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

Clinical study of drug-drug interaction between omeprazole and pyrotinib after meal

AIMS

We aimed to investigate the effect of omeprazole on the pharmacokinetics (PK) of pyrotinib and determine the safety of this combination in healthy Chinese volunteers.

METHODS

Eighteen healthy volunteers were enrolled in this single-dose and self-controlled study. Pyrotinib (400 mg per oral) was administered 30 minutes after the standard meal. Omeprazole was administered from day 6 (D6) to D10 (40 mg, per oral). On D10, the subjects took omeprazole under fasting conditions, followed by pyrotinib 30 minutes after the standard meal. Blood samples for PK analyses in each phase were collected for analysing the drug concentration. Safety was assessed via clinical laboratory tests and physical examinations.

RESULTS

Compared with a single dose of pyrotinib, pyrotinib coadministered with omeprazole showed no significant difference in exposure, elimination, half-life and apparent clearance rate. The mixed-effects model revealed that the least-squares geometric mean ratios of area under the concentration-time curve (AUC)_0-t , AUC_0-∞ and maximum plasma concentration (C_max, 90% confidence intervals) of pyrotinib alone and pyrotinib coadministered with omeprazole were 0.94 (0.82, 1.08), 0.94 (0.83, 1.08) and 0.91 (0.806, 1.038), respectively, indicating the absence of significant differences in AUC_0-t , AUC_0-∞ and C_max . During the treatment period, 6 subjects (33.3%) reported 8 adverse events during pyrotinib monotherapy and omeprazole administration, respectively; 10 subjects (55.6%) reported 34 adverse events in the combined administration phase.

CONCLUSION

Omeprazole, a proton-pump inhibitor, did not significantly impact the PK properties of pyrotinib, and a good safety profile was observed on coadministration.

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.

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.

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

BACKGROUND/PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Efficacy and Pharmacokinetics of Glecaprevir and Pibrentasvir With Concurrent Use of Acid-Reducing Agents in Patients With Chronic HCV Infection

BACKGROUND & AIMS

Proton pump inhibitors (PPIs) are commonly prescribed to treat acid-related disorders. Some direct-acting antiviral regimens for chronic hepatitis C virus (HCV) infection have reduced efficacy in patients taking concomitant acid-reducing agents, including PPIs, due to interactions between drugs. We analyzed data from 9 multicenter, phase 2 and 3 trials to determine the efficacy and pharmacokinetics of an HCV therapeutic regimen comprising glecaprevir and pibrentasvir (glecaprevir/pibrentasvir) in patients taking concomitant acid-reducing agents.

METHODS

We analyzed data from 2369 patients infected with HCV genotypes 1-6 and compensated liver disease treated with an all-oral regimen of glecaprevir/pibrentasvir for 8-16 weeks. We compared efficacy and pharmacokinetics among patients receiving at least 1 dose of an acid-reducing agent (a PPI, an H2 blocker, or antacid). High-dose PPI was defined as daily dose greater than 20 mg omeprazole dose equivalent. The objectives were to evaluate rate of sustained virologic response 12 weeks post-treatment (SVR12) and to assess steady-state glecaprevir and pibrentasvir exposures in patients on acid-reducing agents.

RESULTS

Of the 401 patients (17%) who reported use of acid-reducing agents, 263 took PPIs (11%; 109 patients took a high-dose PPI and 154 patients took a low-dose PPI). Rates of SVR12 were 97.0% among patients who used acid-reducing agents and 97.5% among those not using acid-reducing agents (P = .6). An SVR12 was achieved in 96.3% taking a high-dose PPI and 97.4% taking a low-dose PPI, with no virologic failures in those receiving a high-dose PPI (P = .7). Glecaprevir, but not pibrentasvir, bioavailability was affected; its exposure decreased by 41% in patients taking a high-dose PPI.

CONCLUSIONS

In an analysis of data from 9 clinical trials, we observed a high rate of SVR12 (approximately 97%) among patients treated with glecaprevir/pibrentasvir for HCV infection-even among patients taking concomitant ARA or high-dose PPI. This was despite decreased glecaprevir exposures in patients when on high-dose PPIs. ClinicalTrials.gov numbers, NCT02243280 (SURVEYOR-I), NCT02243293 (SURVEYOR-II), NCT02604017 (ENDURANCE-1), NCT02640482 (ENDURANCE-2), NCT02640157 (ENDURANCE-3), NCT02636595 (ENDURANCE-4), NCT02642432 (EXPEDITION-1), NCT02651194 (EXPEDITION-4), NCT02446717 (MAGELLAN-I).

Gastric-acid-mediated drug-drug interactions with direct-acting antiviral medications for hepatitis C virus infection: clinical relevance and mitigation strategies

Drug-drug interactions (DDIs) between direct-acting antiviral (DAA) medications and acid-reducing agents mediated by gastric acid represent an important issue in drug development and treatment, which could lead to impaired bioavailability and subtherapeutic plasma concentrations of DAA drugs and subsequently compromised treatment outcomes. However, identification of clinically relevant drug interactions associated with elevated gastric pH is not well characterized. Here, we present the first comprehensive analysis of the gastric-acid-mediated drug interactions with all novel DAA medications by analyzing and revisiting in vitro data, prospective DDI trials and retrospective assessments based upon Phase II and III studies, aiming toward an in-depth understanding of the clinical implications and mitigation strategies to circumvent such interactions.

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

PURPOSE

To characterize the pharmacokinetics of ombitasvir, paritaprevir, ritonavir, dasabuvir, and ribavirin in hepatitis C virus (HCV)-infected patients with chronic kidney disease stage 4 (CKD4) or end-stage renal disease (ESRD), including those on dialysis, in the open-label phase 3 RUBY-I and RUBY-II studies.

METHODS

Patients (n = 18 CKD4, n = 68 ESRD) received ombitasvir/paritaprevir/ritonavir 25/150/100 mg once daily ± dasabuvir 250 mg twice daily ± ribavirin 200 mg once daily for 12 or 24 weeks. Intensive pharmacokinetic samples were collected from ten patients; sparse samples were collected from all patients. Arterial and venous samples were collected from three patients during hemodialysis. Area under the plasma concentration-time curve (AUC) was estimated using noncompartmental analyses for intensive data, and steady-state trough concentrations (C_trough) were obtained from the sparse data. Pharmacokinetic results from RUBY-I and RUBY-II were compared empirically to historical data.

RESULTS

The AUC values of ombitasvir, paritaprevir, ritonavir, and dasabuvir were comparable between CKD4 and ESRD patients and were within the range of values observed in historical studies; dialysis had no effect on drug exposures. Ribavirin was extracted during hemodialysis but had similar exposures on dialysis and non-dialysis days. Individual steady-state C_trough values for each drug overlapped between CKD4 and ESRD patients, and values in both groups were similar to historical values.

CONCLUSION

Plasma concentrations of ombitasvir, paritaprevir, ritonavir, and dasabuvir were not altered by renal impairment or dialysis, suggesting these agents can be administered to HCV-infected CKD4 or ESRD patients, including those on dialysis, without dose adjustment.

TRIAL REGISTRATION

Clinicaltrials.gov identifiers: NCT02207088 (RUBY-I) and NCT02487199 (RUBY-II).

Adverse drug reactions during hepatitis C treatment with direct-acting antivirals: The role of medication errors, their impact on treatment discontinuation and their preventability. New insights from the Campania Region (Italy) spontaneous reporting system

WHAT IS KNOWN AND OBJECTIVE

Medication errors, such as unnecessary treatment discontinuation during treatment with direct-acting antivirals (DAAs), can lead to imbalances in the benefit-to-risk ratio. This risk is especially high when the medication error leads to adverse drug reactions (ADRs). However, to date, evidence on the frequency of this phenomenon is scarce. This study aims to provide better insight into ADRs possibly due to medication errors leading to DAA discontinuation and their preventability.

METHODS

The Italian Pharmacovigilance Network database was used to extract individual case safety reports (ICSRs) generated from July 2012 to March 2017 via the Campania Region (Italy) spontaneous reporting system. ICSRs that included ledipasvir/sofosbuvir, ombitasvir/paritaprevir/ritonavir, dasabuvir, daclatasvir, sofosbuvir, simeprevir or elbasvir/grazoprevir as suspected drugs were included in this study. A preventability assessment was then performed utilizing the "P-Method," an algorithm that evaluates known risk factors due to medication errors that can be detected in ICSRs.

RESULTS AND DISCUSSION

Of the 355 cases included in this study, 6 (1.69%) were classified as preventable and 52 (14.6%) were classified as potentially preventable. The most frequently identified critical criteria (risk factor) for preventable or potentially preventable cases were drug-drug interactions and incorrect drug dosing as part of the antiviral treatment scheme. In total, 89 of the 355 cases (25.1%) discontinued use of the DAAs due to ADRs, of which 20 of the 89 cases (22.5%) were due to an unimportant medical event as classified by the European Medicine Agency important medical event list.

WHAT IS NEW AND CONCLUSION

This study found a proportion of preventable/potentially preventable ADRs involving DAA, which could be improved in the Campania Region (Italy). Additionally, the study identified a high proportion of seemingly unnecessary DAA discontinuations among patients who experienced ADRs.

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.

Exposure-Safety Response Relationship for Ombitasvir, Paritaprevir/Ritonavir, Dasabuvir, and Ribavirin in Patients with Chronic Hepatitis C Virus Genotype 1 Infection: Analysis of Data from Five Phase II and Six Phase III Studies

BACKGROUND AND OBJECTIVES

All-oral direct-acting antiviral regimens that include combinations of ombitasvir, paritaprevir, ritonavir, and dasabuvir with or without ribavirin were evaluated in hepatitis C virus-infected patients in phase II/III clinical studies. The objective of these analyses was to quantify the relationship between exposures of the components of the regimen and laboratory values and to determine covariates that could influence the relationship.

METHODS

Exposure-safety response relationships between individual components of the direct-acting antiviral regimens and clinically important laboratory values were explored using data from 2998 patients from 11 phase II/III clinical studies. Multivariate logistic regression analyses were used to identify significant relationships between predictor variables and response variables.

RESULTS

No statistically significant associations were observed between ombitasvir, dasabuvir, or ritonavir exposures and maximum post-baseline alanine aminotransferase (ALT) or total bilirubin grade or minimum hemoglobin grade. A two-fold increase in paritaprevir exposure from therapeutic exposure was predicted to increase the probability of experiencing a grade 3 or higher increase in ALT by 0.5% and bilirubin by 1.1%. In the phase II/III clinical studies, ALT and bilirubin increases were reversible with continued dosing or after treatment cessation. Other correlates with adverse events of clinical importance included concomitant ribavirin treatment, sex, race, and presence of cirrhosis, consistent with previous observations.

CONCLUSIONS

Exposure-response analyses from phase II/III studies with the combination direct-acting antiviral regimen indicated no statistically significant relationships with ombitasvir, dasabuvir, or ritonavir exposure, but a statistically significant association was observed between paritaprevir exposure and the probability of experiencing a grade 3 or higher increase in ALT or bilirubin.

Pharmacokinetics and Tolerability of Anti-Hepatitis C Virus Treatment with Ombitasvir, Paritaprevir, Ritonavir, with or Without Dasabuvir, in Subjects with Renal Impairment

BACKGROUND

The direct-acting antiviral agent (DAA) combination of ombitasvir and paritaprevir (administered with ritonavir) with (3D regimen) or without (2D regimen) dasabuvir has shown very high efficacy rates in the treatment of chronic hepatitis C virus (HCV) infection. Renal impairment, a common comorbidity in patients with chronic HCV infection, can influence the pharmacokinetics of antiviral agents and hence their efficacy and safety profiles.

OBJECTIVE

The aim of this study was to evaluate the influence of renal impairment on the pharmacokinetics and tolerability of the 3D and 2D regimens.

METHODS

Overall, 24 subjects, six in each of four renal function groups (normal, mild, moderate, and severe), received a single dose of the 3D and 2D regimens in separate dosing periods. Plasma and urine were analyzed to assess the effect of renal impairment on drug exposure.

RESULTS

DAA exposures changed by up to 21, 37, and 50 % in subjects with mild, moderate, and severe renal impairment, respectively, versus subjects with normal renal function. Ritonavir exposure increased with the degree of renal impairment (maximum 114 %). The half-lives of DAAs and ritonavir in subjects with renal impairment were generally comparable with those in healthy subjects. No safety or tolerability concerns arose in this study.

CONCLUSION

The 3D and 2D regimens do not require dose adjustment for patients with HCV infection and concomitant renal impairment.

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.

Population Pharmacokinetics of Paritaprevir, Ombitasvir, and Ritonavir in Japanese Patients with Hepatitis C Virus Genotype 1b Infection

BACKGROUND AND OBJECTIVE

Hepatitis C virus (HCV) infection is of considerable clinical concern in Japan. We modeled the population pharmacokinetics of an oral interferon-free, direct-acting antiviral agent (DAA) regimen (i.e., the 2D regimen) recently approved for the treatment of chronic HCV genotype 1 infection as a new option for affected Japanese patients.

METHODS

Using data from a phase III clinical trial (GIFT-I) that enrolled Japanese patients with HCV genotype 1b infection, population pharmacokinetic models were developed for the drugs that comprise the 2D regimen: paritaprevir, ombitasvir, and ritonavir. Demographic and clinical covariates with potential to influence 2D pharmacokinetics were evaluated for their effects on drug exposures. Proposed models were assessed using goodness-of-fit plots, visual predictive checks, and bootstrap evaluations.

RESULTS

One-compartment models with first-order absorption and elimination adequately described the population pharmacokinetics of paritaprevir, ombitasvir, and ritonavir. On average, patients with cirrhosis had approximately 95-145 % higher, 19-24 % lower, and 58-68 % higher exposures of paritaprevir, ombitasvir, and ritonavir, respectively. Female patients had 58-81 % higher ombitasvir exposures, whereas patients with mild renal impairment (creatinine clearance 75 mL/min) had 9-14 % higher ombitasvir exposures than did patients with normal renal function (creatinine clearance 105 mL/min). The DAA exposure values were comparable between responders and non-responders.

CONCLUSION

Population pharmacokinetic modeling did not reveal any patient-related or clinical parameters that would require dose adjustment of the 2D regimen when used for the treatment of HCV genotype 1b infection in Japanese patients.

Application of Exposure-Response Analyses to Establish the Pharmacodynamic Similarity of a Once-Daily Regimen to an Approved Twice-Daily Dosing Regimen for the Treatment of HCV Infection

The triple direct-acting antiviral (3-DAA) regimen (two co-formulated tablets of ombitasvir/paritaprevir/ritonavir once daily and one tablet of dasabuvir twice daily) for patients with hepatitis C virus (HCV) genotype 1 infection has been reformulated for once-daily administration containing all three active DAAs (3QD regimen). Two bioequivalence studies compared the 3-DAA and 3QD regimens. In study 1, fed, single-, and multiple-dose crossover comparisons revealed exposures for drug components that were slightly outside the bioequivalence criteria, i.e., 21 to 29% lower dasabuvir C _trough, paritaprevir C _max, and ritonavir C _max. In study 2, fed and fasted single-dose crossover comparisons demonstrated a large impact of food on exposures, confirming the product's labeling requirement for administration only with food, and revealed a lack of bioequivalence under fasting conditions. Exposure-response analyses using efficacy data from phase 2/3 studies of the 3-DAA regimen demonstrated that the lower dasabuvir C _trough for the 3QD regimen (under fed condition) would have minimal impact on sustained virologic response at week 12 post-treatment (SVR₁₂). Thus, the pharmacodynamic similarity between the regimens was established and the analyses provided the basis for regulatory approval of the 3QD regimen to treat patients with chronic HCV genotype 1 infection.

Paritaprevir and Ritonavir Liver Concentrations in Rats as Assessed by Different Liver Sampling Techniques

The liver is crucial to pharmacology, yet substantial knowledge gaps exist in the understanding of its basic pharmacologic processes. An improved understanding for humans requires reliable and reproducible liver sampling methods. We compared liver concentrations of paritaprevir and ritonavir in rats by using samples collected by fine-needle aspiration (FNA), core needle biopsy (CNB), and surgical resection. Thirteen Sprague-Dawley rats were evaluated, nine of which received paritaprevir/ritonavir at 30/20 mg/kg of body weight by oral gavage daily for 4 or 5 days. Drug concentrations were measured using liquid chromatography-tandem mass spectrometry on samples collected via FNA (21G needle) with 1, 3, or 5 passes (FNA₁, FNA₃, and FNA₅); via CNB (16G needle); and via surgical resection. Drug concentrations in plasma were also assessed. Analyses included noncompartmental pharmacokinetic analysis and use of Bland-Altman techniques. All liver tissue samples had higher paritaprevir and ritonavir concentrations than those in plasma. Resected samples, considered the benchmark measure, resulted in estimations of the highest values for the pharmacokinetic parameters of exposure (maximum concentration of drug in serum [C_max] and area under the concentration-time curve from 0 to 24 h [AUC_0-24]) for paritaprevir and ritonavir. Bland-Altman analyses showed that the best agreement occurred between tissue resection and CNB, with 15% bias, followed by FNA₃ and FNA₅, with 18% bias, and FNA₁ and FNA₃, with a 22% bias for paritaprevir. Paritaprevir and ritonavir are highly concentrated in rat liver. Further research is needed to validate FNA sampling for humans, with the possible derivation and application of correction factors for drug concentration measurements.

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.

Pharmacokinetic Evaluation of Darunavir Administered Once or Twice Daily in Combination with Ritonavir or the Three-Direct-Acting Antiviral Regimen of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir in Adults Coinfected with Hepatitis C and Human Immunodeficiency Viruses

The three-direct-acting antiviral (3D) regimen containing ombitasvir, paritaprevir, ritonavir, and dasabuvir with or without ribavirin (RBV) is approved for treatment of hepatitis C virus (HCV) genotype 1 (GT1)/human immunodeficiency virus type 1 (HIV-1) coinfection. Results of a pharmacokinetic substudy of 3D and darunavir are presented. HCV/HIV-1-coinfected subjects were randomized to maintain an antiretroviral regimen with darunavir at 800 mg once daily (QD) or switched to a regimen with darunavir at 600 mg twice daily (BID). On study day 1, subjects received 3D and RBV plus darunavir for 12 weeks. Pharmacokinetic parameters were compared for darunavir and ritonavir with and without 3D (week 4 and day -1). Pharmacokinetic parameters of 3D were compared to historical data. Ten subjects received darunavir QD, and 12 subjects received darunavir BID. The central value ratios (90% confidence interval [CI]) for maximum concentrations (C_max), area under the plasma concentration-time curve between 0 and 24 h postdose (AUC₂₄), and trough plasma concentration at 24 h postdose (C₂₄) of darunavir administered QD with 3D versus administration of darunavir alone were 0.92 (0.72, 1.18), 0.83 (0.71, 0.98), and 0.64 (0.44, 0.93), respectively. The ratios (90% CI) for darunavir C_max, AUC₁₂, and C₁₂ administered BID with 3D were 0.92 (0.76, 1.12), 0.88 (0.73, 1.05), and 0.73 (0.58, 0.92), respectively. Exposures of 3D were similar to or slightly lower than those in historical data. All darunavir trough concentrations (C_trough) associated with an HIV-1 RNA level of >40 copies/ml were above the darunavir 50% effective concentration (EC₅₀) of 550 ng/ml for resistant virus. In conclusion, the 3D regimen with darunavir QD or BID did not affect darunavir C_max and AUC, whereas the darunavir C_trough decreased. Changes in pharmacokinetic parameters of 3D were not considered clinically significant. Episodes of intermittent HIV-1 viremia were infrequent and were not associated with darunavir C_trough values below 550 ng/ml. (This study has been registered at ClinicalTrials.gov under identifier NCT01939197.).

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.

Evaluation of Drug-Drug Interactions between Direct-Acting Anti-Hepatitis C Virus Combination Regimens and the HIV-1 Antiretroviral Agents Raltegravir, Tenofovir, Emtricitabine, Efavirenz, and Rilpivirine

The three direct-acting antiviral agent (3D) regimen is a novel combination of direct-acting antiviral agents (DAAs) that has proven effective for the treatment of hepatitis C virus (HCV) infection. Given the potential for coadministration in patients with human immunodeficiency virus infection, possible drug interactions with antiretroviral drugs must be carefully considered. Four phase 1, multiple-dose pharmacokinetic studies were conducted in healthy volunteers (n = 66). The 3D regimen of 150/100 mg daily paritaprevir/ritonavir, 25 mg daily ombitasvir, and 400 mg twice-daily dasabuvir was administered alone or in combination with 200 mg daily of emtricitabine and 300 mg daily of tenofovir disoproxil fumarate (tenofovir DF), 25 mg daily of rilpivirine, or 400 mg of raltegravir twice daily. A 2-DAA regimen of 150/100 mg daily paritaprevir/ritonavir and 400 mg of dasabuvir twice daily was also studied in combination with efavirenz/emtricitabine/tenofovir DF at 600/200/300 mg daily, respectively (Atripla; Bristol-Myers Squibb). Pharmacokinetic parameters were determined from plasma drug concentrations. No clinically significant drug interactions were observed (≤32% change in exposure) between the 3D regimen and that of emtricitabine plus tenofovir DF. Raltegravir exposure was increased up to 134% when the drug was coadministered with the 3D regimen. Although coadministration with rilpivirine was well tolerated in healthy volunteers, observed elevations in rilpivirine exposures may increase the potential for adverse drug reactions. Concomitant use of the 2-DAA regimen and efavirenz/emtricitabine/tenofovir DF was discontinued owing to poor tolerability and adverse events. No dose adjustment is required during coadministration of raltegravir, tenofovir DF, or emtricitabine with the 3D regimen. Rilpivirine is not recommended and efavirenz is contraindicated for coadministration with the 3D regimen.