Drug Sofosbuvir Research Articles

Modification of N,S co-doped graphene quantum dots with p-aminothiophenol-functionalized gold nanoparticles for molecular imprint-based voltammetric determination of the antiviral drug sofosbuvir.

A molecularly imprinted polymer (MIP) was developed for the electrochemical determination of the antiviral drug sofosbuvir (SOF). The MIP was obtained by polymerization of p-aminothiophenol (p-ATP) on N,S co-doped graphene quantum dots (N,S@GQDs) in the presence of gold nanoparticles to form gold-sulfur covalent network. The presence of quantum dots improves the electron transfer rate, enhances surface activity and amplifies the signal. The nanocomposites were characterized by FTIR, TEM, EDX, and SEM. The electrochemical performance of the electrode was investigated by differential pulse voltammetry and cyclic voltammetry. The sensor uses hexacyanoferrate as the redox probe and is best operated at a potential of around 0.36V vs. Ag/AgCl. It has a linear response over the concentration range of 1-400nM SOF, with a detection limit of 0.36nM. Other features include high selectivity, good reproducibility and temporal stability. The sensor was applied to the determination of SOF in spiked human plasma. Graphical abstract Novel sofosbuvir imprinted p-ATP polymer was synthesized by the aid of gold nanoparticles on N,S co-doped graphene quantum dots as a good conductive support. The imprintedpolymer was used for detection of sofosbuvir in real samples by using the ferri/ferrocyanide redox probe.

Relation between microRNA‐21, transforming growth factor β and response to treatment among chronic hepatitis C patients

Persistence of hepatitis C virus(HCV) infection and response to antiviral therapy has been shown to be associated with inappropriate levels of cytokines and microRNAs (miRNAs). miRNA levels have been reported to fluctuate during treatment. Thus they could be useful predictors for responses to treatment among HCV infected patients, thereby reducing ineffective treatments. The current study aimed to investigate the relation between miRNA-21 expression profiles, transforming growth factor β (TGF-β) serum levels and response to treatment with the new direct antiviral drugs (sofosbuvir + daclatasvir ± ribavirin), among HCV infected Egyptian patients. This prospective study was conducted on 50 HCV infected patients (before and after treatment) and 20 healthy volunteers. miRNA expression profiles were determined by real-time polymerase chain reaction and TGF-β1 serum levels were measured by using enzyme-linked immunosorbent assay. There was a significant increase in serum albumin, platelets count and a significant decrease in liver enzymes, serum bilirubin, and prothrombin time after treatment. Significant reduction of viral load among HCV patients after receiving the treatment was reported. Concomitantly, there was an increase in the relative quantity of miRNA-21 (P = .001*) and serum levels of TGF-β1 ( P = .337) among HCV patients after receiving treatment. Nearly all responders to direct antiviral drugs showed increased levels of both miRNA-21 and TGF-β1. This may indicate an interplay between TGF-β1 and miRNA-21 during remission or progression of viral infection. Thus miRNA-21 could be used as promising serum biomarker, for assessment of antiviral treatment efficacy and improvement of fibrosis among chronically infected HCV patients.

Activity of Selected Nucleoside Analogue ProTides against Zika Virus in Human Neural Stem Cells.

Zika virus (ZIKV), an emerging flavivirus that causes neurodevelopmental impairment to fetuses and has been linked to Guillain-Barré syndrome continues to threaten global health due to the absence of targeted prophylaxis or treatment. Nucleoside analogues are good examples of efficient anti-viral inhibitors, and prodrug strategies using phosphate masking groups (ProTides) have been employed to improve the bioavailability of ribonucleoside analogues. Here, we synthesized and tested a small library of 13 ProTides against ZIKV in human neural stem cells. Strong activity was observed for 2′-C-methyluridine and 2′-C-ethynyluridine ProTides with an aryloxyl phosphoramidate masking group. Substitution of a 2-(methylthio) ethyl phosphoramidate for the aryloxyl phosphoramidate ProTide group of 2′-C-methyluridine completely abolished antiviral activity of the compound. The aryloxyl phosphoramidate ProTide of 2′-C-methyluridine outperformed the hepatitis C virus (HCV) drug sofosbuvir in suppression of viral titers and protection from cytopathic effect, while the former compound’s triphosphate active metabolite was better incorporated by purified ZIKV NS5 polymerase over time. These findings suggest both a nucleobase and ProTide group bias for the anti-ZIKV activity of nucleoside analogue ProTides in a disease-relevant cell model.

Development and validation of a versatile HPLC-DAD method for simultaneous determination of the antiviral drugs daclatasvir, ledipasvir, sofosbuvir and ribavirin in presence of seven potential impurities. Application to assay of dosage forms and dissolution studies

This study describes a simple, sensitive, specific and generic HPLC-DAD method for simultaneous determination of four drugs prescribed for treatment of Hepatitis C Virus (HCV) infection. Investigated drugs include daclatasvir (DAC), ledipasvir (LED), sofosbuvir (SOF) and ribavirin (RIB). Successful separation was accomplished using Thermohypersil BDS-C8 column (4.6 × 250 mm, 5 µm) with gradient elution of the mobile phase consisted of mixed phosphate buffer pH 7.5 and methanol. Gradient elution started with 25% methanol, ramped up linearly to 80% in 15 min then kept constant till the end of the run. Flow rate was 1.5 mL/min. Peak areas were measured at 235, 260, 315, and 332 nm for RIB, SOF, DAC, and LED, respectively. Peaks of the analytes were perfectly resolved with retention times 2.0, 12.1, 14.7, and 17.2 min for RIB, SOF, DAC, and LED, respectively. The developed method was validated according to ICH guidelines with respect to system suitability, linearity, ranges, accuracy, precision, specificity, robustness, and limits of detection and quantification. The proposed method showed good linearity in the ranges 5–500, 2–300, 0.5–75, and 0.5–75 µg/mL for RIB, SOF, DAC, and LED respectively. Limits of detection were 0.10–0.66 μg/mL for the analyzed drugs. Specificity was established by separation of target drugs from 7 process-related impurities for SOF including its major metabolite (GS-331007). Applicability of the proposed method to real life situations was assessed through the analysis of four different pharmaceutical formulations and satisfactory results were obtained. Additionally, dissolution profiles of the 4 drugs were studied using the developed method.

Development of a high-performance thin-layer chromatographic method for the simultaneous determination of newly co-formulated antiviral drugs sofosbuvir and velpatasvir in their pure forms and tablet dosage form

The discovery of new direct-acting antiviral drugs gave rise to a leap forward in the treatment of hepatitis C viral infections. For the first time since 1998, the Food and Drug Administration (FDA) approved interferon-free oral treatment paradigms. Among the new treatment regimens, the combinations of sofosbuvir/daclat-asvir and sofosbuvir/velpatasvir became ideal treatment regimens for being potent, highly tolerated, and used once daily. For that purpose, a new sensitive high-performance thin-layer chroma-tography (HPTLC) method was developed and validated for the simultaneous determination of sofosbuvir and velpatasvir. The proposed method used Merck HPTLC silica gel 60 F254 aluminum plates as the stationary phase. The mobile phase was a combinat ion of methylene chloride-methanolethyl acetate-ammonia (25%) at a ratio of 5:1:3:1 (v/v). The calibration curves were linear over a wide range of 100–2000 ng per spot for the studied drugs. The limits of detection were 30.02 and 27.60 ng per spot, and the limits of quantification were 90.06 and 82.80 ng per spot for sofosbuvir and velpatasvir, respectively. The suggested method was successfully applied for analysis of the studied drugs in their pharmaceutical dosage forms, and excellent recovery results were obtained. Being simple, fast, robust, and economic, this method is eligible for use in the routine work in pharmaceutical quality control laboratories.

New strategy for determination of anti-viral drugs based on highly conductive layered composite of MnO2/graphene/ionic liquid crystal/carbon nanotubes

In the last decade, the biomedical field has benefited from the progressive development of antiviral drugs. Antiviral drugs Sofosbuvir (SOF), ledipasvir (LED) and acyclovir (ACY) are a class of medications used specifically for treating viral infections as hepatitis C (HCV) and B (HBV) viruses. Sofosbuvir (SOF) and ledipasvir (LED) in a single-tablet regimen represent a revolution in the treatment of chronic hepatitis C which inhibits viral production of HCV. The major problem with simultaneous determination of SOF, LED and ACY by electrochemical methods is the closeness of their oxidation potentials resulting in overlapped voltammetry responses. In such frame an innovative strategy is introduced, based on a novel GC/CNT/ILC/RGO/MnO2 layered electrode, obtained by modifying a glassy carbon surface with layers of multi-walled carbon nanotubes (CNT), an ionic liquid crystal (ILC), graphene (RGO) and MnO2. The layered sensor showed excellent current responses for the simultaneous electrochemical analysis of SOF, LED and ACY in human serum in the concentration ranges 0.20–150μmoldm−3, 0.0070–15μmoldm−3 and 0.010–30μmoldm−3 with low detection limit values of 9.8nmoldm−3, 0.11nmoldm−3 and 0.84nmoldm−3 respectively. Moreover, on the new layered electrode the electro-oxidation of a quinary mixture of ascorbic acid (AA), dopamine (DA), paracetamol (APAP), SOF and LED yielded five well-separated peaks. This electrochemical method is advantageous over other methods mentioned in the literature in terms of cost, time effectiveness, sensitivity, selectivity and lower detection limit. Analysis of ACY and a combination from LED and SOF in their pharmaceutical formulations were achieved with good recovery results.

Novel spectrofluorimetric approach for determination of ledipasvir through UV-irradiation: application to biological fluids, pharmacokinetic study and content uniformity test.

A highly sensitive and specific fluorescence dependent approach was created for quantitation of a recently approved anti-HCV drug (ledipasvir). This approach relies on the innovative enhancement in fluorescence intensity of ledipasvir upon exposing the cited drug to direct UV irradiation as a photo-physical fluorescence enhancer. The fluorescence of the resultant solution was measured at an emission peak of 375 nm (321 nm excitation). The photoluminescence properties of the resultant product were carefully examined and the quantitative rectilinear concentration plot for the method was 5.0–150.0 ng mL−1 with a detection limit of 0.9 ng mL−1 and a quantitation limit of 2.7 ng mL−1. The excellent analytical features of the proposed method allow to the specific and sensitive estimation of ledipasvir either in plasma samples or in tablet dosage form without any interference from pharmaceutical excipients or other co-formulated anti-HCV drugs (sofosbuvir). The developed analytical and bio-analytical procedures were created and validated according to ICH guidelines and FDA guidelines, respectively. Since the main elimination route for ledipasvir is via faecal excretion, the studied drug was determined for the first time in faecal samples by the method with adequate recovery. Moreover, the pharmacokinetic parameters (Cmax, tmax, t1/2, AUC0–t, and AUC0–∞) for ledipasvir were determined by the proposed method. Additionally, the proposed method was successfully applied for supervising the content uniformity for ledipasvir in its pharmaceutical tablets.

Graphite/Nanocrystalline Zeolite Platform for Selective Electrochemical Determination of Hepatitis C Inhibitor Ledipasvir

AbstractA simple and efficient procedure is described for the electrochemical determination of ledipasvir (LDP) in presence of co‐formulated drug sofosbuvir (SOF). Herein, a highly sensitive, low‐cost electrochemical protocol was utilized to fabricate a zeolite modified carbon paste electrode (ZY/CPE) through mixing of zeolite nanostructures with graphite powder. The fabricated sensor displayed high sensitivity, allowing optimal charge transfer/electrode kinetics. Different experimental and chemical factors, including electrode composition, effect of pH, scan rate and amount of ZY were evaluated carefully to obtain the highest electrochemical response. Under optimized conditions and using square wave voltammetry (SWV), the current response of the ZY/CPE electrochemical sensing platform exhibited a detection limit of 7.5×10−9 M and a large linear range from 5.0×10−8 to 1.0×10−4 M. The practical applicability of the suggested electrochemical platform was verified in the assessment of LDP in pharmaceutical formulations with excellent recoveries in the range of 99.50–98.87 %. Moreover, a biological relevance of the developed sensor was established by the analysis of LDP in human urine and plasma samples with satisfactory recoveries of 99.00 and 99.68 %, respectively. Due to the simplicity and ease of preparation of the proposed sensor, it can be used in quality control laboratories and for clinical analysis.

Regulation of human placental drug transporters in HCV infection and their influence on direct acting antiviral medications

IntroductionThe objectives of this study were to determine how HCV infection affects placental drug transporters, and to determine the role of drug transporters on the cellular accumulation of direct-acting antiviral drugs in human trophoblasts. MethodsEighty-four ABC and SLC transporter genes were first screened in normal and HCV infected pregnant women using PCR profiler array. The changes in expression were confirmed by qPCR and Western blot. The impact of selected drug transporters on the cellular accumulation of radiolabeled antiviral drugs sofosbuvir, entecavir, and tenofovir was measured in primary human trophoblasts (PHT) and BeWo b30 cells in the presence or absence of transporter-specific inhibitors. PHT were then treated with CL097, ssRNA40, and imquimod to determine the impact of Toll-like receptor (TLR) 7/8 activation on drug transporter expression. ResultsThe expression of the ABC efflux transporters ABCB1/P-gp and ABCG2/BCRP was increased in placenta of women with HCV, while the nucleoside transporters SLC29A1/ENT1 and SLC29A2/ENT2 remained unchanged. The accumulation of sofosbuvir and tenofovir was unaffected by inhibition of these transporters in trophoblast cells. Entecavir accumulation was decreased by the inhibition of ENT2. P-gp and BCRP inhibition enhanced entecavir accumulation in BeWo b30, but not PHT. Overall, there was little effect of TLR7/8 activation on these drug transporters, and the accumulation of entecavir in PHT. DiscussionThe data suggest that expression of placental drug transporters and selection of antiviral drug may impact fetal drug exposure in pregnancies complicated by HCV infections.

Specific stability indicating spectrofluorimetric method for determination of ledipasvir in the presence of its confirmed degradation products; application in human plasma

A rapid and specific spectrofluorimetric method with higher sensitivity was developed for determination of ledipasvir (LDS) in tablets and human plasma. The proposed method relies on hydrogen bonding formations between the hydroxyl groups of polyoxyethylene 50 stearate and LDS, causing significant enhancement of its native fluorescence. The fluorescence intensity was measured at 430 nm after excitation at 340 nm. The fluorescence–concentration plot was rectilinear over the range 1–400 ng mL−1 with detection and quantification limits of 0.25 and 1.10 ng mL−1, respectively. The high sensitivity of the proposed method permits its application for ledipasvir determinations in real human plasma even in the presence of co-administered drugs sofosbuvir and ribavirin. Moreover, the proposed method was further extended to stability studies of ledipasvir after exposure to different forced degradation conditions according to ICH guidelines, along with the structural elucidation of its degradation products utilizing IR and Mass spectra. A proposal for the degradation pathways was presented.

In depth investigation of quantitative analytical and bioanalytical techniques of hepatitic drug sofosbuvir in different matrices: a review

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OP61 Net Value Of Treating Hepatitis C With Newly Available Direct-Acting Antivirals

Introduction:Recently developed direct-acting antiviral (DAA) treatments for hepatitis C virus (HCV) are groundbreaking in their high efficacy across disease genotypes and lack of severe side effects. This study used a cost-of-illness (COI) approach to estimate the net value conferred by one of these novel drug combinations, sofosbuvir and velpatasir (SOF/VEL), recently licensed for generic manufacture in India.Methods:This study considered COI from lifetime earnings lost due to disability and premature death from HCV infection. Risk of death and disability in future years was calculated using a Markov state-transition model with parameters determined from the literature. The future earnings of sampled patients were predicted using an empirical earnings model, with coefficients determined from India Human Development Survey data. Costs to both the patient and secondarily infected individuals were considered.Results:Preliminary results suggested that curing individuals diagnosed with chronic HCV in India would preserve INR 3.7 million (USD 55,750) in earnings per person. For non-cirrhotic (NC) and compensated cirrhotic (CC) individuals, the expected benefits associated with preventing secondary infections were worth between one and forty-one percent of the value of benefits conferred to the diagnosed individuals (depending on sex and extent of liver damage). Treating decompensated cirrhotic (DC) individuals with DAAs alone offered minimal earnings benefits because these individuals will likely remain disabled and unable to work without a liver transplant. Expected net benefits of treatment were substantial for NC and CC patients, ranging from INR 640,349 (USD 9,531) for NC women to INR 10.7 million (USD 158,968) for CC men. The cost of treatment for DC individuals exceeded the expected earnings benefits.Conclusions:For average NC and CC individuals, the cost of treatment with SOF/VEL is offset by the benefits of increased future productivity. Increased earnings are not sufficient to offset the cost of treatment for DC individuals, but treatment may still be justified on the basis of the intrinsic value of health improvements and other treatment benefits.

Validated Stability Indicating RP-HPLC method for estimation of antiviral class of drugs Sofosbuvir and Velpatasvir in combination and its comparison with reported methods

A simple, specific, accurate and stability-indicating reverse phase high performance liquid chromatographic method was developed for simultaneous determination of Sofosbuvir and Velpatasvir, using a BDS C8 (150 x 4.6 mm, 5 μm) column and a mobile phase composed of Buffer (0.1% OPA): Acetonitrile (50: 50, v/v).The retention time of Sofosbuvir and Velpatasvir was found to be 2.267 mins and 2.983 mins respectively when compared with the developed methods the retention time was very less. Linearity was established in the range of 100–600 μg/ml and 25–150 μg/ml for Sofosbuvir and Velpatasvir respectively. The percentage recoveries of Sofosbuvir and Velpatasvir were found to be 100.34% and 101.37% respectively. The drugs were subjected to acid, alkali, hydrolysis, oxidation, dry heat, photolytic and UV degradation and showed very less degradation where no method has reported about the degradation data. The developed method can be successfully employed for simultaneous quantitative analysis of Sofosbuvir and Velpatasvir in bulk and formulations. When the validation parameters of the method developed are compared with those of the earlier reported methods. The developed method was found to be superior in the aspects such as retention time, system suitability and the method was more economical when compared to others as the run time is only 5 minutes.

Effectiveness of Sofosbuvir, Ribavirin and PEG-IFNα-2a in the Treatment of Naïve Egyptian Patients With Chronic Hepatitis C Virus Genotype 4

BackgroundEgypt is one of the largest epidemic areas of hepatitis C virus (HCV) in the world. Its prevalent genotype is 4 with a majority of subtype 4a. In 2013, the Food and Drug Administration approved a new direct-acting antiviral drug (sofosbuvir) to treat patients with chronic HCV infection. In Egypt, the patients are already being treated with sofosbuvir in conjunction with ribavirin and pegylated interferon alfa-2a (PEG-IFNα-2a) for 12 weeks since 2015. The present study was planned to explain the efficacy of this treatment regimen against the HCV genotype 4a in Egyptian patients and its pretreatment predictive factors of virological response. MethodsIn this population-based study, serum samples were biochemically analyzed and the HCV RNA levels were quantified. The direct sequencing and bioinformatics analysis were utilized to investigate the mutation of the core protein. ResultsThe sustained virological response (SVR) and non-SVR were 72% and 16% respectively, but the nonvirological response was only 12% following the treatment regimen. The multivariable analysis recognized viral (level of viremia and substitution of aa70) and host-related factors (age, alanine aminotransferase and aspartate aminotransferase levels) affecting the virological response in patients infected with high viral load of HCV 4a. ConclusionsOverall, these results concluded that sofosbuvir with ribavirin and PEG-IFNα-2a are highly efficient in HCV-4a Egyptian patients where a high SVR was achieved (72%). In addition to this, there is a significant association between core protein mutations and treatment outcome predominantly at amino acid position 70 (Arg or Gln).

Effectiveness of ravidasvir plus sofosbuvir in interferon-naïve and treated patients with chronic hepatitis C genotype-4

Although treatment of hepatitis C virus (HCV) and HCV-genotype-4 (GT4) has become very effective, it remains very expensive, and affordable options are needed, especially in limited resource countries. The aim of this study was to assess the efficacy and safety of the combination of ravidasvir (an NS5A inhibitor) and sofosbuvir to treat patients with chronic HCV-GT4 infection. A total of 300 patients with HCV-GT4 infection were recruited in three groups: treatment-naïve patients with or without compensated Child-A cirrhosis (Group 1); interferon-experienced patients without cirrhosis (Group 2); and interferon-experienced patients with cirrhosis (Group 3). Groups 1 and 2 received ravidasvir 200 mg QD plus sofosbuvir 400 mg QD for 12 weeks and were randomized 1:1 to treatment with or without weight-based ribavirin. Group 3 patients received ravidasvir plus sofosbuvir with ribavirin and were randomized 1:1 to a treatment duration of 12 weeks or 16 weeks. The primary endpoint was sustained virologic response at 12 weeks post-treatment (SVR12). A total of 298 patients were enrolled: 149 in Group 1, 79 in Group 2 and 70 in Group 3. SVR12 was achieved in 95.3% of all patients who started the study, including 98% of patients without cirrhosis and 91% of patients with cirrhosis, whether treatment-naïve or interferon-experienced. Ribavirin intake and history of previous interferon therapy did not affect SVR12 rates. No virologic breakthroughs were observed and the study treatment was well tolerated. Treatment with ravidasvir plus sofosbuvir, with or without ribavirin, was well tolerated and associated with high sustained virologic response rate for HCV-GT4 infected patients with and without cirrhosis, regardless of previous interferon-based treatments. ClinicalTrials.gov Identifier: NCT02371408. This study evaluated efficacy and safety of the new oral hepatitis C drug ravidasvir in combination with the approved oral drug sofosbuvir in 298 patients infected with hepatitis C type 4. Our results showed that treatment with ravidasvir plus sofosbuvir, with or without ribavirin, was well tolerated and associated with high response rate in patients with and without cirrhosis.

Sofosbuvir as treatment against dengue?

Dengvaxia® (CTD-TDV), the only licensed tetravalent dengue vaccine by Sanofi Pasteur, was made available since 2015. However, administration of CTD-TDV, in general, has not received the prequalification recommendation from the World Health Organization. Having a universal antidengue agent for treatment will therefore beneficial. Accordingly, the development of nucleoside inhibitors specific to dengue viral polymerase that perturb dengue infection has been studied by many. Alternatively, we have used a marketed anti-HCV prodrug sofosbuvir to study its in silico and in vitro effects against dengue. As a result, the active metabolite of sofosbuvir (GS-461203) was predicted to bind to the catalytic motif (Gly-Asp-Asp) of dengue viral polymerase with binding affinity of -6.9kcal/mol. Furthermore, sofosbuvir demonstrated excellent in vitro viral inhibition with an EC90 of 0.4μm. In addition, this study demonstrated the requirement of specific liver enzymes to activate the prodrug into GS-461203 to exert its antidengue potential. All in all, sofosbuvir should be subjected to in-depth studies to provide information of its efficacy toward dengue and its lead potential as DENV polymerase inhibitor in human subjects. In conclusion, we have expended the potential of the clinically available drug sofosbuvir as treatment for dengue.

Chemical genetics-based development of small molecules targeting hepatitis C virus.

Hepatitis C virus (HCV) infection is a major worldwide problem that has emerged as one of the most significant diseases affecting humans. There are currently no vaccines or efficient therapies without side effects, despite today's advanced medical technology. Currently, the common therapy for most patients (i.e. genotype 1) is combination of HCV-specific direct-acting antivirals (DAAs). Up to 2011, the standard of care (SOC) was a combination of peg-IFNα with ribavirin (RBV). After approval of NS3/4A protease inhibitor, SOC was peg-IFNα and RBV with either the first-generation DAAs boceprevir or telaprevir. In the past several years, various novel small molecules have been discovered and some of them (i.e., HCV polymerase, protease, helicase and entry inhibitors) have undergone clinical trials. Between 2013 and 2016, the second-generation DAA drugs simeprevir, asunaprevir, daclatasvir, dasabuvir, sofosbuvir, and elbasvir were approved, as well as the combinational drugs Harvoni®, Zepatier®, Technivie®, and Epclusa®. A number of reviews have been recently published describing the structure-activity relationship (SAR) in the development of HCV inhibitors and outlining current therapeutic approaches to hepatitis C infection. Target identification involves studying a drug's mechanism of action (MOA), and a variety of target identification methods have been developed in the past few years. Chemical biology has emerged as a powerful tool for studying biological processes using small molecules. The use of chemical genetic methods is a valuable strategy for studying the molecular mechanisms of the viral lifecycle and screening for anti-viral agents. Two general screening approaches have been employed: forward and reverse chemical genetics. This review reveals information on the small molecules in HCV drug discovery by using chemical genetics for targeting the HCV protein and describes successful examples of targets identified with these methods.

BIOANALYTICAL METHOD DEVELOPMENT AND VALIDATION FOR THE DETERMINATION OF SOFOSBUVIR FROM HUMAN PLASMA

Objective: This study points to build up and validate a simple methodology to quantify the most used drug sofosbuvir for the treatment of hepatitis C virus (HCV) infection, in human plasma by using atazanavir as an Internal Standard (IS) for preclinical studies and validate as per USFDA guidelines.Methods: Sofosbuvir was isolated from plasma samples by liquid-liquid extraction method using acetonitrile; good chromatographic separation was achieved on Kromasil Column (250 mm ×4.6 mm, 5 µm). The mobile phase consisted of 0.1 % orthophosphoric acid (OPA) buffer pH 2 and acetonitrile in the ratio of (68:32, v/v), respectively. The analysis time was 7 min at a flow rate 1 ml/min. The photodiode array detector (PDA) detection was carried out at 228 nm. The suggested method was validated by performing linearity, system suitability, specificity and sensitivity, accuracy and precision, recovery, ruggedness, stability studies. The method was validated as per USFDA guidelines.Results: The developed method resulted in retention times of sofosbuvir and IS were found out to be 4.7 and 4.2 min respectively. The calibration curves are linear (r2 = 0.999) over the concentration range of 0.050-2.0 µg/ml of plasma analytes concentration. LOQ value was found to be 0.050 µg/ml with precision and accuracy. Within-batch % mean accuracy of the method ranged between 96.00% and 109.09%, and within-batch and total precision, expressed as the coefficient of variation, was 1.40–10.33%. Overall percentage mean recovery of sofosbuvir from spiked plasma was 84.14%. All the validated parameters were found to be within the limit.Conclusion: A simple, accurate, precise, linear, rugged and rapid RP-HPLC method was developed for quantitative estimation of sofosbuvir in human plasma and should be suitable for conducting pharmacokinetics studies and therapeutic drug monitoring.

The clinically approved antiviral drug sofosbuvir inhibits Zika virus replication

Zika virus (ZIKV) is a member of the Flaviviridae family, along with other agents of clinical significance such as dengue (DENV) and hepatitis C (HCV) viruses. Since ZIKV causes neurological disorders during fetal development and in adulthood, antiviral drugs are necessary. Sofosbuvir is clinically approved for use against HCV and targets the protein that is most conserved among the members of the Flaviviridae family, the viral RNA polymerase. Indeed, we found that sofosbuvir inhibits ZIKV RNA polymerase, targeting conserved amino acid residues. Sofosbuvir inhibited ZIKV replication in different cellular systems, such as hepatoma (Huh-7) cells, neuroblastoma (SH-Sy5y) cells, neural stem cells (NSC) and brain organoids. In addition to the direct inhibition of the viral RNA polymerase, we observed that sofosbuvir also induced an increase in A-to-G mutations in the viral genome. Together, our data highlight a potential secondary use of sofosbuvir, an anti-HCV drug, against ZIKV.

Sofosbuvir: Arrival of a paradigm shift in the management of hepatitis C in India

More than 185 million people in the world are affected by hepatitis C, with India having a huge patient load of about 18 million cases. The association of various complications and hepatocellular carcinoma risk with hepatitis C makes it a dangerous health issue. In the early 90s, due to lack of choice for hepatitis C treatment, pegylated interferon (peg-IFN) and ribavirin (RBV) were the widely used agents, but they have low efficacy and multiple side effects. Last decade saw the development of direct-acting antiviral (DAA) agents, including the hepatitis C-specific drug sofosbuvir (SOF). Multiple clinical trials were carried out testing SOF which showed it has excellent efficacy and low side effects. This ultimately led to the approval of SOF in the USA for hepatitis C treatment, in combination with RBV and/or peg-IFN as well as with other newer DAAs. India considered the excellent efficacy and tolerability profile of SOF in the international trials and gave it a marketing approval in early 2015, with a waiver of the national clinical trial data. This has come as a major boost to the millions of hepatitis C patients in the country. However, the exorbitant cost remains a deterrent for its universal use, especially in developing countries like India. The literature search was performed across various databases such as PubMed, EMBASE, and Google Scholar for articles.