Clinical Pharmacokinetics of Dasabuvir

Dasabuvir alleviates 5-fluorouracil-induced intestinal injury through anti-senescence and anti-inflammatory

5-Fluorouracil (5-Fu) is a basic drug that is used to treat colorectal cancer. Patients who receive 5-Fu chemotherapy often experience side effects that affect the digestive system, such as intestinal injury and diarrhoea, which significantly affect patient compliance with anticancer treatment and quality of life. Therefore, identifying approaches to treat or prevent these side effects is urgent. Dasabuvir (DSV) is a hepatitis C virus inhibitor, but its impact on 5-Fu-induced intestinal injury remains unknown. Our study investigated the effects of DSV on 5-Fu-induced intestinal injury in HUVECs, HIECs and male BALB/c mice. We found that 5-Fu caused intestinal damage by inducing senescence, increasing inflammatory factor expression, and generating oxidative stress. Compared with 5-Fu treatment alone, DSV inhibited senescence by reducing senescence-β-galactosidase (SA-β-gal) activity, the senescence-associated secretory phenotype (SASP, including IL-1, IL-6, and TNF-α) and senescence marker expression levels (p16, p21, and p53). Moreover, the anti-senescence effect of DSV was achieved by inhibiting the mTOR signaling pathway. DSV increased antioxidant enzyme levels and alleviated intestinal tissue injury in mice. In addition, DSV suppressed the 5-Fu-induced increase the diarrhoea scores and ameliorated the weight loss, food intake and water intake of the mice. Overall, this study indicated that DSV could be used to treat chemotherapy-induced intestinal damage.

A Synopsis of Hepatitis C Virus Treatments and Future Perspectives

Hepatitis C virus (HCV) infection is a worldwide public health problem. Chronic infection with HCV can lead to liver cirrhosis or cancer. Although some immune-competent individuals can clear the virus, others develop chronic HCV disease due to viral mutations or an impaired immune response. IFNs type I and III and the signal transduction induced by them are essential for a proper antiviral effect. Research on the viral cycle and immune escape mechanisms has formed the basis of therapeutic strategies to achieve a sustained virological response (SVR). The first therapies were based on IFNα; then, IFNα plus ribavirin (IFN-RBV); and then, pegylated-IFNα-RBV (PEGIFNα-RIV) to improve cytokine pharmacokinetics. However, the maximum SVR was 60%, and several significant side effects were observed, decreasing patients' treatment adherence. The development of direct-acting antivirals (DAAs) significantly enhanced the SVR (>90%), and the compounds were able to inhibit HCV replication without significant side effects, even in paediatric populations. The management of coinfected HBV-HCV and HCV-HIV patients has also improved based on DAA and PEG-IFNα-RBV (HBV-HCV). CD4 cells are crucial for an effective antiviral response. The IFNλ3, IL28B, TNF-α, IL-10, TLR-3, and TLR-9 gene polymorphisms are involved in viral clearance, therapeutic responses, and hepatic pathologies. Future research should focus on searching for strategies to circumvent resistance-associated substitution (RAS) to DAAs, develop new therapeutic schemes for different medical conditions, including organ transplant, and develop vaccines for long-lasting cellular and humoral responses with cross-protection against different HCV genotypes. The goal is to minimise the probability of HCV infection, HCV chronicity and hepatic carcinoma.

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 can reach the low μM range, ABT-333 application carries a risk of cardiac side effects especially in case of coadministration with strong inhibitors of CYP2C8.

Non-nucleoside structured compounds with antiviral activity—past 10 years (2010–2020)

Nucleosides and their derivatives are a well-known and well-described class of compounds with antiviral activity. Currently, in the era of the COVID-19 pandemic, scientists are also looking for compounds not related to nucleosides with antiviral properties. This review aims to provide an overview of selected synthetic antiviral agents not associated to nucleosides developed against human viruses and introduced to preclinical and clinical trials as well as drugs approved for antiviral therapy over the last 10 years. The article describes for the first time the wide classification of such antiviral drugs and drug candidates and briefly summarizes the biological target and clinical applications of the compounds. The described compounds are arranged according to the antiviral mechanism of action. Knowledge of the drug's activity toward specific molecular targets may be the key to researching new antiviral compounds and repositioning drugs already approved for clinical use. The paper also briefly discusses the future directions of antiviral therapy. The described examples of antiviral compounds can be helpful for further drug development.

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.

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.

Therapeutic potential of uracil and its derivatives in countering pathogenic and physiological disorders

Uracil is one of the most notable pharmacophores in medicinal chemistry as the pyrimidine nucleobase forms an integral part of many commercial drugs. Though the name uracil is usually associated with cancer drugs, there are many uracil-based compounds which can treat different diseases when they are employed. So far, there has been no in-depth review concerning uracil drugs in the market, or in the different stages of clinical trials, including those approved or discontinued. The current work focuses on the importance of uracil and its derivatives in treating different diseases. The use of uracil compounds in treating viral infections, cancer, diabetic, thyroid and autosomal recessive disorders are discussed in the review. The mechanism of action of each uracil drug with emphasis on their structure and properties are discussed in detail. The targeted action of these drugs on sites or on the different stages of a disorder/pathogenic life cycle are also discussed. This review encompasses uracil drugs approved as well as those in development from the 1950's onwards. The utility of uracil in drug discovery and its association with a wide range of diseases is brought forth within this review to demonstrate its potential to a wider audience.

FDA-Approved Drugs Efavirenz, Tipranavir, and Dasabuvir Inhibit Replication of Multiple Flaviviruses in Vero Cells

Vector-borne flaviviruses (VBFs) affect human health worldwide, but no approved drugs are available specifically to treat VBF-associated infections. Here, we performed in silico screening of a library of U.S. Food and Drug Administration-approved antiviral drugs for their interaction with Zika virus proteins. Twelve hit drugs were identified by the docking experiments and tested in cell-based antiviral assay systems. Efavirenz, tipranavir, and dasabuvir at micromolar concentrations were identified to inhibit all VBFs tested; i.e., two representatives of mosquito-borne flaviviruses (Zika and West Nile viruses) and one representative of flaviviruses transmitted by ticks (tick-borne encephalitis virus). The results warrant further research into these drugs, either individually or in combination, as possible pan-flavivirus inhibitors.

Development and validation of UPLC-MS/MS method for studying the pharmacokinetic interaction of dasabuvir and tamoxifen, 4-hydroxytamoxifen in Wistar rats

Hepatitis C virus (HCV) is the main cause of chronic hepatitis and probably liver cirrhosis. Dasabuvir (DSV) is a direct-acting antiviral agent with efficiency in managing HCV. The anti-viral activity of the anti-estrogen drug tamoxifen (TAM) suggested the synergistic effect of DSV and TAM for blocking the replication of HCV. However, being substrates and inhibitors of efflux transporters (TAM inhibits P-gp, DSV inhibits P-gp and BCRP), there is a possibility for a pharmacokinetic (PK) drug-drug interaction. In this work, a new UPLC-MS/MS method was developed and validated for the simultaneous determination of TAM, its active metabolite 4-hydroxy tamoxifen (TOH), and DSV in rat plasma. The method was applied to investigate the PK interaction between DSV and TAM/TOH following the co-administration of DSV and TAM to Wistar rats. Chromatographic analysis was performed on Waters BEH^TM C18 column using a mobile phase of acetonitrile/water containing 0.1% formic acid (80: 20, v/v). The method allowed the determination of concentration ranges 20–1000, 0.1–500, 0.5–500 ng/mL for DSV, TAM, and TOH, respectively. Unexpectedly, results revealed the absence of PK interactions between DSV and TAM/TOH, compared with their single administration, suggesting the safety of co-administering DSV/TAM as an anti-viral combination without the need of dosage adjustment.

Population Pharmacokinetics of Paritaprevir, Ombitasvir, Dasabuvir, Ritonavir, and Ribavirin in Hepatitis C Virus-Infected Cirrhotic and Non-cirrhotic Patients: Analyses Across Nine Phase III Studies

BACKGROUND

The clinical development program of the direct-acting antiviral (DAA) combination therapy of paritaprevir (coadministered with ritonavir) and ombitasvir, with and without dasabuvir (3-DAA [3D] and 2-DAA [2D] regimens, respectively) used in the treatment of chronic hepatitis C infection has generated a robust dataset across various dosing regimens and patient populations.

OBJECTIVE

The current analysis aimed to characterize the population pharmacokinetics in patients without cirrhosis ('non-cirrhotic') and with compensated cirrhosis ('cirrhotic'), while accounting for differences across hepatitis C virus (HCV) genotypes (GT) 1, 2, and 4, multiple regimens (3D regimen ± ribavirin for GT1 in global studies, 2D regimen for subgenotype 1b in Japan, 2D regimen + ribavirin for GT2 in Japan, and 2D regimen + ribavirin for GT4), and ethnicities.

METHODS

Pharmacokinetic data from nine clinical studies (~ 1850 patients) were used to model the population pharmacokinetics of each component of the DAA regimens. Model development was performed in stages, starting with an initial base model. Covariate-parameter relationships were then assessed using forward inclusion/backward elimination procedures. Model development was guided by goodness-of-fit plots, likelihood ratio tests, plausibility of parameter estimates, and knowledge of DAA, ritonavir, and ribavirin pharmacokinetics. Paritaprevir, ombitasvir, and ritonavir pharmacokinetics were described by a one-compartment model, while dasabuvir and ribavirin pharmacokinetics were characterized by a two-compartment model.

RESULTS

The analysis showed generally overlapping exposures between compensated cirrhotic and non-cirrhotic patients or between subgroups of the identified significant covariates. The largest differences were the approximately 30-60% higher dasabuvir and paritaprevir exposures in compensated cirrhotic patients.

CONCLUSION

These differences did not warrant dose adjustments for the DAAs when used in HCV-infected patients with compensated cirrhosis.

A DNA aptamer reveals an allosteric site for inhibition in metallo-β-lactamases

The hydrolysis of β-lactam antibiotics by β-lactamase enzymes is the most prominent antibiotic resistance mechanism for many pathogenic bacteria. Out of this broad class of enzymes, metallo-β-lactamases are of special clinical interest because of their broad substrate specificities. Several in vitro inhibitors for various metallo-β-lactamases have been reported with no clinical efficacy. Previously, we described a 10-nucleotide single stranded DNA aptamer (10-mer) that inhibits Bacillus cereus 5/B/6 metallo-β-lactamase very effectively. Here, we find that the aptamer shows uncompetitive inhibition of Bacillus cereus 5/B/6 metallo-β-lactamase during cefuroxime hydrolysis. To understand the mechanism of inhibition, we report a 2.5 Å resolution X-ray crystal structure and solution-state NMR analysis of the free enzyme. Chemical shift perturbations were observed in the HSQC spectra for several residues upon titrating with increasing concentrations of the 10-mer. In the X-ray crystal structure, these residues are distal to the active site, suggesting an allosteric mechanism for the aptamer inhibition of the enzyme. HADDOCK molecular docking simulations suggest that the 10-mer docks 26 Å from the active site. We then mutated the three lysine residues in the basic binding patch to glutamine and measured the catalytic activity and inhibition by the 10-mer. No significant inhibition of these mutants was observed by the 10-mer as compared to wild type. Interestingly, mutation of Lys50 (Lys78; according to standard MBL numbering system) resulted in reduced enzymatic activity relative to wild type in the absence of inhibitor, further highlighting an allosteric mechanism for inhibition.

Pharmacokinetics of Ombitasvir, Paritaprevir, Ritonavir, and Dasabuvir in Healthy Chinese Subjects and HCV GT1b-Infected Chinese, South Korean and Taiwanese Patients

BACKGROUND/PURPOSE

The 3 direct-acting antiviral (3D) regimen of ombitasvir/paritaprevir/ritonavir plus dasabuvir has recently been approved in several Asian geographic regions for the treatment of hepatitis C virus (HCV) genotype (GT) 1 infection. The pharmacokinetics of the components of the 3D regimen with or without ribavirin were evaluated in healthy Chinese subjects and HCV GT1b-infected Chinese, South Korean, and Taiwanese patients, with or without cirrhosis, to determine how the drug exposures in Asian populations compare with historical data in Western populations.

METHODS

Participants received ombitasvir/paritaprevir/ritonavir 25/150/100 mg once daily plus dasabuvir 250 mg twice daily for 14 days (healthy subjects, n = 36) or 12 weeks (HCV patients, n = 754). Patients with compensated cirrhosis also received ribavirin 1000 or 1200 mg divided twice daily, per the local label. Intensive or sparse pharmacokinetic sampling was performed for assessments of plasma drug concentrations.

RESULTS

The exposures [maximum plasma concentration (C_max) and area under the plasma concentration-time curve (AUC)] of the components of the 3D regimen were comparable (< 20% difference) in healthy Chinese subjects residing in China or the United States. In addition, the trough plasma concentrations (C_trough) in HCV GT1b-infected Asian patients were either similar to (ombitasvir) or within 75% of (paritaprevir and dasabuvir) those in Western patients without cirrhosis, or similar to (ombitasvir and paritaprevir) or within 100% of (dasabuvir) those in Western patients with cirrhosis, with widely overlapping ranges of individual values. Generally comparable drug exposures were observed among Chinese, South Korean, and Taiwanese ethnicities for noncirrhotic and cirrhotic patients.

CONCLUSION

Collectively, the results of these pharmacokinetic analyses support the use of the same dose of the 3D regimen for Asian and Western patients. CLINICALTRIALS.GOV: NCT02534870, NCT02517515, NCT02517528.

Clopidogrel Increases Dasabuvir Exposure With or Without Ritonavir, and Ritonavir Inhibits the Bioactivation of Clopidogrel

Dasabuvir is mainly metabolized by cytochrome P450 (CYP) 2C8 and is predominantly used in a regimen containing ritonavir. Ritonavir and clopidogrel are inhibitors of CYP3A4 and CYP2C8, respectively. In a randomized, crossover study in 12 healthy subjects, we examined the impact of clinical doses of ritonavir (for 5 days), clopidogrel (for 3 days), and their combination on dasabuvir pharmacokinetics, and the effect of ritonavir on clopidogrel. Clopidogrel, but not ritonavir, increased the geometric mean AUC_0‐∞ of dasabuvir 4.7‐fold; range 2.0–10.1‐fold (P = 8·10⁻⁷), compared with placebo. Clopidogrel and ritonavir combination increased dasabuvir AUC_0‐∞ 3.9‐fold; range 2.1–7.9‐fold (P = 2·10⁻⁶), compared with ritonavir alone. Ritonavir decreased the AUC_0‐4h of clopidogrel active metabolite by 51% (P = 0.0001), and average platelet inhibition from 51% without ritonavir to 31% with ritonavir (P = 0.0007). In conclusion, clopidogrel markedly elevates dasabuvir concentrations, and patients receiving ritonavir are at risk for diminished clopidogrel response.

Clinical Pharmacokinetics of Paritaprevir

Paritaprevir is a potent hepatitis C virus (HCV) nonstructural (NS) protein 3/4A protease inhibitor that is used in combination with other direct-acting antivirals (DAAs) for the treatment of chronic HCV infection. Paritaprevir is primarily metabolized by cytochrome P450 (CYP) 3A4 and is administered with a low dose of ritonavir to achieve drug concentrations suitable for once-daily dosing. Coadministration of paritaprevir with ritonavir increases the half-life of single-dose paritaprevir from approximately 3 h to 5-8 h, doubles the time to maximum plasma concentration (T _max) from 2.3 to 4.7 h, and increases exposures 30-fold for maximum observed plasma concentration (C _max), 50-fold for area under the plasma concentration-time curve (AUC), and >300-fold for trough concentration (C ₂₄). Paritaprevir displays highly variable, nonlinear pharmacokinetics, with C _max and AUC increasing in a greater than dose proportional manner when administered with or without ritonavir. In the presence of ritonavir, paritaprevir is excreted mostly unchanged in feces via biliary excretion. Paritaprevir exposures are higher in Japanese subjects compared with Caucasian subjects; however, no dose adjustment is needed for Japanese patients as the higher exposures are safe and well tolerated. The pharmacokinetic characteristics of paritaprevir are similar between healthy subjects and HCV-infected patients, and are not appreciably altered by mild or moderate hepatic impairment or mild, moderate, or severe renal impairment, including those on dialysis. Paritaprevir exposures are increased in patients with severe hepatic impairment. Although the presence of a low dose of ritonavir in paritaprevir-containing regimens increases the likelihood of drug-drug interactions, results from several drug interaction studies demonstrated that paritaprevir-containing regimens can be coadministered with many comedications that are commonly prescribed in HCV-infected patients.

Clinical Pharmacokinetics of Ombitasvir

Ombitasvir is a potent, nonstructural protein 5A inhibitor of the hepatitis C virus (HCV) that is used in combination with other direct-acting antivirals for the treatment of chronic HCV infection. Ombitasvir is predominantly metabolized by amide hydrolysis followed by oxidative metabolism and is a substrate of P-glycoprotein. Ombitasvir displays linear pharmacokinetics with minimal accumulation and is eliminated via metabolism and biliary excretion. A negligible amount of unchanged drug is excreted in urine. Exposures are comparable across Chinese, Japanese, and non-Asian subjects. The pharmacokinetic characteristics of ombitasvir are similar in healthy subjects and HCV-infected patients, and are not appreciably altered by hepatic or renal impairment. Results from several drug interaction studies demonstrated that ombitasvir has a low potential for drug interactions.

Hepatic Pharmacokinetics and Pharmacodynamics With Ombitasvir/Paritaprevir/Ritonavir Plus Dasabuvir Treatment and Variable Ribavirin Dosage

Background

It is unknown whether ribavirin (RBV) coadministration modifies the early rate of decline of hepatitis C virus (HCV) RNA in the liver versus plasma compartments, specifically.

Methods

This partially randomized, open-label, phase 2 study enrolled treatment-naive, noncirrhotic patients with HCV genotype 1a. Patients were randomized 1:1 into Arms A and B, and then enrolled in Arm C. Patients received ombitasvir/paritaprevir/ritonavir plus dasabuvir for 12 weeks with either: no RBV for the first 2 weeks followed by weight-based dosing thereafter (Arm A), weight-based RBV for all 12 weeks (Arm B), or low-dose RBV (600 mg) once daily for all 12 weeks. Fine needle aspiration (FNA) was used to determine HCV RNA decline within liver.

Results

Baseline HCV RNA was higher and declined more rapidly in plasma than liver; however, RBV dosing did not impact either median plasma or liver HCV RNA decline during the first 2 weeks of treatment. Liver-to-plasma drug concentrations were variable over time. The most common adverse event was pain associated with FNA.

Conclusions

Coadministration of RBV had minimal visible impact on the plasma or liver kinetics of HCV RNA decline during the first 2 weeks of treatment, regardless of RBV dosing.