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This study was conducted as a single-site, open-label, randomized, replicated crossover trial with 4 treatment periods. The aim was to evaluate the bioequivalence of a generic test drug containing velpatasvir and sofosbuvir compared to an established brand-name medication in healthy White subjects under fasting conditions. Blood samples were collected at specified intervals up to 72 hours after dosing to measure the concentrations of velpatasvir and sofosbuvir using a certified high-performance liquid chromatography with tandem mass spectrometry method. The bioequivalence of the 2 formulations was confirmed when statistical analysis showed that confidence intervals for the log-transformed peak concentration and area under the concentration-time curve from time 0 to the last quantifiable sample were within an acceptable range from 80% to 125%. Criteria for bioequivalence were met for both area under the concentration-time curve from time 0 until the last quantifiable sample and peak concentration parameters. No adverse effects were reported during this trial in both groups., (© 2024, The American College of Clinical Pharmacology.)

Sofosbuvir (SOF) is a P-glycoprotein (P-gp) substrate, and carvedilol (CAR) is an inhibitor of P-gp, suggesting that it may affect the oral pharmacokinetics and safety of SOF. The current study investigated the pharmacokinetic interaction of CAR with SOF and its metabolite, GS-331007, and the possible consequent toxicities in rats. To assess the pharmacokinetics of SOF and GS-331007, rats were divided into three groups; all received a single oral dose of SOF preceded with saline (SAL), verapamil (VER) as a standard P-gp inhibitor, or CAR, respectively. The serosal, plasma, and hepatic tissue contents of SOF and GS-331007 were assessed using LC-MS/MS. Renal and hepatic toxicities were assessed using biochemical and histopathological tests. Serosal and plasma concentrations of SOF and GS-331007 were increased in the presence of CAR, suggesting a significant inhibitory effect of CAR on intestinal P-gp. Simultaneously, the pharmacokinetic profile of SOF showed a significant increase in the Cmax, AUC(0-t), AUC (0-∞), t1/2, and a reduction in its apparent oral clearance. While the pharmacokinetic profile of GS-331007 was not significantly affected. However, this notable elevation in drug oral bioavailability was corroborated by a significant alteration in renal functions. Hence, further clinical investigations are recommended to ensure the safety and dosing of CAR/SOF combination., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Royal Pharmaceutical Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Ravidasvir (RDV) is a novel NS5A inhibitor that exhibits potent pan-genotypic inhibition of hepatitis C virus (HCV) replication. Sofosbuvir (SOF) plus RDV was demonstrated to be efficacious and safe in adults with active HCV infection, including those living with HIV (LWHIV), in the STORM-C-1 trial. We assessed the population pharmacokinetics (PK) of RDV in a sub-study nested within STORM-C-1 conducted in Thailand and Malaysia. SOF (400 mg) plus RDV (200 mg) was administered orally once daily for 12 weeks to adults with chronic HCV infection, but without cirrhosis and for 24 weeks to those with compensated cirrhosis. Intensive and sparse PK samples were collected at 4, 8, and 12 weeks after treatment initiation. Population PK parameters of RDV and the impact of covariates were evaluated using nonlinear mixed-effects modeling. Five hundred ninety-four participants were included, 235 (40%) had compensated cirrhosis, and 189 (32%) were LWHIV. RDV plasma concentrations were best described by a two-compartment model with first-order elimination. Oral clearance (CL/F) and volume of distribution (Vd/F) parameters were allometrically scaled on fat-free mass. Concomitant antiretroviral treatment (ART) increased RDV CL/F by 30%-60%, with efavirenz-based ART having the largest impact. Females had 16% lower RDV CL/F than males, and higher albumin levels reduced RDV central volume of distribution. While several covariates impact RDV CL/F and Vd/F, the effect on RDV exposures was not clinically relevant based on the efficacy data reported in this diverse Asian adult population. There were no meaningful drug-drug interactions in adults LWHIV on ART., Competing Interests: C.M., I.R., A.S., and J.-Y.G. are employed by the DNDi. All other authors declare no competing interests.

Sofosbuvir/Velpatasvir (SOF/VEL) is a combination drug used for chronic hepatitis C (HCV) infection. However, limited information exists regarding the pharmacokinetics of SOF/VEL and its metabolites in hemodialysis patients. We conducted a prospective investigation of the pharmacokinetic parameters of SOF/VEL after a single dose of SOF/VEL (400/100 mg) on days with and without dialysis in 12 Thai hemodialysis patients with chronic HCV infection, who had been undergoing hemodialysis for a duration of 0.5-20 years. Blood samples were collected before dose (0) and 0.5, 1.0, 2.0, 2.5, 3.0, 3.5, 4.0, 5.0, 6.0, 8.0, and 12.0 h after dose. Dialysate samples were also collected before dose (0) and 1.0, 2.0, 3.0, and 4.0 h after dose. Plasma and dialysate samples were quantified for SOF and its metabolite, GS-331007, and VEL concentrations using a fully validated LCMS technique. In addition, a preliminary efficacy study was conducted using the proposed SOF/VEL dose reduction regimen in all patients. No differences in SOF/VEL PK parameters between on- and off-dialysis studies. On the contrary, GS-331007 exhibited a 30% reduction in the area under the plasma concentration-time curve from time 0 to 24 h (AUC 0-24h ) on dialysis days compared with non-dialysis days (AUC 0-24h ratio 0.68 vs. 1.04, respectively). The dialysis clearance of SOF and GS-331007 was 9.35 (8.72-15.11) and 8.89 (8.52-14.07) mL/min, respectively. Subsequently, an alternate-day regimen of SOF/VEL (400/100 mg) was administered for 12 weeks, resulting in an undetectable plasma HCV viral load without side effects. Further clinical studies are warranted to validate the efficacy and safety of our proposed dose reduction regimen., (© 2024 The Author(s). Clinical and Translational Science published by Wiley Periodicals LLC on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Background: The safety and efficacy of sofosbuvir-velpatasvir in children aged 3-17 years with chronic hepatitis C virus (HCV) infection of any genotype were evaluated., Methods: In this Phase 2, multicenter, open-label study, patients received once daily for 12 weeks either sofosbuvir-velpatasvir 400/100 mg tablet (12-17 years), 200/50 mg low dose tablet or oral granules (3-11 years and ≥17 kg), or 150/37.5 mg oral granules (3-5 years and <17 kg). The efficacy endpoint was sustained virologic response 12 weeks after therapy (SVR12). Dose appropriateness was confirmed by intensive pharmacokinetics in each age group., Findings: Among 216 patients treated, 76% had HCV genotype 1% and 12% had genotype 3. Rates of SVR12 were 83% (34/41) among 3-5-year-olds, 93% (68/73) among 6-11-year-olds, and 95% (97/102) among 12-17-year-olds. Only two patients experienced virologic failure. The most common adverse events were headache, fatigue, and nausea in 12-17-year-olds; vomiting, cough, and headache in 6-11-year-olds; and vomiting in 3-5-year-olds. Three patients discontinued treatment because of adverse events. Four patients had serious adverse events; all except auditory hallucination (n = 1) were considered unrelated to study drug. Exposures of sofosbuvir, its metabolite GS-331007, and velpatasvir were comparable to those in adults in prior Phase 2/3 studies. Population pharmacokinetic simulations supported weight-based dosing for children in this age range., Interpretation: The pangenotypic regimen of sofosbuvir-velpatasvir is highly effective and safe in treating children 3-17 years with chronic HCV infection., (© 2024 European Society for Pediatric Gastroenterology, Hepatology, and Nutrition and North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition.)

Background: Coadministration of statins and direct acting antiviral agents is frequently used. This study explored the effects of both atorvastatin and lovastatin on pharmacokinetics of a fixed-dose combination of sofosbuvir/ledipasvir "FDCSL"., Methods: 12 healthy volunteers participated in a randomized, three-phase crossover trial and were administered a single atorvastatin dose 80 mg plus tablet containing 400/90 mg FDCSL, a single lovastatin dose 40 mg plus tablet containing 400/90 mg FDCSL, or tablets containing 400/90 mg FDCSL alone. Liquid chromatography-tandem mass spectrometry was used to analyze plasma samples of sofosbuvir, ledipasvir and sofosbuvir metabolite "GS-331007" and their pharmacokinetic parameters were determined., Results: Atorvastatin caused a significant rise in sofosbuvir bioavailability as explained by increasing in AUC 0-∞ and C max by 34.36% and 11.97%, respectively. In addition, AUC 0-∞ and C max of GS-331007 were increased by 73.73% and 67.86%, respectively after atorvastatin intake. Similarly, co-administration of lovastatin with FDCSL increased the bioavailability of sofosbuvir, its metabolite (AUC 0-∞ increase by 17.2%, 17.38%, respectively, and C max increase by 12.03%, 22.24%, respectively). However, neither atorvastatin nor lovastatin showed a change in ledipasvir bioavailability. Hepatic elimination was not affected after statin intake with FDCSL. Compared to lovastatin, atorvastatin showed significant increase in AUC 0-∞ and C max of both sofosbuvir and its metabolite., Conclusions: Both atorvastatin and lovastatin increased AUC of sofosbuvir and its metabolite after concurrent administration with FDCSL. Statins' P-glycoprotein inhibition is the attributed mechanism of interaction. The increase in sofosbuvir bioavailability was more pronounced after atorvastatin intake. Close monitoring is needed after co-administration of atorvastatin and FDCSL., Competing Interests: Authors declare that there is no conflict of interest concerning the content of this article., (Thieme. All rights reserved.)

Background: Sofosbuvir plus daclatasvir achieves high rates of sustained virologic response (SVR), with no differences according to HIV serostatus. However, only limited information is available on the pharmacokinetic variability of sofosbuvir and daclatasvir in HIV/HCV-coinfected patients., Objectives: The aim of this study was to identify patient-, treatment-, and disease-related factors that are significantly associated with sofosbuvir and daclatasvir plasma trough concentrations (C trough ), including liver and renal function, among HIV/HCV-coinfected persons., Methods: In this observational cohort pilot study, HIV/HCV-coinfected patients undergoing sofosbuvir plus daclatasvir treatment were prospectively enrolled. Biochemical and viro-immunological parameters were assessed at baseline, week 4 (W4), end of treatment (EOT), and after EOT. The FIB-4 score and CKD-EPI equation were used to estimate liver disease and glomerular filtration rate (eGFR), respectively. For sofosbuvir, sofosbuvir metabolite (GS-331007), and daclatasvir, C trough was measured at W4 and week 8 (W8), and the mean of the values at those two time points (mean-C trough ) was calculated. The Mann-Whitney test and Spearman's rank correlation were used to evaluate the correlations between the mean-C trough of each direct-acting antiviral (DAA) and the considered variables., Results: Thirty-five patients were included (SVR 94%). An increased GS-331007 mean-C trough was significantly correlated with a decreased eGFR at W4 (rho = -0.36; p = 0.037) and EOT (rho = -0.34; p = 0.048). There was a significant correlation between daclatasvir mean-C trough and FIB-4 at all time points: baseline (rho = -0.35; p = 0.037), W4 (rho = -0.44; p = 0.008), EOT (rho = -0.40; p = 0.023), and after EOT (rho = -0.39; p = 0.028)., Conclusions: In HIV/HCV-coinfected patients in a real-world setting, exposure to a high GS-331007 C trough was associated with a slight decrease in renal function, while advanced hepatic impairment was significantly associated with a lower daclatasvir C trough . Though the clinical and therapeutic relevance of these findings may be limited, increasing clinicians' knowledge regarding DAA exposure in difficult-to-treat patients could be relevant in single cases, and further investigations are warranted., (© 2021. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Background: Sofosbuvir (SOF)/daclatasvir (DCV) is the direct-acting antiviral regimen of choice in many low- and middle-income countries for curative treatment of chronic hepatitis C virus (HCV) infection in adults, but data on the use of DCV in children are lacking. We performed a population pharmacokinetic (PK) analysis to predict DCV exposure in children treated with available adult formulations., Methods: DCV concentration data from HCV-infected adolescents receiving SOF/DCV [400/60 mg, once daily (OD)] who participated in a PK study in Egypt were used for model development. PK parameters were estimated using a population approach. Monte Carlo simulations were run for virtual children weighing 10 to <35 kg receiving 60 or 30 mg OD, and DCV exposures were compared with adults ranges., Results: Seventeen HCV-infected adolescents (13 males) provided 151 DCV concentrations. Median (range) age was 14 (11-18) years and weight 50 (32-63) kg. In these adolescents receiving 60 mg DCV, median (interquartile range) DCV area under the concentration time curve 0 to 24 hours, maximum concentrations, and minimum concentrations were 11,130 (8140-14,690) ng·h/mL, 1030 (790-1220) ng/mL and 130 (110-220) ng/mL, respectively, compared with 10,343 (7661-14,095) ng·h/mL, 1132 (876-1518) ng/mL and 110 (55.7-192) ng/mL predicted in children 10 to <35 kg receiving 30 mg. The proportion of children with DCV exposures above the adult range rapidly increased for children <30 kg using 60 mg OD, similarly for children 10-14 kg using 30 mg., Conclusions: DCV 30 mg OD was predicted to achieve effective and safe exposures in children 14 to <35 kg, perhaps down to 10 kg. These results should be validated clinically. Low-cost available adult DCV formulations together with approved pediatric doses of SOF would expand global access to HCV treatment for children., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction : Sofosbuvir/velpatasvir is a combination of direct-acting antivirals with pangenotypic activity for treatment of chronic hepatitis C virus infection. It was approved in 2020 for use in children aged 6-17 years and in June 2021 by the United States Food and Drug Administration for the age group 3-5 years. Areas covered : A literature search of PUBMED and EMBASE was conducted on April 30th and updated on June 10th. Other citations were identified in references of available literature and from ClinicalTrials.gov. The aim of the present research was to outline and discuss the pharmacokinetics, clinical efficacy, tolerability and safety of sofosbuvir/velpatasvir, exploring its actual and potential use in children and adolescents with chronic hepatitis C virus infection. Expert opinion : Five combinations of direct-acting antivirals, of whom three with pangenotypic activity, are now approved for children. No major differences in efficacy and safety profile have been described. Limited access to treatment still is a major issue, especially in low and middle-income countries.

Purpose: Comorbid conditions of heart and liver disorders added to HCV-induced hepatic steatosis make co-administration of statins, and direct-acting antivirals is common in clinical practice. This study aimed to evaluate the pharmacokinetic interaction of atorvastatin and fixed-dose combination of sofosbuvir/ledipasvir "FDCSL" with rationalization to the underlying mechanism., Methods: A randomized, three-phase crossover study that involves 12 healthy volunteers was performed. Participants received a single-dose of atorvastatin 80 mg alone, atorvastatin 80-mg plus tablets containing 400/90 mg FDCSL, or tablets containing 400/90 mg FDCSL alone. Plasma samples were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for atorvastatin, sofosbuvir, ledipasvir, and sofosbuvir metabolite "GS-331007," and their pharmacokinetics parameters were determined., Results: Compared to atorvastatin alone, the administration of FDCSL caused a significant increase in both areas under the concentration-time curve from time zero to infinity (AUC 0-∞ ) and maximum plasma concentration (C max ) of atorvastatin by 65.5% and 156.0%, respectively. Also, atorvastatin caused a significant increase in the AUC 0-∞ and C max of sofosbuvir by 32.0% and 11.0%, respectively. Similarly, AUC 0-∞ and C max of sofosbuvir metabolite significantly increased by 84.0% and 74.0%, respectively. However, ledipasvir AUC 0-∞ showed no significant change after atorvastatin intake. The elimination rate in all drugs revealed no significant changes., Conclusion: After concurrent administration of FDCSL with atorvastatin, the AUC 0-∞ of both atorvastatin and sofosbuvir were increased. Caution should be taken with close monitoring for possible side effects after co-administration of atorvastatin and FDCSL in clinical practice., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: Available data have suggested that directacting antivirals for hepatitis C virus may decrease calcineurin inhibitor concentrations. In this study, our aim was to determine the effects of hepatitis C directacting antivirals on calcineurin inhibitor doses and trough levels., Materials and Methods: This retrospective, singlecenter study included 52 abdominal transplant recipients treated with sofosbuvir-based regimens between 2014 and 2017. The primary outcome was percent change in calcineurin inhibitor troughs and total daily doses between the week before treatment with direct-acting antivirals, days 21 to 35 oftreatment, and days 21 to 35 aftertreatment. Secondary outcomes included sustained virologic response and biopsyproven acute rejection rates., Results: The median percent difference in calcineurin inhibitor troughs from pretreatment to during treatment was -20.5% (interquartile range, -36.2% to 13.1%) and from pretreatment to posttreatment was -13.5% (interquartile range, -33.7% to 10.7%). Corresponding percent changes in calcineurin inhibitor doses were 0% (interquartile range, 0%-0%) and 0% (interquartile range, -10.5% to 33.3%), respectively. Patients on tacrolimus experienced statistically significant changes in troughs but not doses. During treatment, 65% of patients required no dose change, 23% underwent a dose increase, and 12% had a dose decrease. The sustained virologic response rate was 98%, and the biopsy-proven acute rejection rate was 0%., Conclusions: Hepatitis C direct-acting antiviraltherapy may decrease calcineurin inhibitor levels, but this was not associated with clinically different dosing requirements or rejection rates.

The work aimed to improve both absorption and hepatic availability of sofosbuvir. Bilosomes and galactose-anchored bilosomes were investigated as potential nanocarriers for this purpose. Sofosbuvir is a class III drug with high solubility and low permeability. Thus, the drug entrapment into lipid-based galactose-anchored carriers would enhance drug permeability and improve its liver availability. The galactosylated taurocholate was designed and synthesized based on molecular docking studies, where both galactose and taurocholate molecules were connected in a way to avoid affecting crucial interactions and avoid steric clashes with their cellular uptake receptors. The suggested nano-carriers were prepared using a thin-film hydration technique with sodium taurocholate and span 60 as stabilizers. The prepared formulae were statistically optimized using a central composite design. The optimized plain and galactosylated formulae, composed of SAA to drug ratio of 1:1 w/w and sodium taurocholate to span ratio of 10:1 w/w, have a vesicular size, zeta potential and entrapment efficiency in the range of 140-150 nm, -50 mV and 85%, respectively. The optimized formulae were lyophilized to increase their physical stability and facilitate accurate drug dosing. In vivo results showed that Sofosbuvir availability in the liver was significantly increased after oral administration of the plain and the galactosylated bilosomal formulae when compared to the oral drug solution with relative targeting efficiencies (RTIs) of 1.51 and 3.66, respectively. These findings confirmed the hypothesis of considering the galactosylated bilosomes a promising nanocarrier to efficiently target sofosbuvir to the liver.

Background: There is a medical need for highly effective, safe, and well tolerated treatments for patients infected with hepatitis C virus (HCV) with severe renal impairment. We investigated the safety and efficacy of sofosbuvir with ribavirin or ledipasvir combined with sofosbuvir in a prospective study of patients with genotype 1 or 3 HCV infection and stage 4-5 chronic kidney disease (creatinine clearance by Cockcroft-Gault ≤30 mL/min) who were not on dialysis., Methods: This phase 2b, open-label, non-randomised, multicentre study in the USA and New Zealand investigated three sequentially enrolled cohorts of patients. Patients were recruited from ten hospitals and clinical research centres and were included if they had genotype 1 or 3 HCV infection, a creatinine clearance less than or equal to 30 mL/min, and were not on dialysis. In cohorts 1 and 2, patients received sofosbuvir (200 mg in cohort 1 and 400 mg in cohort 2) plus ribavirin 200 mg once per day for 24 weeks. In cohort 3, 18 patients received ledipasvir combined with sofosbuvir (90 mg ledipasvir and 400 mg sofosbuvir) once per day for 12 weeks. The primary efficacy endpoint was the proportion of patients achieving sustained virological response 12 weeks after the end of treatment (SVR12). Safety and pharmacokinetic data were also collected. The trial is registered with ClinicalTrials.gov, number NCT01958281, and is completed., Findings: This study was done between Oct 7, 2013, and Oct 29, 2017. In the sofosbuvir plus ribavirin cohorts, 32 patients were screened, of whom 20 were enrolled and assessed for efficacy and safety (ten patients in each cohort). In the ledipasvir plus sofosbuvir cohort, 33 patients were screened, of whom 18 were enrolled and assessed for treatment efficacy and safety. Four (40%, 95% CI 12-74) of ten patients in cohort 1 and six (60%, 26-88) of ten patients in cohort 2 achieved SVR12. All 18 (100%, 82-100) patients in cohort 3 achieved SVR12. Adverse events were mostly mild or moderate in severity. The most commonly reported adverse events overall were headache (eight [21%] of 38 patients), anaemia (seven [18%] of 38 patients), and fatigue (six [16%] of 38 patients). Eight patients had serious adverse events, none of which were treatment related. There were no treatment-related cardiac events or clinically significant changes in echocardiographic parameters or creatinine clearance by Cockcroft-Gault., Interpretation: In this phase 2b study, ledipasvir combined with sofosbuvir for 12 weeks was safe and effective in patients with genotype 1 HCV infection and stage 4-5 chronic kidney disease who were not on dialysis., Funding: Gilead Sciences., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Chronic hepatitis C virus (HCV) infection is a leading cause of cirrhosis worldwide and kills more Americans than 59 other infections, including HIV and tuberculosis, combined. While direct-acting antiviral (DAA) treatments are effective, limited uptake of therapy, particularly in high-risk groups, remains a substantial barrier to eliminating HCV. We developed a long-acting DAA system (LA-DAAS) capable of prolonged dosing and explored its cost-effectiveness. We designed a retrievable coil-shaped LA-DAAS compatible with nasogastric tube administration and the capacity to encapsulate and release gram levels of drugs while resident in the stomach. We formulated DAAs in drug-polymer pills and studied the release kinetics for 1 mo in vitro and in vivo in a swine model. The LA-DAAS was equipped with ethanol and temperature sensors linked via Bluetooth to a phone application to provide patient engagement. We then performed a cost-effectiveness analysis comparing LA-DAAS to DAA alone in various patient groups, including people who inject drugs. Tunable release kinetics of DAAs was enabled for 1 mo with drug-polymer pills in vitro, and the LA-DAAS safely and successfully provided at least month-long release of sofosbuvir in vivo. Temperature and alcohol sensors could interface with external sources for at least 1 mo. The LA-DAAS was cost-effective compared to DAA therapy alone in all groups considered (base case incremental cost-effectiveness ratio $39,800). We believe that the LA-DAA system can provide a cost-effective and patient-centric method for HCV treatment, including in high-risk populations who are currently undertreated., Competing Interests: Competing interest statement: M.V., J.N.C., J.A.F.S., F.E., C.S., R.K., R.L., and G.T. are co-inventors on multiple patent applications describing gastric resident systems for extended drug release and intragastric sensing. R.L. and G.T. have a financial interest in Lyndra Therapeutics, Inc.; Suono Bio, Inc.; and Celero Systems, Inc., which are biotechnology companies focused on the development of gastrointestinal drug delivery and sensing technologies. Complete details for R.L. can be found at the following link: https://www.dropbox.com/s/yc3xqb5s8s94v7x/Rev%20Langer%20COI.pdf?dl=0. Complete details for G.T. can be found at the following link: https://www.dropbox.com/sh/szi7vnr4a2ajb56/AABs5N5i0q9AfT1IqIJAE-T5a?dl=0. The remaining authors disclose no competing interests.

Sofosbuvir (SOF) is a nucleotide prodrug which has been used as a backbone for the clinical treatment of hepatitis C viral infection. Because sofosbuvir undergoes complex first pass metabolism, including metabolic activation to form its pharmacologically active triphosphate (GS-331007-TP) to inhibit the viral RNA polymerase in the liver, it is difficult to project the human dose for clinical evaluation based on preclinical data. Selecting an appropriate animal model for drug exposure in the target tissue is challenging due to differences in absorption, stability, hepatic uptake, and intracellular activation across species. Efficient liver delivery has been established in human liver following administration in a clinical trial of patients receiving sofosbuvir prior to liver transplantation. Using the clinical liver exposure as a benchmark, we assessed and compared the pharmacokinetic profile in mouse, rat, hamster, dog and monkey. Liver accumulation was also assessed in the PXB mouse model in which the liver is mostly populated with human hepatocytes. At human equivalent dose, the hepatic concentrations of GS-331007-TP in dog and PXB mouse were comparable to those observed in the human livers. In these species, high and sustained levels of GS-331007-TP were observed in both primary hepatocytes in vitro and the liver in vivo., Competing Interests: Declaration of competing interest All the authors are current or former employee of Gilead Sciences., (Copyright © 2020 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.)

Objective: Sofosbuvir is an NS5B nucleotide inhibitor that was approved for hepatitis C treatment. Generic sofosbuvir has been produced to improve the affordability. The present study investigated the pharmacokinetics (PK) and safety of generic sofosbuvir as well as the effect of food intake on its PK parameters in healthy Chinese subjects., Materials and Methods: This open-label, randomized, multiple-dose, dose-escalating, and food effect trial enrolled 12 healthy Chinese subjects. The subjects received a single oral dose of 400 mg of generic sofosbuvir in fasted state or after a high-fat meal, or 800 mg in fasted state, in a three-way crossover design, and then all subjects were administered with 400 mg daily for 8 days. The PK parameters for sofosbuvir and its metabolites were determined, and the safety was monitored., Results: Sofosbuvir was absorbed rapidly into plasma, with a half-life of 0.46 - 0.48 hours. Plasma exposure to sofosbuvir and its metabolite GS-566500 was increased in an approximately proportional manner to the increased dose. Repeated dosing did not result in drug accumulation in the blood. Sofosbuvir was mainly excreted as the metabolite GS-331007 in the urine. Drug administration after a high-fat meal increased the plasma sofosbuvir exposure by 1.29-fold, without substantially altering the absorption rate. No serious adverse events were observed, and all subjects tolerated the doses well., Conclusion: This generic sofosbuvir was well absorbed, the plasma concentration was increased with an increased dose, and it was safe in healthy subjects. A high-fat meal appeared to promote the bioavailability of sofosbuvir and the metabolite GS-566500.

In this study, the authors report the case of a patient diagnosed with hepatitis C virus who was treated with sofosbuvir-velpatasvir (400/100 mg). As the patient was unable to swallow whole tablets, therapeutic drug monitoring was performed to evaluate the effect of crushing sofosbuvir-velpatasvir tablets on drug absorption and global exposure.

Purpose: Ledipasvir/sofosbuvir and sofosbuvir/velpatasvir have been approved worldwide for the treatment of chronic hepatitis C virus (HCV) infection. Although both have been approved in China, there are currently no data on their pharmacokinetic profiles in Chinese individuals. Two studies investigated the pharmacokinetic properties, safety, and tolerability of ledipasvir/sofosbuvir and sofosbuvir/velpatasvir, respectively, in healthy Chinese subjects., Methods: Two Phase I, open-label, single- and multiple-dose studies were conducted in healthy Chinese subjects. Ledipasvir/sofosbuvir (90/400 mg) or sofosbuvir/velpatasvir (400/100 mg), respectively, was administered orally once daily under fasted conditions. Subjects received a single dose (day 1) and multiple doses (days 8-17 [ledipasvir/sofosbuvir]; days 8-14 [sofosbuvir/velpatasvir]). Plasma pharmacokinetic parameters were estimated by using noncompartmental models, and safety was assessed through clinical evaluation and monitoring of adverse events., Findings: Fourteen subjects were enrolled in each study (7 men, 7 women each; mean age, 30 years [ledipasvir/sofosbuvir] and 29 years [sofosbuvir/velpatasvir]). The pharmacokinetic parameters for sofosbuvir, GS-566500, GS-331007, and ledipasvir or velpatasvir were similar to historical values in non-Chinese subjects. Consistent with the t 1/2 of ledipasvir relative to 24-h dosing, accumulation of 177% (AUC) and 107% (C max ) was observed. There was no significant accumulation of velpatasvir, sofosbuvir, GS-566500, or GS-331007. Both drugs were generally well tolerated; no serious adverse events or discontinuations due to adverse events were reported., Implications: Overall, ledipasvir/sofosbuvir and sofosbuvir/velpatasvir exhibited pharmacokinetic and safety profiles in healthy Chinese subjects similar to those in non-Chinese subjects in historical studies, supporting their use in the Chinese population with HCV infection. ChinaDrugTrials.org.cn identifiers: CTR20160149 (ledipasvir/sofosbuvir); CTR20160602 (sofosbuvir/velpatasvir)., (Copyright © 2020 Elsevier Inc. All rights reserved.)

The present study describes synthesis of amino-decorated mesoporous silica nanoparticles (MSNs) for sustained delivery and enhanced bioavailability of sofosbuvir. Sofosbuvir is active against hepatitis C virus and pharmaceutically classified as class III drug according to biopharmaceutics classification system (BCS). MSNs were synthesized using modified sol-gel method and the surface was decorated with amino functionalization. Drug loaded MSNs were also grafted with polyvinyl alcohol in order to compare it with the amino-decorated MSNs for sustained drug release. The prepared MSNs were extensively characterized and the optimized formulation was toxicologically and pharmacokinetically evaluated. The functionalized MSNs of 196 nm size entrapped 29.13% sofosbuvir in the pores, which was also confirmed by the decrease in surface area, pore volume and pore size. The drug-loaded amino-decorated MSNs revealed an improved thermal stability as confirmed by thermal analysis. Amino-decorated MSNs exhibited Fickian diffusion controlled sofosbuvir release as compared with non-functionalized and PVA grafted MSNs. Amino-decorated MSNs were deemed safe to use in Sprague-Dawley rats after 14-days exposure as confirmed by the toxicological studies. More interestingly, we achieved a 2-fold higher bioavailability of sofosbuvir in Sprague-Dawley rats in comparison with sofosbuvir alone, and the T max was delayed 3-times indicating a sustained release of sofosbuvir., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background/aims: Direct-acting antivirals (DAAs) play a key role in the eradication of hepatitis C virus (HCV) infection. However, limited data are available on DAA for treating HCV infection in hemodialysis (HD) patients. This study was to evaluate the pharmacokinetic characteristics and effectiveness of daclatasvir/sofosbuvir (DAC/SOF) and ledipasvir/SOF (LDV/SOF) in HD patients., Methods: Seven patients were given SOF coadministered with DAC or LDV once daily for 12 weeks. The plasma concentrations of SOF007, DAC, and LDV were determined by high-performance liquid chromatography-electrospray ionization tandem mass spectrometry., Results: A sustained virologic response in week 12 (SVR12) was achieved in 6 (100%) patients, except for 1 patient dying due to severe cerebral hemorrhage not related to antiviral therapy. The extraction ratio of SOF007 was 66.67%, and the estimated HD clearance of SOF007 was 5.65 L/h., Conclusion: The combination of SOF with either DAC or LDV is well tolerated and offers high SVR12 in HD patients., (© 2020 S. Karger AG, Basel.)

Sofosbuvir is an NS5B nucleotide inhibitor for the treatment of hepatitis C viral infection. In this study the pharmacokinetics (PK) and safety of single and multiple doses of generic sofosbuvir were investigated in healthy Chinese subjects. Twelve subjects (6 male and 6 female) were enrolled in this study. The PK parameters of sofosbuvir and its metabolite (GS-331007) in both blood and urine samples were analyzed after dosing by the established liquid chromatography tandem mass spectrometry analytical method. The safety/tolerability assessment consisted of documenting adverse events, vital signs, electrocardiogram, and laboratory test results. Sofosbuvir was well tolerated. Major PK parameters of the generic formulation of sofosbuvir were similar to those found in previous reports. These data support further clinical evaluation of this generic formulation of sofosbuvir., (© 2019, The American College of Clinical Pharmacology.)

We aimed to evaluate the effect of the acid beverage Coca-Cola on the pharmacokinetics of velpatasvir (VEL) when given with omeprazole. This was an open-label, randomized, crossover trial in 11 healthy adults. A single dose of sofosbuvir/velpatasvir (SOF/VEL) 400/100 mg was administered alone (reference) or with omeprazole 40 mg once daily with water (intervention I); in the intervention II arm, omeprazole 40 mg was combined with 250 mL of Coca-Cola. Geometric mean ratios (GMRs) were calculated for VEL area under the concentration-time curve from zero to infinity (AUC 0-inf ) and maximum plasma concentration (C max ). VEL exposure was reduced by 26.7% when SOF/VEL was coadministered with omeprazole vs. reference: GMRs (90% confidence interval (CI)) were 73.3% (55.6-96.8) and 69.1% (52.3-91.2) for AUC 0-inf and C max , respectively. Intake of SOF/VEL with Coca-Cola compensated for the interaction with omeprazole and resulted in a higher VEL exposure. GMRs (90% CI) were 161.6% (122.4-213.3) for AUC 0-inf and 143.9% (109.0-190.0) for C max . Therefore, Coca-Cola can be used to overcome the drug-drug interaction between VEL and omeprazole., (© 2019 The Authors. Clinical Pharmacology & Therapeutics published by Wiley Periodicals, Inc. on behalf of American Society for Clinical Pharmacology and Therapeutics.)

Purpose: Direct-acting antiviral agents have demonstrated their efficacy in treating HCV recurrence after liver transplantation and particularly the sofosbuvir/daclatasvir combination. Pharmacokinetic data on both calcineurin inhibitors and direct-acting antiviral exposure in liver transplant recipients remain sparse., Methods: Patients were enrolled from the ANRS CO23 CUPILT cohort. All patients treated with sofosbuvir/daclatasvir with or without ribavirin were included in this study when blood samples were available to estimate the clearance of immunosuppressive therapy before direct-acting antiviral initiation and during follow-up. Apparent tacrolimus and cyclosporine clearances were estimated from trough concentrations measured using validated quality control assays., Results: Sixty-seven mainly male patients (79%) were included, with a mean age of 57 years and mean MELD score of 8.2; 50 were on tacrolimus, 17 on cyclosporine. Ribavirin was combined with sofosbuvir/daclatasvir in 52% of patients. Cyclosporine clearance remained unchanged as well as tacrolimus clearance under the ribavirin-free regimen. Tacrolimus clearance increased 4 weeks after direct-acting antivirals and ribavirin initiation versus baseline (geometric mean ratio 1.81; 90% CI 1.30-2.52). Patients under ribavirin had a significantly higher fibrosis stage (> 2) (p = 0.02) and lower haemoglobin during direct-acting antiviral treatment (p = 0.02) which impacted tacrolimus measurements. Direct-acting antiviral exposure was within the expected range., Conclusion: Our study demonstrated that liver transplant patients with a recurrence of hepatitis C who are initiating ribavirin combined with a sofosbuvir-daclatasvir direct-acting antiviral regimen may be at risk of lower tacrolimus concentrations because of probable ribavirin-induced anaemia and higher fibrosis score, although there are no effects on cyclosporine levels., Trial Registration: NCT01944527.

A series of deuterated sofosbuvir analogs were designed and prepared with the aim of improving their pharmacokinetic properties. The devised synthetic routes allow for site-selective deuterium incorporation with high levels of isotopic purity. As expected, the deuterated analogs (37-44) are as efficacious as sofosbuvir when tested in vitro inhibition of viral replication (replicon) assays. Compared with sofosbuvir, deuterated analog 40 displays improved in vivo pharmacokinetics profiles in rats and dogs in terms of the metabolite and the prodrug. The Cmax and area under the curve (AUC) of 40 in dogs were increased by 3.4- and 2.7-fold, respectively. Due to the enhanced pharmacokinetic properties and the great synthetic advantage of an inexpensive deuterium source (D 2 O) for 40, it was chosen for further investigation., (© 2019 John Wiley & Sons, Ltd.)

Sofosbuvir along with ribavirin is being widely used for treatment of HCV in Pakistan but it may show delayed response and reoccurrence of disease in some cases. The aim of the study was to investigate pharmacokinetics and concentration effect analysis of sofosbuvir. HCV patients (n=100) received 400 mg sofosbuvir along with low dose or weight based ribavirin (400 mg). Nonlinear mixed effects modeling (NONMEM) and unpaired t-test were used for the association of concentrations and treatment outcomes. Average day 10 sofosbuvir metabolite BM 331007 concentration was higher in patients having haemoglobin nadir value <10 g/dl compared to the patients having heamoglobin nadir value >10 g/dl (5.34 versus 4.87 pmol/106 cells; p=0.03). The average concentration trends of GS331007 at day 10 was towards being higher in the patients achieved sustained virologic response (SVR) as compare to the patients relapsed (5.19 versus 4.86 pmol/106 cells; p=0.05). Sofosbuvir (GS331007) thresholds concentration (suggested at day 10 through receiver operating characteristic curve) was 5.4 pmol/10 6 cells for SVR (p=0.05) and haemoglobin nadir cells was 6.3 pmol/10 6 with sensitivity and specificity of >60%. Dosing simulations shows that 400 mg sofosbuvir twice daily produce day 10 concentration range of 5.4 to 6.7 pmol/10 6 cells. The range of therapeutic values was identified for HCV patients receiving sofosbuvir in combination with ribavirin for 24 weeks, suggesting a potential pharmaceutical basis for individualized therapeutic dosing.

A simple, fast and highly sensitive RP-UPLC-MS/MS method was developed and validated for the simultaneous determination of sofosbuvir (SR) and its metabolite GS331007 in human plasma using ketotifen as an internal standard (IS). The separation was achieved on Acquity UPLC BEH C 18 (50 × 2.1 mm, i.d. 1.7 µm, Waters, USA) column using acetonitrile:5 mM ammonium formate:0.1% formic acid (85:15:0.1% v / v / v ) as a mobile phase at a flow rate of 0.35 mL/min in an isocratic elution. The Xevo TQD UPLC-MS/MS was operated under the multiple-reaction monitoring mode using positive electrospray ionization. Extraction with dichloromethane was used in the sample preparation. Method validation was performed as per the Food and Drug Administration (FDA) guidelines and the calibration curves of the proposed method were found to be linear in the range of 1-1000 ng/mL for SR and in the range of 10-1500 ng/mL for its metabolite (GS331007) with an elution time of 1.83 min. All validation parameters were within the acceptable range according to the bioanalytical methods validation guidelines. Furthermore, the obtained results of matrix effects indicate that ion suppression or enhancement from human plasma components was negligible under the optimized conditions. The proposed method can be applied in high-throughput analysis required for pharmacokinetic and bioequivalence studies in human samples.

Background: Limited data exist on the pharmacokinetic profile of novel direct-acting antivirals in kidney transplant recipients. Daclatasvir is primarily eliminated through the biliary route and sofosbuvir through the renal route; here, we report the pharmacokinetic profile of combined treatment with these compounds in a prospective study of hepatitis C virus (HCV)-positive kidney transplant recipients (EudraCT: 2014-004551-32)., Methods: In this study, plasma samples of 16 HCV-positive kidney transplant recipients receiving daclatasvir and sofosbuvir were collected at 4 time points at days 1, 7, 14, 21, 56, and 84 after start of treatment. Inclusion criteria were stable graft function and an estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m. Daclatasvir, sofosbuvir, and GS-331007 (inactive metabolite of sofosbuvir) plasma concentrations were determined using ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry., Results: All patients showed a rapid virological response with HCV RNA below the detection limit 21 days after the start of therapy (medium time to viral clearance). No difference of the areas under the concentration-time curve (AUC) of daclatasvir, sofosbuvir, and GS-331007 was observed between patients with an eGFR below or ≥60 mL/min. For GS-331007, no relevant changes of trough levels were observed over time. Mean GS-331007 trough levels were 339.5 ± 174.9 ng/mL in patients with an eGFR ≥60 mL/min and 404.3 ± 226 ng/mL in patients with an eGFR <60 mL/min at day 7 (P = 0.52). At day 84, GS-331007 trough levels were 357.8 ± 200.8 and 404.2 ± 70.2 ng/mL in patients with an eGFR ≥60 mL/min and in patients with an eGFR <60 mL/min, respectively (P = 0.51). The accumulation ratios of renally eliminated GS-331007 for AUC and Cmax did not significantly differ between the 2 eGFR groups at day 7., Conclusions: An impaired eGFR (30-60 mL/min) does not lead to a dose accumulation of daclatasvir, sofosbuvir, and GS-331007. This study provides the rationale for future studies investigating the pharmacokinetic profile of sofosbuvir-based HCV treatment in kidney transplant recipients with an eGFR <30 mL/min.

A novel, rapid and validated LC-MS/MS bioanalytical method has been developed for the extraction and determination of sofosbuvir and velpatasvir simultaneously in human plasma using ledipasvir as an internal standard (IS). The simple and reproducible protein precipitation technique with acetonitrile was successfully used for the deproteinization and extraction of the analytes from human plasma matrix. The developed method achieved consistent recoveries over different concentrations with average extraction recoveries of 81.72% and 80.46% for sofosbuvir and velpatasvir, respectively. The chromatographic separation was performed within only 2.80 min as a run time by an isocratic elution through C18 Zorbox eclipse plus (100 × 4.6 mm, 5 μm). Optimum mobile phase consisted of 0.1% formic acid in water: acetonitrile: methanol (30:60:10, v/v/v) pumped at a flow rate of 0.55 mL min -1 and injection volume was 10 μL. LC-MS/MS detection was done by multiple reaction monitoring transitions operating at positive ionization mode for both analytes and IS. Bioanalytical method validation as per EMA guidelines was carried out where the proposed method revealed linearity over the concentration range of 5-5000 and 10-1500 ng mL -1 for sofosbuvir and velpatasvir, respectively. After validation, the method was applied to the analysis of the two drugs after a single oral administration of Epclusa 400/100 mg tablets to Egyptian healthy volunteers., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A novel and sensitive LC-MS/MS method was developed, optimized and validated for quantification of sofosbuvir (SOF) and velpatasvir (VEL) in human plasma using ledipasvir as an internal standard (IS). Sample preparation was done using acetonitrile for precipitation of plasma proteins. Chromatographic analysis was done on an Acquity UPLC BEH C 18 column using 0.1% formic acid and acetonitrile as a mobile phase. The Xevo TQD LC-MS/MS system was run with electrospray ionization mode. The developed method was optimized and then validated according to the US Food and Drug Administration guidelines. Linearity was found to be in the range of 0.25-3500 ng/mL for SOF and 1-1000 ng/mL for VEL. A short run time of 1.5 min allows swift analysis of many plasma samples per day. The developed method was successfully utilized for estimating both SOF and VEL in the plasma of healthy human volunteers participated in a bioequivalence study., (© 2018 John Wiley & Sons, Ltd.)

NS3/4A serine protease is a prime target for direct-acting antiviral therapies against hepatitis C virus (HCV) infection. Several NS3/4A inhibitors have been widely used in clinic, while new inhibitors with better characteristics are still urgently needed. GP205 is a new macrocyclic inhibitor of NS3/4A with low nanomolar activities against HCV replicons of genotypes 1b, 2a, 4a, and 5a, with EC 50 values ranging from 1.5 to 12.8 nmol/L. In resistance selection study in vitro, we found resistance-associated substitutions on D168: The activity of GP205 was significantly attenuated against 1b replicon with D168V or D168A mutation, similar as simeprevir. No cross resistance of GP205 with NS5B or NS5A inhibitor was observed. Combination of GP205 with sofosbuvir or daclatasvir displayed additive or synergistic efficacy. The pharmacokinetic profile of GP205 was characterized in rats and dogs after oral administration, which revealed good drug exposure both in plasma and in liver and long plasma half-life. The in vitro stability test showed ideal microsomal and hepatic cells stability of GP205. The preclinical profiles of GP205 support further research on this NS3/4A inhibitor to expand the existing HCV infection therapies.

Background: The pharmacokinetics and safety of velpatasvir, a potent pangenotypic hepatitis C virus NS5A inhibitor, were evaluated in two hepatic impairment studies: a phase I study in hepatitis C virus-uninfected subjects and a phase III study (ASTRAL-4) in hepatitis C virus-infected patients., Methods: In the phase I study, subjects with moderate or severe hepatic impairment (Child-Pugh-Turcotte Class B or C), and demographically matched subjects with normal hepatic function received a single dose of velpatasvir 100 mg. Pharmacokinetics and safety assessments were performed, and pharmacokinetic parameters were calculated using non-compartmental methods and summarized using descriptive statistics and compared statistically by geometric least-squares mean ratios and 90% confidence intervals. In ASTRAL-4, subjects with decompensated cirrhosis (Child-Pugh-Turcotte Class B) were randomized to receive treatment with either sofosbuvir/velpatasvir ± ribavirin for 12 weeks or sofosbuvir/velpatasvir for 24 weeks. Pharmacokinetic and safety assessments were performed and pharmacokinetic parameters were calculated using a non-compartmental analysis and summarized using descriptive statistics and were compared to pharmacokinetics from ASTRAL-1 [subjects without cirrhosis or with compensated (Child-Pugh-Turcotte Class A) cirrhosis]., Results: In the phase I study, plasma exposures (area under the concentration-time curve) were similar in subjects with Child-Pugh-Turcotte Class B (n = 10) or Child-Pugh-Turcotte Class C hepatic impairment (n = 10) compared with normal hepatic function (n = 13). Percent free velpatasvir was similar in subjects without or with any degree of hepatic impairment. In the phase III study, velpatasvir overall exposure (area under the concentration-time curve over the 24-h dosing interval; AUC tau ) was similar and sofosbuvir exposures were higher (~ 100%) for patients with Child-Pugh-Turcotte Class B hepatic impairment compared with the ASTRAL-1 population, which was not considered clinically relevant., Conclusions: No sofosbuvir/velpatasvir dose modification is warranted for patients with any degree of hepatic impairment.

Sofosbuvir (SOF) and daclatasvir (DCS) are novel, recently developed direct acting antiviral agents characterized by potent anti-hepatitis C virus action. A fast and efficient HPLC-UV method was developed, validated and applied for simultaneous determination of SOF and DCS in pharmaceutical formulations and biological fluids based on coupling liquid-liquid extraction with ultrasound and dual wavelength detection at λ max ; 260 and 313 nm for SOF and DCS, respectively. This approach provided simple, sensitive, specific and cost-effective determination of the SOF-DCS mixture with good recoveries of the analytes from plasma. Analytes were separated within 7 min on C 18 analytical column with acetonitrile-10 mM acetate buffer of pH 5.0 at a flow rate of 1.0 mL min -1 . The linear ranges were 1-20 μg mL -1 for SOF and 0.6-6 μg mL -1 for DCS with correlation coefficients ≥0.9995. The detection limits in spiked rabbit plasma were 0.20 and 0.19 μg mL -1 for SOF and DCS, respectively. The method was validated according to ICH and US-FDA guidelines. Finally, the method was successfully applied for simultaneous pharmacokinetic studies of SOF and DCS in rabbits using rofecoxib as internal standard., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Purpose: The purpose of this study was to investigate the safety, tolerability, and pharmacokinetic profile of sofosbuvir and its metabolites after a single dose of sofosbuvir 400mg and once daily dosing of sofosbuvir 400mg for 7days in healthy Chinese subjects., Methods: This Phase I, open-label, single- and multiple-dose study enrolled 14 Chinese subjects aged 18 to 45years with an approximately even distribution of healthy male (n = 9) and nonpregnant, nonlactating female subjects (n = 5). Subjects received a single oral dose of sofosbuvir 400mg (one tablet) (morning, fasted conditions; single-dose treatment). After a 3-day washout, subjects received oral sofosbuvir 400mg (one tablet) (morning, fasted) for 7days (multiple dose treatment)., Findings: No significant accumulation of sofosbuvir, GS-566500, or GS-331007 was observed. Steady state of the major metabolite GS-331007 was achieved after 4days of consecutive dosing with sofosbuvir 400mg once daily. Sofosbuvir was generally well tolerated., Implications: Overall, this study supports the further evaluation of sofosbuvir 400mg in the Chinese population. The pharmacokinetic properties of sofosbuvir, GS-556500, and GS-311007 were found to be broadly similar in healthy Chinese subjects compared with non-Chinese subjects in previous sofosbuvir studies. ChinaDrugTrials.org.cn identifier: CTR20150249., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Introduction: The combination of daclatasvir (DCV), sofosbuvir (SOF), and ribavirin (RBV) is a direct-acting antiviral (DAA) regimen for the treatment of hepatitis C virus (HCV) infection. The inclusion of newer effective DAAs such as SOF and DCV with high efficacy and excellent tolerance introduced a new scenario in HCV infection therapy: high rates of sustained virological response (SVR), shorter therapies, less toxicity, and interferon-free treatments. This combination was approved for the treatment of HCV in treatment-naive or treatment-experienced patients with chronic HCV genotype 1 or 3 infection. Areas covered: This review summarizes the pharmacokinetics, pharmacodynamics, efficacy, and safety of DCV plus SOF and RBV therapy in the treatment of HCV infection. The topics include data regarding drug absorption, distribution, metabolism, excretion, and antiviral activity strategies, such as clinical dose selection and treatment duration. Expert opinion: This combination, taken orally with or without food, has an excellent pharmacokinetic and pharmacodynamic profile. DAC/SOF/RBV achieves very high rates of SVR in treatment-naive and treatment-experienced patients with chronic HCV infection, including difficult-to-treat patients such as those with compensated cirrhosis, post-transplant recurrence, or HIV-1 co-infection.

Background: Combining antiviral regimens in the hepatitis C virus (HCV)/human immunodeficiency virus (HIV)-coinfected population can be complex as they share overlapping mechanisms for elimination that may result in drug interactions. The pharmacokinetics, safety, and tolerability of sofosbuvir/velpatasvir (SOF/VEL) with multiple antiretroviral (ARV) regimens were evaluated., Methods: Healthy volunteers were enrolled into 2 phase 1, open-label, randomized, multiple-dose, cross-over studies. SOF/VEL and ARV regimens were administered alone and in combination; ARVs (and pharmacokinetic enhancers) included atazanavir (ATV), cobicistat (COBI), darunavir (DRV), dolutegravir (DTG), efavirenz (EFV), elvitegravir (EVG), emtricitabine (FTC), lopinavir (LPV), raltegravir (RAL), rilpivirine (RPV), ritonavir (RTV), tenofovir alafenamide (TAF), and tenofovir disoproxil fumarate (TDF). Geometric least squares means ratios (coadministration:alone) and 90% confidence intervals were constructed for area under the plasma concentration-time curve over the dosing interval, maximum concentration, and trough, for all analytes. Safety and tolerability were also evaluated., Results: In total, 237 participants were enrolled. No clinically relevant differences in the pharmacokinetics (PK) of SOF, SOF metabolite GS-331007, or VEL were observed other than an approximate 50% decrease in VEL exposure when administered with EFV/FTC/TDF. No clinically relevant differences in the PK of ARVs were observed when administered with SOF/VEL. Study treatments were well tolerated, including no observed creatinine clearance changes during evaluation of TDF-containing regimens., Conclusions: SOF/VEL and ARV regimens including ATV, COBI, DRV, DTG, EVG, FTC, LPV, RAL, RPV, RTV, TAF, or TDF may be coadministered without dose adjustment. Use of SOF/VEL with EFV-containing regimens is not recommended due to an approximate 50% reduction in VEL exposure.

The phase 2, open-label ACCORDION (ClinicalTrials.gov: NCT02349048) study investigated the efficacy, safety and pharmacokinetics of a 6- or 8-week regimen of simeprevir, daclatasvir and sofosbuvir in treatment-naïve patients with chronic hepatitis C virus (HCV) genotype (GT) 1 infection and either early-stage fibrosis or compensated cirrhosis. Patients were assigned to treatment groups according to their fibrosis stage. Early-stage fibrosis: simeprevir 150 mg, daclatasvir 60 mg, sofosbuvir 400 mg once daily for 6 weeks; compensated cirrhosis: same regimen for 8 weeks. The primary endpoint was sustained virologic response 12 weeks after the end of treatment (SVR12). Safety, tolerability and pharmacokinetics of simeprevir, daclatasvir and sofosbuvir were investigated. Sixty-eight patients were treated (6-week group: n = 59; 8-week group: n = 9). SVR12 was achieved by 86.4% (51/59) of patients with early-stage fibrosis and by 100% (9/9) of patients with cirrhosis. The main reason for not achieving SVR12 in the 6-week group was viral relapse (11.9%; 7/59). One patient had on-treatment failure due to an early withdrawal (lost to follow-up due to incarceration). One patient with SVR12 in the 6-week group had a late viral relapse at post-treatment week 24. No clinically significant drug-drug interactions were observed. Adverse events were reported in 63.2% of patients (43/68) and were mainly grade 1/2. None of these led to treatment discontinuation. The 3 direct-acting antiviral regimens of simeprevir, daclatasvir and sofosbuvir were safe and well tolerated in treatment-naïve, HCV GT1-infected patients with early-stage fibrosis or compensated cirrhosis., (© 2017 John Wiley & Sons Ltd.)

Vitamin D levels and genetic variants were associated with drug outcome/toxicity and concentrations. The plasma exposure of GS-331007, the main sofosbuvir metabolite, has been related to SVR. We evaluated the impact of polymorphisms in genes (CYP27B1, CYP24A1, VDBP and VDR) related to vitamin D pathway on sofosbuvir and GS-331007 plasma levels in HCV mono-infected patients at one month of treatment. Polymorphisms were investigated through real-time PCR; drug plasma quantification was performed through a UHPLC-MS/MS method. GS-331007 levels were associated with CYP24A1rs2248359 and VDRCdx2 variants in all the analyzed patients and linear regression analysis showed that sex, body mass index, HCV genotype, baseline estimated glomerular filtration rate, VDRCdx2AG/GG and CYP27B1-1260TT genotypes significantly predict concentrations. We performed sub-analyses considering the HCV genotype and the concomitant drug, identifying polymorphisms associated with GS-331007 concentrations. This is the first study focusing on vitamin D pathway gene variants and DAAs concentrations, but further studies are required., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Simultaneous determination of sofosbuvir (SOF), and daclatasvir (DAC) in their dosage forms, human urine and human plasma using simple and rapid micellar high performance liquid chromatographic method coupled with UV detection (HPLC-UV) had been developed and validated. These drugs are described as co-administered for treatment of Hepatitis C virus (HCV). HCV is the cause of Hepatitis C and some cancers such as liver cancer (hepatocellular carcinoma) and lymphomas in humans. Separation and quantitation were carried out on anonyx™ C 8 monolithic (100 × 4.6 mm (i.d.) analytical column maintained at 25 °C. The mobile phase consisted of 0.1 M sodium dodecyl sulfate (SDS) solution containing 20% (V/V) n-propanolol and 0.3% (V/V) triethylamine and pH was adjusted to 6.5 using 0.02 M phosphoric acid, respectively. The retention times of SOF and DAC were 4.8 min, and 6.5 min, respectively. Measurements were made at flow rate of 0.5 mL/min with injection volume of 20 μL and ultraviolet (UV) detection at 226 nm. Linearity of SOF and DAC was obtained over concentration ranges of 50-400, and 40-400 ng/mL, respectively in pure form, 60-300 and 50-300 ng/mL, respectively for human plasma and over 50-400, and 40-400 ng/mL, respectively for human urine with correlation coefficient >0.999. The proposed method demonstrated excellent intra- and inter-day precision and accuracy. The suggested method was applied for determination of the drugs in pure, dosage form, and in real human plasma, real human urine and drug-dissolution test of their tablets. The obtained results have been statistically compared to reported method to give a conclusion that there is no significant differences., (Copyright © 2018 Elsevier B.V. All rights reserved.)

A simple and highly sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) bioanalytical method was developed and fully validated for the first time for the simultaneous determination of newly discovered antiviral drugs, namely sofosbuvir (SOF) and daclatasvir (DAC) in human plasma. Tadalafil (TAD) was used as internal standard (IS). SOF, DAC and TAD (IS) were extracted from plasma using liquid-liquid extraction technique with methyl tert-butyl ether. The chromatographic separation was carried out using ZorbaxSB-C 18 column (4.6 × 50 mm,5 μm) and 5 mm ammonium formate buffer (pH 3.5)-acetonitrile (50:50, v/v) as mobile phase in an isocratic elution mode pumped at a flow rate 0.7 mL min -1 . The quantitation was performed on API4500 triple quadrupole tandem mass spectrometer with positive electrospray ionization interface in multiple reaction monitoring mode. Validation was applied according to US Food and Drug Administration guidelines for bio-analytical methodswith respect to linearity, precision, accuracy, selectivity, carry-over, stability and dilution integrity. Linearity was obtained over concentration ranges of 0.3-3000 and 3-3000 ng mL -1 for SOF and DAC, respectively, by applying a weighted least-squares linear regression method (1/x 2 ). The proposed method could be applied successfully in bioequivalence and/or clinical studies for therapeutic drug monitoring of patients undergoing dual combination therapy as the latter combination proved more efficacious and powerful tool for the complete treatment of hepatitis C genotype 3 within 16 weeks. The suggested method has been applied successfully to pharmacokinetic studies with excellent assay ruggedness and reproducibility., (Copyright © 2018 John Wiley & Sons, Ltd.)

Chronic hepatitis C virus (HCV) infection can be cured with treatment using direct-acting antivirals (DAAs). Although these drugs have been widely studied, information about certain special populations is missing. In this case report we describe a treatment-experienced patient with chronic HCV infection genotype 1b, treated with 150 mg/day simeprevir, 400 mg/day sofosbuvir, and 1,000 mg/ day ribavirin for 24 weeks, after a Roux-and-Y gastric bypass. At steady-state a pharmacokinetic curve was recorded of sofosbuvir, GS-331007, and simeprevir. Ribavirin trough plasma concentration (Ctrough) was determined. The simeprevir area under the-concentration time curve (AUClast) and Ctrough were 9.42 h.mg/L and 0.046 mg/L, respectively. Compared to what was described in the literature, simeprevir exposure was low and therefore the simeprevir dose was increased to 300 mg/day. The increased dose of simeprevir was well tolerated and Ctrough was 0.532 mg/L. Sofosbuvir AUClast and Ctrough were 0.63 h.mg/L and 0.0013 mg/L. GS-331007 AUClast and Ctrough were 21.02 h.mg/L and 0.35 mg/L. Ribavirin Ctrough was 2.5 mg/L. Sofosbuvir, GS-331007, and ribavirin exposure were comparable with levels described in literature. The patient achieved a sustained virological response twelve weeks after the completion of treatment.

Background and Objectives: The purpose of this study was to apply the reference-scaled average bioequivalence (RSABE) approach to evaluate the bioequivalence and to investigate the pharmacokinetic properties of two formulations of fixed dose combination (FDC) tablet of sofosbuvir (SOF) and ledipasvir (LED) (400/90 mg) in 36 healthy Egyptian volunteers., Methods: The study was performed in single-dose, randomized-sequence, open-label, reference-replicated, 3-period crossover design (RTR, TRR, RRT), with a washout period of 2 weeks. A rapid and simple LC-MS/MS method was developed and validated for the simultaneous estimation of SOF and LED using eplerenone as an internal standard (IS)., Results: The results showed that the 90% confidence intervals (CIs) for natural log-transformed ratios of C max , AUC last and AUC ∞ of SOF (89.95-115.31, 98.77-109.75 and 98.79-109.75) were within the RSABE acceptance limits. The 90% CIs for natural log-transformed ratios of C max and AUC last of LED (87.33-115.15 and 83.82-112.26) were within the FDA bioequivalence limits (80.00-125.00). In addition, the in vitro dissolution study was done and both formulations released > 85% of drug within 15 min in the proposed dissolution medium., Conclusions: In conclusion, bioequivalence between the two fixed-dose combination products was demonstrated for both active ingredients.

Sofosbuvir and ribavirin exert their anti-hepatitis C virus (anti-HCV) activity following metabolic activation in the liver. However, intrahepatic concentrations of the pharmacologically active nucleotide metabolites in humans are poorly characterized due to the inaccessibility of tissue and technical challenges with measuring nucleotide levels. A clinical study assessing the efficacy of sofosbuvir and ribavirin administered prior to liver transplantation to prevent HCV recurrence provided a unique opportunity to quantify nucleotide concentrations in human liver. We analyzed nucleotides using high-performance liquid chromatography coupled to tandem mass spectrometry in liver tissue from 30 HCV-infected patients with hepatocellular carcinoma who were administered sofosbuvir (400 mg/day) and ribavirin (1,000 to 1,200 mg/day) for 3 to 52 weeks prior to liver transplantation. Median total hepatic metabolite concentrations (the sum of nucleoside and mono-, di-, and triphosphates) were 77.1 μM for sofosbuvir and 361 μM for ribavirin in patients on therapy at the time of transplantation. Ribavirin and sofosbuvir efficiently loaded the liver, with total hepatic metabolite concentrations exceeding maximal levels in plasma by approximately 30-fold. Ribavirin metabolite levels suggest that its monophosphate is in great excess of its inhibition constant for IMP dehydrogenase and that its triphosphate is approaching the binding constant for incorporation by the HCV NS5B RNA-dependent RNA polymerase. In accordance with the potent antiviral activity of sofosbuvir, these results demonstrate that the liver triphosphate levels achieved following sofosbuvir administration greatly exceed the inhibition constant for HCV NS5B. In conclusion, this study expands the quantitative understanding of the pharmacology of sofosbuvir and ribavirin by establishing efficient hepatic delivery in the clinic. (This study has been registered at ClinicalTrials.gov under identifier NCT01559844.)., (Copyright © 2018 American Society for Microbiology.)

Hepatitis C virus (HCV) is a significant public health burden worldwide, owing in large part to ineffective and poorly tolerated treatments. The antivirals have evolved over time to become more effective and better tolerated with cure rates increasing from an average of 50% to a complete virologic response. This article summarizes the latest Food and Drug Administration (FDA)-approved addition to combination treatment for patients with HCV, voxilaprevir plus sofosbuvir/velpatasvir., (Copyright 2018 Clarivate Analytics.)

Background: Possible drug-drug interactions (DDIs) between antiretrovirals (ARVs) and direct-acting antiviral agents (DAAs) are of some concern., Objectives: To investigate ARV plasma trough concentrations (Ctrough) before and during DAAs in patients treated in the real world., Methods: Single-centre, prospective, observational study including HIV/HCV coinfected persons undergoing DAA treatment. Self-reported adherence was assessed and ARVs Ctrough measured by HPLC-UV. Blood samples were collected before and after 2 months of DAA treatment., Results: One-hundred and thirty-seven patients were included: 21.2% treated with ombitasvir/paritaprevir/ritonavir ± dasabuvir (2D/3D) and 78.8% with sofosbuvir-based regimens. Suboptimal Ctrough before and during DAA was found, respectively, in 3 (10.3%) and 3 (10.3%) cases treated with 2D/3D, and 16 (14.8%) and 11 (10.2%) with sofosbuvir-based regimens, even if self-reported ARV adherence was always ≥93%. In 2D/3D-treated patients, median darunavir Ctrough during DAAs was significantly lower than observed before DAAs [1125 ng/mL (IQR, 810-1616) versus 1903 ng/mL (IQR 1387-3983), respectively] (n = 5; P = 0.009), with a 40.9% decrease. In the same group, no differences in atazanavir or raltegravir concentrations were found. In patients treated with sofosbuvir-based regimens, Ctrough of all ARVs were similar before and during DAAs., Conclusions: In the real world of HIV/HCV coinfected patients, ARV plasma concentrations during DAAs were generally not different from those found before anti-HCV treatment. Although assessed in a small number of patients, darunavir concentrations during 2D/3D showed a significant reduction when compared with those found before DAAs. ARV plasma concentrations measurement during anti-HCV treatment may give useful information for managing HIV/HCV coinfected persons receiving treatment for both infections., (© The Author 2017. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Hepatitis C is the most common health problem worldwide and is major cause of death due to proliferation of hepatocellular carcinoma. The medicines available for HCV treatment overcome up-to 95% complications of HCV. However, liver cancer needs some additional care. Normally Sorafenib tosylate 200 mg is recommended for liver cancer. There is no such trial in which this drug could effectively be used in combination of direct acting antivirals for HCV. The study was conducted for HCV patients (n=30) with liver cancer having decompensated stage. Combination of Sorafenib tosylate, Ribavirn and Sofosbuvir were used for the pharmacokinetics of these medicines. Child pugh score less then 7 (CP A) in adults during treatment phase (received 12 weeks of Sorafenib tosylate 200 mg, Ribavirn and Sofosbuvir 400 mg once daily) have no side effect while child pugh score 7-9 (CP B) have evidence of hypertension. The main efficiency end point sustained virology response with overcoming liver cancer as well in 12 weeks after end treatment (SVR-LLC 12). Mean pharmacokinetic exposure to Sorafenib tosylate 200 mg, Ribavirn and Sofosbuvir at week 8th was 2.1, 1.5,1.2 times greater in CP B than in CP A. Adverse effects (AEs) were observed in 12 out of 30 patients but not severe as lethal for life. Treatment with Sorafenib tosylate, Ribavirn and Sofosbuvir for twelve weeks was harmless and well accepted, 100 % patients achieve (SVR LLC 12) with 10-fold cure rate more than previous ones. The combination therapy of Sorafenib tosylate, Ribavirn and Sofosbuvir was found helpful for the management of decompensated liver cancer.

Children with chronic hepatitis C virus infection have limited treatment options. We evaluated the all-oral combination of sofosbuvir and ribavirin in adolescents aged 12-17 with hepatitis C virus genotype 2 or 3 (ClinicalTrials.gov NCT02175758). Fifty-two patients received sofosbuvir 400 mg once daily and weight-based ribavirin twice daily for 12 (genotype 2) or 24 (genotype 3) weeks. The pharmacokinetics of sofosbuvir and its metabolite GS-331007 were evaluated by intensive plasma sampling at day 7 in the first 10 patients enrolled and by sparse sampling in all patients throughout treatment. The primary efficacy endpoint was the percentage of patients with a sustained virologic response 12 weeks after treatment (SVR12). The median age of patients was 15 years, and 75% had genotype 3. Eighty-three percent of patients were treatment-naive, and 73% were infected by vertical transmission. Forty percent were assessed as not having cirrhosis; the remainder did not have a cirrhosis determination. Overall, SVR12 was achieved by 98% of patients (51/52; 95% confidence interval, 90%-100%). SVR12 rates were 100% (13/13) for patients with genotype 2 and 97% (38/39) for those with genotype 3. The single patient who did not achieve SVR12 was lost to follow-up after achieving SVR4. The most commonly reported adverse events were nausea (27%) and headache (23%). When compared with the exposure in adults treated in phase 2 and 3 sofosbuvir studies, the area under the curve and maximum concentration for sofosbuvir and GS-331007 in adolescents were within predefined pharmacokinetic equivalence boundaries of 50%-200%., Conclusion: Sofosbuvir and ribavirin was safe and highly effective in adolescents with chronic hepatitis C virus genotype 2 or 3 infection. (Hepatology 2017;66:1102-1110)., (© 2017 by the American Association for the Study of Liver Diseases.)

Although for many analyses tandem mass spectrometry (LC-MS/MS) systems have significant advantage over the high-performance liquid chromatography with diode array detection (HPLC-DAD) however, the HPLC methods are easier, cheaper and more available to perform. As no published method is available for quantitative HPLC analysis of sofosbuvir (SOF), an orally administered anti-hepatitis drug in human serum, this study was aimed to evaluate applicability of the HPLC technique to quantify sofosbuvir and comparison of the two methods for analytical performance. Following extraction of the drug and an internal standard (Hexobarbital), same chromatographic conditions were used for both the systems. After the chromatographic separation on a reverse phase C18 column using a mobile phase consisting of water (containing formic acid 0.5mL/L) and acetonitrile (57:43; v/v) at a flow rate of 0.8mL/min, the eluate was introduced into a DAD detector set at 261nm, then passed through the mass spectrometry system in single ion monitoring mode (SIM). For UV and mass spectrometry detections the calibration curves were linear over a concentration range of 25-3200 and 10-3200ng/mL, respectively and the linearity was over 0.998 for both the systems. Lower limit of quantification (LLOQ) for mass spectrometry and DAD detections were 10 and 25ng/mL, respectively. In conclusion sensitivity of DAD detection is sufficient enough to determine concentrations down to 0.5% of C max which achieved in bioequivalence study of sofosbuvir and meet FDA requirements for these types of studies., (Copyright © 2017 Elsevier B.V. All rights reserved.)