Targeting the vital non-structural proteins (NSP12, NSP7, NSP8 and NSP3) from SARS-CoV-2 and inhibition of RNA polymerase by natural bioactive compound naringenin as a promising drug candidate against COVID-19

The prevalence of SARS-CoV-2-induced respiratory infections is now a major challenge worldwide. There is currently no specific antiviral drug to prevent or treat this disease. Infection with COVID-19 seriously needs to find effective therapeutic agents. In the present study, naringenin, as a potential inhibitor candidate for RNA Polymerase SARS-CoV-2 was compared with remdesivir (FDA-approved drug) and GS-441,524 (Derivative of the drug remdesivir) by screening with wild-type and mutant SARS-CoV-2 NSP12 (NSP7-NSP8) and NSP3 interfaces, then complexes were simulated by molecular dynamics (MD) simulations to gain their stabilities. The docking results displayed ​scores of -3.45 kcal/mol and -4.32 kcal/mol against NSP12 and NSP3, respectively. Our results showed that naringenin had ΔG values more negative than the ΔG values of Remdesivir (RDV) and GS-441,524. Hence, naringenin was considered to be a potential inhibitor. Also, the number of hydrogen bonds of naringenin with NSP3 and later NSP12 are more than Remdesivir and its derivative. In this research, Mean root mean square deviation (RMSD) values of NSP3 and NSP12with naringenin ligand (5.55±1.58 nm to 3.45±0.56 nm and 0.238±0.01 to 0.242±0.021 nm, respectively showed stability in the presence of ligand. The root mean square fluctuations (RMSF) values of NSP3 and NSP12 amino acid units in the presence of naringenin in were 1.5 ± 0.31 nm and 0.118±0.058, respectively. Pharmacokinetic properties and prediction of absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of naringenin and RDV showed that ​these two compounds had no potential cytotoxicity.

Rescue and characterization of the first West African Marburg virus 2021 from Guinea

Marburg virus (MARV) is a causative agent of a severe hemorrhagic fever with high fatality rates endemic in central Africa. Current outbreaks of MARV in Equatorial Guinea and Tanzania underline the relevance of MARV as a public health emergency pathogen. In 2021, the first known human MARV case was confirmed in Guinea, West Africa. Since no infectious virus could be isolated from that fatal case in 2021, we generated recombinant (rec) MARV Guinea by reverse genetics in order to study and characterize this new MARV, which occurred in West Africa for the first time, in terms of its growth properties, detection by antibodies, and therapeutic potential compared to known MARV strains. Our results showed a solid viral replication of recMARV Guinea in human, bat, and monkey cell lines in comparison to other known MARV strains. We further demonstrated that replication of recMARV Guinea in cells can be inhibited by the nucleoside analogue remdesivir. Taken together, we could successfully reconstitute de novo the first West African MARV from Guinea showing similar replication kinetics in cells compared to other central African MARV strains. Our reverse genetics approach has proven successful in characterizing emerging viruses, especially when virus isolates are missing and viral genome sequences are incomplete.

Successful dual antiviral therapy with remdesivir and ensitrelvir in a case of prolonged COVID-19 following B-cell depleting immunotherapy for malignant lymphoma

Prolonged COVID-19 following B-cell depleting immunotherapy for malignant lymphoma is characterized by repeated cycles of remission followed by symptom recurrence, persistent detection of SARS-CoV-2, and profound humoral immunodeficiency. To the best of our knowledge, the present report is the first to describe dual antiviral therapy with remdesivir and ensitrelvir for prolonged COVID-19 following B-cell depleting immunotherapy for malignant lymphoma. A 59-year-old, female patient with a history of follicular lymphoma treated with obinutuzumab and bendamustine contracted COVID-19 despite receiving a single course of standard remdesivir therapy. She received dual antiviral therapy with remdesivir following a five-day course of oral ensitrelvir, which improved her clinical symptoms and chest radiology findings and cleared SARS-CoV-2 from respiratory samples. Dual antiviral therapy with remdesivir and ensitrelvir may be sufficient to stop viral replication and promote clinical resolution in prolonged COVID-19 following B-cell depleting immunotherapy for malignant lymphoma.

Which severe COVID-19 patients could benefit from high dose dexamethasone? A Bayesian post-hoc reanalysis of the COVIDICUS randomized clinical trial

BACKGROUND

The respective benefits of high and low doses of dexamethasone (DXM) in patients with severe acute respiratory syndrome coronavirus 2 (SARS-Cov2) and acute respiratory failure (ARF) are controversial, with two large triple-blind RCTs reaching very important difference in the effect-size. In the COVIDICUS trial, no evidence of additional benefit of high-dose dexamethasone (DXM20) was found. We aimed to explore whether some specific patient phenotypes could benefit from DXM20 compared to the standard of care 6 mg dose of DXM (DXMSoC).

METHODS

We performed a post hoc exploratory Bayesian analysis of 473 patients who received either DXMSoc or DXM20 in the COVIDICUS trial. The outcome was the 60 day mortality rate of DXM20 over DXMSoC, with treatment effect measured on the hazard ratio (HR) estimated from Cox model. Bayesian analyses allowed to compute the posterior probability of a more than trivial benefit (HR < 0.95), and that of a potential harm (HR > 1.05). Bayesian measures of interaction then quantified the probability of interaction (Pr Interact) that the HR of death differed across the subsets by 20%. Primary analyses used noninformative priors, centred on HR = 1.00. Sensitivity analyses used sceptical and enthusiastic priors, based on null (HR = 1.00) or benefit (HR = 0.95) effects.

RESULTS

Overall, the posterior probability of a more than trivial benefit and potential harm was 29.0 and 51.1%, respectively. There was some evidence of treatment by subset interaction (i) according to age (Pr Interact, 84%), with a 86.5% probability of benefit in patients aged below 70 compared to 22% in those aged above 70; (ii) according to the time since symptoms onset (Pr Interact, 99%), with a 99.9% probability of a more than trivial benefit when lower than 7 days compared to a < 0.1% probability when delayed by 7 days or more; and (iii) according to use of remdesivir (Pr Interact, 91%), with a 90.1% probability of benefit in patients receiving remdesivir compared to 19.1% in those who did not.

CONCLUSIONS

In this exploratory post hoc Bayesian analysis, compared with standard-of-care DXM, high-dose DXM may benefit patients aged less than 70 years with severe ARF that occurred less than 7 days after symptoms onset. The use of remdesivir may also favour the benefit of DXM20. Further analysis is needed to confirm these findings.

TRIAL REGISTRATION

NCT04344730, date of registration April 14, 2020 ( https://clinicaltrials.gov/ct2/show/NCT04344730?term=NCT04344730&draw=2&rank=1 ); EudraCT: 2020-001457-43 ( https://www.clinicaltrialsregister.eu/ctr-search/search?query=2020-001457-43 ).

Remdesivir plus dexamethasone is associated to improvement in the clinical outcome of COVID-19 hospitalized patients regardless of their vaccination status

INTRODUCTION

Remdesivir seems to reduce the risk of hospitalization and improve clinical outcome in hospitalized patients with COVID-19.

OBJECTIVES

To compare the clinical outcome of COVID-19 hospitalized patients treated with remdesivir plus dexamethasone versus dexamethasone alone, according to their vaccination status.

MATERIAL AND METHODS

A retrospective observational study was carried out in 165 patients hospitalized for COVID-19 from October 2021 to January 2022. Multivariate logistic regression, Kaplan-Meier and the log-rank tests were used to evaluate the event (need for ventilation or death).

RESULTS

Patients treated with remdesivir plus dexamethasone (n=87) compared with dexamethasone alone (n=78) showed similar age (60±16, 47-70 vs. 62±37, 51-74 years) and number of comorbidities: 1 (0-2) versus 1.5 (1-3). Among 73 fully vaccinated patients, 42 (47.1%) were in remdesivir plus dexamethasone and 31 (41%) in dexamethasone alone. Patients treated with remdesivir plus dexamethasone needed intensive care less frequently (17.2% vs. 31%; p=0.002), high-flow oxygen (25.3% vs. 50.0%; p=0.002) and non-invasive mechanical ventilation (16.1% vs. 47.4%; p<0.001). Furthermore, they had less complications during hospitalization (31.0% vs. 52.6%; p=0.008), need of antibiotics (32.2% vs. 59%; p=0.001) and radiologic worsening (21.8% vs. 44.9%; p=0.005). Treatment with remdesivir plus dexamethasone (aHR, 0.26; 95% CI: 0.14-0.48; p<0.001) and vaccination (aHR 0.39; 95% CI: 0.21-0.74) were independent factors associated with lower progression to mechanical ventilation or death.

CONCLUSIONS

Remdesivir in combination with dexamethasone and vaccination independently and synergistically protects hospitalized COVID-19 patients requiring oxygen therapy from progression to severe disease or dead.

Association of Remdesivir use with bradycardia: A systematic review and meta-analysis

Remdesivir has been used for coronavirus disease 2019 (COVID-19) pneumonia with oxygen requirements that do not require mechanical intubation, and several studies showed a reduction in disease duration. However, there is a concern about bradycardia as its side effect. We aimed to investigate the association between Remdesivir and bradycardia by integrating findings from prior studies. We queried PubMed and EMBASE in February 2023 and performed a meta-analysis of studies investigating bradycardia in patients who did or did not receive Remdesivir. The outcome of interest was the rate of bradycardia and in-hospital mortality. We identified eight studies involving 8993 patients, of which seven studies investigated bradycardia. Six studies were observational, one was a case-control, and one was a randomized trial. Incidence of bradycardia was 400/3480 patients (22.3%, 95% confidence interval, CI: [6.5-54.4], I2  = 99%) in the Remdesivir group and 294/5005 (9.8%, 95% CI: [2.8-29], I2  = 98.61) in the non-Remdesivir group. The odds ratio of bradycardia was 2.11 (95% CI: [1.65-2.71], I2  = 22%, p < 0.001) for the Remdesivir group. There was no difference in mortality between the two groups. Patients who received Remdesivir for COVID-19 were more likely to develop bradycardia. The effect of confounding factors should be considered to further clarify the possible association.

Differential activity of nucleotide analogs against tick-borne encephalitis and yellow fever viruses in human cell lines

With no approved antiviral therapies, the continuous emergence and re-emergence of tick-borne encephalitis virus (TBEV) and yellow fever virus (YFV) is a rising concern. We performed head-to-head comparisons of the antiviral activity of available nucleos(t)ide analogs (nucs) using relevant human cell lines. Eight existing nucs inhibited TBEV and/or YFV with differential activity between cell lines and viruses. Remdesivir, uprifosbuvir and sofosbuvir were the most potent drugs against TBEV and YFV in liver cells, but they had reduced activity in neural cells, whereas galidesivir retained uniform activity across cell lines and viruses. Ribavirin, valopicitabine, molnupiravir and GS-6620 exhibited only moderate antiviral activity. We found antiviral activity for drugs previously reported as inactive, demonstrating the importance of using human cell lines and comparative experimental assays when screening the activity of nucs. The relatively high antiviral activity of remdesivir, sofosbuvir and uprifosbuvir against TBEV and YFV merits further investigation in clinical studies.

Remdesivir use in severe and critical COVID-19 patients might be associated with lower incidence of arterial thrombotic events

INTRODUCTION

Venous thromboembolism (VTE) and arterial thrombotic (AT) events are a striking feature of severe COVID-19, however, relationship of remdesivir use and the risk of thrombotic events is unknown and has not been investigated before.

METHODS

We retrospectively analyzed a cohort of 876 consecutive hospitalized severe and critical COVID-19 patients who were treated with remdesivir and compared them to 876 case-matched control patients. All patients were treated in our tertiary-level institution in period from 10/2020 to 6/2021. VTE and AT were diagnosed by objective imaging and laboratory methods.

RESULTS

After exclusion of 71 VTE and 37 AT events present at the time of hospital admission, there were a total of 70 VTE (35 in the remdesivir and 35 in the control group) and 38 AT events occurring during hospitalization (13 in the remdesivir and 25 in the control group). There was a similar cumulative post-admission VTE incidence among both remdesivir and matched control patients (P = 0.287). Significantly lower cumulative post-admission AT incidence was observed among patients treated with remdesivir than among matched control patients (1.7% vs 3.3%, HR = 0.51, P = 0.035). Tendency for lower AT rates was evident in subgroups of patients stratified according to the type of AT, as well as according to the intensity of required oxygen supplementation at the time of remdesivir use.

CONCLUSION

Remdesivir use in severe and critical COVID-19 patients might be associated with lower occurrence of AT during hospitalization, whereas similar rates of VTE events were observed among both patients treated with remdesivir and control patients.

Late remdesivir treatment initiation partially protects African green monkeys from lethal Nipah virus infection

Remdesivir is a nucleotide prodrug with preclinical efficacy against lethal Nipah virus infection in African green monkeys when administered 1 day post inoculation (dpi) (Lo et al., 2019). Here, we determined whether remdesivir treatment was still effective when treatment administration initiation was delayed until 3 dpi. Three groups of six African green monkeys were inoculated with a lethal dose of Nipah virus, genotype Bangladesh. On 3 dpi, one group received a loading dose of 10 mg/kg remdesivir followed by daily dosing with 5 mg/kg for 11 days, one group received 10 mg/kg on 12 consecutive days, and the remaining group received an equivalent volume of vehicle solution. Remdesivir treatment initiation on 3 dpi provided partial protection from severe Nipah virus disease that was dose dependent, with 67% of animals in the high dose group surviving the challenge. However, remdesivir treatment did not prevent clinical disease, and surviving animals showed histologic lesions in the brain. Thus, early administration seems critical for effective remdesivir treatment during Nipah virus infection.

Outcomes of high-risk adult outpatients treated with early remdesivir therapy during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) omicron era: experiences from the national centre of Hungary

Emerging evidence suggests that remdesivir might improve clinical outcome of high-risk outpatients with coronavirus disease 2019 (COVID-19). Our aim was to evaluate characteristics and outcomes of nonhospitalised adults diagnosed with COVID-19 and treated with early remdesivir therapy during the omicron wave. A single-centre prospective cohort study was performed among adult patients between February and June 2022, during the circulation of phylogenetic assignment of named global outbreak (PANGO) subvariants BA.2, BA.4, and BA.5 in Hungary. Patients were enrolled based on pre-defined criteria. Clinical characteristics (demography, comorbidities, vaccination status, imaging, treatment, and disease course) and outcomes (COVID-19 related hospitalisation, oxygen supplementation, intensive care support, and all-cause death) were assessed at 28 days post-treatment. A subgroup analysis of patients with and without active haematological malignancies was also carried out. Altogether, 127 patients were enrolled: 51.2% (65/127) were female with a median age of 59 (IQR: 22, range: 21‒92) years, and 48.8% (62/127) had active haematological malignancy. At 28 days post-treatment, 7.1% (9/127) of patients required COVID-19-related hospitalisation, 2.4% (3/127) required oxygen supplementation, 1.6% (2/127) required intensive care, and 0.8% (1/127) died due to a non-COVID-19-related secondary infection at the intensive care unit, all with haematological malignancies. Early remdesivir treatment might be a feasible strategy among high-risk outpatients with COVID-19 during the omicron wave.

In silico evidence of Remdesivir action in blood coagulation cascade modulation in COVID-19 treatment

BACKGROUND

Coronavirus disease 2019 (COVID-19) has demonstrated several clinical manifestations which include not only respiratory system issues but also liver, kidney, and other organ injuries. One of these abnormalities is coagulopathies, including thrombosis and disseminated intravascular coagulation. Because of this, the administration of low molecular weight heparin is required for patients that need to be hospitalized. In addition, Remdesivir is an antiviral that was used against Middle East Acute Respiratory Syndrome, Ebola, Acute Respiratory Syndrome, and other diseases, showing satisfactory results on recovery. Besides, there is evidence suggesting that this medication can provide a better prognosis for patients with COVID-19.

AIM

To investigate in silico the interaction between Remdesivir and clotting factors, pursuing a possibility of using it as medicine.

METHODS

In this in silico study, the 3D structures of angiotensin-converting enzyme 2 (ACE2), Factor I (fibrinogen), Factor II (prothrombin), Factor III (thromboplastin), Factor V (proaccelerin), Factor VII (proconvertin), Factor VIII (antihemophilic factor A), Factor IX (antihemophilic factor B), Factor X (Stuart-Prower factor), and Factor XI (precursor of thromboplastin (these structures are technically called receptors) were selected from the Protein Data Bank. The structures of the antivirals Remdesivir and Osetalmivir (these structures are called ligands) were selected from the PubChem database, while the structure of Atazanavir was selected from the ZINC database. The software AutoDock Tools (ADT) was used to prepare the receptors for molecular docking. Ions, peptides, water molecules, and other ones were removed from each ligand, and then, hydrogen atoms were added to the structures. The grid box was delimited and calculated using the same software ADT. A physiological environment with pH 7.4 is needed to make the ligands interact with the receptors, and still the software Marvin sketch^® (ChemAxon^®) was used to forecast the protonation state. To perform molecular docking, ADT and Vina software was connected. Using PyMol^® software and Discovery studio^® software from BIOVIA, it was possible to analyze the amino acid residues from receptors that were involved in the interactions with the ligands. Ligand tortions, atoms that participated in the interactions, and the type, strength, and duration of the interactions were also analyzed using those software.

RESULTS

Molecular docking analysis showed that Remdesivir and ACE2 had an affinity energy of -8.8 kcal/moL, forming a complex with eight hydrogen bonds involving seven atoms of Remdesivir and five amino acid residues of ACE2. Remdesivir and prothrombin had an interaction with six hydrogen bonds involving atoms of the drug and five amino acid residues of the clotting factor. Similar to that, Remdesivir and thromboplastin presented interactions via seven hydrogen bonds involving five atoms of the drug and four residues of the clotting factor. While Remdesivir and Factor V established a complex with seven hydrogen bonds between six antiviral atoms and six amino acid residues from the factor, and Factor VII connected with the drug by four hydrogen bonds, which involved three atoms of the drug and three residues of amino acids of the factor. The complex between Remdesivir and Factor IX formed an interaction via 11 hydrophilic bonds with seven atoms of the drug and seven residues of the clotting factor, plus one electrostatic bond and three hydrophobic interactions. Factor X and Remdesivir had an affinity energy of -9.6 kcal/moL, and the complex presented 10 hydrogen bonds and 14 different hydrophobic interactions which involved nine atoms of the drug and 16 amino acid residues of the clotting factor. The interaction between Remdesivir and Factor XI formed five hydrogen bonds involving five amino acid residues of the clotting factor and five of the antiviral atoms.

CONCLUSION

Because of the in silico significant affinity, Remdesivir possibly could act in the severe acute respiratory syndrome coronavirus 2 infection blockade by interacting with ACE2 and concomitantly act in the modulation of the coagulation cascade preventing the hypercoagulable state.

Adjusted green spectrophotometric determination of favipiravir and remdesivir in pharmaceutical form and spiked human plasma sample using different chemometric supported models

The environmentally friendly design of analytical methods is gaining interest in pharmaceutical analysis to reduce hazardous environmental impacts and improve safety and health conditions for analysts. The adaptation and integration of chemometrics in the development of environmentally friendly analytical methods is strongly recommended in the hope of promising benefits. Favipiravir and remdesivir have been included in the COVID-19 treatment guidelines panel of several countries. The main objective of this work is to develop green, tuned spectrophotometric methods based on chemometric based models for the determination of favipiravir and remdesivir in spiked human plasma. The UV absorption spectra of favipiravir and remdesivir has shown overlap to some extent, making simultaneous determination difficult. Three advanced chemometric models, classical least squares, principal component regression, and partial least squares, have been developed to provide resolution and spectrophotometric determination of the drugs under study. A five-level, two-factor experimental design has been used to create the described models. The spectrally recorded data of favipiravir and remdesivir has been reviewed. The noise region has been neglected as it has a negative impact on the significant data. On the other hand, the other spectral data provided relevant information about the investigated drugs. A comprehensive evaluation and interpretation of the results of the described models and a statistical comparison with accepted values have been considered. The proposed models have been successfully applied to the spectrophotometric determination of favipiravir and remdesivir in pharmaceutical form spiked human plasma. In addition, the environmental friendliness of the described models was evaluated using the analytical eco-scale, the green analytical procedure index and the AGREE evaluation method. The results showed the compliance of the described models with the environmental characteristics.

Assessment of the frequency of SARS-CoV-2 Omicron variant escape from RNA-dependent RNA polymerase inhibitors and 3C-like protease inhibitors

The emergence and spread of antiviral-resistant SARS-CoV-2 is of great concern. In this study, we evaluated the propensity of Omicron variants to escape from RNA-dependent RNA polymerase (RdRP) inhibitors and 3C-like protease (3CLpro) inhibitors. SARS-CoV-2 Delta and Omicron variants were serially passaged in vitro in the presence of RdRP inhibitors (remdesivir and molnupiravir) and 3CLpro inhibitors (nirmatrelvir and lufotrelvir) to detect SARS-CoV-2 escape mutants. After five passages with 3CLpro inhibitors, mutant viruses that escaped from 3CLpro inhibitors emerged; however, in the presence of RdRP inhibitors all variants disappeared within 2-4 passages. Our findings suggest that the frequency of SARS-CoV-2 mutant escape from RdRP inhibitors is lower than that from 3CLpro inhibitors. We also found that Delta variants were more likely to acquire amino acid substitutions associated with resistance to 3CLpro inhibitors under the selective pressure of this drug compared with Omicron variants.

Real-world use of remdesivir for the treatment of patients admitted to Italian hospitals with COVID-19: the nationwide retrospective FADOI-RECOVER study

BACKGROUND

Remdesivir is widely used for treatment of SARS-CoV-2 pneumonia. The aim of this study was to evaluate the characteristics of patients with moderate-to-severe COVID-19 treated with remdesivir, and their outcomes during hospitalization.

METHODS

This retrospective observational multicenter study included consecutive patients, hospitalized for moderate-to-severe COVID-19 (September 2020-September 2021), who were treated with remdesivir.

RESULTS

One thousand four patients were enrolled, all with onset of symptoms occurring less than 10 days before starting remdesivir; 17% of patients had 4 or more concomitant diseases. Remdesivir was well tolerated, adverse drug reactions (ADRs) being reported in 2.3% of patients. In-hospital death occurred in 80 patients (8.0%). The median timing of the first remdesivir dose was 5 days after symptom onset. The following endpoints did not differ according to the time span from the onset of symptoms to the first dose: length of hospitalization, in-hospital death, composite outcome (in-hospital death and/or endotracheal intubation). Advanced age, number of comorbidities ≥ 4, and severity of respiratory failure at admission were associated with poor in-hospital outcomes.

CONCLUSION

In a real-world setting, remdesivir proved to be a safe and well-tolerated treatment for moderate-to-severe COVID-19. In patients receiving remdesivir less than 3 or 5 days from the onset of SARS-CoV-2 symptoms, mortality and the need for mechanical ventilation did not differ from the rest of the sample.

The use and safety risk of repurposed drugs for COVID-19 patients: lessons learned utilizing the Food and Drug Administration's Adverse Event Reporting System

Objectives

This study was designed to assess the disproportionality analyses of adverse drug reactions (ADRs) related to hydroxychloroquine and remdesivir and how ADR reporting fluctuated during the COVID-19 pandemic.

Methods

A retrospective observational study was conducted utilizing the Food and Drug Administration's Adverse Event Reporting System (FAERS) data between 2019 and 2021. The study was conducted in two phases. In the first phase, all reports associated with the drugs of interest were evaluated to assess all related adverse drug reactions. In the second phase, specific outcomes of interest (i.e., QT prolongation and renal and hepatic events) were determined to study their association with the drugs of interest. A descriptive analysis was conducted for all adverse reactions related to the drugs being studied. In addition, disproportionality analyses were conducted to compute the reporting odds ratio, the proportional reporting ratio, the information component, and the empirical Bayes geometric mean. All analyses were conducted using RStudio.

Results

A total of 9,443 ADR reports related to hydroxychloroquine; 6,160 (71.49) patients were female, and higher percentage of patients of both sexes were over the age of 65 years. QT prolongation (1.48%), pain (1.38%), and arthralgia (1.25%) were most frequently reported ADRs during the COVID-19 pandemic. The association of QT prolongation with use of hydroxychloroquine was statistically significant (ROR 47.28 [95% CI 35.95-62.18]; PRR 42.41 [95% CI 32.25-55.78]; EBGM 16.08; IC 4.95) compared with fluoroquinolone. The outcome was serious medical events in 48.01% of ADR reports; 27.42% required hospitalization and 8.61% resulted in death. Of 6,673 ADR reports related to remdesivir, 3,928 (61.13%) patients were male. During 2020, the top three ADR reports were elevated liver function tests (17.26%), acute kidney injury (5.95%) and death (2.84%). Additionally, 42.71% of ADR reports indicated serious medical events; 19.69% resulted in death and 11.71% indicated hospitalization. The ROR and PRR of hepatic and renal events associated with remdesivir were statistically significant, (4.81 [95% CI 4.46-5.19] and 2.96 [95% CI 2.66-3.29], respectively.

Conclusion

Our study showed that several serious ADRs were reported with the use of hydroxychloroquine, which resulted in hospitalization and death. Trends with the use of remdesivir were similar, but to a lesser extent. Therefore, this study showed us that off-label use should be based on thorough evidence-based evaluation.

Remdesivir Prescription in Pregnant Women Infected with COVID-19: A Report of Compassionate Use

Background

Coronavirus disease 2019 (COVID-19) is an infectious disease that the physiological changes in pregnancy can make pregnant patients more susceptible to more severe forms of this infection. Hence, the treatment of COVID-19 in pregnant women can be challenging. This study was designed to evaluate the safety and efficacy of Remdesivir in pregnant women with COVID-19.

Materials and Methods

This study was conducted on 150 pregnant women with moderate to severe COVID-19 infection. Remdesivir was prescribed and continued for 5 or 10 days according to the patient's condition. Maternal and pregnancy outcomes and also recovery rates were evaluated. Moreover, additional variables were examined: age, gestational age, symptoms, O2 saturation and laboratory tests at admission, the interval between symptom initiation and admission to hospital and Remdesivir prescription, hospitalization days, and ICU admission.

Results

The mean age was 32.37 years. Cough and dyspnea were the most prevalent symptoms (74% and 68.7%, respectively). At the time of admission, 79 (52.7%) women needed low-flow oxygen support, 67 (44.7%) needed high-flow oxygen support, and 4 (2.7%) were intubated. Fifty-four (36%) patients required ICU care. In patients who died (12 women), Remdesivir was prescribed later than those discharged (P value, 0.04). Patients with favorable pregnancy outcomes received Remdesivir earlier than those with unfavorable pregnancy outcomes (P value: 0.008). The recovery rate was 70% (89.9% in the low-flow oxygen, 50.7% in the NIPPV/high flow oxygen, and 0% in the intubated women).

Conclusion

The results suggest that the early prescription of Remdesivir in pregnant women with moderate COVID-19 can improve the outcomes.

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.

Clinical efficacy of remdesivir for COVID-19 in children: A propensity-score-matched analysis

Clinical efficacy of remdesivir in children with COVID-19 is unclear. This propensity-score-matched retrospective cohort study of children with COVID-19 showed that the rate of patients achieving defervescence on Day 4 was higher in the remdesivir group than in the non-remdesivir group, but was not statistically different (86.7% vs 73.3%, P = 0.333).

Potential herb‒drug interactions between anti-COVID-19 drugs and traditional Chinese medicine

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide. Effective treatments against COVID-19 remain urgently in need although vaccination significantly reduces the incidence, hospitalization, and mortality. At present, antiviral drugs including Nirmatrelvir/Ritonavir (Paxlovid^TM), Remdesivir, and Molnupiravir have been authorized to treat COVID-19 and become more globally available. On the other hand, traditional Chinese medicine (TCM) has been used for the treatment of epidemic diseases for a long history. Currently, various TCM formulae against COVID-19 such as Qingfei Paidu decoction, Xuanfei Baidu granule, Huashi Baidu granule, Jinhua Qinggan granule, Lianhua Qingwen capsule, and Xuebijing injection have been widely used in clinical practice in China, which may cause potential herb-drug interactions (HDIs) in patients under treatment with antiviral drugs and affect the efficacy and safety of medicines. However, information on potential HDIs between the above anti-COVID-19 drugs and TCM formulae is lacking, and thus this work seeks to summarize and highlight potential HDIs between antiviral drugs and TCM formulae against COVID-19, and especially pharmacokinetic HDIs mediated by metabolizing enzymes and/or transporters. These well-characterized HDIs could provide useful information on clinical concomitant medicine use to maximize clinical outcomes and minimize adverse and toxic effects.

Clinical study to compare the efficacy and safety of casirivimab & imdevimab, remdesivir, and favipravir in hospitalized COVID-19 patients

Background

Corona Virus disease - 2019 (COVID-19) disease induces scientific research to find a control to this pandemic from 2020 year up to now. Recently, various advances in pharmacotherapy against COVID-19 have emerged.

Objectives

To compare the efficacy and safety of antibodies cocktail (casirivimab and imdevimab), Remdesivir, and Favipravir in the COVID-19 patients.

Study design

This study is a single-blind non-Randomized Controlled Trial (non-RCT). The drugs of the study are prescribed by lectures on chest diseases, faculty of medicine-Mansoura University. The duration of the study is about six months after ethical approval.265 hospitalized COVID-19 patients were used to represent the COVID-19 population and were assigned into three groups in a ratio of (1:2:2) respectively, Group (A) received REGN3048-3051(Antibodies cocktail (casirivimab and imdevimab)), group (B) received remdesivir, and group (C) received favipravir.

Results

Casirivimab and imdevimab achieve less 28-day mortality rate, and less mortality at hospital discharge than Remdesivir, and Favipravir.

Conclusion

From all of these results, it is concluded that Group A (Casirivimab & imdevimab) achieves more favorable outcomes than B (Remdesivir) & C (Favipravir) intervention groups.

Clinical trial registration

NCT05502081, 16/08/2022, Clinicaltrials.gov.

Bradycardia and Outcomes in COVID-19 Patients on Remdesivir: A Multicenter Retrospective Study

Background

Antiviral agents, such as remdesivir, have shown promising results in helping reduce the morbidity and healthcare burden of coronavirus disease 2019 (COVID-19) in hospitalized patients. However, many studies have reported a relationship between remdesivir and bradycardia. Therefore, this study aimed to analyze the relationship between bradycardia and outcomes in patients on remdesivir.

Methods

We conducted a retrospective study of 2,935 consecutive COVID-19 patients admitted to seven hospitals in Southern California in the United States between January 2020 and August 2021. First, we did a backward logistic regression to analyze the relationship between remdesivir use and other independent variables. Finally, we did a backward selection Cox multivariate regression analysis on the sub-group of patients who received remdesivir to evaluate the mortality risk in bradycardic patients on remdesivir.

Results

The mean age of the study population was 61.5 years; 56% were males, 44% received remdesivir, and 52% developed bradycardia. Our analysis showed that remdesivir was associated with increased odds of bradycardia (odds ratio (OR): 1.9, P < 0.001). Patients that were on remdesivir in our study were sicker patients with increased odds of having elevated C-reactive protein (CRP) (OR: 1.03, P < 0.001), elevated white blood cell (WBC) on admission (OR: 1.06, P < 0.001), and increased length of hospital stay (OR: 1.02, P = 0.002). However, remdesivir was associated with decreased odds of mechanical ventilation (OR: 0.53, P < 0.001). In the sub-group analysis of patients that received remdesivir, bradycardia was associated with reduced mortality risk (hazard ratio (HR): 0.69, P = 0.002).

Conclusions

Our study showed that remdesivir was associated with bradycardia in COVID-19 patients. However, it decreased the odds of being on a ventilator, even in patients with increased inflammatory markers on admission. Furthermore, patients on remdesivir that developed bradycardia had no increased risk of death. Clinicians should not withhold remdesivir from patients at risk of developing bradycardia because bradycardia in such patients was not found to worsen the clinical outcome.

Evaluation of antiviral drugs against newly emerged SARS-CoV-2 Omicron subvariants

Ongoing emergence of SARS-CoV-2 Omicron subvariants and their rapid worldwide spread pose a threat to public health. From November 2022 to February 2023, newly emerged Omicron subvariants, including BQ.1.1, BF.7, BA.5.2, XBB.1, XBB.1.5, and BN.1.9, became prevalent global strains (>5% global prevalence). These Omicron subvariants are resistant to several therapeutic antibodies. Thus, the antiviral activity of current drugs such as remdesivir, molnupiravir, and nirmatrelvir, which target highly conserved regions of SARS-CoV-2, against newly emerged Omicron subvariants need to be evaluated. We assessed the antiviral efficacy of the drugs using the half-maximal inhibitory concentration (IC50) against human isolates of 23 Omicron subvariants and four former SARS-CoV-2 variants of concern (VOCs) and compared it with the antiviral efficacy of these drugs against the SARS-CoV-2 reference strain (hCoV/Korea/KCDC03/2020). Maximal IC50-fold changes of remdesivir, molnupiravir, and nirmatrelvir were 1.9 (BA.2.75.2), 1.2 (B.1.627.2), and 1.4 (BA.2.3), respectively, compared to median IC50 values of the reference strain. Moreover, median IC50-fold changes of remdesivir, molnupiravir, and nirmatrelvir against the Omicron variants were 0.96, 0.4, and 0.62, respectively, similar to the 1.02, 0.88, and 0.67, respectively, median IC50-fold changes for previous VOCs. Although K90R and P132H in Nsp 5, and P323L, A529V, G671S, V405F, and ins823D in Nsp 12 mutations were identified, these amino acid substitutions did not affect drug antiviral activity. These results indicate that current antivirals retain antiviral efficacy against newly emerged Omicron subvariants. It is important to continue active surveillance and testing of new variants for drug resistance to enable early identification of drug-resistant strains.

Antiviral Treatment of Coronavirus Disease-2019 Pneumonia

Direct acting antivirals and monoclonal antibodies reduce morbidity and mortality associated with severe acute respiratory syndrome coronavirus 2 infection. Persons at higher risk for disease progression and hospitalized patients with coronavirus disease-2019 (COVID-19) benefit most from available therapies. Following an emphasis on inpatient treatment of COVID-19 during the early pandemic, several therapeutic options were developed for outpatients with COVID-19. Additional clinical trials and real-world studies are needed to keep pace with the evolving pandemic.

The kinetics of SARS-CoV-2 viremia in COVID-19 patients receiving remdesivir

Detection of SARS-CoV-2 RNA in serum, viremia, has been linked to disease severity and outcome. The kinetics of viremia in patients receiving remdesivir has not been thoroughly studied and could help predict treatment response and outcome. We investigated the kinetics of SARS-CoV-2 viremia and factors associated with baseline viremia, viral clearance and 30-day mortality in patients receiving remdesivir. An observational study including 378 hospitalised patients (median age 67 years, 67% male) sampled with serum SARS-CoV-2 RT-PCR within ± 24 h of initiation of remdesivir treatment. Baseline viremia was present in 206 (54%) patients with a median Ct value of 35.3 (IQR = 33.3-37.1). In patients with baseline viremia, the estimated probability of viral clearance was 72% by day 5. Ct values decreased significantly during remdesivir treatment for viremic patients, indicating an increase in viral load. In total, 44 patients (12%) died within 30 days, and mortality was significantly associated with viremia at baseline (OR = 2.45, p = 0.01) and lack of viral clearance by day 5 (OR = 4.8, p =  < 0.01). Viral clearance was not associated with any individual risk factor. Viremia appears to be a prognostic marker before and during remedesivir treatment. The resolution of viremia was similar to patients not receiving remdesivir in other studies, and the decrease in Ct values during treatment questions the antiviral capacity of remdesivir in vivo. Prospective studies are warranted to confirm our findings.

Remdesivir for Hospitalized COVID-19 Patients in the United States: Optimization of Health Care Resources

INTRODUCTION

In addition to significant morbidity and mortality, the coronavirus disease (COVID-19) has strained health care systems globally. This study investigated the cost-effectiveness of remdesivir + standard of care (SOC) for hospitalized COVID-19 patients in the USA.

METHODS

This cost-effectiveness analysis considered direct and indirect costs of remdesivir + SOC versus SOC alone among hospitalized COVID-19 patients in the US. Patients entered the model stratified according to their baseline ordinal score. At day 15, patients could transition to another health state, and on day 29, they were assumed to have either died or been discharged. Patients were then followed over a 1-year time horizon, where they could transition to death or be rehospitalized.

RESULTS

Treatment with remdesivir + SOC avoided, per patient, a total of 4 hospitalization days: two general ward days and a day for both the intensive care unit and the intensive care unit plus invasive mechanical ventilation compared to SOC alone. Treatment with remdesivir + SOC presented net cost savings due to lower hospitalization and lost productivity costs compared to SOC alone. In increased and decreased hospital capacity scenarios, remdesivir + SOC resulted in more beds and ventilators being available versus SOC alone.

CONCLUSIONS

Remdesivir + SOC alone represents a cost-effective treatment for hospitalized patients with COVID-19. This analysis can aid in future decisions on the allocation of healthcare resources.

Remdesivir treatment and clinical outcome in non-severe hospitalized COVID-19 patients: a propensity score matching multicenter Italian hospital experience

INTRODUCTION

Remdesivir exerts positive effects on clinical improvement, even though it seems not to affect mortality among COVID-19 patients; moreover, it was associated with the occurence of marked bradycardia.

METHODS

We retrospectively evaluated 989 consecutive patients with non-severe COVID-19 (SpO₂ ≥ 94% on room air) admitted from October 2020 to July 2021 at five Italian hospitals. Propensity score matching allowed to obtain a comparable control group. Primary endpoints were bradycardia onset (heart rate < 50 bpm), acute respiratory distress syndrome (ARDS) in need of intubation and mortality.

RESULTS

A total of 200 patients (20.2%) received remdesivir, while 789 standard of care (79.8%). In the matched cohorts, severe ARDS in need of intubation was experienced by 70 patients (17.5%), significantly higher in the control group (68% vs. 31%; p < 0.0001). Conversely, bradycardia, experienced by 53 patients (12%), was significantly higher in the remdesivir subgroup (20% vs. 1.1%; p < 0.0001). During follow-up, all-cause mortality was 15% (N = 62), significantly higher in the control group (76% vs. 24%; log-rank p < 0.0001), as shown at the Kaplan-Meier (KM) analysis. KM furthermore showed a significantly higher risk of severe ARDS in need of intubation among controls (log-rank p < 0.001), while an increased risk of bradycardia onset in the remdesivir group (log-rank p < 0.001). Multivariable logistic regression showed a protective role of remdesivir for both ARDS in need of intubation (OR 0.50, 95%CI 0.29-0.85; p = 0.01) and mortality (OR 0.18, 95%CI 0.09-0.39; p < 0.0001).

CONCLUSIONS

Remdesivir treatment emerged as associated with reduced risk of severe acute respiratory distress syndrome in need of intubation and mortality. Remdesivir-induced bradycardia was not associated with worse outcome.

Prolonged infective SARS-CoV-2 omicron variant shedding in a patient with diffuse large B cell lymphoma successfully cleared after three courses of remdesivir

We report a case of prolonged shedding of the infective SARS-CoV-2 omicron variant BA.1.1.2 in a 79-year-old male patient with diffuse large B-cell lymphoma, after receiving chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP). The patient was admitted to our hospital in late March 2022 for the sixth course of R-CHOP chemotherapy. Initially, the patient tested negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using an in-hospital loop-mediated amplification assay with a nasopharyngeal swab, both on the day of admission and three days later. However, the patient developed fever and was diagnosed with coronavirus disease (COVID-19) six days after admission and was suspected to have contracted the infection in the ward. Viral shedding continued for more than three months, with confirmed viral infectivity. As compared to the original Wuhan-Hu-1/2019 strain, amino acid substitutions including S36N in non-structural protein (NSP)2, S148P and SL1265I in NSP3, G105D in NSP4, G496S, A831V, or V987F in spike protein, and I45T in open-reading frame (ORF)9b were randomly detected in isolated viruses. Although the patient had received two doses of the BNT162b2 vaccine approximately six months earlier and the third dose on day 127 after the infection, both serum anti-spike and anti-nuclear protein IgG and IgM tests were negative at day 92, 114, and 149 after the infection. The patient finally cleared the virus after the third course of remdesivir and did not have further recurrence.

Time from symptoms onset to remdesivir is associated with the risk of ICU admission: a multicentric analyses

BACKGROUND

Shorter duration of symptoms before remdesivir has been associated with better outcomes. Our goal was to evaluate variables associated with the need of ICU admission in a cohort of hospitalized patients for COVID-19 under remdesivir including the period from symptoms onset to remdesivir.

METHODS

We conducted a retrospective multicentric study analysing all patients admitted with COVID-19 in 9 Spanish hospitals who received treatment with remdesivir in October 2020. The main outcome was the need of ICU admission after 24 h of the first dose of remdesivir.

RESULTS

In our cohort of 497 patients, the median of days from symptom onset to remdesivir was 5 days, and 70 of them (14.1%) were later admitted into ICU. The clinical outcomes associated with ICU admission were days from symptoms onset (5 vs. 6; p = 0.023), clinical signs of severe disease (respiratory rate, neutrophil count, ferritin levels and very-high mortality rate in SEIMC-Score) and the use of corticosteroids and anti-inflammatory drugs before ICU. The only variable significatively associated with risk reduction in the Cox-regression analyses was ≤ 5 days from symptoms onset to RDV (HR: 0.54, CI95%: 0.31-0.92; p = 0.024).

CONCLUSION

For patients admitted to the hospital with COVID-19, the prescription of remdesivir within 5 days from symptoms onset diminishes the need of ICU admission.

Resolution of persistent SARS-CoV-2 infection with prolonged intravenous remdesivir and vaccination in a patient post CAR-T

SARS-CoV-2 virus is a single-stranded enveloped RNA virus, which causes coronavirus disease. Most of the immunocompetent patients with SARS-CoV-2 infection do have mild to moderate respiratory illness; however, in immunocompromised patients, the course of infection is unpredictable with high rates of infectivity and mortality. So, it is important to identify the immunocompromised patients early and establish the course of treatment accordingly. Here, we describe a 25-year-old male with background of B cell ALL, post-BMT and CAR-T therapy who received treatment with remdesivir and vaccination and was followed up for six months from the onset of symptoms to post vaccination, which showed resolution of symptoms and improvement of immunological markers. Here, we review the literature concerning the course and treatment of SARS-CoV-2 infection aimed at achieving cure in this patient.

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.

Cost-effectiveness of remdesivir for the treatment of hospitalized patients with COVID-19: a systematic review

BACKGROUND

Remdesivir is being studied and used to treat coronavirus disease 2019 (COVID-19). This study aimed to systematically identify, critically evaluate, and summarize the findings of the studies on the cost-effectiveness of remdesivir in the treatment of hospitalized patients with COVID-19.

METHODS

In this systematic review, PubMed, EMBASE, Web of Science, SCOPUS, and the Cochrane Library were searched for studies published between 2019 and 2022. We included all full economic evaluations of remdesivir for the treatment of hospitalized patients with COVID-19. Data were summarized in a structured and narrative manner.

RESULTS

Out of 616 articles obtained in this literature search, 12 studies were included in the final analysis. The mean score of the Quality of Health Economic Studies (QHES) for the studies was 87.66 (high quality). All studies were conducted in high-income countries (eight studies in the USA and one study in England), except for three studies from middle-to-high-income countries (China, South Africa, and Turkey). Six studies conducted their economic analysis in terms of a health system perspective; five studies conducted their economic analysis from a payer perspective; three studies from the perspective of a health care provider. The results of five studies showed that remdesivir was cost-effective compared to standard treatment. Furthermore, the therapeutic strategy of combining remdesivir with baricitinib was cost-effective compared to remdesivir alone.

CONCLUSIONS

Based on the results of the present study, remdesivir appears to be cost-effective in comparison with the standard of care in China, Turkey, and South Africa. Studies conducted in the United States show conflicting results, and combining remdesivir with baricitinib is cost-effective compared with remdesivir alone. However, the cost-effectiveness of remdesivir in low-income countries remains unknown. Thus, more studies in different countries are required to determine the cost-effectiveness of this drug.

Use of anti-viral therapies in hospitalised COVID-19 patients in the United Arab Emirates: a cost-effectiveness and health-care resource use analysis

BACKGROUND

This study attempts to estimate the cost-effectiveness of the antiviral remdesivir, as recommended in the 2021 COVID treatment guidelines for the United Arab Emirates, compared to standard of care (SOC), but also favipiravir (FAVI), which was also recommended for the treatment of hospitalized COVID patients.

METHODS

A cost-effectiveness model was built using published efficacy data for RDV, FAVI and SOC as well as local epidemiology data. The outcomes measured included hospital bed days averted, mortality, costs and cost per outcome over one year. One-way, probabilistic and scenario analyses were undertaken to reflect uncertainty in the estimates.

RESULTS

When modelled over one year, the results indicated that treatment of adults in need of supplemental oxygen with RDV + SOC could result in 11,338 fewer general ward bed days, 7,003 fewer ICU days and 5,451 fewer ICU + MIV bed days compared to SOC alone and similar results when compared with FAVI + SOC. The model results also showed that there were 374 fewer deaths associated with the use of RDV + SOC compared to SOC alone. The model also estimates substantial potential cost-savings associated with RDV + SOC treatment compared with SOC alone (USD 3,454 per patient). The results of the one-way sensitivity analysis showed that the model was sensitive to estimates of length of stay and the cost of hospitalization. Despite this, the model predicted cost-savings in all scenarios versus all comparators.

CONCLUSIONS

The model estimated that using RDV + SOC could result in substantial reductions in HCRU and cost savings regardless of the comparator. However, it should be noted that reliable clinical information on FAVI was limited therefore it is challenging to interpret these results. All the potential benefits modelled here for RDV + SOC can have implications not only for the health of the UAE population but for improving hospital capacity to deal with other conditions.

Consistent Effects of Early Remdesivir on Symptoms and Disease Progression Across At-Risk Outpatient Subgroups: Treatment Effect Heterogeneity in PINETREE Study

INTRODUCTION

In the PINETREE study, early remdesivir treatment reduced risk of coronavirus disease 2019 (COVID-19)-related hospitalizations or all-cause death versus placebo by 87% by day 28 in high-risk, non-hospitalized patients. Here we report results of assessment of heterogeneity of treatment effect (HTE) of early outpatient remdesivir, focusing on time from symptom onset and number of baseline risk factors (RFs).

METHODS

PINETREE was a double-blind, placebo-controlled trial of non-hospitalized patients with COVID-19 who were randomized within 7 days of symptom onset and had ≥ 1 RF for disease progression (age ≥ 60 years, obesity [body mass index ≥ 30], or certain coexisting medical conditions). Patients received remdesivir intravenously (200 mg on day 1 and 100 mg on days 2 and 3) or placebo.

RESULTS

In this subgroup analysis, HTE of remdesivir by time from symptom onset at treatment initiation and number of baseline RFs was not detected. Treatment with remdesivir reduced COVID-19-related hospitalizations independent of stratification by time from symptom onset to randomization. Of patients enrolled ≤ 5 days from symptom onset, 1/201 (0.5%) receiving remdesivir and 9/194 (4.6%) receiving placebo were hospitalized (hazard ratio [HR] 0.10; 95% confidence interval [CI] 0.01-0.82). Of those enrolled at > 5 days from symptom onset, 1/78 (1.3%) receiving remdesivir and 6/89 (6.7%) receiving placebo were hospitalized (HR 0.19; 95% CI 0.02-1.61). Remdesivir was also effective in reducing COVID-19-related hospitalizations when stratified by number of baseline RFs for severe disease. Of patients with ≤ 2 RFs, 0/159 (0.0%) receiving remdesivir and 4/164 (2.4%) receiving placebo were hospitalized; of those with ≥ 3 RFs, 2/120 (1.7%) receiving remdesivir and 11/119 (9.2%) receiving placebo were hospitalized (HR 0.16; 95% CI 0.04-0.73).

CONCLUSIONS

In the outpatient setting, benefit of remdesivir initiated within 7 days of symptoms appeared to be consistent across patients with RFs. Therefore, it may be reasonable to broadly treat patients with remdesivir regardless of comorbidities.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT04501952.

Acute kidney injury in COVID-19 patients receiving remdesivir: A systematic review and meta-analysis of randomized clinical trials

OBJECTIVES

Remdesivir is an antiviral agent with positive effects on the prognosis of Coronavirus Disease (COVID-19). However, there are concerns about the detrimental effects of remdesivir on kidney function which might consequently lead to Acute Kidney Injury (AKI). In this study, we aim to determine whether remdesivir use in COVID-19 patients increases the risk of AKI.

METHODS

PubMed, Scopus, Web of Science, the Cochrane Central Register of Controlled Trials, medRxiv, and bioRxiv were systematically searched until July 2022, to find Randomized Clinical Trials (RCT) that evaluated remdesivir for its effect on COVID-19 and provided information on AKI events. A random-effects model meta-analysis was conducted and the certainty of evidence was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation. The primary outcomes were AKI as a Serious Adverse Event (SAE) and combined serious and non-serious Adverse Events (AE) due to AKI.

RESULTS

This study included 5 RCTs involving 3095 patients. Remdesivir treatment was not associated with a significant change in the risk of AKI classified as SAE (Risk Ratio [RR]: 0.71, 95% Confidence Interval [95% CI] 0.43‒1.18, p = 0.19, low-certainty evidence) and AKI classified as any grade AEs (RR = 0.83, 95% CI 0.52‒1.33, p = 0.44, low-certainty evidence), compared to the control group.

CONCLUSION

Our study suggested that remdesivir treatment probably has little or no effect on the risk of AKI in COVID-19 patients.

Approaches to the synthesis of heterocyclic C-nucleosides

This review is focused on the synthetic strategies to heterocyclic C-nucleosides and covers the literature from 2011 to 2021. The main attention is paid to the following three approaches: the direct C-C coupling of a carbohydrate moiety with a preformed aglycon unit, the construction of a (pseudo)sugar residue on a pre-formed aglycon, and the construction of an aglycon on a pre-formed (pseudo)sugar. In each Section, the literature data are categorized in terms of the size of aglycon from simple to complex, the advantages and drawbacks of the reviewed approaches are discussed.

Investigational medications in 9,638 hospitalized patients with severe COVID-19: lessons from the "fail-and-learn" strategy during the first two waves of the pandemic in 2020

BACKGROUND

The early surge of the novel coronavirus disease 2019 (COVID-19) pandemic introduced a significant clinical challenge due to the high case-fatality rate in absence of evidence-based recommendations. The empirical treatment modalities were relegated to historical expertise from the traditional management of acute respiratory distress syndrome (ARDS) in conjunction with off-label pharmaceutical agents endorsed under the "emergency use authorization" (EUA) paradigm by regulatory agencies. This study was designed to evaluate the insights from the "fail-and-learn" strategy in 2020 before the availability of COVID-19 vaccines and access to reliable insights from high-quality randomized controlled trials.

METHODS

A retrospective, multicenter, propensity-matched, case-control study was performed on a data registry comprising 186 hospitals from a national health care system in the United States, designed to investigate the efficacy of empirical treatment modalities during the early surge of the COVID-19 pandemic in 2020. Reflective of the time-windows of the initial two surges of the pandemic in 2020, patients were stratified into "Early 2020" (March 1-June 30) versus "Late 2020" (July 1-December 31) study cohorts. Logistic regression was applied to determine the efficacy of prevalent medications (remdesivir, azithromycin, hydroxychloroquine, corticosteroids, tocilizumab) and supplemental oxygen delivery modalities (invasive vs. non-invasive ventilation) on patient outcomes. The primary outcome measure was in-hospital mortality. Group comparisons were adjusted for covariates related to age, gender, ethnicity, body weight, comorbidities, and treatment modalities pertinent to organ failure replacement.

RESULTS

From a total of 87,788 patients in the multicenter data registry screened in this study, 9,638 patients were included who received 19,763 COVID-19 medications during the first two waves of the 2020 pandemic. The results showed a minimal, yet statistically significant, association with hydroxychloroquine in "Early 2020" and remdesivir in "Late 2020" with reduced odds of mortality (odds ratios 0.72 and 0.76, respectively; P = 0.01). Azithromycin was the only medication associated with decreased odds of mortality during both study time-windows (odds ratios 0.79 and 0.68, respectively; P < 0.01). In contrast, the necessity for oxygen supply showed significantly increased odds of mortality beyond the effect of all investigated medications. Of all the covariates associated with increased mortality, invasive mechanical ventilation had the highest odds ratios of 8.34 in the first surge and 9.46 in in the second surge of the pandemic (P < 0.01).

CONCLUSION

This retrospective multicenter observational cohort study on 9,638 hospitalized patients with severe COVID-19 during revealed that the necessity for invasive ventilation had the highest odds of mortality, beyond the variable effects observed by administration of the prevalent EUA-approved investigational drugs during the first two surges of the early 2020 pandemic in the United States.

Green fitted second derivative synchronous spectrofluorometric method for simultaneous determination of remdesivir and apixaban at Nano gram scale in the spiked human plasma

Remdesivir and apixaban have been included in the treatment guidelines of several countries for severe COVID-19 infections. To date, no analytical method has been developed for the determination of remdesivir and apixaban in plasma matrix. The main objective of this work was to develop a highly sensitive, green-adapted spectrofluorometric method for the determination of remdesivir and apixaban at the Nanoscale. Remdesivir and apixaban showed overlapping fluorescence emission spectra at 403 nm and 456 nm when excited at 246 nm and 285 nm, respectively. This overlap was resolved in two steps. The first step was synchronous fluorescence scanning of remdesivir and apixaban, and the second step was manipulation of the second-order derivative for the obtained spectra. These steps allowed complete resolution of the overlapping fluorescence spectra and selective determination of remdesivir and apixaban at 410 and 469 nm, respectively. The variables affecting the synchronous scanning of the aforementioned drugs were optimized in terms of sensitivity parameters and principles of green analytical chemistry. The described method allowed sensitive determination of remdesivir and apixaban over the concentration range of 5-200 ng/mL and 50-3000 ng/mL, respectively. The described method was validated and successfully applied for the simultaneous determination of the mentioned drugs in pure form and in spiked human plasma.

Fabrication of Fe(III)-doped mesoporous silica nanoparticles as biocompatible and biodegradable theranostic system for Remdesivir delivery and MRI contrast agent

Coronavirus causes the majority of common colds and is spread in the same way that all viruses attack the respiratory system. Despite the trials and efforts to produce a suitable vaccine, there are solutions for the quick, effective and efficient use of existing drugs to prevent infections and improve the condition of patients. In this study, we synthesized mSiO₂ NPs doped with Fe(III) (Fe(III)-mSiO₂) and loaded with Rd, and then the NPs coated with PDA as gatekeeper. The several surface methods successfully approved fabrication of the nanosystem. Finally, the application of nanosystem as theranostic system was studied. The DLS measurements showed the average sizes of 115 ± 2 and 124 ± 3.6 nm for Fe-SiO₂ and Fe-SiO₂@PDA NPs, respectively, suitable for theranostic intentions. The drug release experiments, the in-vitro MRI measurements and MTT test were accomplished, respectively, to show applicability of the nanosystem as a biodegradable Rd delivery system, MRI contrast agent, and the biocompatibility nanocarrier. The results achieved through in-vitro tests exhibited that the Fe-SiO₂ system has potential application as a contrast agent in MRI with relaxivity (r₁) of 14 ± 1 mM^-1 s^-1. The Rd drug was released from the Fe-SiO₂(Rd)_load@PDA system more efficient and faster than SiO₂(Rd)_load@PDA at 7.4, supporting the doping of Fe in SiO₂ induces a biodegradability feature in that. The in-vitro biocompatibility studies showed that the Fe-SiO₂ NPs (without drug) is not toxic.

Effect of remdesivir on mortality and the need for mechanical ventilation among hospitalized patients with COVID-19: real-world data from a resource-limited country

OBJECTIVES

Georgia introduced remdesivir for the treatment of COVID-19 in December 2020. We evaluated the real-world effect of remdesivir on mortality and the need for mechanical ventilation among inpatients with COVID-19.

METHODS

The study included 346 remdesivir recipients and 346 controls not receiving remdesivir selected through propensity score matching based on age, gender, presence of any chronic comorbid condition, and oxygen saturation at admission. Factors associated with in-hospital mortality and the need for mechanical ventilation were assessed in a multivariable logistic regression model.

RESULTS

The groups were comparable by age, gender, comorbidities, and baseline oxygen saturation. Among 346 remdesivir recipients, 265 (76.6%) received a generic formulation of the drug. Eight (2.3%) patients died in the remdesivir group and 18 (5.2%) in the control group (P = 0.046). In the multivariable analysis, remdesivir was associated with non-statistically significant reduced odds of death (odds ratio: 0.39, 95% confidence interval: 0.14-1.04, P = 0.06). Significantly fewer patients in the remdesivir group required mechanical ventilation compared to controls: 2.9% vs 6.4% (P = 0.03). Statistically significant difference was maintained in multivariable analysis (odds ratio: 0.40, 95% confidence interval: 1.04-5.60, P = 0.04).

CONCLUSION

Borderline reduction in the odds of death and statistically significant decrease in the need for mechanical ventilation support use of remdesivir in hospitalized patients with COVID-19.

Photocatalytic degradation of remdesivir nucleotide pro-drug using [Cu(1-methylimidazole)4(SCN)2] nanocomplex synthesized by sonochemical process: Theoretical, hirshfeld surface analysis, degradation kinetic, and thermodynamic studies

The first ultrasonic synthesis of [Cu(L)₄(SCN)₂] (L = 1-methylimidazole) nanocomplex was carried out under ultrasonic irradiation, and its photocatalytic performance for the degradation of remdesivir (RS) under sunlight irradiation was comprehensively investigated for the first time in this study. The physicochemical properties of the synthesized photocatalyst were examined by Fourier-transform infrared (FT-IR), field emission scanning electron microscopy (FE-SEM), diffuse reflectance spectroscopy (DRS), and thermogravimetric analysis (TGA) techniques. The band gap of the synthesized [Cu(L)₄(SCN)₂] nanocomplex was determined to be 2.60 eV by the diffuse reflectance spectroscopy method using Kubelka-Munk formula. The photocatalytic performance of nanocomplex was examined for the removal of remdesivir under sunlight from water for which the results indicated that an amount of 0.5 gL^-1 of the [Cu(L)₄(SCN)₂] nanocomplex was sufficient to remove more than 96% remdesivir from its 2 mg L^-1 concentration within 20 min, at pH = 6. The kinetic data showed that the photodegradation onto the [Cu(L)₄(SCN)₂] nanocomplex has a high correlation (0.98) with the pseudo-second-order kinetic model. The decrease in chemical oxygen demand (COD) (from 70.5 mg L^-1 to 36.4 mg L^-1) under optimal conditions clearly confirmed the mineralization of the RS drug. The values of ΔS° (-0.131 kJ mol^-1 K^-1) and ΔH° (-49.750 kJ mol^-1) were negative, indicating that the adsorption process was spontaneous and more favorable in lower temperatures. Moreover, the RS structure in the open shell state and the high HOMO and LUMO gaps based on the M06/6-31 + G (d) level of theory may be a confirmation of this fact. In addition, the Hirshfeld surface analysis (HSA) of the crystal packing of the prepared complex was discussed in detail to evaluate the interactions between the crystal packings. The results of this study confirm that the [Cu(L)₄(SCN)₂] nanocomplex can be successfully used for the photodegradation of pharmaceutical contaminants.

Food and Drug Administration Adverse Event Reporting System

BACKGROUND

Evidence about remdesivir-associated acute kidney injury (AKI) among patients with novel coronavirus disease 2019 (COVID-19) was controversial.

AIM

To investigate the signal of disproportionate reporting of remdesivir-related AKI in COVID-19 patients over time with data from US Food and Drug Administration Adverse Event Reporting System.

METHOD

Adverse events in COVID-19 patients reported between April 2020 and September 2022 were included. Reporting odds ratios (RORs) of AKI and renal disorders (a more sensitive definition for AKI) were estimated to compare remdesivir with other medications prescribed in comparable situations of COVID-19.

RESULTS

During the entire study period, significant signals were identified for remdesivir-related AKI (ROR 2.00, 95% CI: 1.83-2.18) and renal disorder (ROR 2.35, 95% CI: 2.17-2.54) when compared to all comparable drugs. However, in the third quarter of 2022 (the most recent quarter) signals disappeared as the ROR of AKI was 1.50 (95% CI 0.91-2.45) and ROR of renal disorder was 1.69 (95% CI 1.06-2.70). Number of signals in sensitivity analyses and the proportion of AKI in remdesivir-associated events decreased over time.

CONCLUSION

In COVID-19 patients, we observed diminishing signals of remdesivir-associated AKI over time and no significant signal in the most recent quarter, suggesting remdesivir might not be nephrotoxic.

Evaluation of Remdesivir to the outcomes of hospitalized patients with COVID-19 infection in a tertiary-care hospital in southern India

INTRODUCTION

Remdesivir was the only antiviral used in the treatment of COVID-19 in the first wave of the COVID-19 pandemic, following the adaptive COVID-19 treatment trial-1 interim analysis report. However, its use in moderate to critical hospitalized COVID-19 patients continues to be controversial.

METHODOLOGY

In a cohort of 1,531 moderate to critical COVID-19 patients, we retrospectively performed a nested case-control study where 515 patients on Remdesivir were compared to 411 patients with no Remdesivir. Cases and controls were matched for age, sex and severity. The primary outcome was in-hospital mortality and secondary outcomes were duration of hospital stay, need for intensive care unit (ICU), progression to oxygen therapy, progression to non-invasive ventilation, progression to mechanical ventilation, and duration of ventilation.

RESULTS

Mean age of the cohort was 57.05 + 13.5 years. 75.92% were males. Overall, in-hospital mortality was 22.46% (n = 208). There was no statistically significant difference in all-cause mortality among cases and controls (20.78% vs. 24.57%, p = 0.17). Progression to non-invasive ventilation was lower in the Remdesivir group (13.6% vs 23.7%, p < 0.001), however progression to mechanical ventilation was higher in the Remdesivir group (11.3% vs 2.7%, p value < 0.001*). In a subgroup analysis of critically ill patients, the use of Remdesivir lowered mortality (OR 0.32 95% CI: 0.13 - 0.75).

CONCLUSIONS

Remdesivir did not decrease the in-hospital mortality in moderate to severe COVID-19 but decreased progression to non-invasive ventilation. Its mortality benefit in critically ill patients needs further evaluation. Remdesivir may be useful if given early in the treatment of patients with moderate COVID-19.

Potential RNA-dependent RNA polymerase (RdRp) inhibitors as prospective drug candidates for SARS-CoV-2

The SARS-CoV-2 pandemic is considered as one of the most disastrous pandemics for human health and the world economy. RNA-dependent RNA polymerase (RdRp) is one of the key enzymes that control viral replication. RdRp is an attractive and promising therapeutic target for the treatment of SARS-CoV-2 disease. It has attracted much interest of medicinal chemists, especially after the approval of Remdesivir. This study highlights the most promising SARS-CoV-2 RdRp repurposed drugs in addition to natural and synthetic agents. Although many in silico predicted agents have been developed, the lack of in vitro and in vivo experimental data has hindered their application in drug discovery programs.

Liver and Renal Injury with Remdesivir Treatment in SARS-CoV-2 Patients

Objective

To determine the effect of Remdesivir on liver enzymes and renal functions in SARS-CoV-2 patients.

Methods

This prospective cohort study was conducted at Dr. Ruth KM Pfau, Civil Hospital Karachi between 1st December 2021 to 31st January, 2022. All patients of severe SARS-CoV-2 infection who received Inj. Remdesivir for five days as per protocol of SARS-CoV-2 management were included. Biodata of selected patients including age, gender, diabetic, hypertensive status was recorded. Patients Liver Function Tests and Serum Creatinine were performed on days 0, 3, 5, 7 and 14.

Result

This study included 85 patients, out of which 55 (64.7%) were males and 30 (35.3%) were females. Out of 85 patients, Remdesivir was stopped in 3 (3.5%) patients. Among these three patients Remdesivir was stopped in one patient on day three because of decrease in CrCl to <30 ml/min. His CrCl improved after stopping Remdesivir. In the remaining two patients, Remdesivir was stopped due to increase in ALT to greater than 10 times from normal values on day three. Similarly, in these two patients the ALT improved after stopping Remdesivir.

Conclusion

Only three patients developed adverse effects resulting in stopping of Remdesivir, however these were reversible on stopping the drug. Therefore, Remdesivir is a relatively safe drug and well tolerated in SARS-CoV-2 patients.

Elucidation of the liver pathophysiology of COVID-19 patients using liver-on-a-chips

SARS-CoV-2 induces severe organ damage not only in the lung but also in the liver, heart, kidney, and intestine. It is known that COVID-19 severity correlates with liver dysfunction, but few studies have investigated the liver pathophysiology in COVID-19 patients. Here, we elucidated liver pathophysiology in COVID-19 patients using organs-on-a-chip technology and clinical analyses. First, we developed liver-on-a-chip (LoC) which recapitulating hepatic functions around the intrahepatic bile duct and blood vessel. We found that hepatic dysfunctions, but not hepatobiliary diseases, were strongly induced by SARS-CoV-2 infection. Next, we evaluated the therapeutic effects of COVID-19 drugs to inhibit viral replication and recover hepatic dysfunctions, and found that the combination of anti-viral and immunosuppressive drugs (Remdesivir and Baricitinib) is effective to treat hepatic dysfunctions caused by SARS-CoV-2 infection. Finally, we analyzed the sera obtained from COVID-19 patients, and revealed that COVID-19 patients, who were positive for serum viral RNA, are likely to become severe and develop hepatic dysfunctions, as compared with COVID-19 patients who were negative for serum viral RNA. We succeeded in modeling the liver pathophysiology of COVID-19 patients using LoC technology and clinical samples.

Remdesivir-induced bradycardia in patients hospitalized with SARS-CoV2 infection: a possible vagally-mediated mechanism

Recently, case series studies on patients with SARS-CoV-2 infection reported an association between remdesivir (RDV) administration and incidental bradycardia. However, the phenomenon has not yet been described in detail. We conducted a retrospective case-control study to evaluate the occurrence of RDV-related bradycardia in patients hospitalized for SARS-CoV2 pneumoniae. We retrospectively evaluated 71 patients, hospitalized in six internal medicine wards of the Milan area, affected by mild-to-moderate COVID-19 who received RDV (RDV group) and 54 controls, matched for sex, age and disease severity on admission (CTR group). The mean heart rate value recorded during the first two days of hospitalization was considered as baseline heart rate (HRb). Heart rate values relative to the 5-days treatment and the 5-days post-treatment were extracted for RDV group, while heart rate values relative to 10 days of hospitalization were considered for the CTR group. ΔHR values were calculated as maximum HR drop versus HRb. Possible associations between ΔHR and clinical-demographic factors were assessed through regression analysis. The RDV group experienced a significantly higher incidence of bradycardia compared to the CTR group (56% vs 33%, OR 2.6, 95% CI 1.2-5.4, p value = 0.011). Moreover, the RDV group showed higher ΔHR values than the CTR group. The HR progressively decreased with daily administration of RDV, reaching the maximun drop on day six (-8.6±1.9 bpm). In RDV group, patients who experienced bradycardia had higher drop in HR, higher alanine aminotransferase (ALT) values at the baseline (bALT) and during the RDV administration period. ΔHR was positively associated with HRb (β = 0.772, p < 0.001) and bALT (β = 0.245, p = 0.005). In conclusion, our results confirmed a significant association between RDV administration and development of bradycardia. This effect was proportional to baseline HR and was associated with higher levels of baseline ALT, suggesting a possible interaction between RDV liver metabolism and a vagally-mediated effect on HR due to increased availability of RDV metabolites.

Current and Emerging Therapies for COVID-19 in Lung Transplantation

Purpose of Review

The landscape of the coronavirus disease 2019 (COVID-19) pandemic has rapidly changed over the past 3 years. Paralleling this evolution, the scientific and medical communities have reported many novel findings relating to the infection's epidemiology, transmission, diagnosis, and treatment. We review pertinent studies of COVID-19 therapeutics with an emphasis on their application to lung transplant recipients.

Recent Findings

Agents that have been well-studied for treating COVID-19 include antivirals (remdesivir, nirmatrelvir/ritonavir, molnupiravir), monoclonal antibodies, and immunomodulators (for example, corticosteroids and tocilizumab).

Summary

Remdesivir remains an essential therapy for managing mild-moderate COVID-19. Though highly efficacious for mild-moderate COVID-19 for outpatient therapy, ritonavir-boosted nirmatrelvir has limited use in lung transplant recipients due to significant drug-drug interactions. Monoclonal antibodies, though useful, are the most affected by the emergence of new viral variants.

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.