Lack of clinically significant pharmacokinetic interaction between the thrombopoietin receptor agonist eltrombopag and hepatitis C virus protease inhibitors boceprevir and telaprevir

Bioequivalence and Food Effect Assessment of Eltrombopag Olamine Tablets in Healthy Chinese Subjects: An Open, Randomized, Single-Dose, and Two-Period Crossover Study

Eltrombopag, a nonpeptide thrombopoietin receptor agonist, is primarily used for treating immune thrombocytopenic purpura. The aim of this study was to investigate the pharmacokinetic profile and food-drug interaction of test and reference eltrombopag olamine tablets among healthy Chinese volunteers. An open, randomized, single-dose, 2-period crossover design was employed, involving fasting and fed conditions with a 10-day washout period. Ninety-six healthy volunteers received a single oral dose of 25 mg of the 2 eltrombopag formulations, with 48 participants in each group: fasting volunteers and those consuming a high-fat, low-calcium meal. Plasma eltrombopag concentrations were analyzed using liquid chromatography-tandem mass spectrometry, and pharmacokinetic parameters were derived from the concentration-time profiles. The geometric mean ratios, with 90% confidence intervals, for the maximum plasma concentration, area under the concentration-time curve from time 0 to the last measurable concentration, and area under the concentration-time curve from time 0 to infinity fell within the bioequivalence acceptance criteria (80%-125%) under both fasting and fed conditions, indicating bioequivalence between the test and reference formulations. Administration of eltrombopag with a high-fat, low-calcium diet reduced the net systemic exposure by approximately 40%. Adverse events were recorded, and no serious adverse events were observed in either fasting or fed conditions. In conclusion, eltrombopag is well tolerated and exhibits a favorable safety profile in the Chinese population. The achievement of bioequivalence under fasting and fed conditions supports the demonstration of biosimilarity between the test and reference formulations.

The Thrombopoietin Receptor Agonist Eltrombopag Inhibits Human Cytomegalovirus Replication Via Iron Chelation

The thrombopoietin receptor agonist eltrombopag was successfully used against human cytomegalovirus (HCMV)-associated thrombocytopenia refractory to immunomodulatory and antiviral drugs. These effects were ascribed to the effects of eltrombopag on megakaryocytes. Here, we tested whether eltrombopag may also exert direct antiviral effects. Therapeutic eltrombopag concentrations inhibited HCMV replication in human fibroblasts and adult mesenchymal stem cells infected with six different virus strains and drug-resistant clinical isolates. Eltrombopag also synergistically increased the anti-HCMV activity of the mainstay drug ganciclovir. Time-of-addition experiments suggested that eltrombopag interfered with HCMV replication after virus entry. Eltrombopag was effective in thrombopoietin receptor-negative cells, and the addition of Fe³⁺ prevented the anti-HCMV effects, indicating that it inhibits HCMV replication via iron chelation. This may be of particular interest for the treatment of cytopenias after hematopoietic stem cell transplantation, as HCMV reactivation is a major reason for transplantation failure. Since therapeutic eltrombopag concentrations are effective against drug-resistant viruses, and synergistically increase the effects of ganciclovir, eltrombopag is also a drug-repurposing candidate for the treatment of therapy-refractory HCMV disease.

Boceprevir and Antiretroviral Pharmacokinetic Interactions in HIV/HCV Co-infected Persons: AIDS Clinical Trials Group Study A5309s

OBJECTIVE

The objective of this study was to determine the magnitude of drug interactions between the hepatitis C virus (HCV) protease inhibitor boceprevir (BOC) and antiretroviral (ARV) agents in persons with HIV/HCV co-infection.

METHODS

Participants taking two nucleos(t)ide analogs with either efavirenz, raltegravir, or ritonavir-boosted atazanavir, darunavir, or lopinavir underwent intensive pharmacokinetic (PK) sampling for ARV 2 weeks before (week 2) and 2 weeks after initiating BOC (week 6) and for BOC at week 6. Geometric mean ratios (GMRs) and 90% confidence intervals (CIs) were used to compare ARV PK at weeks 2 and 6 and BOC PK at week 6 to historical data (HD) in healthy volunteers and HCV mono-infected patients.

RESULTS

ARV PK was available for 55 participants. BOC reduced atazanavir and darunavir exposures by 30 and 42%, respectively. BOC increased raltegravir maximum concentration (C _max) by 71%. BOC did not alter efavirenz PK. BOC PK was available for 53 participants. BOC exposures were similar in these HIV/HCV co-infected participants compared with HD in healthy volunteers, but BOC minimum concentrations (C _min) were lower with all ARV agents (by 34-73%) compared with HD in HCV mono-infected patients.

CONCLUSIONS

Effects of BOC on ARV PK in these HIV/HCV co-infected individuals were similar to prior studies in healthy volunteers. However, some differences in the effects of ARV on BOC PK were observed, indicating the magnitude of interactions may differ in HCV-infected individuals versus healthy volunteers. Findings highlight the need to conduct interaction studies with HCV therapies in the population likely to receive the combination.

Viruses, anti-viral therapy, and viral vaccines in children with immune thrombocytopenia

Immune thrombocytopenia (ITP) might be preceded by silent or overt viral infections. Similarly, anti-viral drugs and viral vaccines could also trigger ITP and might play a central role in its pathogenesis. The seasonal nature of childhood ITP suggests that viral infections might initiate immune responses that increase the predisposition and occurrence of ITP. Active cytomegalovirus or Epstein-Barr virus should be considered in differential diagnosis when thrombocytopenia is associated with lymphadenopathy, especially with splenomegaly. This review will focus on the specific association of ITP in association with viral disease and vaccinations, and will discuss the effectiveness of current therapies in light of our current understanding of viral-associated ITP.

Clinical pharmacology profile of boceprevir, a hepatitis C virus NS3 protease inhibitor: focus on drug-drug interactions

Boceprevir is a potent, orally administered ketoamide inhibitor that targets the active site of the hepatitis C virus (HCV) non-structural (NS) 3 protease. The addition of boceprevir to peginterferon plus ribavirin resulted in higher rates of sustained virologic response (SVR) than for peginterferon plus ribavirin alone in phase III studies in both previously treated and untreated patients with HCV infection. Because boceprevir is metabolized by metabolic routes common to many other drugs, and is an inhibitor of cytochrome P450 (CYP) 3A4/5, there is a high potential for drug-drug interactions when boceprevir is administered with other therapies, particularly when treating patients with chronic HCV infection who are often receiving other medications concomitantly. Boceprevir is no longer widely used in the US or EU due to the introduction of second-generation treatments for HCV infection. However, in many other geographic regions, first-generation protease inhibitors such as boceprevir continue to form an important treatment option for patients with HCV infection. This review summarizes the interactions between boceprevir and other therapeutic agents commonly used in this patient population, indicating dose adjustment requirements where needed. Most drug interactions do not affect boceprevir plasma concentrations to a clinically meaningful extent, and thus efficacy is likely to be maintained when boceprevir is coadministered with the majority of other therapeutics. Overall, the drug-drug interaction profile of boceprevir suggests that this agent is suitable for use in a wide range of HCV-infected patients receiving concomitant therapies.

Modeling and simulation support eltrombopag dosing in thrombocytopenic patients with chronic HCV infection

PURPOSE

The pharmacokinetics of eltrombopag and its stimulation of platelet production were characterized in patients with chronic hepatitis C virus (HCV) infection to optimize an eltrombopag dosing regimen for treatment of HCV-related thrombocytopenia before and throughout peginterferon (pegIFN)-based antiviral therapy.

METHODS

Population pharmacokinetic analysis for eltrombopag included 663 individuals (healthy subjects, n = 28; patients with HCV, n = 635). Population pharmacokinetic/pharmacodynamic analysis for platelet response involved patients with HCV only. Simulations were conducted using various dosing scenarios in the same patient population.

RESULTS

Eltrombopag pharmacokinetics were described by a two-compartment model with dual sequential first-order absorption and elimination. Age, race, sex, and severity of hepatic impairment were predictors of eltrombopag clearance. The effect of eltrombopag on platelet counts was adequately described by a model with four transit compartments in which eltrombopag concentrations stimulated the production rate of platelet precursors in an Emax manner.

CONCLUSIONS

Modeling and simulation results support once-daily eltrombopag 25 mg as an appropriate starting dosing regimen followed by biweekly dose escalation (in 25-mg increments) up to once-daily eltrombopag 100 mg to raise platelet counts sufficiently for initiation of pegIFN-based antiviral therapy in patients with HCV. Biweekly dose adjustment allows patients to stay on the lowest possible eltrombopag dose during antiviral therapy.