Drug-drug interactions during antiviral therapy for chronic hepatitis C

Effectiveness and safety of direct-acting antivirals in the therapy of HCV-infected elderly people

BACKGROUND

The introduction of direct-acting antivirals (DAAs) with their effectiveness and safety has revolutionized the approach to treating hepatitis C virus (HCV) infections. Nevertheless, elderly patients have often been excluded from clinical trials, so the results of real-world studies are particularly important in the context of the geriatric population. The study aimed to analyze the effectiveness and safety of antiviral DAA treatment in HCV-infected patients over the age of 65, with notable inclusion of those over the age of 85.

METHODS

The analyzed patients were divided by age into three groups: group A (65-74 years), group B (75-84 years) and group C (85 years or older). Patients started DAA based therapy at 22 hepatology centers between July 2015 and December 2022.

RESULTS

A total of 3505 elderly patients were included in the analysis, and this group consisted of 2501 patients in group A, 893 in group B, and 111 in group C. The study population, regardless of age, was dominated by women. Patients had a high prevalence of comorbidities (84.9%, 92.2%, and 93.7%, respectively) as well as a high rate of concomitant medications. The sustained virological response was 97.9% in groups A and B and 100% in group C. The therapy was well-tolerated, with a comparable safety profile observed in all analyzed groups.

CONCLUSIONS

DAA-based therapies are highly effective and well tolerated by the elderly patients, including those over 85. Age should not be a barrier to treatment, but careful management is necessary.

SASLT guidelines: Update in treatment of hepatitis C virus infection, 2024

ABSTRACT

Hepatitis C virus (HCV) infection has been a major global health concern, with a significant impact on public health. In recent years, there have been remarkable advancements in our understanding of HCV and the development of novel therapeutic agents. The Saudi Society for the Study of Liver Disease and Transplantation formed a working group to develop HCV practice guidelines in Saudi Arabia. The methodology used to create these guidelines involved a comprehensive review of available evidence, local data, and major international practice guidelines regarding HCV management. This updated guideline encompasses critical aspects of HCV care, including screening and diagnosis, assessing the severity of liver disease, and treatment strategies. The aim of this updated guideline is to assist healthcare providers in the management of HCV in Saudi Arabia. It summarizes the latest local studies on HCV epidemiology, significant changes in virus prevalence, and the importance of universal screening, particularly among high-risk populations. Moreover, it discusses the promising potential for HCV elimination as a public health threat by 2030, driven by effective treatment and comprehensive prevention strategies. This guideline also highlights evolving recommendations for advancing disease management, including the treatment of HCV patients with decompensated cirrhosis, treatment of those who have previously failed treatment with the newer medications, management in the context of liver transplantation and hepatocellular carcinoma, and treatment for special populations.

Safety considerations in the management of hepatitis C and HIV co-infection

INTRODUCTION

Both HCV and HIV are highly prevalent infections with current estimates of 57 and 38 million people infected worldwide, respectively. Oral antivirals can be curative for HCV and rescue HIV patients from disease progression. Dual therapy in coinfected patients requires expertise.

AREAS COVERED

Four major issues challenge dual HCV and HIV treatment, including overlapping drug-related side effects, hepatitis B reactivation, immune reconstitution inflammatory syndromes (IRIS), and drug-drug interactions (DDI). A search was conducted in PubMed from January 2010 to March 2023.

EXPERT OPINION

The advent of second-generation direct-acting antivirals (DDA) that depict higher antiviral potency, fewer side effects, pangenotypic activity and are co-formulated has expanded the indication of HCV therapy and particularly in HIV-coinfected individuals. Sequential initiation of antiretrovirals (ARV) followed by DAA is generally preferred to start dual treatment concomitantly. Close monitoring of rare episodes of HBV reactivation and IRIS is warranted. The most frequent DDI between DAA and ARV affect drug metabolism by CYP450 induction/inhibition, leading to abnormal drug exposures. Throughout this mechanism interact most HCV and HIV protease inhibitors and non-nucleoside polymerase inhibitors. Exposure to some HIV and HCV nucleos(t)ide analogues (e.g. tenofovir and sofosbuvir, respectively) is subject to induction/inhibition of drug transporters and requires special attention in patients with renal insufficiency.

Drug-drug interactions between direct-acting antivirals and co-medications: a territory-wide cohort study

BACKGROUND

The increasing number of direct-acting antiviral (DAA) regimens along with limited number of subjects and co-medications involved in clinical trials results in drug-drug interactions (DDIs) with DAAs is to be determined. We aimed to examine the prevalence and degree of DDIs between DAAs and other co-medications in a territory-wide cohort of chronic hepatitis C virus (HCV) patients.

METHODS

DDIs were assigned to three risk categories: Category 1-no clinically significant DDI; category 2-potential clinically significant interaction (monitoring and caution required); category 3-contraindicated (should not be co-administered).

RESULTS

Of 2981 patients (mean age 59.3 ± 12.3 years; male 60.6%), 810 (48.8%) had genotype 1 and 552 (33.2%) genotype 6 HCV among the 1661 patients with HCV genotype tested; 769 (25.8%) received sofosbuvir/velpatasvir, 510 (17.1%) sofosbuvir/ledipasvir, and 865 (29.0%) glecaprevir/pibrentasvir. More than one-fourth (26.3%) of the patients have polypharmacy (≥ 3 co-medications) in all patients, 27.0% in patients received sofosbuvir/velpatasvir, 25.1% in elbasvir/grazoprevir, and 21.2% in glecaprevir/pibrentasvir. 2037 (68.3%) patient experienced DDI (Category 2: 53.1%; Category 3: 15.2%). The commonest drugs leading to DDIs were calcium channel blockers (31.5%) and proton pump inhibitors (23.0%) in category 2; statins (10.2%), antiplatelet/anticoagulants (3.0%) and antipsychotics (2.9%) in category 3. Changing medication was the most common response from physicians in both category 2 and 3 DDIs.

CONCLUSION

The commonest co-medications leading to contraindication during DAA treatment were statins and antipsychotics. Category 2 and 3 DDIs are often managed by appropriate dose adjustments or temporary discontinuation of relevant co-medications. Careful assessment for potential DDI before DAA use is mandatory to avoid potential harmful effects.

The use of technology-based adherence monitoring in the treatment of hepatitis C virus

Direct-acting antivirals (DAAs) achieve high hepatitis C virus (HCV) cure rates and are forgiving to missed doses, but adherence–efficacy relationships have not been well defined. Traditional adherence measures (e.g. pill counts, self-report and pharmacy refills) over-estimate medication adherence. Newer technology-based tools have been used to provide more objective adherence data. Herein, electronic medication diaries (e-diaries), medication events monitoring system (MEMS^®) caps, electronic blister packs, electronic pill boxes, video-based directly observed therapy (vDOT), artificial intelligence platforms (AIPs), and ingestible sensor systems are described, and compared based on existing studies using DAA. Percent adherence, predictors of adherence, and HCV cure rates utilizing these technologies are included. DAA adherence with e-diaries was 95–96%, MEMS^® caps and ingestible biosensors were between 95% and 97%, blister pack weekly dosing ranged 73–98%, and daily dosing 73–94%, whereas electronic pill boxes ranged between 39% and 89%, vDOT was 98% and AIP 91–96%. Despite a wide range of adherence, high sustained virologic response (SVR) rates (86–100%) were observed across all studies utilizing these different technology-based tools. Current data support the forgiveness of DAA therapies to missed doses using tools that provide more quantitative adherence measures compared with self-report and provide insight on adherence–efficacy relationships for contemporary DAA.

Nanomedicine based approaches for combating viral infections

Millions of people die each year from viral infections across the globe. There is an urgent need to overcome the existing gap and pitfalls of the current antiviral therapy which include increased dose and dosing frequency, bioavailability challenges, non-specificity, incidences of resistance and so on. These stumbling blocks could be effectively managed by the advent of nanomedicine. Current review emphasizes over an enhanced understanding of how different lipid, polymer and elemental based nanoformulations could be potentially and precisely used to bridle the said drawbacks in antiviral therapy. The dawn of nanotechnology meeting vaccine delivery, role of RNAi therapeutics in antiviral treatment regimen, various regulatory concerns towards clinical translation of nanomedicine along with current trends and implications including unexplored research avenues for advancing the current drug delivery have been discussed in detail.

Evaluating the utility of therapeutic drug monitoring in the clinical use of small molecule kinase inhibitors: a review of the literature

Introduction: Orally administered small molecule kinase inhibitors (KI) are a key class of targeted anti-cancer medicines that have contributed substantially to improved survival outcomes in patients with advanced disease. Since the introduction of KIs in 2001, there has been a building body of evidence that the benefit derived from these drugs may be further enhanced by individualizing dosing on the basis of concentration.Areas covered: This review considers the rationale for individualized KI dosing and the requirements for robust therapeutic drug monitoring (TDM). Current evidence supporting TDM-guided KI dosing is presented and critically evaluated, and finally potential approaches to address translational challenges for TDM-guided KI dosing and alternate approaches to support individualization of KI dosing are discussed.Expert opinion: Intuitively, the individualization of KI dosing through an approach such as TDM-guided dosing has great potential to enhance the effectiveness and tolerability of these drugs. However, based on current literature evidence it is unrealistic to propose that TDM-guided KI dosing should be routinely implemented into clinical practice.

Sofosbuvir Resistance-associated Substitutions in the Palm Domain of HCV-NS5B RNA Dependent RNA Polymerase; Study of two Sofosbuvir non-responders

OBJECTIVE

In current study we performed sequencing of palm domain of HCV-NS5B gene, its ancestral analysis along with amino acids substitution analysis. These analysis were done to find the molecular basis of the viral resistance against Sofosbuvir drug.

METHODS

Blood samples from individuals with chronic Hepatitis C infection that were resistant to Sofosbuvir were collected. The samples were processed for their molecular characterization that included RNA extraction, Complementary DNA (cDNA) synthesize, nested PCR, gel elution, Sequencing, ancestral and 3D structure analysis.

RESULTS

Evolutionary analysis revealed that current study sequences (QAU-01, QAU-02) clustered with a previously studied sequence, KY971494.1. Moreover, we reports multiple novel amino acid substitutions in the palm domain of NS5B gene such as Ile116Val, Asn117Gly, Glu246Ala, Val252Ala, Glu258Gln, Cys262Leu, Ser269Arg, Ala272Thr, Ile293Leu, Lys304Arg, Asn307Gly, Ala338Val and Arg345Gly in our query sequence (QAU-01). At 246 and 269 position in (QAU-02), no substitution was observed.

CONCLUSIONS

We have noticed that the current sequences are relatively emerging and could have been originated from aforementioned sequence recently. Based on the current results, we suggests that these substitutions could be associated with structural or functional impairment of protein and could also be may be considered as resistance associated substitutions (RAS) to Sofosbuvir drug.

Hepatitis C Virus Infection and the New Therapeutical Approach

Hepatitis C virus represents one of the most important public health problems nowadays. Several epidemiological studies have shown a continuous increasing rate of prevalence and incidence with severe consequences in terms of mortality. During the last decades, the treatment of the liver infection has evolved, and now there are available new therapies with better side-effect' profiles and bigger efficiency. The needs for more therapeutically efficacy also stand behind the numerous comorbidities associated to the liver disease, and also for assuring better quality of life for patients and their families.

Succinic acid inhibits the activity of cytochrome P450 (CYP450) enzymes

CONTEXT

Succinic acid, extracted from amber, is widely used in cardiovascular therapy.

OBJECTIVE

The effect of succinic acid on the activity of cytochrome P450 (CYP450) enzymes was investigated in this study.

MATERIALS AND METHODS

The effect of succinic acid (100 μM) on the activity of eight isoforms of CYP450 (i.e., 1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19 and 2C8) was investigated compared to the specific inhibitor and blank controls in pooled human liver microsomes in vitro. The inhibition of CYPs was fitted with competitive or non-competitive inhibition models and corresponding parameters were also obtained.

RESULTS

Succinic acid exerted inhibitory effect on the activity of CYP3A4, 2D6, and 2C9 with the IC₅₀ values of 12.82, 14.53, and 19.60 μM, respectively. Succinic acid inhibited the activity of CYP3A4 in a non-competitive manner with the Ki value of 6.18 μM, and inhibited CYP2D6 and 2C9 competitively with Ki values of 7.40 and 9.48 μM, respectively. Furthermore, the inhibition of CYP3A4 was found to be time-dependent with the KI/K_inact value of 6.52/0.051 min^-1·μM^-1.

DISCUSSION AND CONCLUSIONS

Succinic acid showed in vitro inhibitory effects on the activity of CYP3A4, 2D6, and 2C9, which indicated the potential drug-drug interactions. Succinic acid should be carefully co-administrated with the drugs metabolized by CYP3A4, 2D6, and 2C9.

Development and Validation of a New LC-MS/MS Analytical Method for Direct-Acting Antivirals and Its Application in End-Stage Renal Disease Patients

BACKGROUND AND OBJECTIVE

The effectiveness of direct-acting antivirals (DAAs) is not well established in end-stage renal disease (ESRD) patients. Assessment of the plasma concentrations may support understanding of their therapeutic outcomes in this population. The aim of this study is to develop a direct, yet matrix-effect tolerant, analytical method for determining DAAs in the plasma of ESRD patients while maintaining a moderate cost per sample and with an improved analyte extraction recovery.

METHODS

In this study, a liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed for the analysis of ombitasvir (OMB), paritaprevir (PRT) and ritonavir (RIT) in plasma. Sample preparation was performed using the liquid-liquid extraction (LLE) method. Isocratic separation was performed using a mixture of methanol and 10 mM ammonium acetate (79:21, v/v) followed by MS/MS detection. The method was validated and applied to determine DAAs in the plasma of ESRD patients (n = 7).

RESULTS

The developed method was linear (r²> 0.995), accurate (89.4 ± 7.8 to 108.3 ± 3.0) and precise (% CV 0.9-15.0) and showed improved recovery (> 80) over previously published ones in the range 5-250, 30-1,500, 20-1,000 ng/mL for OMB, PRT and RIT, respectively. Relative matrix effect was absent, and the method accurately determined the three DAAs in real-life samples (n = 7).

CONCLUSIONS

An efficient analytical method for the determination of DAAs is presented. The method overcomes the potential analytical response fluctuation in ESRD. The developed method show improved extraction recoveries and is suitable for routine application in developing economies where hepatitis C virus is most prevalent.

Cardiovascular Risk Management and Hepatitis C: Combining Drugs

Direct-acting antivirals (DAAs) are known victims (substrate) and perpetrators (cause) of drug–drug interactions (DDIs). These DAAs are used for the treatment of hepatitis C virus (HCV) infections and are highly effective drugs. Drugs used for cardiovascular risk management are frequently used by HCV-infected patients, whom also are treated with DAAs. Therefore, the aim of this review was to describe DDIs between cardiovascular drugs (CVDs) and DAAs. An extensive literature search was performed containing search terms for the marketed DAAs and CVDs (β-blocking agents, ACE inhibitors, angiotensin II antagonists, renin inhibitors, diuretics, calcium channel blockers, statins/ezetimibe, fibrates, platelet aggregation inhibitors, vitamin K antagonists, heparins, direct Xa inhibitors, nitrates, amiodarone, and digoxin). In particular, the drug labels from the European Medicines Agency and the US Food and Drug Administration were used. A main finding of this review is that CVDs are mostly victims of DDIs with DAAs. Therefore, when possible, monitoring of pharmacodynamics is recommended when coadministering these drugs with DAAs. Nevertheless, it is sometimes better to discontinue a drug on a temporary basis (statins, ezetimide). The DAAs are victims of DDIs in combination with bisoprolol, carvedilol, labetalol, verapamil, and gemfibrozil. Despite there are many DDIs predicted in this review, most of these DDIs can be managed by monitoring the efficacy and toxicity of the victim drug or by switching to another CVD/DAA.

Analysis of drug-resistance-associated mutations and genetic barriers in hepatitis C virus NS5B sequences in China

The hepatitis C virus (HCV) NS5B protein is an RNA-dependent RNA polymerase that is required for viral genome replication and constitutes the most important target region for drugs being developed as direct-acting antivirals (DAAs) against HCV genotype 1. However, the extreme genetic variability leading to drug resistance mutations and genetic barriers has dramatically compromised the effectiveness of DAA therapy. The purpose of this study was to analyze the genetic variability of NS5B polymerase in HCV patients from different provinces of China to identify the impact of these resistance sites on genetic barriers. We analyzed 3489 NS5B sequences of HCV strains circulating in different regions of China, obtained from the GenBank database, 153 of which were from three cities in Sichuan Province (Yibin, Zigong and Zhangzhou). Sequence alignment was conducted using MEGA 6.0, the genetic information was translated into amino acids, and the percentage of polymorphic amino acid sites was calculated. The Vijver method was used to evaluate the occurrence of genetic barriers in HCV NS5B sequences. Blood samples were collected from 153 HCV patients from Sichuan for NS5B sequence analysis using real-time PCR and the Sanger method. Of the 17 antiviral drug resistance sites summarized from the published literature, nine were found in Chinese NS5B sequences, and C316Y was identified as the dominant mutation. Analysis of genetic barriers revealed that the probability of mutation to a drug-resistance-associated amino acid, in response to selective pressure from antiviral drugs was 100% at site 96 and 99.7% at site 282. Our study is the first to analyze the drug resistance sites and to evaluate genetic barriers in NS5B sequences that could affect the responsiveness of Chinese HCV patients to DAA therapy. The results provide a valuable basis for drug development and introduction of foreign-origin antiviral drugs in China that targeting the HCV NS5B region.

Drug-drug interactions between direct-acting antivirals and statins in the treatment of chronic hepatitis C

As the first line of treatment for hepatitis C virus (HCV) infection, direct-acting antivirals (DAAs) have greater efficacy and fewer adverse effects than other treatments; however, drug-drug interactions (DDIs) must be avoided when used in combination with other medications, such as statins. HCV patients are mostly in the need for polypharmacy, particularly the comedication of DAAs and cardiovascular drugs such as statins. This poses a risk of pharmacokinetic interactions between the two classes of drugs that may lead to severe myopathy or even rhabdomyolysis. Therefore, evaluating the severity of the DDIs and managing them is important. A multidisciplinary team-based model of care for HCV patients receiving DAAs can review the pharmacology profiles of other drugs for relevant DDIs with the DAAs, before prescription. Such a model can also follow the patients through the therapeutic cycle to make sure that their medical regimen is safe and effective. This article reviews the comedication rate and DDI-prevalence in HCV patients receiving statins along with the DAAs, details the mechanisms involved, gives recommendations for management, and shares our experience with a multidisciplinary team-based care program for the treatment of HCV patients.

Frequency of Potential Drug-Drug Interactions in the Changing Field of HCV Therapy

Background

With the introduction of direct-acting antivirals (DAAs) for hepatitis C virus (HCV) infection, drug-drug interactions (DDIs) emerged as significant challenge. Since then, HCV therapy and the infected population have rapidly changed. So far, very limited data are available regarding the clinical relevance of DDIs when using most modern DAA regimens. We aimed to assess how the importance of DDIs has evolved over time.

Methods

From January 2014 to July 2018, 668 consecutive HCV patients were evaluated for their outpatient medication and assessed for DDIs with DAAs. Different time periods were defined based on market approval of key DAAs: A (01/2014-11/2014), B (11/2014-08/2016), and C (08/2016-07/2018).

Results

The frequency of patients with real-world DDIs was highest in period B (A: 37.1%, B: 49.6%, C: 38.8%). The recently approved DAAs (period C) theoretically showed a lower DDI risk profile. However, real-world DDIs were still comparable to period A, as HCV patients' characteristics changed (eg, age ≥75 years: A: 3.1%, B: 9.8%, C: 5.6%; polypharmacy/patients with ≥8 drugs: A: 11.1%, B: 15.2%, C: 17.2%). Furthermore, although DDIs via CYP 3A4 became less important for some modern regimens, other mechanisms like an altered pH value in the stomach, causing reduced bioavailability, evolved. Relevant DDIs most frequently occurred with proton pump inhibitors, metamizole, statins, and carvedilol.

Conclusions

DDIs during antiviral treatment still affect about 40% of HCV patients. The lower DDI potential of modern DAA regimens is partly counteracted by changing patient characteristics. Therefore, DDIs should not be underestimated.

Real-life use of elbasvir/grazoprevir in adults and elderly patients: a prospective evaluation of comedications used in the PITER cohort

BACKGROUND

In patients treated for HCV infection, potential drug-drug interactions (DDIs) can occur among direct-acting antiviral drugs (DAAs) and comedications used. The real-life effectiveness and safety of elbasvir/grazoprevir (ELB/GZR) among co-medicated HCV patients was evaluated.

METHODS

We prospectively evaluated consecutive patients from 15 clinical centres participating in PITER who were treated with ELB/GZR and had been followed for at least 12 weeks after treatment. Data were prospectively collected on the use of comedications (including discontinuation, dose modification and addition of drugs) and potential DDIs with DAAs.

RESULTS

Of the 356 patients with at least 12-week post-treatment follow-up (median age 67, range 50-88 years), 338 (95%) achieved sustained virological response. Of these, 219 (60%) had at least one comorbidity (median 2, range 1-6); information on comedication was available for 212 of them. Of 190 comedications used, 15 (8%) drugs were modified during ELB/GZR therapy, specifically in 9 (4%) patients they were interrupted, in 2 (1%) of whom, the comedication was interrupted before the DAA therapy because of potential DDI (that is, patients treated with carbamazepine); in 12 (6%) patients the comedications were modified in terms of dosage. In 29 (14%) patients, the comedications required monitoring when used with ELB/GZR, as well as with all available DAAs. Of the 190 drugs, 27 (14%) used in 67% of patients were free of DDIs when used with ELB/GZR, whereas they required monitoring if used with other DAA regimens.

CONCLUSIONS

The results of this prospective study support findings that ELB/GZR is effective and safe in most treated patients.

Effect of comedication on ombitasvir/paritaprevir/ritonavir ± dasabuvir ± ribavirin therapy in chronic hepatitis C - a real-world study

Aim of the study

This multicentre study aimed to examine the actual risk for drug-drug interactions in a cohort of Polish patients, and their impact on antiviral therapy.

Material and methods

Concomitant medications were analyzed in hepatitis C virus (HCV)-infected patients treated with still valuable therapy with OBV/PTV/r ± DSV ± RBV. An established online tool (http://www.hep-druginteractions.org/) was used to assess potential drug interactions. To assess the impact of comedications on virologic outcomes, HCV RNA levels were measured at given time points during and after the treatment. The results were compared between subgroups depending on the number of drugs used.

Results

Among the 209 patients included in this multicentre study, concomitant medications were taken by 140 (67.0%) patients. Modification of treatment due to expected interactions was required in 33 (15.8%) patients, of whom nine (4.3%) had at least one comedication replaced or discontinued. Sustained virologic response rates ranged from 95.1% to 100.0%, and were lowest in patients taking one to five comedications who were null-responders to pegylated interferon or cirrhotic.

Conclusions

Although most HCV-infected patients received concomitant medications, only some required treatment modification. OBV/PTV/r ± DSV ± RBV was effective in all subgroups, irrespective of the number of comedications taken. Multimorbidity and polypharmacy in patients with chronic hepatitis C should not discourage the decision to initiate antiviral therapy, although caution should be exercised for potential drug-drug interactions.

Relationships among neurotransmitters, cytokines and cognitive performance for individuals with hepatitis C achieving sustained virologic response: A pilot study

An important extrahepatic consequence of Hepatitis C is its adverse impact on the central nervous system and cognitive performance. We aimed to determine whether there is a significant relationship between selected neurotransmitters and cytokines and cognitive performance in patients with Chronic Hepatitis C before and after achieving sustained virologic response (SVR). Pre-SVR, elevated kynurenine was associated with increased immediate and delayed visual memory, whereas post-SVR the positive associations are between kynurenine and immediate and delayed verbal memory. TGF-B was consistently negatively associated with both immediate and delayed visual memory pre- and post-SVR. These concomitant changes may have important clinical relevance.

Single nucleotide polymorphisms associated with elevated alanine aminotransferase in patients receiving asunaprevir plus daclatasvir combination therapy for chronic hepatitis C

Aims

Drug-induced liver damage characterized by serum alanine aminotransferase (ALT) elevation often occurs in direct-acting antiviral (DAA) combination therapy for chronic hepatitis C virus (HCV) infection. This study explored single nucleotide polymorphisms (SNPs) at drug metabolism- or transport-related genes that were associated with ALT elevation in asunaprevir plus daclatasvir therapy.

Methods

Subjects were 185 Japanese patients with chronic HCV genotype 1b infection who received asunaprevir plus daclatasvir therapy. Tag SNPs at possible metabolizing enzyme and transporter genes, which were involved in the pharmacokinetics of asunaprevir and daclatasvir, were selected.

Results

Among the tag SNPs analyzed, CYP3A4 rs4646437 was significantly associated with ALT elevation (p = 0.013): maximum ALT values in patients with genotype CC were higher than those in patients with genotype non-CC (allele T). The proportion of grades 2–4 in genotype CC patients were significantly greater than those in genotype non-CC patients (p = 0.028). No patients with genotype non-CC showed grade ≥2 ALT elevation. In multivariate analysis, rs4646437 genotype CC and cirrhosis were significant, independent factors associated with grade ≥1 ALT elevation (odds ratio, 2.83 and 1.88; p = 0.040 and 0.045, respectively). In exploratory analyses, although serum concentrations of asunaprevir and daclatasvir were not correlated with maximum ALT values or rs4646437 genotypes, asunaprevir concentrations in patients with grade ≥1 ALT elevation were significantly higher than those in patients with grade <1 ALT elevation (P = 0.023).

Conclusions

CYP3A4 rs4646437 was found to be significantly and independently associated with ALT elevation in Japanese patients receiving ASV plus DCV therapy. Notably, none of the patients with rs4646437 genotype non-CC (allele T) had grade ≥2 ALT elevation. SNP genotyping prior to treatment might be useful for carefully monitoring patients to complete treatment safely.

Comorbidities, concomitant medications and potential drug-drug interactions with interferon-free direct-acting antiviral agents in hepatitis C patients in Taiwan

BACKGROUND

While direct-acting antivirals have been approved for treating hepatitis C, the guidelines highlight the importance of considering potential drug-drug interactions between DAAs and concomitant medications.

AIM

To assess comorbidity prevalence, concomitant medication use and potential drug-drug interactions between DAAs and concomitant medications for hepatitis C patients in Taiwan.

METHODS

This cross-sectional study enrolled 822 patients from May to August 2016 in Taiwan. Patient demographics, comorbidities and concomitant medications were evaluated by physician surveys.

RESULTS

A total of 709 (86.3%) patients had ≥1 comorbidity; the most prevalent comorbidity categories were diseases of the digestive system (40.1%), circulatory system (38.7%) and endocrine/nutritional/metabolic diseases (35.2%). Elderly patients had more comorbidities. A total of 622 (75.7%) patients received ≥1 concomitant medication; the average number of concomitant medications was 3.2. The most common concomitant medication classes were cardiovascular (34.4%), gastrointestinal (25.7%) and central nervous system drugs (22.7%). Among patients without cirrhosis or with compensated cirrhosis, contraindications were most prevalent with paritaprevir/ritonavir/ombitasvir plus dasabuvir, daclatasvir/asunaprevir and glecaprevir/pibrentasvir (13.3%, 6.0% and 5.4% respectively), and least prevalent with sofosbuvir, sofosbuvir/daclatasvir, sofosbuvir/ledipasvir and sofosbuvir/velpatasvir (0.8%, 1.3%, 1.4% and 2.1% respectively). Sofosbuvir-based regimens had no contraindications in patients with decompensated cirrhosis.

CONCLUSION

Our population represented an elderly demographic, with a high prevalence of comorbidities and widespread use of concomitant medications. The potential drug-drug interactions between these concomitant medications and DAA regimens differed, with the fewest potential interactions with sofosbuvir-based regimens.

Effects of Herbal Formulas Bojungikgi-tang and Palmijihwang-hwan on Inflammation in RAW 264.7 Cells and the Activities of Drug-Metabolizing Enzymes in Human Hepatic Microsomes

In the present study, Bojungikgi-tang (BJIKT: Buzhongyiqi-tang, Hochuekki-to) and Palmijihwang-hwan (PMJHH: Baweidìhuang-wan, Hachimijio-gan), traditional herbal formulas, investigated anti-inflammatory efficacies in murine macrophage cell line and the influence on the activities of drug-metabolizing enzymes (DMEs). The anti-inflammatory potentials of the herbal formulas were evaluated to inhibit the production of the inflammatory mediators and cytokines and the protein expression of inducible nitric oxide and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-treated RAW 264.7 cells. The activities of the major human DMEs, cytochrome P450 isozymes (CYP450s) and UDP-glucuronosyltransferase isozymes (UGTs), were measured by in vitro enzyme assay systems. BJIKT and PMJHH significantly suppressed the prostaglandin E₂ (PGE₂) production (IC₅₀ = 317.3 and 282.2 μg/mL, respectively) and the protein expression of COX-2 in LPS-treated RAW264.7 cells. On the human microsomal DMEs, BJIKT inhibited the activities of CYP1A2 (IC₅₀ = 535.05 μg/mL), CYP2B6 (IC₅₀ > 1000 μg/mL), CYP2C9 (IC₅₀ = 800.78 μg/mL), CYP2C19 (IC₅₀ = 563.11 μg/mL), CYP2D6 (IC₅₀ > 1000 μg/mL), CYP2E1 (IC₅₀ > 1000 μg/mL), CYP3A4 (IC₅₀ = 879.60 μg/mL), UGT1A1 (IC₅₀ > 1000 μg/mL), and UGT1A4 (IC₅₀ > 1000 μg/mL), but it showed no inhibition of the UGT2B7 activity at doses less than 1000 μg/mL. PMJHH inhibited the CYP2D6 activity (IC₅₀ = 280.89 μg/mL), but IC₅₀ values of PMJHH exceeded 1000 μg/mL on the activities of CYP1A2, CYP2C19, CYP2E1, and CYP3A4. At concentrations less than 1000 μg/mL, PMJHH did not affect the activities of CYP2B6, CYP2C9, UGT1A1, UGT1A4, and UGT2B7. The results indicate that both BJIKT and PMJHH may be potential candidates to prevent and treat PGE₂- and COX-2-mediated inflammatory diseases. In addition, this study will expand current knowledge about herb-drug interactions by BJIKT and PMJHH.

Effectiveness and Safety of Direct-Acting Antiviral Combination Therapies for Treatment of Hepatitis C Virus in Elderly Patients: Results from the German Hepatitis C Registry

BACKGROUND

With the aging of the hepatitis C virus (HCV)-infected patient cohort and the availability of highly effective and tolerable treatment regimens, an increasing number of elderly patients are now eligible for HCV therapy. This study investigated clinical and epidemiologic characteristics of elderly HCV-infected patients as well as the effectiveness and safety of available therapies.

METHODS

Patients were enrolled into the German Hepatitis C Registry (DHC-R), a prospective, multicenter, real-world cohort study. Patients were treated at the discretion of the physician, and data were collected by a web-based system.

RESULTS

Of 7133 patients who initiated treatment, 686 (9.6%) were > 70 years of age. In patients > 70 years, intent-to-treat (ITT) SVR12 was 92.6% (514/555) compared to 90.7% (4521/4985) in patients ≤ 70 years of age. Overall, adverse events (AEs) were reported in 374 (54.5%) and 3435 patients (53.3%) > 70 or ≤ 70 years of age; 7.6% (52) and 3.6% (235) in the respective age groups had a serious AE. Twenty-two (3.2%) and 62 (1.0%) of the patients > 70 or ≤ 70 years discontinued treatment due to AEs. Death was reported in 34 patients, of whom eight were > 70 years of age. Frequent comorbidities in patients > 70 years of age were cardiac disease, renal disease and diabetes. Psychiatric disorders, substance abuse and viral co-infection were more frequent in younger patients.

CONCLUSION

Direct-acting antiviral therapies were well tolerated in patients older than 70 years. SVR12 rates in the elderly patient group were similar to those observed in younger patients. Differences in the prevalence of comorbidities between age groups warrant individualized attention with respect to drug-drug interactions and therapy adherence. The study was registered in the German Clinical Trials Register, DRKS-ID: DRKS00009717.

Serum asunaprevir concentrations showing correlation with the extent of liver fibrosis as a factor inducing liver injuries in patients with genotype-1b hepatitis C virus receiving daclatasvir plus asunaprevir therapy

AIMS

Liver injury can occur during antiviral therapies with direct-acting antivirals (DAAs), potentially necessitating discontinuation of the therapies, with consequent worsening of the sustained viral response (SVR) rates, in patients with hepatitis C virus (HCV). To clarify the mechanisms involved in serum transaminase level elevation, we performed a retrospective evaluation of the serum concentrations of daclatasvir and asunaprevir, both classified as DAAs, in patients receiving treatment with a combination of the two drugs.

METHODS

Subjects were 278 Japanese patients with genotype-1b HCV who received daclatasvir plus asunaprevir therapy for more than 4 weeks. Serum concentrations of both the DAAs were measured at 4 weeks after the initiation of therapy.

RESULT

Liver injuries including serum AST and/or ALT level elevation to 150 U/L or over were found in 34 patients (12.2%). Multivariate logistic regression analysis identified serum asunaprevir concentrations as being significantly associated with developing liver injury, with an odds ratio of 1.046 (95% confidence interval 1.011-1.082, p<0.05). Serum asunaprevir concentrations showed correlation with the extent of liver fibrosis, estimated by peripheral platelets counts and serum albumin levels and baseline and FIB4 index and serum Mac-2 binding protein glycosylation isomer (M2BPGi) levels at 4 weeks of the therapy; the concentrations were significantly higher among patients showing 3.0 or more of M2BPGi levels than among those with the levels less than 3.0; on the other hand, no such correlation/difference was found in serum daclatasvir concentrations.

CONCLUSION

High serum concentrations of serum asunaprevir, which were associated with the extent of liver fibrosis, appear to provoke the occurrence of liver injury in patients with genotype-1b HCV receiving combined daclatasvir plus asunaprevir therapy.

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.

Intrahepatic Sampling for the Elucidation of Antiviral Clinical Pharmacology

Although the importance of the liver in clinical pharmacology is widely recognized, little is known in humans concerning its function in vivo at the hepatocyte level and how pharmacological functions are altered in the setting of advanced liver disease. Several recent proof-of-principle studies with first-generation DAAs have demonstrated the feasibility of serial liver sampling for pharmacological studies. These studies have begun to describe the liver-to-plasma concentration ratio and how this ratio is altered in the setting of advanced liver disease. These data are particularly relevant to individuals with substance-use disorders because many have advanced liver disease as a consequence of long-standing viral hepatitis infection or continued use of hepatotoxins such as alcohol. Future research should attempt to develop standardized and reproducible methods to assess liver drug concentration, complex drug interactions, and pharmacogenomics in humans to permit elucidation of the clinical pharmacology within the liver.

Impact of Sofosbuvir-Based Regimens for the Treatment of Hepatitis C After Liver Transplant on Renal Function: Results of a Canadian National Retrospective Study

OBJECTIVES

We assessed the impact of sofosbuvir-based regimens on renal function in liver transplant recipients with recurrent hepatitis C virus and the role of renal function on the efficacy and safety of these regimens.

MATERIALS AND METHODS

In an expanded pan-Canadian cohort, 180 liver transplant recipients were treated with sofosbuvir-based regimens for hepatitis C virus recurrence from January 2014 to May 2015. Mean age was 58 ± 6.85 years, and 50% had F3/4 fibrosis. Patients were stratified into 4 groups based on baseline estimated glomerular filtration rate (calculated by the Modification of Diet in Renal Disease formula): < 30, 30 to 45, 46 to 60, and > 60 mL/min/173 m2. The primary outcome was posttreatment changes in renal function from baseline. Secondary outcomes included sustained virologic response at 12 weeks posttreatment and anemia-related and serious adverse events.

RESULTS

Posttreatment renal function was improved in most patients (58%). Renal function declined in 22% of patients, which was more marked in those with estimated glomerular filtration rate < 30 mL/min/173 m2, advanced cirrhosis (P = .05), and aggressive hepatitis C virus/fibrosing cholestatic hepatitis (P < .05). High rates (80%-88%) of sustained virologic response at 12 weeks posttreatment were seen across all renal function strata. Cirrhotic patients with glomerular filtration rates < 30 mL/min/173 m2 had sustained virologic response rates at 12 weeks posttreatment comparable to the overall patient group. Rates of anemia-related adverse events and transfusion requirements increased across decreasing estimated glomerular filtration rate groups, with notably more occurrences with ribavirin-based regimens.

CONCLUSIONS

Sofosbuvir-based regimens improved overall renal function in liver transplant recipients, with sustained virologic response, suggesting an association of subclinical hepatitis C virus-related renal disease. Sustained virologic response rates at 12 weeks posttreatment (80%-88%) were comparable regardless of baseline renal function but lower in cirrhosis.

Management of Chronic Hepatitis C in End-stage Renal Disease

Treatment for chronic viral hepatitis C has advanced dramatically to current standard of care all-oral direct-acting antiviral regimens with relatively short treatment duration and high efficacy. Patients with comorbid end-stage renal disease have constituted a "special patient population" with data and treatment options lagging behind that of the broader population of patients with chronic hepatitis C until recently. Herein we review the current evidence base for direct-acting antiviral therapy in this population. We provide a suggested algorithm for the evaluation of such patients for therapy. We highlight special considerations in regards to the choice of regimen, duration, and timing in regards to potential kidney transplantation.

Effectiveness and security of chronic hepatitis C treatment in coinfected patients in real-world

Background HIV-HCV coinfection produces high morbi-mortality. Direct-acting antivirals (DAAs) have shown high efficacy, although special attention should be paid to the risk of drug interactions. However, due to the lack of representativeness of coinfected patients in clinical trials, it is important to know real-world results. Objective To evaluate DAA treatment effectiveness in coinfected patients. We also analyse safety profile of DAA treatment and drug interactions between HCV and HIV therapy. Setting Descriptive study carried in a tertiary hospital of Spain Method HIV-HCV coinfected patients treated with DAAs between November 2014 and June 2016 were included. Main outcome measure Efficacy was measured in terms of sustained virologic response at week 12 after the end of therapy. Adverse events that led to treatment discontinuation were registered to evaluate the safety profile, and also drug interactions between DAAs and antiretroviral treatment were evaluated. Results Main HCV genotypes were 1a (34.9%) and 4 (24.5%). 51.9% were HCV previously treated, 54.7% had grade 4 liver fibrosis. SVR12 was reported in 90.6%. HCV treatment was well tolerated and there were no discontinuations because of adverse events. 30.2% of HIV treatments had to be modified before DAA treatment was started due to interactions, HIV suppression was not compromised. Conclusion DAA treatment in coinfected patients seems to be highly effective and secure. Evaluation of drug interactions must be a priority in order to maximize effectiveness and avoid toxicity.

Drug-Drug Interactions Between Direct-Acting Antivirals and Psychoactive Medications

Treatment options for chronic hepatitis C virus (HCV) infection have drastically changed since the development and licensing of new potent direct-acting antivirals (DAAs). The majority of DAAs are extensively metabolized by liver enzymes and have the ability to influence cytochrome P450 (CYP) enzymes. Additionally, these DAAs are both substrates and inhibitors of drug transporters, which makes the DAAs both possible victims or perpetrators of drug–drug interactions (DDIs). There is a high prevalence of mental illnesses such as depression or psychosis in HCV-infected patients; therefore, psychoactive medications are frequently co-administered with DAAs. The majority of these psychoactive medications are also metabolized by CYP enzymes but remarkably little information is available on DDIs between psychoactive medications and DAAs. Hence, the aim of this review is to provide an overview of the interaction mechanisms between DAAs and psychoactive agents. In addition, we describe evidenced-based interactions between DAAs and psychoactive drugs and identify safe options for the simultaneous treatment of mental illnesses and chronic HCV infection.

An insight into the molecular characteristics of hepatitis C virus for clinicians

Hepatitis C virus (HCV) consists of envelope proteins, core proteins, and genome RNA. The structural genes and non-structural genes in the open reading frame of its genome encode functional proteins essential to viral life cycles, ranging from virus attachment to progeny virus secretion. After infection, the host cells suffer damage from virus-induced oxidative stress, steatosis, and activation of proto-oncogenes. Every process during the viral life cycle can be considered as targets for direct acting antivirals. However, protective immunity cannot be easily acquired for the volatility in HCV antigenic epitopes. Understanding its molecular characteristics, especially pathogenesis and targets the drugs act on, not only helps professionals to make optimal therapeutic decisions, but also helps clinicians who do not specialize in infectious diseases/hepatology to provide better management for patients. This review serves to provide an insight for clinicians and this might provide a possible solution for any possible collision.

Rad51 Interacts with Non-structural 3 Protein of Hepatitis C Virus and Regulates Viral Production

Hepatitis C virus (HCV) is a leading cause of chronic liver disease affecting over 170 million people worldwide. Chronic infection with HCV progresses to liver fibrosis, cirrhosis, and hepatocellular carcinoma. HCV exploits host cellular factors for viral propagation. To investigate the cellular factors required for HCV propagation, we screened a siRNA library targeting human cell cycle genes using cell culture grown HCV-infected cells. In the present study, we selected and characterized a gene encoding Rad51. Rad51, a member of a conserved recombinase family, is an essential factor for homologous recombination and repair of double-strand DNA breaks. We demonstrated that siRNA-mediated knockdown of Rad51 significantly inhibited HCV propagation without affecting HCV RNA replication. Silencing of Rad51 impaired secretion of infectious HCV particles and thus intracellular viruses were accumulated. We showed that HCV NS3 specifically interacted with Rad51 and accumulated Rad51 in the cytosol. Furthermore, Rad51 was coprecipitated with NS3 and HCV RNA. By employing membrane flotation and protease protection assays, we also demonstrated that Rad51 was co-fractionated with HCV NS3 on the lipid raft. These data indicate that Rad51 may be a component of the HCV RNA replication complex. Collectively, these data suggest that HCV may exploit cellular Rad51 to promote viral propagation and thus Rad51 may be a potential therapeutic target for HCV.

Effects of Mild and Moderate Renal Impairment on Ombitasvir, Paritaprevir, Ritonavir, Dasabuvir, and Ribavirin Pharmacokinetics in Patients with Chronic HCV Infection

BACKGROUND AND AIMS

Ombitasvir, paritaprevir (given with low-dose ritonavir), and dasabuvir are direct-acting antivirals (DAAs) used with or without ribavirin for the treatment of chronic hepatitis C virus (HCV) infection. The objective of this analysis was to evaluate the effect of renal function as determined by creatinine clearance (CrCL) on the pharmacokinetics of the DAAs, ritonavir, and ribavirin in HCV genotype 1-infected patients with or without cirrhosis.

METHODS

Total exposure, measured by area under the plasma concentration-time curve (AUC), was generated for the DAAs, ritonavir, and ribavirin using population pharmacokinetic modeling of data (N = 2093 patients) from 6 Phase 3 studies and 1 Phase 2 study. The effect of CrCL on the AUC values of each DAA, ritonavir, and ribavirin was separately evaluated and adjusted for any significant patient-specific covariates including, age, sex, body weight, cirrhosis, and Asian race in multiple linear regression analysis. Using the final models, AUC values were predicted for patients with normal renal function (CrCL = 105 mL/min), mild renal impairment (CrCL = 75 mL/min) and moderate renal impairment (CrCL = 45 mL/min).

RESULTS

CrCL was not a statistically significant predictor of DAA or ritonavir AUC values. Age, sex, and cirrhosis were significant covariates for the AUC values of all the DAAs and body weight was a significant covariate for the AUC values of ombitasvir and dasabuvir. Asian race was significant only for dasabuvir. Only age and sex were statistically significant predictors for the AUC values of ritonavir. CrCL showed a significant relationship with the ribavirin AUC values, consistent with ribavirin's renal excretion. Age, sex, body weight, and cirrhosis were also significant covariates for the AUC values of ribavirin. The DAA and ritonavir AUC values were comparable (≤10 % difference) among different levels of renal function, while ribavirin AUC values were up to 17 % higher in mild/moderate renal impairment compared with normal renal function.

CONCLUSIONS

No dose adjustments are needed for the 3D regimen in HCV genotype-1 infected patients with mild or moderate renal impairment. Ribavirin doses should be adjusted for renal impairment as recommended in the ribavirin label.

Changes in renal function indices in cirrhotic chronic hepatitis C patients treated with sofosbuvir-containing regimens

This study aimed to explore changes in hepatic and renal function indices in chronic hepatitis C (CHC) patients treated with direct-acting antivirals (DAAs). Forty-three CHC patients treated with sofosbuvir (SOF)-containing regimens were enrolled. At the end of treatment, the estimated glomerular filtration rate (eGFR) level was significantly decreased and the serum creatinine (Scr) and uric acid (UA) levels were significantly increased compared with baseline levels (eGFR: 86.7 ± 20.4 vs 80.5 ± 21.3, P₀₁ = 0.005; Scr: 83.9 ± 19.1 vs 89.6 ± 21.1, P₀₁ < 0.001; UA: 323.7± 86.2 vs 358.5 ± 93.2, P₀₁ < 0.001); no significant improvements were observed at 24 w post-treatment (eGFR: 86.7 ± 20.4 vs 81.4 ± 18.6, P₀₂ = 0.013; Scr: 83.6 ± 17.9 vs 87.9 ± 18.3, P₀₂ = 0.014; UA: 320.8 ± 76.3 vs 349.3 ± 91.0, P₀₂ = 0.004). When the patients were grouped by liver conditions, non-cirrhotic patients and cirrhotic patients had decreased eGFR levels and increased Scr levels at the end of treatment; at 24 w post-treatment, the eGFR and Scr levels were significantly improved in non-cirrhotic patients (88.4 ± 21.7 vs 83.8 ± 18.5, P₀₂ = 0.142; 84.4 ± 20.4 vs 87.0 ± 16.9, P₀₂ = 0.088), while no obvious improvements were observed in cirrhotic patients (84.3 ± 18.7 vs 78.1 ± 18.6, P₀₂ = 0.002; 83.2 ± 17.7 vs 89.2 ± 20.6, P₀₂ = 0.006). Clinical physicians should closely monitor renal function in patients treated with SOF-containing regimens, especially in cirrhotic patients.

Direct Acting Anti-hepatitis C Virus Drugs: Clinical Pharmacology and Future Direction

Chronic hepatitis C virus (HCV) infection is a leading cause of chronic liver disease. The introduction of direct acting antiviral agents (DAAs) for its treatment represents a major advance in terms of sustained virologic response (SVR) rates and adverse effect profiles. Mechanistically, DAAs inhibit specific HCV non-structural proteins (NS) that are vital for its replication. Boceprevir, telaprevir, simeprevir, asunaprevir, grazoprevir and paritaprevir are NS3/4A inhibitors. Ombitasvir, ledipasvir, daclatasvir, elbasvir and velpatasvir are NS5A inhibitors. Sofosbuvir and dasabuvir are NS5B inhibitors. Currently, a combination of two or more DAAs is the corner stone for the treatment of HCV infection. However, the success of DAA therapy is facing several challenges, including the potential of drug-drug interactions and resistant variance. Moreover, the shortage of relevant clinical pharmacological data and drug interaction regarding DAA is a clinical concern. The present review discusses the clinical pharmacology of DAAs with special emphasis on drug-drug interaction.

Real-life data on potential drug-drug interactions in patients with chronic hepatitis C viral infection undergoing antiviral therapy with interferon-free DAAs in the PITER Cohort Study

BACKGROUND

There are few real-life data on the potential drug-drug interactions (DDIs) between anti-HCV direct-acting antivirals (DAAs) and the comedications used.

AIM

To assess the potential DDIs of DAAs in HCV-infected outpatients, according to the severity of liver disease and comedication used in a prospective multicentric study.

METHODS

Data from patients in 15 clinical centers who had started a DAA regimen and were receiving comedications during March 2015 to March 2016 were prospectively evaluated. The DDIs for each regimen and comedication were assigned according to HepC Drug Interactions (www.hep-druginteractions.org).

RESULTS

Of the 449 patients evaluated, 86 had mild liver disease and 363 had moderate-to-severe disease. The use of a single comedication was more frequent among patients with mild liver disease (p = 0.03), whereas utilization of more than three drugs among those with moderate-to-severe disease (p = 0.05). Of the 142 comedications used in 86 patients with mild disease, 27 (20%) may require dose adjustment/closer monitoring, none was contraindicated. Of the 322 comedications used in 363 patients with moderate-to-severe liver disease, 82 (25%) were classified with potential DDIs that required only monitoring and dose adjustments; 10 (3%) were contraindicated in severe liver disease. In patients with mild liver disease 30% (26/86) used at least one drug with a potential DDI whereas of the 363 patients with moderate-to-severe liver disease, 161 (44%) were at risk for one or more DDI.

CONCLUSIONS

Based on these results, we can estimate that 30-44% of patients undergoing DAA and taking comedications are at risk of a clinically significant DDI. This data indicates the need for increased awareness of potential DDI during DAA therapy, especially in patients with moderate-to-severe liver disease. For several drugs, the recommendation related to the DDI changes from "dose adjustment/closer monitoring", in mild to moderate liver disease, to "the use is contraindicated" in severe liver disease.

Managing drug-drug interactions with new direct-acting antiviral agents in chronic hepatitis C

Several direct-acting antiviral agents (DAAs) have marketing authorization in Europe and in the USA and have changed the landscape of hepatitis C treatment: each DAA has its own metabolism and drug-drug interactions (DDIs), and managing them is a challenge. To compile the pharmacokinetics and DDI data of the new DAA and to provide a guide for management of DDI. An indexed MEDLINE search was conducted using the keywords: DAA, hepatitis C, simeprevir, daclatasvir, ledipasvir, sofosbuvir, 3D regimen (paritaprevir/ritonavir, ombitasvir, dasabuvir), DDI and pharmacokinetics. Data were also collected from hepatology, and infectious disease and clinical pharmacology conferences abstracts. Food can play a role in the absorption of DAAs. Most of the interactions are linked to metabolism (cytochrome P450-3 A4 [CYP3A4]) or hepatic and/or intestinal transporters (organic anion-transporting polypeptide and P-glycoprotein [P-gp]). To a lesser extent other pathways can be involved such as breast cancer resistance protein transporter or UDP-glucuronosyltransferase metabolism. DDI are more likely to occur with 3D regimen, daclatasvir, simeprevir and ledipasvir, as they are all both substrates and inhibitors of P-gp and/or CYP3A4, than with sofosbuvir. They can increase concentrations of coadministered drugs and their concentrations may be influenced by P-gp or CYP3A4 inducers or inhibitors. Overdosage or low dosage can be encountered with potent inducers or inhibitors of CYP3A4 or drugs with a narrow therapeutic range. The key to interpret DDI data is a good understanding of the pharmacokinetic profiles of the drugs involved. Their ability to inhibit CYP450-3A4 and transporters (hepatic and/or intestinal) can have significant clinical consequences.

Treatment optimization for HIV/HCV co-infected patients

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections affect millions of persons around the globe and cause profound morbidity and mortality. A major intersection exists between these two epidemics, with HCV infection being more common in persons with HIV than in the general population, largely due to shared routes of transmission. HCV co-infection increases risk for liver- and non-liver-related morbidity and mortality, making HCV treatment a priority in HIV co-infected persons, but the treatment of HCV in co-infected patients has been daunting for multiple reasons. Until recently, HCV treatment has frequently been deferred due to the low rates of cure, significant adverse effects, burdensome duration of therapy and drug-drug interactions with HIV antiretroviral medications. Untreated HCV has resulted in significant health consequences for the millions of those infected and has led to multiple downstream impacts on our healthcare systems around the world. The development of a remarkable number of new HCV direct-acting agents (DAAs) that are significantly more efficacious and tolerable than the previous interferon-based regimens has transformed this important field of medicine, with the potential to dramatically reduce the burden of infection and improve health outcomes in this population. This review will summarize the epidemiology and clinical impact of HIV/HCV co-infection and current approaches to the treatment of HCV in HIV/HCV co-infected patients.

The majority of hepatitis C patients treated with direct acting antivirals are at risk for relevant drug-drug interactions

BACKGROUND

Direct-acting antivirals have improved treatment of chronic hepatitis C virus infection significantly. Direct-acting antivirals inhibit/induce and can also be substrates of drug-metabolising enzymes and transporters. This increases the risk for drug-drug interactions.

OBJECTIVE

The purpose of this study was to predict drug-drug interactions with co-medication used by hepatitis C virus-infected patients.

METHODS

We assembled a nationwide cohort of hepatitis C patients and collected cross-sectional data on co-medication use. We compiled a list of currently available direct-acting antiviral regimens and cross-checked for potential drug-drug interactions with used co-medication.

RESULTS

The cohort included 461 patients of which 77% used co-medication. We identified 260 drugs used as co-medication. Antidepressants (7.4%), proton pump inhibitors (7.1%) and benzodiazepines (7.1%) were most frequently used. Of the patients, 60% were at risk for a clinically relevant drug-drug interaction with at least one of the direct-acting antiviral regimens. Interactions were most common with paritaprevir/ritonavir/ombitasvir/dasabuvir and least interactions were predicted with grazoprevir/elbasvir.

CONCLUSION

Co-medication use is rich in frequency and diversity in chronic hepatitis C patients. The majority of patients are at risk for drug-drug interactions which may affect efficacy or toxicity of direct-acting antivirals or co-medication. The most recently introduced direct-acting antivirals are associated with a lower risk of drug-drug interactions.

A Review of Daclatasvir Drug-Drug Interactions

The treatment of hepatitis C virus (HCV) infection has been revolutionized in recent years by the development of direct-acting antiviral regimens that do not contain peginterferon (pegIFN) and/or ribavirin (RBV). While direct-acting antiviral-based regimens have been shown to be greatly superior to pegIFN/RBV-based regimens in terms of efficacy and safety, they have a greater susceptibility to drug-drug interactions (DDIs). Daclatasvir (DCV)-the benchmark pangenotypic nonstructural protein 5A inhibitor-has been shown to be efficacious and generally well tolerated in partnership with other HCV direct-acting antivirals, including sofosbuvir, asunaprevir (ASV), and ASV plus beclabuvir. DCV may be the object of a DDI via the induction or inhibition of cytochrome P450 (CYP) 3A4 and/or P-glycoprotein (P-gp) by the concomitant medication, or the precipitant of a DDI via DCV-based induction/inhibition of CYP 3A4 or inhibition of P-gp, organic anion transporting polypeptide 1B1/B3, and/or breast cancer resistance protein. This article presents an overview of the drug interaction studies conducted during the clinical development of DCV, the findings of these studies that led to the guidance on concomitant medication use and dosage along with any required DCV dose modifications, and the use of the known metabolic pathway of DCV to guide concomitant dosing where direct drug-drug studies have not been conducted. The robust characterization of the DCV clinical pharmacology program has demonstrated that DCV has few or no clinically relevant DDIs with medications with which it is likely to be co-administered, and the majority of DDIs that do occur can be predicted and easily managed.

FUNDING

Bristol-Myers Squibb.

Safety of direct antiviral agents in the management of hepatitis C

INTRODUCTION

Hepatitis C virus is a hepatotropic virus that generally leads to chronic hepatitis and various harmful sequelae. The lone standard of treatment has been pegylated interferon and ribavirin, which produces a modest response and many side effects. However, a new era of management was declared with the introduction of various directly acting antiviral agents. Areas covered: Recent direct antiviral agents (DAAs) primarily target the non-structural proteins of the virus and affect its replication. These agents successfully achieve a sustained virologic response. However, some serious side effects were reported, which may or may not be drug-related effects. Important drug-drug interactions were also reported. The treating physician should be reasonably familiar with these effects. We review the safety profile of these agents in the management of HCV. Expert opinion: Cautious concomitant drug intake is necessary for the new HCV therapies. Future HCV management will depend on interferon-free and likely ribavirin-free regimens. The co-administration of direct antiviral agents of different classes increases the probability of side effects and drug-drug interactions.

Deep sequencing of hepatitis C virus reveals genetic compartmentalization in cerebrospinal fluid from cognitively impaired patients

BACKGROUND & AIMS

Hepatitis C virus (HCV) causes neuropsychiatric impairment and fatigue with recent studies suggesting HCV invasion of the central nervous system (CNS). Our previous finding that endothelial cells from the blood-brain barrier support HCV infection warrants further investigation to elucidate whether the CNS can serve as a reservoir for independent HCV evolution.

METHODS

Cerebrospinal fluid (CSF) and plasma from six HCV-infected patients without liver disease or co-morbidities together with plasma from six healthy subjects were profiled for markers of immune activation and viral quasispecies measured by deep sequencing. Unsupervised data analyses were used to identify any associations between cytokine activation markers and clinical outcomes.

RESULTS

Four of six HCV-infected patients showed significant evidence of cognitive dysfunction and fatigue. Deep sequencing revealed independent viral evolution within the CNS of two cognitively impaired patients. Principal component analysis of peripheral cytokines demonstrated that individuals without cognitive impairment clustered together while a distinct cytokine pattern emerged with patients exhibiting cognitive dysfunction and fatigue.

CONCLUSIONS

Deep sequencing demonstrated unique viral variants in the CSF of two cognitively impaired patients consistent with CNS replication or sequestration. Meanwhile, compartmentalization was absent in infected patients with no neurocognitive impairment. Examination of cytokine profiles in HCV-infected patients with cognitive dysfunction revealed elevated peripheral cytokine levels resulting in a distinct cytokine profile that may be related to cognitive impairment or viral penetration into the CNS. Further studies to determine the significance of unique HCV variants within the CNS are warranted.

The efficacy and safety of direct acting antiviral treatment and clinical significance of drug-drug interactions in elderly patients with chronic hepatitis C virus infection

BACKGROUND

Direct antiviral therapies for chronic hepatitis C virus (HCV) infection have expanded treatment options for neglected patient populations, including elderly patients who are ineligible/intolerant to receive interferon (IFN)-based therapy.

AIM

To investigate the efficacy, tolerability and potential for drug-drug interactions (DDIs) of IFN-free treatment in patients aged ≥65 years in a large real-world cohort.

METHODS

A total of 541 patients were treated with different combinations of direct antiviral agents (DAAs: ledipasvir/sofosbuvir ±ribavirin; daclatasvir/sofosbuvir ±ribavirin; paritaprevir/ombitasvir ±dasabuvir ±ribavirin or simeprevir/sofosbuvir ±ribavirin in genotype 1/4, and daclatasvir/sofosbuvir ±ribavirin or sofosbuvir/ribavirin in genotype 2/3). Efficacy, safety and potential DDIs were analysed and compared between patients aged <65 years (n = 404) and patients aged ≥65 years (n = 137) of whom 41 patients were ≥75 years.

RESULTS

Sustained virological response rates were 98% and 91% in patients aged ≥65 years and <65 years, respectively. Elderly patients took significantly more concomitant medications (79% vs. 51%; P < 0.0001). The number of concomitant drugs per patient was highest in patients ≥65 years with cirrhosis (median, three per patient; range, 0-10). Based on the hep-druginteractions database, the proportion of predicted clinically significant DDIs was significantly higher in elderly patients (54% vs. 28%; P < 0.0001). The number of patients who experienced treatment-associated adverse events was similar between the two age groups (63% vs. 65%; P = n.s.).

CONCLUSIONS

Elderly patients are at increased risk for significant DDIs when treated with DAAs for chronic HCV infection. However, with careful pre-treatment assessment of concomitant medications, on-treatment monitoring or dose-modifications, significant DDIs and associated adverse events can be avoided.

HIV/HCV Antiviral Drug Interactions in the Era of Direct-acting Antivirals

Therapy for human immunodeficiency virus (HIV) and chronic hepatitis C has evolved over the past decade, resulting in better control of infection and clinical outcomes; however, drug-drug interactions remain a significant hazard. Joint recommendations from the American Association for the Study of Liver Diseases and the Infectious Diseases Society of America regarding drug-drug interactions between HIV antiretroviral agents and direct-acting antiviral agents for treatment of hepatitis C virus (HCV) infection are reviewed here. This review is oriented to facilitate appropriate selection of an antiviral therapy regimen for HCV infection based on the choice of antiretroviral therapy being administered and, if necessary, switching antiretroviral regimens.