ABT-333 (Dasabuvir) Increases Action Potential Duration and Provokes Early Afterdepolarizations in Canine Left Ventricular Cells via Inhibition of IKr.

ABT-333 (dasabuvir) is an antiviral agent used in hepatitis C treatment. The molecule, similarly to some inhibitors of hERG channels, responsible for the delayed rectifier potassium current (IKr), contains the methanesulfonamide group. Reduced IKr current leads to long QT syndrome and early afterdepolarizations (EADs), therefore potentially causing life-threatening arrhythmias and sudden cardiac death. Our goal was to investigate the acute effects of ABT-333 in enzymatically isolated canine left ventricular myocardial cells. Action potentials (APs) and ion currents were recorded with a sharp microelectrode technique and whole-cell patch clamp, respectively. Application of 1 µM ABT-333 prolonged the AP in a reversible manner. The maximal rates of phases 0 and 1 were irreversibly decreased. Higher ABT-333 concentrations caused larger AP prolongation, elevation of the early plateau potential, and reduction of maximal rates of phases 0, 1, and 3. EADs occurred in some cells in 3-30 µM ABT-333 concentrations. The 10 µM ABT-333-sensitive current, recorded with AP voltage clamp, contained a late outward component corresponding to IKr and an early outward one corresponding to transient outward potassium current (Ito). ABT-333 reduced hERG-channel-mediated ion current in a concentration-dependent, partially reversible manner with a half-inhibitory concentration of 3.2 µM. As the therapeutic plasma concentration of ABT-333 is 1 nM, the arrhythmic risk of ABT-333 is very low, even in the case of drug overdose.

Development of a validated stability-indicating HPLC- DAD method for dasabuvir and the characterization of its degradation products using LC-QToF-MS/MS

Abstract A stability-indicating HPLC-DAD method was developed and validated for the simultaneous determination of dasabuvir and its degradation products in the pharmaceutical formulation. The proposed method utilized a Symmetry® C18 (4.6 x 75 mm, 3.5 µm) column, and the mobile phase consisted of an isocratic elution of formic acid (0.1%) and acetonitrile (55:45, v/v), at a flow of 1 mL min-1; analytes were detected at 244 nm. Dasabuvir was submitted to different stress degradation conditions, such as acidic, alkaline, neutral, thermal, oxidative and photolytic, and the structural elucidation of degradation products was performed using LC-QToF-MS/MS. The HPLC-DAD stability-indicating method was validated for selectivity, linearity, limit of detection and quantification, accuracy, precision and robustness, according to ICH guidelines. Dasabuvir produced two degradation products (DP1 and DP2) from the alkaline stress conditions, which were characterized in negative ion mode. Dasabuvir was linear in the range 9.78 to 136.92 µg mL-1, and DP and DP were linear in the range 2.9 to 20.2 µg mL-1 and 1.3 to 14.9 µg mL-1, respectively. The 1 2 recovery ranged between 99.16 and 100.86%, while precision ranged from 1.02 to 2.89%. As the method can effectively separate the dasabuvir from its degradation products and quantitate them, it may be employed as a stability-indicating method for the pharmaceutical formulation.

Effectiveness and safety of generic and brand direct acting antivirals for treatment of chronic hepatitis C.

BACKGROUND: Direct acting antivirals (DAAs) are a very effective treatment for hepatitis C virus (HCV). However, brand DAAs are expensive. The licensing of cheaper generic DAAs may address this issue, but there is a lack of clinical studies comparing the efficacy of generic vs brand DAA formulations. AIM: To compare the efficacy and safety of generic against brand DAAs for chronic hepatitis C treatment in Bahrain. METHODS: This was a retrospective observational study involving 289 patients with chronic HCV infection during 2016 to 2018. There were 149 patients who were treated with brand DAAs, while 140 patients were treated with generic DAAs. Commonly used DAAs were Ombitasvir/Paritaprevir/Ritonavir ± Dasabuvir ± Ribavirin, and Sofosbuvir/Daclatasvir ± Ribavirin. SVR at 12 wk post treatment was the main outcome variable. RESULTS: Overall, 87 patients (30.1%) had cirrhosis and 68.2% had genotype 1 HCV infection. At 12 wk post treatment, SVR was achieved by 271 (93.8%) of the patients. In patients who were treated with generic medications, 134 (95.7%) achieved SVR at 12 wk post treatment, compared to 137 (91.9%) among those treated with brand medications (P = 0.19). Having cirrhosis [odds ratio (OR): 9.41, 95% confidence interval (CI): 2.47-35.84] and having HCV genotype 3 (OR: 3.56, 95%CI: 1.03-12.38) were significant independent predictors of not achieving SVR. Alanine transaminase, gamma-glutamyl transpeptidase, and total bilirubin levels decreased significantly following therapy with both generic and brand DAAs. CONCLUSION: Generic and brand DAAs demonstrate comparable effectiveness in the treatment of chronic hepatitis C patients. Both are safe and equally effective in improving biochemical markers of hepatic inflammation.

Effects of a ritonavir-containing regimen on the pharmacokinetics of sirolimus or everolimus in healthy adult subjects.

The immunosuppressive agents sirolimus and everolimus are sensitive CYP3A4 substrates with narrow therapeutic index. Ritonavir is a strong CYP3A inhibitor. A phase 1 study was conducted to evaluate the pharmacokinetics, safety, and tolerability of the co-administration of sirolimus or everolimus with the ritonavir-containing 3D regimen of the direct-acting antiviral agents ombitasvir, ritonavir-boosted paritaprevir, and dasabuvir in healthy subjects. This study had two independent arms, each with a two-period, single-sequence, crossover study design. A single dose of sirolimus 2 mg (N = 12) or everolimus 0.75 mg (N = 12) was administered in Period 1. In Period 2, multiple doses of the 3D regimen (ombitasvir/paritaprevir/ritonavir 25/150/100 mg once daily and dasabuvir 250 mg twice daily) were administered for 34 or 28 days, with a single dose of sirolimus 0.5 mg or everolimus 0.75 mg co-administered on Day 15. Following co-administration with the 3D regimen, the sirolimus dose-normalized maximum observed blood concentration (Cmax ) and area under the blood concentration-time curve from time zero to infinity (AUCinf ) increased to 6.4-fold and 38-fold, respectively. Following co-administration with the 3D regimen, the everolimus Cmax and AUCinf increased to 4.7-fold and 27-fold, respectively. Sirolimus and everolimus half-lives increased from 96 to 249 h, and 42 to 118 h, respectively. There were no major safety or tolerability issues in this study. The ritonavir-containing 3D regimen resulted in a significant increase in sirolimus or everolimus exposure, consistent with the known strong inhibitory effect of ritonavir on CYP3A requiring dose and/or frequency modification when co-administered with each other.

The effectiveness and safety of direct-acting antivirals for hepatitis C virus treatment: A single-center experience in Saudi Arabia.

Background: The introduction of direct-acting antivirals (DAA) to treat the hepatitis C virus (HCV) overcame many drawbacks of interferon-based therapy. DAA achieved sustained viral response (SVR) rates above 90% and overcame many drawbacks of pegylated interferon regimens.The HCV genotype (GT) distribution varies by geographical area, with GT-4 being most prevalent in the Middle East region, including Saudi Arabia. Yet, the real-world evidence about using DAAs in the Saudi population is limited.Thus, the aim of this study to investigate the effectiveness and safety of DAAs in Saudi patients with HCV infection. Methods: A retrospective cohort study included patients treated with DAAs from 2015 to 2017 at a tertiary care hospital in Riyadh, Saudi Arabia. All patients with HCV treated with either ledipasvir plus sofosbuvir (LDS/SOF) ± ribavarin (RBV) or ombitasvir-paritaprevir-ritonavir (OBV/PTV/r) ± dasabuvir (DSV) ± RBV were included. Using a per-protocol analysis, the effectiveness outcome was the end-of-treatment response (EOTr) and Sustained virologic reponce12 weeks after competing the regimen (SVR12). The secondary safety outcome was the adverse event related to the therapy reported by the patients. Results: A total of 97 patients were included; with the majority infected with GT-4 (64 %), followed by GT-1 (18 %), in addition to 8 % having a mixed GT (1 + 4). The EOTr and SVR12 rates were 98 % and 96 %, respectively. SVR12 was 94.4 % within the LDS/SOF ± RBV group and 97.7 % within the OBV/PTV/r ± DSV ± RBV group. Only 4 % had a response failure due to relapse or breakthrough, and all were infected with mixed GT1 + 4. Medications were well tolerated with minimal side effects, including vomiting, nausea, and weakness. Conclusion: DAAs regimens are associated with high rates of SVR12 and are well tolerated with a good safety profile in Saudi HCV-infected patients.

Combination of dasabuvir and PSI-6206 for the treatment of coxsackievirus B3 infection.

Coxsackievirus B3 (CVB3) infections may cause life-threatening diseases and have no approved specific treatment. Some promising approaches to treat viral diseases include drug repurposing and combination therapy. We have selected in this study dasabuvir, an approved antiviral drug, and PSI-6206, an experimental drug and determined their individual and combined antiviral activity against CVB3 replication in vitro. Our results show that the individual drugs inhibited CVB3 infection in a dose-dependent manner, at a selective index >10 with a strong synergetic antiviral effect of the two compounds. Given that dasabuvir has already been approved for the treatment of hepatitis C virus infection, treatment of CVB3-related disease with this drug may represent a promising treatment strategy.

Characteristics of hepatitis C virus resistance in an international cohort after a decade of direct-acting antivirals.

Background & Aims: Direct-acting antiviral (DAA) regimens provide a cure in >95% of patients with chronic HCV infection. However, in some patients in whom therapy fails, resistance-associated substitutions (RASs) can develop, limiting retreatment options and risking onward resistant virus transmission. In this study, we evaluated RAS prevalence and distribution, including novel NS5A RASs and clinical factors associated with RAS selection, among patients who experienced DAA treatment failure. Methods: SHARED is an international consortium of clinicians and scientists studying HCV drug resistance. HCV sequence linked metadata from 3,355 patients were collected from 22 countries. NS3, NS5A, and NS5B RASs in virologic failures, including novel NS5A substitutions, were examined. Associations of clinical and demographic characteristics with RAS selection were investigated. Results: The frequency of RASs increased from its natural prevalence following DAA exposure: 37% to 60% in NS3, 29% to 80% in NS5A, 15% to 22% in NS5B for sofosbuvir, and 24% to 37% in NS5B for dasabuvir. Among 730 virologic failures, most were treated with first-generation DAAs, 94% had drug resistance in ≥1 DAA class: 31% single-class resistance, 42% dual-class resistance (predominantly against protease and NS5A inhibitors), and 21% triple-class resistance. Distinct patterns containing ≥2 highly resistant RASs were common. New potential NS5A RASs and adaptive changes were identified in genotypes 1a, 3, and 4. Following DAA failure, RAS selection was more frequent in older people with cirrhosis and those infected with genotypes 1b and 4. Conclusions: Drug resistance in HCV is frequent after DAA treatment failure. Previously unrecognized substitutions continue to emerge and remain uncharacterized. Lay summary: Although direct-acting antiviral medications effectively cure hepatitis C in most patients, sometimes treatment selects for resistant viruses, causing antiviral drugs to be either ineffective or only partially effective. Multidrug resistance is common in patients for whom DAA treatment fails. Older patients and patients with advanced liver diseases are more likely to select drug-resistant viruses. Collective efforts from international communities and governments are needed to develop an optimal approach to managing drug resistance and preventing the transmission of resistant viruses.

Overcoming Bioavailability Challenges of Dasabuvir and Enabling a Triple-Combination Direct-Acting Antiviral HCV Regimen through a Salt of Very Weak Acid for Oral Delivery.

Dasabuvir is a non-nucleoside polymerase inhibitor for the treatment of hepatitis C virus (HCV) infection. It is an extremely weak diacidic drug (pKa = 8.2 and 9.2) and a prolific solvate former. Due to its exceedingly low aqueous solubility (≤0.127 µg/mL at pH 1-6.8, dose number of 1.31 × 104), crystalline dasabuvir free acid exhibited poor oral bioavailability in initial animal pharmacokinetic (PK) assessment. This necessitated the development of enabling formulation for human clinical studies to achieve the required therapeutic in vivo concentration of dasabuvir. While salt formation has been widely used to enhance the solubility and dissolution rate of solids, this approach has rarely been applied to develop oral solid dosage forms for acidic drugs as weak as dasabuvir due to concerns of rapid disproportionation and crystallization of its free acid. In this contribution, we detail our efforts in identifying dasabuvir monosodium monohydrate as a drug substance that is stable, manufacturable, and, most importantly, significantly enhances the dissolution and oral absorption of this poorly soluble drug. The oral delivery of dasabuvir through the salt approach has enabled the commercialization of the triple-combination direct-acting antiviral HCV regimen, Viekira Pak. The methodologies and solutions identified in targeted studies to overcome technical challenges encountered along the way (i.e., incorporation of polymers to inhibit crystallization and disproportionation and species mapping to enable salt manufacturing process, etc.) can be applied to other insoluble compounds.

Screening of SARS-CoV-2 antivirals through a cell-based RNA-dependent RNA polymerase (RdRp) reporter assay.

COVID-19 (Coronavirus Disease 2019) caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome CoronaVirus-2) continues to pose an international public health threat and thus far, has resulted in greater than 6.4 million deaths worldwide. Vaccines are critical tools to limit COVID-19 spread, but antiviral drug development is an ongoing global priority due to fast-spreading COVID-19 variants that may elude vaccine efficacies. The RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 is an essential enzyme of viral replication and transcription machinery complex. Therefore, the RdRp is an attractive target for the development of effective anti-COVID-19 therapeutics. In this study, we developed a cell-based assay to determine the enzymatic activity of SARS-CoV-2 RdRp through a luciferase reporter system. The SARS-CoV-2 RdRp reporter assay was validated using known inhibitors of RdRp polymerase, remdesivir along with other anti-virals including ribavirin, penciclovir, rhoifolin, 5'CT, and dasabuvir. Dasabuvir (an FDA-approved drug) exhibited promising RdRp inhibitory activity among these inhibitors. Anti-viral activity of dasabuvir was also tested on the replication of SARS-CoV-2 through infection of Vero E6 cells. Dasabuvir inhibited the replication of SARS-CoV-2, USA-WA1/2020 as well as B.1.617.2 (delta variant) in Vero E6 cells in a dose-dependent manner with EC50 values 9.47 µM and 10.48 µM, for USA-WA1/2020 and B.1.617.2 variants, respectively. Our results suggest that dasabuvir can be further evaluated as a therapeutic drug for COVID-19. Importantly, this system provides a robust, target-specific, and high-throughput screening compatible (z- and z'-factors of >0.5) platforms that will be a valuable tool for screening SARS-CoV-2 RdRp inhibitors.

Mechanism of dasabuvir inhibition of acetaminophen glucuronidation.

OBJECTIVES: Acetaminophen (APAP) (paracetamol) is a widely used non-prescription drug for pain relief and antipyretic effects. The clearance of APAP is mainly through phase-2 biotransformation catalysed by UDP-glucuronosyl transferases (UGT). Dasabuvir is an anti-hepatitis C drug reported to inhibit several UGT isoforms. The study evaluated the in-vitro inhibitory capacity of dasabuvir versus APAP glucuronidation. METHODS: Procedures included human liver microsomal incubations with APAP and isoform-selective probe substrates. KEY FINDINGS: Dasabuvir inhibited APAP metabolism by a reversible, mixed-type (competitive and non-competitive) partial inhibition, with an inhibition constant Ki = 3.4 µM. The index constant 'a' was 6.7, indicating the relative contribution of competitive and non-competitive inhibition. The enzyme-inhibitor complex was still able to catalyse the reaction by 12% of the control capacity. Dasabuvir produced strong partial inhibition effect of UGT1A1 and UGT1A9 and relatively complete inhibition of UGT1A6. CONCLUSIONS: Consistent with previous reports, dasabuvir inhibits the activity of 3 UGT isoforms associated with APAP metabolism. In-vitro to in-vivo scaling by 2 different approaches showed identical results, predicting an increased AUC of APAP by a factor of 1.3-fold with coadministration of dasabuvir. Until the findings are confirmed in clinical drug interaction studies, APAP dosage should not exceed 3 g per day in dasabuvir-treated patients to avoid potentially hepatotoxic APAP exposures.

Dasabuvir Inhibits Human Norovirus Infection in Human Intestinal Enteroids.

Human noroviruses (HuNoVs) are acute viral gastroenteritis pathogens that affect all age groups, yet no approved vaccines and drugs to treat HuNoV infection are available. In this study, we screened an antiviral compound library to identify compound(s) showing anti-HuNoV activity using a human intestinal enteroid (HIE) culture system in which HuNoVs are able to replicate reproducibly. Dasabuvir (DSB), which has been developed as an anti-hepatitis C virus agent, was found to inhibit HuNoV infection in HIEs at micromolar concentrations. Dasabuvir also inhibited severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and human rotavirus A (RVA) infection in HIEs. To our knowledge, this is the first study to screen an antiviral compound library for HuNoV using HIEs, and we successfully identified dasabuvir as a novel anti-HuNoV inhibitor that warrants further investigation. IMPORTANCE Although there is an urgent need to develop effective antiviral therapy directed against HuNoV infection, compound screening to identify anti-HuNoV drug candidates has not been reported so far. Using a human HIE culture system, our compound screening successfully identified dasabuvir as a novel anti-HuNoV inhibitor. Dasabuvir's inhibitory effect was also demonstrated in the cases of SARS-CoV-2 and RVA infection, highlighting the usefulness of the HIE platform for screening antiviral agents against various viruses that target the intestines.

Comparative effectiveness of 8 versus 12 weeks of Ombitasvir/Paritaprevir/ritonavir and Dasabuvir in treatment-naïve patients infected with HCV genotype 1b with non-advanced hepatic fibrosis.

PURPOSE: Since 2017 treatment-naïve patients infected with genotype 1b of hepatitis C virus and minimal or moderate fibrosis can be treated with Ombitasvir/Paritaprevir/ritonavir + Dasabuvir (OPrD) for 8 weeks according to updated Summary of Product Characteristics. The aim of our study was to assess the comparative efficacy of 8 and 12-weeks therapy with OPrD in large cohort of patients eligible for 8 weeks regimen treated in real-world setting. MATERIALS AND METHODS: We analysed data of 3067 HCV genotype 1b infected patients treated with OPrD between 2015 and 2017. Final analysis included patients with none, minimal or moderate fibrosis (F0-F2). RESULTS: A total of 771 patients were enrolled in the study, including 197 (26%) treated for 8-weeks and 574 patients fulfilling criteria for 8-weeks but assigned to 12-weeks regimen. Majority of patients had no or minimal fibrosis (F0-F1). Longer treatment duration was more often administered in patients with moderate fibrosis, comorbidities, concomitant medications. SVR was achieved in 186 (94%) patients treated for 8 weeks and 558 (97%) for 12 weeks (p = 0.07). After exclusion of lost to follow-up patients, sustained virological response (SVR) rate reached 95% and 99%, respectively (p = 0.01). We were not able to identify factors associated with non-response. CONCLUSIONS: This real-word experience study confirmed similar, high effectiveness of 8 and 12-weeks regimens of OPrD in genotype 1b HCV infected patients with non-advanced fibrosis. Despite of reduced SVR rate after 8-weeks regimen, there is no need to extend therapy to 12-weeks in vast majority of such patients and no need to add ribavirin.

Recurrence rate of hepatocellular carcinoma in patients with treated hepatocellular carcinoma and hepatitis C virus-associated cirrhosis after ombitasvir/paritaprevir/ritonavir+dasabuvir+ribavirin therapy.

Introduction: Recent studies have suggested a higher recurrence rate of hepatocellular carcinoma (HCC) in patients with a history of HCC and hepatitis C virus (HCV)-associated cirrhosis treated with direct-acting antiviral (DAA) agents. Material and methods: We conducted a prospective analysis of 24 patients with HCV-associated cirrhosis and treated HCC who received ombitasvir/paritaprevir/ritonavir+dasabuvir+ribavirin for 12 weeks. Prior therapies for HCC included resection (9/24 patients), radiofrequency ablation (RFA) (7/24) and trans-arterial chemoembolization (TACE) (8/24). All patients were eligible for treatment if they had no HCC recurrence 6 months after their last procedure. A control group was defined. All patients were followed every 6 months, with dynamic computed tomography and/or magnetic resonance imaging. Results: The sustained virological response rate per protocol was 21/24 (87.5%). The study group included 14 (59%) males, median age 64 years (51-77), 50% with associated non-alcoholic steatohepatitis and 24% with Child-Pugh A6 points. HCC recurrence rate/100 patient-years was lower in the DAA-HCC group versus control: 5.5 versus 24.6% patient-years for the resection+RFA group (p = 0.044), respectively, and 18.6 versus 72.7% patient-years for TACE group (p = 0.002). Survival without recurrence was higher in the resection+RFA group (45 compared to 18 months (p < 0.001)) and also in the TACE group (44 compared to 11.5 months (p = 0.002)). Conclusions: DAA therapy significantly reduced the recurrence rate of HCC and improved survival without recurrence in patients with treated HCV-associated HCC.

Ombitasvir/paritaprevir/ritonavir + dasabuvir +/- ribavirin in real world hepatitis C patients.

BACKGROUND: The hepatitis C virus (HCV) NS5A inhibitor ABT-267 (ombitasvir, OBV), the HCV NS4/4A protease inhibitor ABT-450 (paritaprevir, PTV), the CYP3A inhibitor ritonavir (r) and the non-nucleoside NS5B polymerase inhibitor ABT-333 (dasabuvir, DSV) (OBV/PTV/r + DSV) with or without ribavirin (RBV) is a direct-acting antiviral regimen approved in the United States and other major countries for the treatment of HCV in genotype 1 (GT1) infected patients. Patients with HCV who are considered "hard-to-cure" have generally been excluded from registration trials due to rigorous study inclusion criteria, presence of comorbidities and previous treatment failures. AIM: To investigate the efficacy of this regimen in HCV G1-infected patients historically excluded from clinical trials. METHODS: Patients were ≥ 18 years old and chronically infected with HCV GT1 (GT1a, GT1b or GT1a/1b). Patients were treatment-naïve or previously failed a regimen including pegylated interferon/RBV +/- telaprevir, boceprevir, or simeprevir. One hundred patients were treated with the study drug regimen, which was administered for 12 or 24 wk +/- RBV according to GT1 subtype and presence/absence of cirrhosis. Patients were evaluated every 4 wk from treatment day 1 and at 4 and 12 wk after end-of-treatment. RESULTS: Many of the patients studied had comorbidities (44.2% hypertensive, 33.7% obese, 20.2% cirrhotic) and 16% previously failed HCV treatment. Ninety-six patients completed study follow-up and 99% achieved 12-wk sustained virologic response. The majority (88.4%) of patients had undetectable HCV RNA by week 4. The most common adverse events were fatigue (12%), headache (10%), insomnia (9%) and diarrhea (8%); none led to treatment discontinuation. Physical and mental patient reported outcomes scores significantly improved after treatment. Almost all (98%) patients were treatment compliant. CONCLUSION: In an all-comers HCV GT1 population, 12 or 24-wk of OBV/PTV/r + DSV +/- RBV is highly effective and tolerable and results in better mental and physical health following treatment.

Paritaprevir/ritonavir, ombitasvir plus dasabuvir for East Asian non-cirrhotic hepatitis C virus genotype 1b patients receiving hemodialysis.

BACKGROUND AND AIM: Data regarding the efficacy and safety of paritaprevir/ritonavir, ombitasvir plus dasabuvir (PrOD) for East Asian non-cirrhotic hepatitis C virus genotype 1b (HCV GT1b) patients receiving hemodialysis were limited. METHODS: Forty-six HCV GT1b non-cirrhotic patients receiving hemodialysis who received PrOD for 12 weeks were prospectively enrolled in seven academic centers in Taiwan. The primary efficacy endpoint was sustained virologic response 12 weeks off-therapy (SVR12 ). Patients' baseline characteristics, early virokinetics, and HCV resistance-associated substitutions (RASs) potentially related to SVR12 were analyzed. The safety profiles were also assessed. RESULTS: The SVR12 rate was 100% (46 of 46 patients). Patients' baseline characteristics, on-treatment viral decline, and baseline HCV resistance-associated substitutions did not affect SVR12 . All patients tolerated treatment well. One patient with folliculitis temporarily discontinued treatment, and another two patients had serious adverse events (SAEs), which were considered not related to PrOD treatment. The common adverse events were pruritus (19.6%), fatigue (15.2%), and upper respiratory tract infection (6.5%). Twelve (19.6%) and one (2.2%) patients had hemoglobin levels < 10 and 8.5 g/dL, respectively, which were related to renal impairment. Five (10.9%) patients had on-treatment total bilirubin level of 1.5-3.0 mg/dL, but none developed hepatic decompensation. The bilirubin levels peaked at week 1 of treatment and then declined with continuous treatment. CONCLUSION: Treatment with PrOD for 12 weeks is efficacious and well-tolerated for East Asian non-cirrhotic HCV GT1b patients receiving hemodialysis.

Effects of chronic kidney disease stage 4, end-stage renal disease, or dialysis on the plasma concentrations of ombitasvir, paritaprevir, ritonavir, and dasabuvir in patients with chronic HCV infection: pharmacokinetic analysis of the phase 3 RUBY-I and RUBY-II trials.

PURPOSE: To characterize the pharmacokinetics of ombitasvir, paritaprevir, ritonavir, dasabuvir, and ribavirin in hepatitis C virus (HCV)-infected patients with chronic kidney disease stage 4 (CKD4) or end-stage renal disease (ESRD), including those on dialysis, in the open-label phase 3 RUBY-I and RUBY-II studies. METHODS: Patients (n = 18 CKD4, n = 68 ESRD) received ombitasvir/paritaprevir/ritonavir 25/150/100 mg once daily ± dasabuvir 250 mg twice daily ± ribavirin 200 mg once daily for 12 or 24 weeks. Intensive pharmacokinetic samples were collected from ten patients; sparse samples were collected from all patients. Arterial and venous samples were collected from three patients during hemodialysis. Area under the plasma concentration-time curve (AUC) was estimated using noncompartmental analyses for intensive data, and steady-state trough concentrations (Ctrough) were obtained from the sparse data. Pharmacokinetic results from RUBY-I and RUBY-II were compared empirically to historical data. RESULTS: The AUC values of ombitasvir, paritaprevir, ritonavir, and dasabuvir were comparable between CKD4 and ESRD patients and were within the range of values observed in historical studies; dialysis had no effect on drug exposures. Ribavirin was extracted during hemodialysis but had similar exposures on dialysis and non-dialysis days. Individual steady-state Ctrough values for each drug overlapped between CKD4 and ESRD patients, and values in both groups were similar to historical values. CONCLUSION: Plasma concentrations of ombitasvir, paritaprevir, ritonavir, and dasabuvir were not altered by renal impairment or dialysis, suggesting these agents can be administered to HCV-infected CKD4 or ESRD patients, including those on dialysis, without dose adjustment. TRIAL REGISTRATION: Clinicaltrials.gov identifiers: NCT02207088 (RUBY-I) and NCT02487199 (RUBY-II).

Eight weeks of Paritaprevir/r/Ombitasvir + Dasabuvir in HCV genotype 1b with mild-moderate fibrosis: Results from a real-world cohort.

BACKGROUND & AIMS: The interferon-free regimen paritaprevir/ritonavir, ombitasvir + dasabuvir (PTV/r/OBV/DSV) has shown high efficacy in patients with hepatitis C virus (HCV) genotype 1b infection when administered for 8 or 12 weeks, but data regarding the 8-week treatment are scarce. The aim of our study was to assess the efficacy and safety of the 8-week administration of PTV/r/OBV/DSV in a real-world cohort. METHODS: We performed a multicentre observational study from Spanish Hepa-C database including patients receiving 8 weeks of PTV/r/OBV/DSV (October 2016-November 2017). Those with advanced fibrosis, with non-genotype 1b or who were treatment-experienced were excluded. RESULTS: A total of 211 patients were registered from 23 Spanish centres; eleven were excluded. At baseline, 42.5% (n = 85) were male, median (range) age was 57 (23-86), ALT was 45 (11-494) IU/mL, viral load was 6.1 (3.3-8.2) log10 IU/mL, and 74.5% had mild liver fibrosis (F0-F1) and 25.5% moderate fibrosis (F2). At the end of treatment (EOT), HCV viral load was undetectable in 100% (200/200). Seven patients relapsed after treatment discontinuation. Sustained virological response (SVR12) rates by intention-to-treat analysis were 96% (192/200). Regarding treatment safety, 2 patients developed ALT elevation >5x ULN, but there were no treatment discontinuations. One patient died 7 weeks after EOT. CONCLUSION: Treatment with PTV/r/OBV/DSV in genotype 1b-infected treatment-naive patients with mild-moderate fibrosis shows excellent efficacy and safety in real life, similarly to clinical trials. Clinicaltrials.gov, number: NCT03122132.

Burden of disease in patients with chronic hepatitis C in the Austrian REAL study.

BACKGROUND: The direct-acting antiviral regimen of ombitasvir/paritaprevir/ritonavir (OBV/PTV/r) ± dasabuvir (DSV) ± ribavirin (RBV) is approved to treat patients with chronic hepatitis C (CHC) infection genotypes 1 or 4, including compensated cirrhosis. The aim of the prospective, multicenter, observational REAL study was to provide evidence of the effectiveness of this regimen in an Austrian real-world setting and to determine the impact on patient-reported outcomes (PROs). METHODS: Effectiveness was defined as sustained virologic response 12 weeks after the end of treatment (SVR12). EuroQol 5 Dimension 5 Level (EQ-5D-5L) and Work Productivity and Activity Impairment HepC v2.0 (WPAI) questionnaires were used to assess PROs. RESULTS: A total of 173 patients were enrolled. The SVR12 was 95.9% (140/146) in the core population with sufficient follow-up (i. e. patients without SVR12 data not due to efficacy/safety reasons, such as lost to follow-up, were excluded) and 84.8% (140/165) in the core population (CP). Data at all timepoints for the EQ-5D-5L index score and visual analog scale and the total activity impairment score of the WPAI were available for 88, 95 and 72 patients, respectively. All PROs remained generally unaltered during treatment with OBV/PTV/r ± DSV ± RBV but showed a statistically significant (p < 0.01) improvement 12 weeks after the end of treatment versus baseline. CONCLUSIONS: These are the first data on PROs in a real-world setting with OBV/PTV/r ± DSV ± RBV treatment; this study demonstrated that treatment did not negatively impact quality of life. Results from the Austrian REAL study support the effectiveness of OBV/PTV/r ± DSV ± RBV in patients with CHC genotype 1 and 4 in everyday clinical practice.

Baseline dasabuvir resistance in Hepatitis C virus from the genotypes 1, 2 and 3 and modeling of the NS5B-dasabuvir complex by the in silico approach.

Background: Current combination treatments with direct-acting antiviral agents (DAAs) can cure more than 95% of hepatitis C virus (HCV) infections. However, resistance-associated substitutions (RASs) may emerge and can also be present in treatment-naïve patients. Methods, results and discussion: In this study, a semi-pan-genotypic population sequencing method was developed and used to assess all NS5B amino acid variants between residue positions 310 and 564. Our method successfully sequenced more than 90% of genotype (GT) 1a, 1b, 2b and 3a samples. By using the population sequencing method with a cut-off of 20%, we found the dasabuvir RASs A553V and C445F to be a baseline polymorphism of GT 2b (8 out of 8) and GT 3a (18 out of 18) sequences, respectively. In GT 1a and 1b treatment-naïve subjects (n=25), no high-fold resistance polymorphism/RASs were identified. We further predicted dasabuvir's binding pose with the NS5B polymerase using the in silico methods to elucidate the reasons associated with the resistance of clinically relevant RASs. Dasabuvir was docked at the palm-I site and was found to form hydrogen bonds with the residues S288, I447, Y448, N291 and D318. The RAS positions 316, 414, 448, 553 and 556 were found to constitute the dasabuvir binding pocket.

The pharmacological interactions between direct-acting antivirals for the treatment of chronic hepatitis c and psychotropic drugs.

INTRODUCTION: Most direct-acting antivirals (DAAs) and psychotropic drugs are metabolized by or induct/inhibit CYP enzymes and drug transporters. Although they are frequently coadministered, the drug-drug interactions (DDIs) have been little studied. Therefore, the aim of this review is to describe the interactions between the approved DAA or combination regimens and the main psychoactive substances, including legal and illegal drugs of abuse. Areas covered: We performed a literature search on PubMed database on drug interactions with the currently available antivirals for hepatitis C and a review of the information on pharmacokinetics, metabolism, and drug interactions from www.hep-druginteractions.org and from all the Summary of Product Characteristics (SmPC). This review covers the DDI between the DAA regimens approved, such as simeprevir and sofosbuvir, paritaprevir, glecaprevir, voxilaprevir, ombitasvir, ledipasvir, daclatasvir and sofosbuvir, elbasvir and grazoprevir, sofosbuvir and velpatasvir, glecaprevir/pibrentasvir, sofosbuvir and velpatasvir, and main psychotropic agents. Expert Commentary: DAA regimens based on sofosbuvir combination usually have less DDI than protease inhibitor-based regimens. Among protease inhibitors regimens, new combinations, such as glecaprevir/elbasvir and grazoprevir/elbasvir, seemed to have less DDI than the combination POrD (paritaprevir/ombitasvir/ritonavir/dasabuvir). However, the analysis of each interaction is theoretical and further interaction studies would be necessary to confirm actual effect.