Pharmacokinetics of Sofosbuvir/Velpatasvir and efficacy of an alternate-day treatment in hemodialysis patients with chronic hepatitis C infection.

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 (AUC0-24h) on dialysis days compared with non-dialysis days (AUC0-24h 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.

Effect of carvedilol on pharmacokinetics of sofosbuvir and its metabolite GS-331007: role of P-glycoprotein.

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.

Population pharmacokinetics of ravidasvir in adults with chronic hepatitis C virus infection and impact of antiretroviral treatment.

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.

Sofosbuvir-velpatasvir in children 3-17 years old with hepatitis C virus infection.

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.

Statins Increase the Bioavailability of Fixed-Dose Combination of Sofosbuvir/Ledipasvir by Inhibition of P-glycoprotein.

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 AUC0-∞ and Cmax by 34.36% and 11.97%, respectively. In addition, AUC0-∞ and Cmax 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 (AUC0-∞ increase by 17.2%, 17.38%, respectively, and Cmax 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 AUC0-∞ and Cmax 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.

Association of Sofosbuvir and Daclatasvir Plasma Trough Concentrations with Patient-, Treatment-, and Disease-Related Factors Among HIV/HCV-Coinfected Persons.

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 (Ctrough), 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, Ctrough was measured at W4 and week 8 (W8), and the mean of the values at those two time points (mean-Ctrough) was calculated. The Mann-Whitney test and Spearman's rank correlation were used to evaluate the correlations between the mean-Ctrough of each direct-acting antiviral (DAA) and the considered variables. RESULTS: Thirty-five patients were included (SVR 94%). An increased GS-331007 mean-Ctrough 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-Ctrough 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 Ctrough was associated with a slight decrease in renal function, while advanced hepatic impairment was significantly associated with a lower daclatasvir Ctrough. 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.

Sofosbuvir/velpatasvir for the treatment of hepatitis C in pediatric patients.

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.

Effective and Safe Daclatasvir Drug Exposures Predicted in Children Using Adult Formulations.

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.

Pharmacokinetic interaction between atorvastatin and fixed-dose combination of sofosbuvir/ledipasvir in healthy male Egyptian volunteers.

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 (AUC0-∞) and maximum plasma concentration (Cmax) of atorvastatin by 65.5% and 156.0%, respectively. Also, atorvastatin caused a significant increase in the AUC0-∞ and Cmax of sofosbuvir by 32.0% and 11.0%, respectively. Similarly, AUC0-∞ and Cmax of sofosbuvir metabolite significantly increased by 84.0% and 74.0%, respectively. However, ledipasvir AUC0-∞ 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 AUC0-∞ 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.

Effects of Sofosbuvir-Based Hepatitis C Treatment Regimens on Calcineurin Inhibitor Dosing in Liver and Kidney Transplant Recipients.

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.

Molecular docking and statistical optimization of taurocholate-stabilized galactose anchored bilosomes for the enhancement of sofosbuvir absorption and hepatic relative targeting efficiency.

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.

Sofosbuvir plus ribavirin and sofosbuvir plus ledipasvir in patients with genotype 1 or 3 hepatitis C virus and severe renal impairment: a multicentre, phase 2b, non-randomised, open-label study.

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.

Development of a long-acting direct-acting antiviral system for hepatitis C virus treatment in swine.

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.

Effect of Hemodialysis on Efficacy and Pharmacokinetics of Sofosbuvir Coformulated with Either Daclatasvir or Ledipasvir in Patients with End-Stage Renal Disease.

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.

Species differences in liver accumulation and metabolism of nucleotide prodrug sofosbuvir.

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.

Therapeutic Drug Monitoring-Guided Crushed Sofosbuvir-Velpatasvir Treatment: A Case Study.

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.

Pharmacokinetics, Safety, and Tolerability of Ledipasvir/Sofosbuvir and Sofosbuvir/Velpatasvir in Healthy Chinese Subjects.

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 t1/2 of ledipasvir relative to 24-h dosing, accumulation of 177% (AUC) and 107% (Cmax) 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).

Evaluation of the pharmacokinetics and food intake effect of generic sofosbuvir in healthy Chinese subjects
.

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.