Dosing Recommendations for Concomitant Medications During 3D Anti-HCV Therapy

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.

Non-Invasive Indirect Markers of Liver Fibrosis after Interferon-Free Treatment for Hepatitis C

The effectiveness of interferon-free therapy during the course of HCV infection has already been confirmed. Liver fibrosis can be assessed in several ways, from biopsies to imaging tests. The present study evaluates the usefulness of non-invasive indirect biomarkers of liver fibrosis (APRI, GAPRI, FORNS, FIB-4, the AP index and HUI score) as markers of the effective treatment of HCV with the 3D regimen. Blood samples were collected from 70 patients suffering from chronic hepatitis C. Patients received the 3D AbbVie regimen for hepatitis C. All patients had HCV genotype 1b. The APRI, GAPRI, FIB-4, FORNS, HUI and AP index (age–platelet score) values were calculated with their respective algorithms. The stage of fibrosis was evaluated on the basis of a liver biopsy and confirmed by FibroScan-based transient elastography. An undetectable level of HCV RNA after 12 weeks of treatment with the 3D regimen indicates 100% eradication of hepatitis C virus. After the treatment, non-invasive indirect markers of liver fibrosis achieved levels below the limit for significant fibrosis, Thus, non-invasive indirect biomarkers of hepatic fibrosis failed to detect the presence of significant fibrosis, which was proved in histopathological examination. However, the eradication of hepatitis C virus by means of the 3D regimen treatment does not mean that patients were completely cured.

Real-world clinical outcomes among individuals with chronic HCV infection in China: CCgenos study

BACKGROUND

This 5-year follow-up of the CCgenos cross-sectional study aimed to observe real-life outcomes in a cohort of 997 Han Chinese patients with chronic HCV infection and to explore the impacts of HCV genotype, patient characteristics and treatment status.

METHODS

Clinical information and centralized HCV RNA measures were collected every 6/3 months for untreated/treated patients. Overall disease progression was defined as ≥1 of: de novo development of cirrhosis, Child-Turcotte-Pugh score increased by ≥2 points (if cirrhosis at baseline), progression to decompensated cirrhosis, hepatocellular carcinoma (HCC), liver transplant or death. Cox regression assessed risk factors for the time from estimated infection to cirrhosis or HCC. Logistic regression assessed risk factors for incidence rates of cirrhosis and overall disease progression.

RESULTS

281 of 514 patients enrolled across China completed 5 years of follow-up. Overall disease progression occurred in 36/364 (9.9%) treated patients and 35/148 (23.6%) untreated patients (odds ratio = 0.35; 95% CI 0.21, 0.59; P<0.0001). Overall disease progression occurred in 6/231 (2.6%) patients achieving sustained virological response at 24 weeks (SVR24) versus 11/82 (13.4%) who did not (P=0.0002). Cirrhosis development was significantly associated with abnormal aspartate aminotransferase (AST), age ≥40 years, body mass index ≥28 kg/m², HCV GT1, platelet count <100×10⁹/l, and AST to platelet ratio index (APRI) ≥2 (multivariate Cox regression, P<0.05). HCC was significantly associated with HCV GT1 and platelet count <100×10⁹/l (multivariate Cox regression, P<0.05).

CONCLUSIONS

Achieving SVR24 significantly reduced the probability of overall disease progression but no significant difference was seen for both cirrhosis and HCC during 5 years of follow-up.

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.

Minor contribution of CYP3A5 to the metabolism of hepatitis C protease inhibitor paritaprevir in vitro

Paritaprevir (PTV) is a non-structural protein 3/4A protease inhibitor developed for the treatment of hepatitis C disease as a fixed dose combination of ombitasvir (OBV) and ritonavir (RTV) with or without dasabuvir. The aim of this study was to evaluate the effects of cytochrome P450 (CYP) 3A5 on in vitro PTV metabolism using human recombinant CYP3A4, CYP3A5 (rCYP3A4, rCYP3A5) and human liver microsomes (HLMs) genotyped as either CYP3A5*1/*1, CYP3A5*1/*3 or CYP3A5*3/*3. The intrinsic clearance (CL_int, V_max/K_m) for the production of a metabolite from PTV in rCYP3A4 was 1.5 times higher than that in rCYP3A5. The PTV metabolism in CYP3A5*1/*1 and CYP3A5*1/*3 HLMs expressing CYP3A5 was comparable to that in CYP3A5*3/*3 HLMs, which lack CYP3A5. CYP3A4 expression level was significantly correlated with PTV disappearance rate and metabolite formation. In contrast, there was no such correlation found for CYP3A5 expression level. This study represents that the major CYP isoform involved in PTV metabolism is CYP3A4, with CYP3A5 having a minor role in PTV metabolism. The findings of the present study may provide foundational information on PTV metabolism, and may further support dosing practices in HCV-infected patients prescribed PTV-based therapy.

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.

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 Dasabuvir

Dasabuvir is a nonstructural (NS) 5B non-nucleoside inhibitor of the hepatitis C virus (HCV) used in combination with ombitasvir/paritaprevir/ritonavir for the treatment of chronic HCV infection. It is primarily metabolized by cytochrome P450 (CYP) 2C8, with a minor contribution from CYP3A. Biotransformation of dasabuvir forms the M1 metabolite, which retains antiviral activity. Dasabuvir exhibits linear pharmacokinetics with a terminal half-life of approximately 5-8 h, allowing for twice-daily dosing. The M1 metabolite of dasabuvir is the major metabolite in plasma and has a half-life similar to that of dasabuvir. Dasabuvir exposures in Asian subjects are comparable with Caucasian subjects. The pharmacokinetic characteristics of dasabuvir are similar between healthy subjects and HCV-infected patients, and are not appreciably altered by mild, moderate, or severe renal impairment or dialysis. Dasabuvir pharmacokinetic parameters were not significantly altered in subjects with mild or moderate hepatic impairment; however, exposures were significantly increased in subjects with severe hepatic impairment. Dasabuvir should be administered with food to maximize absorption. Coadministration of dasabuvir with a strong CYP2C8 inhibitor increased dasabuvir exposures by greater than tenfold, whereas coadministration with strong CYP3A inhibitors increased dasabuvir exposures by less than 50%. Furthermore, coadministration of dasabuvir with a CYP3A inducer decreased dasabuvir exposures by 55-70%. Coadministration of dasabuvir with strong CYP2C8 inhibitors or strong CYP3A/CYP2C8 inducers is contraindicated. Results from several drug interaction studies demonstrated that dasabuvir in combination with ombitasvir/paritaprevir/ritonavir can be coadministered with most 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.

Comorbidities and co-medications in populations with and without chronic hepatitis C virus infection in Japan between 2015 and 2016

BACKGROUND

Direct-acting anti-viral agents have improved the treatment of chronic hepatitis C virus (HCV) infection, but this treatment is challenging for patients using co-medications because of potential drug-drug interactions. This study aimed to examine the comorbidities and co-medications of Japanese chronic HCV patients by age group, compared with a non-HCV patient population.

METHODS

This was a retrospective observational study using a hospital-based medical claims database. We extracted data of patients with chronic HCV aged ≥18 years, and age-, sex-, and hospital-matched patients without HCV, for the period from January 2015 to November 2016, and then examined chronic comorbidities, long-term co-medications, and medications prescribed at least once during the study period.

RESULTS

We analysed data from 128,967 chronic HCV patients and 515,868 non-HCV patients. The median age was 70 years, and 51.0% of patients were male. More chronic HCV patients than non-HCV patients (70.5% vs. 47.1%) had at least one comorbidity, and older patients had more comorbidities than younger patients. The most common comorbidities in chronic HCV patients were diseases of oesophagus, stomach and duodenum (41.7%), followed by hypertensive diseases (31.4%). Chronic HCV patients used co-medications more commonly than non-HCV patients, and older patients used more co-medications. The most common long-term co-medications in chronic HCV patients were proton pump inhibitors (14.0%), which were prescribed to 31.9% of chronic HCV patients at least once during the study period.

CONCLUSIONS

Patients with chronic HCV in Japan had more comorbidities than patients without chronic HCV regardless of age. Particularly older patients, who constitute the majority of the HCV patient population in Japan, commonly had multiple comorbidities and used co-medications. To optimise HCV treatment, physicians need to know the exact medication profiles of patients and take appropriate action to manage drug-drug interactions.

Potential drug-drug interactions of OMBITASVIR, PARITAPREVIR/ritonavir ± DASABUVIR ± ribavirin in clinical practice

BACKGROUND & AIMS

Drug-drug interactions (DDIs) with ombitasvir/paritaprevir/ritonavir with or without dasabuvir and with or without ribavirin (OBV/PTV/r ± DSV ± RBV) are common in clinical trials. Our aim was to analyze the prevalence and management of potential DDIs and adverse events (AEs) related to DDIs in patients with chronic hepatitis C (CHC) receiving OBV/PTV/r ± DSV ± RBV in clinical practice.

METHODS

177 CHC patients started OBV/PTV/r ± DSV ± RBV in 4 Spanish hospitals and were screened for potential DDIs using the University of Liverpool database. Patients were classified according to the most serious potential DDIs at baseline and AEs during therapy.

RESULTS

At least one potential DDI was found in 110 (62.1%) patients: 100 (56.5%) had at least one manageable potential DDI and 10 (5.6%) at least one contraindicated. Patients with potential DDIs were receiving a higher number of concomitant drugs (4 vs. 2, P < 0.001). Routine medication was modified at baseline due to potential DDIs in 49 (27.7%) patients. During antiviral treatment, 67 (37.9%) patients presented at least one AE. In 9 (4.5%) patients, a DDI was suspected between OBV/PTV/r ± DSV ± RBV and the concomitant drug, requiring antiviral discontinuation in 4 patients.

CONCLUSIONS

Potential DDIs are frequent with OBV/PTV/r ± DSV ± RBV, although a change in baseline medication is made in only one-quarter of patients. More than half of potential DDIs were only followed, and only 5% of patients developed AEs in which the implication of DDIs could not be excluded.

Pharmacokinetics of Tacrolimus and Cyclosporine in Liver Transplant Recipients Receiving 3 Direct-Acting Antivirals as Treatment for Hepatitis C Infection

BACKGROUND

Interactions between tacrolimus and cyclosporine (CSA) and the 3 direct-acting antiviral regimen (3D) of ombitasvir, paritaprevir/ritonavir, and dasabuvir necessitate a priori dose adjustments for the immunosuppressants to achieve desired levels. Modeling and simulations based on data in healthy subjects predicted that tacrolimus 0.5 mg every 7 days or 0.2 mg every 3 days, and CSA at one-fifth the total daily dose administered once daily, would achieve desired trough concentrations (Ctrough) during 3D treatment. The success of these dosing recommendations was evaluated by analyzing pharmacokinetic data from liver transplant recipients in the CORAL-I study.

METHODS

A population pharmacokinetic model was developed using tacrolimus dosing and Ctrough data before and during 3D treatment (n = 29). The model was used to simulate various tacrolimus dosing regimens and predict tacrolimus concentration-time profiles during 3D treatment. CSA Ctrough data before and during 3D treatment (n = 5) were also summarized.

RESULTS

A one-compartment model with first-order absorption adequately described tacrolimus pharmacokinetic profiles during the first 4 weeks of 3D treatment. Estimated tacrolimus Ctrough values (median; interquartile range) before and during 3D treatment were comparable (5.7 ng/mL; 4.9-6.5 ng/mL versus 5.2 ng/mL; 4.2-6.3 ng/mL, respectively). Based on simulations, in a patient with a starting Ctrough of 6 ng/mL, 0.5 mg tacrolimus every 7 or 14 days or 0.2 mg tacrolimus every 3 days will result in Ctrough levels of 6-9 ng/mL, 4-6 ng/mL, and 6-10 ng/mL, respectively, during 3D treatment. For CSA, Ctrough values (median; interquartile range) before and during 3D treatment were comparable (126 ng/mL; 94-140 ng/mL versus 104 ng/mL; 82-140 ng/mL).

CONCLUSIONS

Observed data for tacrolimus and CSA in liver transplant recipients confirm that the recommended dosing strategies are valid and therapeutic levels of immunosuppression can be maintained during 3D treatment.

Dose- and Formulation-Dependent Non-Linear Pharmacokinetic Model of Paritaprevir, a Protease Inhibitor for the Treatment of Hepatitis C Virus Infection: Combined Analysis from 12 Phase I Studies

BACKGROUND AND OBJECTIVES

Paritaprevir is a direct-acting antiviral agent that is a component of approved multidrug regimens used in the treatment of hepatitis C virus (HCV) infection. A population pharmacokinetic model for paritaprevir was developed using data from formulation, bioavailability, and drug-drug interaction studies that evaluated the pharmacokinetics of paritaprevir (coadministered with ritonavir to enhance exposure) with or without ombitasvir and/or dasabuvir at different paritaprevir dose levels.

METHODS

A non-linear mixed-effects modeling approach was applied to data from 12 phase I, single- and multiple-dose studies that enrolled a total of 369 healthy volunteers. Age, sex, race, ethnicity, body weight, body surface area, body mass index, and baseline creatinine clearance were evaluated as covariates during model development. In addition, the influences of dose, formulation, and concomitant medications (e.g. ombitasvir and dasabuvir) on paritaprevir bioavailability were included in the model.

RESULTS

A two-compartment model with first-order absorption and elimination optimally described paritaprevir plasma concentration-time data. Paritaprevir bioavailability was formulation- and dose-dependent, and increased supraproportionally. The accumulation of paritaprevir was 1.57-fold on repeated dosing compared with the first dose. Coadministration of dasabuvir increased paritaprevir bioavailability by 59 %; however, ombitasvir coadministration did not affect the pharmacokinetic profile of paritaprevir. No subject-specific covariate influenced the paritaprevir pharmacokinetics. The pharmacokinetic model was robust in bootstrap evaluations and was consistent with observed data based on diagnostic goodness-of-fit plots and visual predictive checks.

CONCLUSION

The complex pharmacokinetics of paritaprevir were well described by the model, which can be used as a basis for clinical trial dosing and further evaluations in patients with HCV.

Drug-Drug Interactions Between the Anti-Hepatitis C Virus 3D Regimen of Ombitasvir, Paritaprevir/Ritonavir, and Dasabuvir and Eight Commonly Used Medications in Healthy Volunteers

Background and Aims

The three direct-acting antiviral regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir (3D regimen) is approved for treatment of hepatitis C virus (HCV) genotype 1 infection. Drug–drug interaction (DDI) studies of the 3D regimen and commonly used medications were conducted in healthy volunteers to provide information on coadministering these medications with or without dose adjustments.

Methods

Three phase I studies evaluated DDIs between the 3D regimen (ombitasvir/paritaprevir/ritonavir 25/150/100 mg once daily + dasabuvir 250 mg twice daily) and hydrocodone bitartrate/acetaminophen (5/300 mg), metformin hydrochloride (500 mg), diazepam (2 mg), cyclobenzaprine hydrochloride (5 mg), carisoprodol (250 mg), or sulfamethoxazole/trimethoprim (SMZ/TMP) (800/160 mg twice daily), all administered orally. DDI magnitude was determined using geometric mean ratios and 90 % confidence intervals for the maximum plasma concentration (C_max) and area under the plasma concentration–time curve (AUC).

Results

Changes in exposures (C_max and AUC geometric mean ratios) of acetaminophen, metformin, sulfamethoxazole, trimethoprim, and diazepam were ≤25 % upon coadministration with the 3D regimen. The C_max and AUC of nordiazepam, an active metabolite of diazepam, increased by 10 % and decreased by 44 %, respectively. Exposures of cyclobenzaprine and carisoprodol decreased by ≤40 and ≤46 %, respectively, whereas exposures of hydrocodone increased up to 90 %. Ombitasvir, paritaprevir, ritonavir, and dasabuvir exposures changed by ≤25 %, except for a 37 % decrease in paritaprevir C_max with metformin and a 33 % increase in dasabuvir AUC with SMZ/TMP.

Conclusions

Acetaminophen, metformin, sulfamethoxazole, and trimethoprim can be coadministered with the 3D regimen without dose adjustment. Higher doses may be needed for diazepam, cyclobenzaprine, and carisoprodol based on clinical monitoring. A 50 % lower dose and/or clinical monitoring should be considered for hydrocodone. No dose adjustment is necessary for the 3D regimen.

Discovery and preclinical development of dasabuvir for the treatment of hepatitis C infection

Hepatitis C virus (HCV) is a leading cause of liver-related morbidity and mortality. Positively, the introduction of new directly-acting antivirals (DAAs) have led to dramatic improvements in response rates to antiviral therapy. Furthermore, newer generations of DAAs have demonstrated better safety profiles as well as efficacy than older generations. Current treatment recommendations are based on different combinations of DAAs. Current combination therapies rely on agents that target the different steps of viral replication by using different molecules from various DAAs families. Areas covered: In this review, the authors summarize data from of one of the recently developed NS5B polymerase inhibitors, dasabuvir, formerly known as ABT-333. Herein, the authors discuss the drug discovery data for dasabuvir including data from preclinical, toxicological resistance studies. The authors also review dasabuvir's clinical efficacy across various clinical challenges, in addition to its limitations in clinical practice. Expert opinion: Dasabuvir represents an important medical advance when used as a combination therapy for HCV. Unfortunately, it does present limitations like low genotypic coverage and further research is still required to address some of the lingering issues.

Population pharmacokinetics of paritaprevir, ombitasvir, dasabuvir, ritonavir and ribavirin in hepatitis C virus genotype 1 infection: analysis of six phase III trials

AIM

The aim of the current study was to characterize the population pharmacokinetics of a triple direct-acting antiviral (DAA) regimen (3D) (ombitasvir, paritaprevir-ritonavir and dasabuvir) and adjunctive ribavirin, and estimate covariate effects in a broad spectrum of subjects with hepatitis C virus (HCV) genotype 1 infection.

METHODS

Pharmacokinetic data from six phase III studies and one phase II study in subjects receiving the currently approved doses of the 3D ± ribavirin regimen for treating HCV genotype 1 infection for 12 weeks or 24 weeks were characterized using separate population pharmacokinetic models, built using each component of the regimen from nonlinear mixed-effects methodology in NONMEM 7.3. In the models, demographic and clinical covariates were tested. Models were assessed via goodness-of-fit plots, visual predictive checks and bootstrap evaluations.

RESULTS

The population pharmacokinetic models for each component of the 3D ± ribavirin regimen (DAAs and ritonavir, n = 2348) and ribavirin (n = 1841) adequately described their respective plasma concentration-time data. Model parameter estimates were precise and robust, and all models showed good predictive ability. Significant covariate effects associated with apparent clearance and volume of distribution included age, body weight, gender, cirrhosis, HCV subtype, opioid or antidiabetic agent use, and creatinine clearance.

CONCLUSION

The population pharmacokinetics of the 3D ± ribavirin regimen components in HCV-infected patients were characterized using phase II and III HCV clinical trial data. Although several statistically significant covariates were identified, their effects were modest and not clinically meaningful to necessitate dose adjustments for any component of the 3D regimen.

Hepatitis C Virus: A Review of Treatment Guidelines, Cost-effectiveness, and Access to Therapy

Hepatitis C virus (HCV) infection remains a significant medical concern in the United States and around the world. It is still one of the leading causes of chronic liver disease, and, for more than 20 years, there has been little progress in the treatment of HCV infection. The advent of direct-acting antivirals (DAAs) initiated the era of high efficacy and well-tolerated medications with high cure rates. The efficacy of these medications has prompted many professional societies around the world to update their treatment guidelines to include DAAs as first-line treatment. Guidelines by the American Association for the Study of Liver Disease/Infectious Disease Society of America, World Health Organization, Asian-Pacific Association for the Study of Liver and the European Association for the Study of Liver have all incorporated DAAs into their treatment guidelines. Despite the promising data supporting these medications, however, their cost represents a limiting factor to their use, even though studies have shown DAAs to be cost-effective. In addition to the expense of these medications and limited resources, there are many barriers preventing patients from receiving this potentially life-saving treatment. In order to overcome these barriers, these issues need to be recognized and addressed.

Drug-Drug Interaction between the Direct-Acting Antiviral Regimen of Ombitasvir-Paritaprevir-Ritonavir plus Dasabuvir and the HIV Antiretroviral Agent Dolutegravir or Abacavir plus Lamivudine

The direct-acting antiviral regimen of 25 mg ombitasvir-150 mg paritaprevir-100 mg ritonavir once daily (QD) plus 250 mg dasabuvir twice daily (BID) is approved for the treatment of hepatitis C virus genotype 1 infection, including patients coinfected with human immunodeficiency virus. This study was performed to evaluate the pharmacokinetic, safety, and tolerability effects of coadministering the regimen of 3 direct-acting antivirals with two antiretroviral therapies (dolutegravir or abacavir plus lamivudine). Healthy volunteers (n = 24) enrolled in this phase I, single-center, open-label, multiple-dose study received 50 mg dolutegravir QD for 7 days or 300 mg abacavir plus 300 mg lamivudine QD for 4 days, the 3-direct-acting-antiviral regimen for 14 days, followed by the 3-direct-acting-antiviral regimen with dolutegravir or abacavir plus lamivudine for 10 days. Pharmacokinetic parameters were calculated to compare combination therapy with 3-direct-acting-antiviral or antiretroviral therapy alone, and safety/tolerability were assessed throughout the study. Coadministration of the 3-direct-acting-antiviral regimen increased the geometric mean maximum plasma concentration (Cmax) and the area under the curve (AUC) of dolutegravir by 22% (central value ratio [90% confidence intervals], 1.219 [1.153, 1.288]) and 38% (1.380 [1.295, 1.469]), respectively. Abacavir geometric mean Cmax and AUC values decreased by 13% (0.873 [0.777, 0.979]) and 6% (0.943 [0.901, 0.986]), while those for lamivudine decreased by 22% (0.778 [0.719, 0.842]) and 12% (0.876 [0.821, 0.934]). For the 3-direct-acting-antiviral regimen, geometric mean Cmax and AUC during coadministration were within 18% of measurements made during administration of the 3-direct-acting-antiviral regimen alone, although trough concentrations for paritaprevir were 34% (0.664 [0.585, 0.754]) and 27% (0.729 [0.627, 0.847]) lower with dolutegravir and abacavir-lamivudine, respectively. All study treatments were generally well tolerated, with no evidence of increased rates of adverse events during combination administration. These data indicate that the 3-direct-acting-antiviral regimen can be administered with dolutegravir or abacavir plus lamivudine without dose adjustment.

Effect of co-medications on paritaprevir, ritonavir, ombitasvir, dasabuvir and ribavirin pharmacokinetics: analysis of data from seven Phase II/III trials

BACKGROUND

The three drug direct-acting antiviral regimen (3D regimen) of ombitasvir, paritaprevir/ritonavir and dasabuvir, with and without ribavirin, was evaluated in one Phase II trial and six Phase III trials in over 2,300 HCV genotype-1-infected patients. Patients continued taking their protocol-permitted co-medications while receiving the 3D ± ribavirin regimen. The effects of the co-medications on exposures of the 3D regimen and ribavirin were examined.

METHODS

Population pharmacokinetic model-predicted steady-state area under the curve (AUC_24,ss) values were evaluated in the presence/absence of the co-medications. Interactions resulting in a greater than 50% reduction or 100% increase in an AUC_24,ss value were examined as covariates for an effect on apparent clearance (CL/F).

RESULTS

More than 1,200 co-medications belonging to 15 drug classes and/or 19 enzyme and transporter inhibitor and/or inducer categories were used concomitantly with the 3D regimen in the trials. Approximately 1,500 patients (65%) in Phase III trials received two or more co-medications from multiple drug classes or categories. No co-medication class/category decreased or increased ombitasvir, dasabuvir, ritonavir or ribavirin AUC_24,ss by more than half or twofold, respectively. Opioids, antipsychotics, anti-epileptics, antidiabetics and non-ethinyl estradiol-containing hormone replacement therapies appeared to have an effect (AUC_24,ss ratio ≤0.5 or ≥2.0) on paritaprevir exposures. However, when these classes were included in the paritaprevir population pharmacokinetic model, only opioids and antidiabetics had a statistically significant effect on CL/F, but with no clinically meaningful increase in exposures (≤55%).

CONCLUSIONS

No dose adjustment is necessary for the 3D ± ribavirin regimen when used with the co-medications included in this analysis as there were no clinically meaningful effects on exposures of the DAAs.

Evaluation of a Potential Interaction Between New Regimens to Treat Hepatitis C and Warfarin

OBJECTIVE

New regimens to treat hepatitis C virus infection have expanded the eligible patient population to include more patients receiving concurrent warfarin. The primary objective of this study was to assess whether a drug interaction occurs when these regimens are added to warfarin therapy.

METHODS

This was a retrospective cohort design using a nationwide database of the Veterans Affairs Health System. Patients on warfarin therapy treated with sofosbuvir or ombitasvir, paritaprevir-ritonavir, and dasabuvir (OBV-PTV/r-DSV) from March 2014 through October 2015 were identified. The warfarin dose response was calculated using a warfarin sensitivity index (WSI) defined as the steady-state INR divided by the mean daily warfarin dose. The primary outcome was the change in WSI from hepatitis C treatment initiation to completion.

RESULTS

The final sample consisted of 271 patients. The WSI decreased 23% from a mean baseline value of 0.53 to 0.39 (decrease of 0.14; 95% CI = 0.11 to 0.16; P < 0.001). OBV-PTV/r-DSV produced a significantly greater decrease than any sofosbuvir regimen. Concurrent ribavirin accounted for an additional decrease in warfarin sensitivity of -0.09 (95% CI = -0.06 to -0.12; P < 0.001). The percentage of subtherapeutic INR results increased from 26% prior to hepatitis C treatment to 58% during treatment.

CONCLUSIONS

Results indicate a clinically significant reduction in warfarin dose-response when hepatitis C treatment regimens were added to warfarin. They were most profound with OBV-PTV/r-DSV. Ribavirin was associated with an additive effect. Clinicians should be aware of this potential drug interaction to closely monitor and minimize subtherapeutic levels of anticoagulation.

Exposure-Response Relationship for Ombitasvir and Paritaprevir/Ritonavir in Hepatitis C Virus Subgenotype 1b-Infected Japanese Patients in the Phase 3 Randomized GIFT-I Study

INTRODUCTION

The all-oral 2 direct-acting antiviral (DAA) regimen of ombitasvir/paritaprevir/ritonavir 25/150/100 mg once a day has been evaluated in hepatitis C virus subgenotype 1b-infected Japanese adults in the GIFT-I study. The aim of this analysis was to evaluate potential relationships between DAA exposures and laboratory abnormalities/adverse events of peripheral edema in patients in GIFT-I.

METHODS

The GIFT-I study consisted of a randomized, double-blind, placebo-controlled substudy in patients without cirrhosis and an open-label substudy in patients with compensated cirrhosis. Patients received ombitasvir/paritaprevir/ritonavir for 12 weeks. Exposure-response relationships between individual components of the ombitasvir/paritaprevir/ritonavir regimen and clinical parameters of interest were explored using pharmacokinetic and clinical data from patients in the study. Graphical analyses were performed. For events that occurred in at least 10 patients (total bilirubin elevation ≥grade 2 and peripheral edema ≥grade 1), multivariate logistic regression analyses were used to identify significant relationships between predictor variables (drug exposures) and response variables (probability of adverse events or laboratory abnormalities), with consideration for the effect of potential covariates and baseline status of response variables.

RESULTS

Data from 321 noncirrhotic and 42 compensated cirrhotic patients were analyzed. There were 14 events of peripheral edema (10 at grade 1 and 4 at grade 2) in patients who received concomitant administration of calcium channel blockers and ombitasvir/paritaprevir/ritonavir. There was no apparent relationship between the incidences of peripheral edema and exposures of paritaprevir, ombitasvir, or ritonavir. There was a shallow relationship between total bilirubin elevation and exposures of paritaprevir which is an inhibitor of bilirubin transporter organic anion-transporting polypeptide 1B. Based on graphical analyses, exposures of paritaprevir, ombitasvir, or ritonavir were weakly associated with hemoglobin decrease, but not associated with post baseline alanine aminotransferase or aspartate aminotransferase elevations.

CONCLUSIONS

In Japanese patients, there were no associations or only shallow relationships between DAA exposures and peripheral edema or laboratory abnormalities. Consequently, therapeutic drug monitoring is not expected to be beneficial in managing patients on the 2-DAA regimen.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02023099.

FUNDING

AbbVie Inc.

Drug-Drug Interaction of Omeprazole With the HCV Direct-Acting Antiviral Agents Paritaprevir/Ritonavir and Ombitasvir With and Without Dasabuvir

Paritaprevir (administered with low-dose ritonavir), ombitasvir, and dasabuvir are direct-acting antiviral agents administered as combination regimens for the treatment of chronic hepatitis C virus infection. Drug-drug interactions between 2D (ombitasvir/paritaprevir/ritonavir) or 3D (ombitasvir/paritaprevir/ritonavir and dasabuvir) regimens and omeprazole, a CYP2C19 substrate and acid-reducing agent, were evaluated in 24 healthy volunteers. Subjects received omeprazole (40 mg once daily) on day 1 and days 20-24 and the 2D or 3D regimen (ombitasvir/paritaprevir/ritonavir 25/150/100 mg once daily ± dasabuvir 250 mg twice daily) on days 6-24. Compared with omeprazole alone, coadministration with the 2D or 3D regimen decreased omeprazole geometric mean Cmax and AUCt values by 40% to 50%. Ombitasvir, dasabuvir, and ritonavir mean exposures showed <10% change, and paritaprevir mean exposures showed <20% change when the 2D or 3D regimen was administered with omeprazole compared with administration without omeprazole. Although no a priori dose adjustment is needed, a higher omeprazole dose should be considered if clinically indicated when coadministered with the 2D or 3D regimen. No dose adjustment is required for the 2D or 3D regimen when administered with omeprazole, other acid-reducing agents, or CYP2C19 inhibitors.

Drug Interactions with the Direct-Acting Antiviral Combination of Ombitasvir and Paritaprevir-Ritonavir

The two direct-acting antiviral (2D) regimen of ombitasvir and paritaprevir (administered with low-dose ritonavir) is being developed for treatment of genotype subtype 1b and genotypes 2 and 4 chronic hepatitis C virus (HCV) infection. Drug-drug interactions were evaluated in healthy volunteers to develop dosing recommendations for HCV-infected subjects. Mechanism-based interactions were evaluated for ketoconazole, pravastatin, rosuvastatin, digoxin, warfarin, and omeprazole. Interactions were also evaluated for duloxetine, escitalopram, methadone, and buprenorphine-naloxone. Ratios of geometric means with 90% confidence intervals for the maximum plasma concentration and the area under the plasma concentration-time curve were estimated to assess the magnitude of the interactions. For most medications, coadministration with the 2D regimen resulted in a <50% change in exposures. Ketoconazole, digoxin, pravastatin, and rosuvastatin exposures increased by up to 105%, 58%, 76%, and 161%, respectively, and omeprazole exposures decreased by approximately 50%. Clinically meaningful changes in ombitasvir, paritaprevir, or ritonavir exposures were not observed. In summary, all 11 medications evaluated can be coadministered with the 2D regimen, with most medications requiring no dose adjustment. Ketoconazole, digoxin, pravastatin, and rosuvastatin require lower doses, and omeprazole may require a higher dose. No dose adjustment is required for the 2D regimen.

Population Pharmacokinetics of Paritaprevir, Ombitasvir, Dasabuvir, Ritonavir, and Ribavirin in Patients with Hepatitis C Virus Genotype 1 Infection: Combined Analysis from 9 Phase 1b/2 Studies

Direct-acting antiviral agents (DAAs) are established as the standard of care for chronic hepatitis C virus (HCV) infection. One of the newest additions to the HCV arsenal is an oral three-DAA combination therapy (i.e., the 3D regimen) that does not require concomitant use of pegylated interferon. The clinical development program for the 3D regimen has yielded a robust dataset that is inclusive of various dosing schemes and a diverse patient population. Using data from nine phase 1b/2a/2b studies that enrolled patients with HCV genotype 1 infection, population pharmacokinetic models were developed for each component of the 3D regimen (ombitasvir, paritaprevir, ritonavir, and dasabuvir) and for ribavirin, an adjunctive therapy used to enhance therapeutic efficacy in some populations. Formulation effects, accumulation, relative bioavailability, and interactions between DAAs were assessed during model development, and demographic and clinical covariates were identified and evaluated for their effects on drug exposures. Proposed models were assessed via goodness-of-fit plots, visual predictive checks, and bootstrap evaluations. Population pharmacokinetic models adequately described their respective plasma concentration-time data with precise and reliable model parameter estimates and with good predictive performance. Covariates, including age, sex, body weight, cytochrome P450 2C8 inhibitor use, non-Hispanic ethnicity, and creatinine clearance, were associated with apparent clearance and/or apparent volume parameters; however, the magnitude of effect on drug exposure was modest and not considered to be clinically significant. No patient-related or clinical parameters were identified that would necessitate dose adjustment of the 3D regimen in patients with HCV genotype 1 infection.