production and marketing. Thus, new analytical methods must be available for its analysis in a fast and easy manner with low cost to be applicable in all laboratories.

Objective

In the current study, a green and economic micellar electrokinetic chromatographic (MEKC) method is proposed for remdesivir analysis.

Methods

A fused-silica capillary (58.5 cm × 50 μm id, 50 cm effective length) with 20 mM borate buffer (pH 9) and 25 mM sodium dodecyl sulfate was used under a positive potential of 30 kV at 25°C with detection at 245 nm.

Results

Remdesivir analysis was achieved in approximately 5 min. The method proved to be linear in range of 1–50 μg/mL with correlation coefficient, r > 0.999.

Conclusion

The MEKC method proposed was applied to the analysis of remdesivir in its commercial vials. The method was validated per International Conference on Harmonization guidelines.

Highlights

Green chemistry has been the focus of the analytical community in the past few years. This method is considered green due to its low energy and solvent consumption without sacrificing the method’s sensitivity or selectivity. The method’s green profile has been assessed by different greenness assessment scales to ensure the method is eco-friendly and can be used in the pharmaceutical industry.

Significance of Chromatographic Techniques in Pharmaceutical Analysis

This work presents an overview of the modern approaches embracing advanced equipment and validation parameters of both liquid and gas chromatography techniques, including thin-layer chromatography (TLC), column liquid chromatography (CLC), and gas chromatography (GC), suitable for the identification and quantitative determination of various bioactive compounds occurring in pharmaceutical products and medicinal plants in the time from 2020 to 2021 (November). This review confirmed that HPLC is an incredibly universal tool, especially when combined with different detectors, such as UV-Visible spectroscopy, mass spectrometry (MS), and fluorescence detection for numerous active ingredients in different pharmaceutical formulations without interferences from other excipients. TLC, in combination with densitometry, is a very efficient tool for the determination of biologically active substances present in pharmaceutical preparations. In addition, TLC coupled to densitometry and mass spectrometry could be suitable for preliminary screening and determination of the biological activity (e.g., antioxidant properties, thin layer chromatography (TLC) by 2,2-diphenyl-1-picrylhydrazyl (DPPH) method) of plant materials. Gas chromatography, coupled with a mass spectrometer (GC-MS, GC-MS/MS), is of particular importance in the testing of any volatile substances, such as essential oils. LC, coupled to NMR and MS, is the best solution for identifying and studying the structure of unknown components from plant extracts, as well as degradation products (DPs). Thanks to size-exclusion chromatography, coupled to multi-angle light scattering, the quality control of biological pharmaceuticals is possible.

Environmental Impact of the Reported Chromatographic Methods for the Determination of the First FDA-Approved Therapy for COVID-19 Patients, Remdesivir: A Comparative Study

Remdesivir (REM) is considered the first therapeutic option approved by US Food and Drug Administration (FDA) for clinical care in case of hospitalized patients suffering in COVID-19 epidemic. In the presented multilateral comparative search, four eco friendlessness approaches —National Environmental Methods Index (NEMI), Eco-Scale Assessment (ESA), Green Analytical Procedure Index (GAPI), and Analytical Greenness metric (AGREE) are tested to assess 16 analytical chromatographic procedures reported for the analysis of the commonly used antiviral drug; Remdesivir (REM). The values of testing more than one approach when estimating the eco-friendly characters for analytical methods are illustrated in this study. On the light of the outcomes, ESA and AGREE approaches are recommended as they are easily applied and digitally presented. Furthermore, GAPI is also a reliable tool in terms of comprehensiveness for the whole analytical procedures, from sampling till the final assessment. NEMI is the easiest and fastest greenness evaluation tool; however, the information it provides is particularly of limited scope and sometimes inaccurate. To ensure greenness of chromatographic analytical methods, there must be clear planning beforehand, to reduce chemical hazards sent to environment. Additionally, it is highly recommended in method validation protocols to consider the greenness of a given analytical procedure before releasing to routine use.

The LC-MS/MS analysis for the active metabolite of REM (Nuc) reported by Avataneo et al. and Du et al. proved to be the best bio-analytical methods regarding the environmental aspects depending on the GAPI and AGREE tools. However, the HPLC method for REM analysis in intravenous solution reported by Jitta et al. proved to be the greenest analytical method for determination of REM in the pharmaceutical dosage forms according to the ESA, GAPI, and AGREE tools.

Liposomal remdesivir inhalation solution for targeted lung delivery as a novel therapeutic approach for COVID-19

Strong infectivity enables coronavirus disease 2019 (COVID-19) to rage throughout the world. Moreover, the lack of drugs with definite therapeutic effects further aggravates the spread of the pandemic. Remdesivir is one of the most promising anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) drugs. However, the limited clinical effects make its therapeutic effect controversial, which may result from the poor accumulation and activation of remdesivir in the lung. Therefore, we developed lyophilized remdesivir liposomes (Rdv-lips) which can be reconstituted as liposomal aerosol for pulmonary delivery to improve the in vivo behavior of existing remdesivir cyclodextrin conclusion compound (Rdv-cyc) injections. Liposome encapsulation endowed remdesivir with much higher solubility and better biocompatibility. The in vitro liposomal aerosol characterization demonstrated that Rdv-lips possessed a mass median aerodynamic diameter of 4.118 µm and fine particle fraction (<5 µm) higher than 50%, indicating good pulmonary delivery properties. Compared to the Rdv-cyc intravenous injection group, the Rdv-lips inhalation group displayed a nearly 100-fold increase in the remdesivir-active metabolite nucleotide triphosphate (NTP) concentration and better NTP accumulation in the lung than the Rdv-cyc inhalation group. A faster transition from remdesivir to NTP of Rdv-lips (inhalation) could also be observed due to better cell uptake. Compared to other preparations, the superiority of Rdv-lips was further evidenced by the results of an in vivo safety study, with little possibility of inducing inflammation. In conclusion, Rdv-lips for pulmonary delivery will be a potent formulation to improve the in vivo behavior of remdesivir and exert better therapeutic effects in COVID-19 treatment.