Review of drug interactions with telaprevir and antiretrovirals

The pharmacological interactions between direct-acting antivirals for the treatment of chronic hepatitis c and psychotropic drugs

INTRODUCTION

Most direct-acting antivirals (DAAs) and psychotropic drugs are metabolized by or induct/inhibit CYP enzymes and drug transporters. Although they are frequently coadministered, the drug-drug interactions (DDIs) have been little studied. Therefore, the aim of this review is to describe the interactions between the approved DAA or combination regimens and the main psychoactive substances, including legal and illegal drugs of abuse. Areas covered: We performed a literature search on PubMed database on drug interactions with the currently available antivirals for hepatitis C and a review of the information on pharmacokinetics, metabolism, and drug interactions from www.hep-druginteractions.org and from all the Summary of Product Characteristics (SmPC). This review covers the DDI between the DAA regimens approved, such as simeprevir and sofosbuvir, paritaprevir, glecaprevir, voxilaprevir, ombitasvir, ledipasvir, daclatasvir and sofosbuvir, elbasvir and grazoprevir, sofosbuvir and velpatasvir, glecaprevir/pibrentasvir, sofosbuvir and velpatasvir, and main psychotropic agents. Expert Commentary: DAA regimens based on sofosbuvir combination usually have less DDI than protease inhibitor-based regimens. Among protease inhibitors regimens, new combinations, such as glecaprevir/elbasvir and grazoprevir/elbasvir, seemed to have less DDI than the combination POrD (paritaprevir/ombitasvir/ritonavir/dasabuvir). However, the analysis of each interaction is theoretical and further interaction studies would be necessary to confirm actual effect.

Similar effectiveness of direct-acting antiviral against hepatitis C virus in patients with and without HIV infection

OBJECTIVE

We compared the baseline characteristics, effectiveness, and tolerance of direct-acting antiviral drug (DAA)-based regimens taken by hepatitis C virus (HCV)-monoinfected and HCV/HIV-coinfected individuals in clinical practice.

DESIGN

We performed a prospective observational study in two tertiary centres in Madrid, Spain, which included all HCV-monoinfected and HCV/HIV-coinfected patients undergoing HCV treatment with all-oral DAA regimens in a routine clinical setting, from April 2015 to November 2015. We evaluated sustained virological response 12 weeks after the end of therapy (SVR12), adverse events, and baseline and treatment characteristics.

RESULTS

The study population comprised 1634 patients: 1152 HCV-monoinfected patients (70%) and 482 HCV/HIV-coinfected patients (30%). Fifty percent had cirrhosis, and 47% were peginterferon/ribavirin-experienced. HCV/HIV-coinfected patients were younger [median age (interquartile range) 51 (48-54) years vs. 59 (50-68) years; P < 0.001), more frequently male (76 vs. 54%; P < 0.001), and infected with genotypes 1a (37 vs. 17%; P < 0.001), 3 (15 vs. 7%; P < 0.001), and 4 (23 vs. 4%; P < 0.001). One of every three patients took ribavirin. SVR12 was 94% (95% confidence interval 91.7-96%) and 97% (95% confidence interval 95.7-99.4%) in coinfected and monoinfected patients, respectively, with no significant differences between the groups after adjustment for cirrhosis, genotype, and DAA combination. DAA-based regimens were well tolerated, and only 1% of patients had severe adverse events, with no differences between the populations.

CONCLUSIONS

HCV/HIV-infected patients treated with all-oral DAA combinations achieved high rates of SVR12 that were similar to those of HCV-monoinfected patients under real-life conditions. Safety and tolerance were excellent, even in patients with end-stage liver disease.

Telaprevir-based therapy for treatment of HIV-1 and hepatitis C virus co-infected patients: An early access programme

OBJECTIVES

HPC3005 is a multicentre, open-label, telaprevir trial in HCV/HIV coinfected patients with severe fibrosis or compensated cirrhosis.

METHODS

Patients were treated with telaprevir 750 mg every 8 h (1125 mg if on efavirenz) plus pegylated interferon-alpha (PEG-IFN, 180 μg once-weekly) and ribavirin (RBV, 800 mg/day) for 12 weeks, followed by 36 weeks of PEG-IFN/RBV.

RESULTS

Mean age was 44 years, 97/118 patients were male and all were Caucasian, 68 had severe fibrosis and 50 had cirrhosis. Seventy-eight had HCV RNA levels ≥800 000 IU/mL, 72 had HCV genotype 1a, baseline HIV RNA was <50 copies/mL in 112 patients. Overall, 114/118 patients continued antiretroviral treatment, 4 were untreated. Seventy-five patients received tenofovir and 74 emtricitabine; in addition 53 received atazanavir/ritonavir, 43 raltegravir, and 24 efavirenz. By intention-to-treat, 78 (66%) patients achieved SVR24. Nineteen discontinued telaprevir, 8 for virological endpoint, 5 for adverse events (2 anaemia, 2 rash, 1 asthenia), 5 for non-compliance and 1 withdrew consent. The most common adverse events were anaemia (36 patients), thrombocytopaenia (33), rash (26), bilirubin increase (17), and neutropenia (16).

CONCLUSIONS

In this early access programme in coinfected patients with severe fibrosis or cirrhosis, 66% of patients achieved SVR. The most common adverse events were haematological.

CLINICAL TRIAL NUMBER

NCT01500616.

Hepatitis C in HIV-infected patients: impact of direct-acting antivirals

Approximately 30% of HIV-infected patients are co-infected with hepatitis C virus (HCV). After the release of highly active antiretroviral therapy, liver disease has become the leading cause of morbidity and mortality in HIV patients. Prior to 2011, HCV treatment with pegylated-interferon and ribavirin in HCV/HIV co-infected patients only allowed 14-38% of patients with HCV genotype 1 to achieve a sustained virologic response (SVR). Additionally, treatment was commonly discontinued as a result of adverse events. Recently, simeprevir and sofosbuvir have been approved by the US Food and Drug Administration (FDA) for HCV mono-infection. Sofosbuvir has been given FDA approval in co-infected patients offering unprecedented SVR rates and the potential for interferon-free therapy. HCV therapies that are in the pipeline offer improved treatment times, safety profiles, and rates of SVR. Despite these improvements, several new issues including adherence, drug-drug interactions with antiretroviral therapies, adverse events, resistance, and patient selection may complicate therapy. This article reviews the current status of direct-acting antivirals (DAA)-containing regimens for HIV/HCV co-infected patients in the USA. New results investigating telaprevir and boceprevir are also discussed as they are relevant for locations where new DAAs are not available. The impact future interferon-free therapies may have on co-infected patients is also discussed.

Drug-drug interactions of telaprevir and boceprevir in HCV-monoinfected and HIV/HCV-coinfected patients can modify the adherence

BACKGROUND & AIMS

The first generation protease inhibitors, boceprevir (BOC) and telaprevir (TVR), are both CYP3A4 inhibitors, which predispose drug-drug interactions (DDIs). The aim of this study was to evaluate the prevalence of potential DDIs, the management of outpatient medication and its impact on adherence and efficacy to antiviral treatment in hepatitis C virus (HCV)-monoinfected and human immunodeficiency virus (HIV)/HCV-coinfected patients receiving BOC and TVR.

METHODS

The usual medication starting with BOC or TVR was screened by the pharmacist of the multidisciplinary support programme (MSP) for potential DDIs. Recommendations were made to avoid significant DDIs, and changes in the baseline medication were recorded. Adherence to antiviral treatment was considered as 80/80/95% of total doses. Sustained virological response was assessed at week 12 (SVR12).

RESULTS

At least one potential DDI was found in 70 (64.8%) patients, 45 (54.2%) being HCV-monoinfected and 25 (100%) HIV/HCV-coinfected (P < 0.01). Baseline treatment modifications were required in 38 (35.2%) patients. Adherence and SVR12 were higher in patients without DDIs (86.8%) and (67.6%) compared to those with DDIs (62.8%) (P = 0.021) and (47.2%) (P = 0.097) respectively.

CONCLUSIONS

More than half of the patients were at risk of presenting DDIs, leading to changes in the baseline medication in one-third of the patients. Drug interactions are frequent in patients with lower adherence.

HIV-1, HCV and alcohol in the CNS: potential interactions and effects on neuroinflammation

Approximately 25% of the HIV-1 positive population is also infected with HCV. The effects of alcohol on HIV-1 or HCV infection have been a research topic of interest due to the high prevalence of alcohol use in these infected patient populations. Although it has long been known that HIV-1 infects the brain, it has only been a little more than a decade since HCV infection of the CNS has been characterized. Both viruses are capable of infecting and replicating in microglia and increasing the expression of proinflammatory cytokines and chemokines, including IL-6 and IL-8. Investigations focusing on the effects of HIV-1, HCV or alcohol on neuroinflammation have demonstrated that these agents are capable of acting through overlapping signaling pathways, including MAPK signaling molecules. In addition, HIV-1, HCV and alcohol have been demonstrated to increase permeability of the blood-brain barrier. Patients infected with either HIV-1 or HCV, or those who use alcohol, exhibit metabolic abnormalities in the CNS that result in altered levels of n-acetyl aspartate, choline and creatine in various regions of the brain. Treatment of HIV/HCV co-infection in alcohol users is complicated by drug-drug interactions, as well as the effects of alcohol on drug metabolism. The drug-drug interactions between the antiretrovirals and the antivirals, as well as the effects of alcohol on drug metabolism, complicate existing models of CNS penetration, making it difficult to assess the efficacy of treatment on CNS infection.

Hepatitis C and HIV Coinfection for Social Workers in Public Health, Medical and Substance Use Treatment Settings

Hepatitis C virus (HCV) infection is a leading cause of liver disease and liver-related deaths among those living with human immunodeficiency virus (HIV) infection. Due to recent pharmacologic advancements with direct acting antivirals, if detected and treated, HCV antiviral therapy can prevent liver disease progression and permanently cure coinfected patients of HCV. The objectives of this article are to inform public health social workers and social workers in medical and substance use treatment settings of the public health burden of HCV/HIV coinfection and to highlight state-of-the art pharmacologic advancements in HCV antiviral therapy.

Outcome and management of HCV/HIV coinfection pre- and post-liver transplantation. A 2015 update

Liver transplantation is increasingly performed in selected HIV-infected patients in most developed countries, with excellent results reported in patients with liver diseases unrelated to HCV. In contrast, survival in HCV/HIV-coinfected liver recipients is poorer than in HCV-monoinfected patients, due to more aggressive recurrence of HCV and consequent graft loss and death. Results from American, French, and Spanish cohort studies showed a 5-year survival rate of only 50-55%. Therefore, it is debated whether liver transplantation should be offered to HCV/HIV-coinfected patients. Studies have shown that the variables more consistently associated with poor outcome are: (1) the use of old or HCV-positive donors, (2) dual liver-kidney transplantation, (3) recipients with very low body mass index and (4) less site experience. However, the most effective factor influencing transplantation outcome is the successful treatment of HCV recurrence with anti-HCV. Survival is 80% in patients whose HCV infection resolves. Unfortunately, the rates of sustained virological response with pegylated-interferon plus ribavirin in coinfected recipients are low, particularly for genotype 1 (only 10%). Here we present a non-systematic review of the literature based on our own experience in different liver transplant scenarios. This review covers selection criteria in HIV-infected patients, pre- and post-LT management, donor selection, anti-HCV treatment, drug interactions with antiretrovirals and anti-HCV direct antiviral agents, hepatocellular carcinoma, and liver retransplantation. Recommendations are rated. Finally, we explain how the introduction of new effective and more tolerable direct antiviral agents may improve significantly the outcome of HCV/HIV-coinfected liver recipients.

Pharmacokinetic interactions between telaprevir and antiretroviral drugs in HIV/HCV-coinfected patients with advanced liver fibrosis and prior HCV non-responders

Complex drug-drug interactions have been reported with concurrent administration of telaprevir (TVR) and human immunodeficiency virus (HIV) protease inhibitors (PIs), leading to relevant limitations of the therapeutic options for patients coinfected with hepatitis C virus (HCV) and HIV. However, little is known about the pharmacokinetics and drug interactions between TVR and antiretrovirals in HIV/HCV-coinfected patients with advanced liver fibrosis. Here we report the pharmacokinetics of TVR and antiretrovirals in a cohort of HIV/HCV genotype 1-coinfected patients with advanced liver fibrosis treated with TVR-based triple anti-HCV therapy. No significant differences were observed in the pharmacokinetics of atazanavir, amprenavir or tenofovir at baseline and at Day 15 of TVR, whereas the AUC0-4h of darunavir was 36% lower in the presence of TVR (AUC0-4h 15007ngh/mL and 9563ngh/mL at baseline and at Day 15 of TVR administration, respectively). Noteworthy, the AUC0-4h, Cmin and Cmax of raltegravir were reduced by 61%, 50% and 64%, respectively. However, none of the patient's plasma levels of tenofovir, atazanavir, amprenavir or raltegravir declined below their minimum effective concentrations even in association with TVR, and no HIV treatment failure occurred. A non-significant trend for lower TVR exposure was seen in patients concomitantly given amprenavir versus those given atazanavir (AUC0-4h, 9840ngh/mL and 13345ngh/mL, respectively). In conclusion, this study highlighted the feasibility of maintaining the current antiretroviral regimen in HIV/HCV-coinfected patients, even when significant interactions with TVR are predictable, whenever a change of HIV PIs is not deemed appropriate.

Treatment of chronic hepatitis C in patients with HIV/HCV coinfection

Hepatitis C virus (HCV) infection is one of the most frequent causes of comorbidity and mortality in the human immunodeficiency virus (HIV) population, and liver-related mortality is now the second highest cause of death in HIV-positive patients, so HCV infection should be countered with adequate antiviral therapy. In 2011 began the era of directly acting antivirals (DAAs) and the HCV NS3/4A protease inhibitors telaprevir and boceprevir were approved to treat HCV-genotype-1 infection, each one in combination with pegylated interferon alfa (Peg-IFN) + ribavirin (RBV). The addition of the first generation DAAs, strongly improved the efficacy of antiviral therapy in patients with HCV-genotype 1, both for the HCV-monoinfected and HIV/HCV coinfected, and the poor response to Peg-IFN + RBV in HCV/HIV coinfection was enhanced. These treatments showed higher rates of sustained virological response than Peg-IFN + RBV but reduced tolerability and adherence due to the high pill burden and the several pharmacokinetic interactions between HCV NS3/4A protease inhibitors and antiretroviral drugs. Then in 2013 a new wave of DAAs arrived, characterized by high efficacy, good tolerability, a low pill burden and shortened treatment duration. The second and third generation DAAs also comprised IFN-free regimens, which in small recent trials on HIV-positive patients have shown comforting preliminary results in terms of efficacy, tolerability and adherence.

Antiviral drug discovery: broad-spectrum drugs from nature

Covering: up to April 2014. The development of drugs with broad-spectrum antiviral activities is a long pursued goal in drug discovery. It has been shown that blocking co-opted host-factors abrogates the replication of many viruses, yet the development of such host-targeting drugs has been met with scepticism mainly due to toxicity issues and poor translation to in vivo models. With the advent of new and more powerful screening assays and prediction tools, the idea of a drug that can efficiently treat a wide range of viral infections by blocking specific host functions has re-bloomed. Here we critically review the state-of-the-art in broad-spectrum antiviral drug discovery. We discuss putative targets and treatment strategies, with particular focus on natural products as promising starting points for antiviral lead development.

Management of acute and chronic HCV infection in persons with HIV coinfection

Due to shared routes of transmission, acute and chronic infection with hepatitis C virus is common among persons living with HIV infection in many regions of the world. In the era of effective antiretroviral therapy, acute HCV infection has been increasingly recognized in HIV-infected persons, particularly men who have sex with men, and liver disease, including hepatocellular carcinoma, has emerged as a leading cause of morbidity and mortality in those with chronic HCV infection, particularly older adults with long-standing coinfection. Over the past decade, the foundation for the management of acute and chronic HCV infection has been interferon alfa. However, due the high burden of treatment-related side effects and low likelihood of sustained virologic response, the impact of treatment with peginterferon/ribavirin on the burden of HCV disease in has been limited. However, the anticipated availability of safe, tolerable and highly efficacious interferon-free, oral HCV direct-acting antiviral combination therapies promise to dramatically change the management of acute and chronic HCV infection in HIV-infected persons. Preliminary data from studies of such oral DAA regimens in HIV/HCV coinfected patients suggest that coinfection with HIV will not impair HCV cure with these regimens. Indeed, in the coming era of high effective oral HCV DAA treatments, the only special feature concerning treatment of acute and chronic HCV infection in HIV-infected patients may be drug interactions between the antiretroviral drugs for HIV infection and direct-acting antiviral drugs for HCV infection.

Medication use and medical comorbidity in patients with chronic hepatitis C from a US commercial claims database: high utilization of drugs with interaction potential

BACKGROUND

With the advent of the direct-acting antiviral agents, significant drug-drug interaction (DDI) potential now exists for patients treated for chronic hepatitis C virus (HCV) infection. However, little is known about how often patients with HCV infection use medications that may interact with newer HCV treatments, especially those with cytochrome P450 3A (CYP3A) DDI potential.

METHODS

Using a large US commercial insurance database, medication use and comorbidity burden were examined among adult patients with a chronic HCV diagnosis from 2006 to 2010. Medications were examined in terms of total number of prescription claims, proportion of patients exposed, and DDI potential with the prototypical CYP3A direct-acting antiviral agents boceprevir and telaprevir, for which data were available.

RESULTS

Patient comorbidity burden was high and increased over the study period. Medication use was investigated in 53 461 patients with chronic HCV. Twenty-one (53%) of the top 40 most utilized medications were classified as having interaction potential, with 62% of patients receiving at least one of the top 22 interacting medications by exposure. Of these, 59 and 41% were listed in a common DDI resource but not in medication-prescribing information, 77 and 77% had not been investigated in DDI studies, 41 and 36% did not have clear recommendations for DDI management, and only 14 and 23% carried a recommendation to avoid coadministration for boceprevir and telaprevir, respectively.

CONCLUSION

Practitioners may expect a medication with CYP3A DDI potential in two-thirds of patients with HCV and may expect almost one-half of the most frequently used medications to have CYP3A DDI potential. However, DDI potential may not be reflected in prescribing information.

Medication use and medical comorbidity in patients with chronic hepatitis C from a US commercial claims database: high utilization of drugs with interaction potential

BACKGROUND

With the advent of the direct-acting antiviral agents, significant drug-drug interaction (DDI) potential now exists for patients treated for chronic hepatitis C virus (HCV) infection. However, little is known about how often patients with HCV infection use medications that may interact with newer HCV treatments, especially those with cytochrome P450 3A (CYP3A) DDI potential.

METHODS

Using a large US commercial insurance database, medication use and comorbidity burden were examined among adult patients with a chronic HCV diagnosis from 2006 to 2010. Medications were examined in terms of total number of prescription claims, proportion of patients exposed, and DDI potential with the prototypical CYP3A direct-acting antiviral agents boceprevir and telaprevir, for which data were available.

RESULTS

Patient comorbidity burden was high and increased over the study period. Medication use was investigated in 53 461 patients with chronic HCV. Twenty-one (53%) of the top 40 most utilized medications were classified as having interaction potential, with 62% of patients receiving at least one of the top 22 interacting medications by exposure. Of these, 59 and 41% were listed in a common DDI resource but not in medication-prescribing information, 77 and 77% had not been investigated in DDI studies, 41 and 36% did not have clear recommendations for DDI management, and only 14 and 23% carried a recommendation to avoid coadministration for boceprevir and telaprevir, respectively.

CONCLUSION

Practitioners may expect a medication with CYP3A DDI potential in two-thirds of patients with HCV and may expect almost one-half of the most frequently used medications to have CYP3A DDI potential. However, DDI potential may not be reflected in prescribing information.

[GeSIDA/National AIDS Plan: Consensus document on antiretroviral therapy in adults infected by the human immunodeficiency virus (Updated January 2014)]

OBJECTIVE

This consensus document is an update of combined antiretroviral therapy (cART) guidelines for HIV-1 infected adult patients.

METHODS

To formulate these recommendations a panel composed of members of the Grupo de Estudio de Sida and the Plan Nacional sobre el Sida reviewed the efficacy and safety advances in clinical trials, cohort and pharmacokinetic studies published in medical journals (PubMed and Embase) or presented in medical scientific meetings. Recommendations strength and the evidence in which they are supported are based on modified criteria of the Infectious Diseases Society of America.

RESULTS

In this update, antiretroviral therapy (ART) is recommended for all patients infected by type 1 human immunodeficiency virus (HIV-1). The strength and grade of the recommendation varies with the clinical circumstances: CDC stage B or C disease (A-I), asymptomatic patients (depending on the CD4+ T-lymphocyte count: <350cells/μL, A-I; 350-500 cells/μL, A-II, and >500 cells/μL, B-III), comorbid conditions (HIV nephropathy, chronic hepatitis caused by HBV or HCV, age >55years, high cardiovascular risk, neurocognitive disorders, and cancer, A-II), and prevention of transmission of HIV (mother-to-child or heterosexual, A-I; men who have sex with men, A-III). The objective of ART is to achieve an undetectable plasma viral load. Initial ART should always comprise a combination of 3 drugs, including 2 nucleoside reverse transcriptase inhibitors and a third drug from a different family (non-nucleoside reverse transcriptase inhibitor, protease inhibitor, or integrase inhibitor). Some of the possible initial regimens have been considered alternatives. This update presents the causes and criteria for switching ART in patients with undetectable plasma viral load and in cases of virological failure where rescue ART should comprise 2 or 3 drugs that are fully active against the virus. An update is also provided for the specific criteria for ART in special situations (acute infection, HIV-2 infection, and pregnancy) and with comorbid conditions (tuberculosis or other opportunistic infections, kidney disease, liver disease, and cancer).

CONCLUSIONS

These new guidelines updates previous recommendations related to cART (when to begin and what drugs should be used), how to monitor and what to do in case of viral failure or drug adverse reactions. cART specific criteria in comorbid patients and special situations are equally updated.

Clinical and virological efficacy of etravirine plus two active Nucleos(t)ide analogs in an heterogeneous HIV-infected population

Etravirine (ETV) is recommended in combination with a boosted protease inhibitor plus an optimized background regimen for salvage therapy, but there is limited experience with its use in combination with two nucleos(t)ide reverse-transcriptase inhibitors (NRTIs). This multicenter study aimed to assess the efficacy of this combination in two scenarios: group A) subjects without virologic failure on or no experience with non-nucleoside reverse-transcriptase inhibitors (NNRTIs) switched due to adverse events and group B) subjects switched after a virologic failure on an efavirenz- or nevirapine-based regimen. The primary endpoint was efficacy at 52 weeks analysed by intention-to-treat. Virologic failure was defined as the inability to suppress plasma HIV-RNA to <50 copies/mL after 24 weeks on treatment, or a confirmed viral load >200 copies/mL in patients who had previously achieved a viral suppression or had an undetectable viral load at inclusion. Two hundred eighty seven patients were included. Treatment efficacy rates in group A and B were 88.0% (CI_95, 83.9–92.1%) and 77.4% (CI₉₅, 65.0–89.7%), respectively; the rates reached 97.2% (CI₉₅, 95.1–99.3%) and 90.5% (CI₉₅, 81.7–99.3), by on-treatment analysis. The once-a-day ETV treatment was as effective as the twice daily dosing regimen. Grade 1–2 adverse events were observed motivating a treatment switch in 4.2% of the subjects. In conclusion, ETV (once- or twice daily) plus two analogs is a suitable, well-tolerated combination both as a switching strategy and after failure with first generation NNRTIs, ensuring full drug activity.

Trial registration

ClinicalTrials.gov NCT01437241

Pros and cons of liver transplantation in human immunodeficiency virus infected recipients

Before the introduction of combined highly active antiretroviral therapy, a positive human immunodeficiency virus (HIV) serological status represented an absolute contraindication for solid organ transplant (SOT). The advent of highly effective combined antiretroviral therapy in 1996 largely contributed to the increased demand for SOT in HIV-positive individuals due to increased patients’ life expectancy associated with the increasing prevalence of end-stage liver disease (ESLD). Nowadays, liver failure represents a frequent cause of mortality in the HIV-infected population mainly due to coinfection with hepatitis viruses sharing the same way of transmission. Thus, liver transplantation (LT) represents a reasonable approach in HIV patients with stable infection and ESLD. Available data presently supports with good evidence the practice of LT in the HIV-positive population. Thus, the issue is no longer “whether it is correct to transplant HIV-infected patients”, but “who are the patients who can be safely transplanted” and “when is the best time to perform LT”. Indeed, the benefits of LT in HIV-infected patients, especially in terms of mid- and long-term patient and graft survivals, are strictly related to the patients’ selection and to the correct timing for transplantation, especially when hepatitis C virus coinfection is present. Aim of this article is to review the pros and cons of LT in the cohort of HIV infected recipients.

Drug interactions and protease inhibitors used in the treatment of hepatitis C: how to manage?

PURPOSE

The first-generation protease inhibitors (PI) boceprevir and telaprevir combined with pegylated interferon have revolutionized the treatment of type-1 hepatitis C by increasing the rates of sustained virologic response. However, they induce drug interactions, and their clinical relevance is difficult to predict. This review compiles available data on drug-drug interactions (DDI) based on their pharmacokinetic and pharmacodynamic properties with the aim of assisting clinicians in managing DDI METHODS: PubMed, drug interaction databases and hepatology and infectious disease conference abstracts were systematically searched using the key search terms "interaction", "hepatitis C", "telaprevir" and "boceprevir". All known interactions were compiled and reclassified according to their pharmacokinetic and pharmacodynamic mechanisms. The state of knowledge of interaction mechanisms are reported and a therapeutic approach is proposed.

RESULTS

Boceprevir and telaprevir are both substrates and potent inhibitors of cytochrome P450 3A4 and the drug transporter P-glycoprotein. They induce overdosage but can sometimes decrease the effect of other drugs by inducing other cytochromes. Overdosage or low dosage mainly affects drugs with a narrow therapeutic range, such as immunosuppressants or antiretrovirals. The distribution and elimination of PI are unaffected by interactions. In terms of pharmacodynamic interactions, PI can trigger drug-induced QT interval prolongation, which means that clinicians should manage such risk factors as potassium/magnesium levels or avoid other QT-prolonging drugs.

CONCLUSIONS

Management of hepatitis C therapy is complex. The key to interpreting DDI data is a solid understanding of the pharmacokinetic and pharmacodynamic profiles of the drugs involved. Their ability to inhibit cytochrome P450 3A4 and prolong the QT interval can have significant clinical consequences. This review provides a practical guide to the safe and effective management of therapy with boceprevir and telaprevir.

Towards hepatitis C eradication from the HIV-infected population

Around 10-15% of the 35 million people living with HIV worldwide have chronic hepatitis C virus (HCV) infection and are prone to develop liver-related complications. Exposure to HCV is almost universal among injecting drug users and is on the rise among homosexual men. Response to peginterferon-ribavirin therapy is generally lower in coinfection compared to HCV monoinfection. For this reason, the advent of direct-acting antivirals (DAA) is eagerly awaited for this population. The results of trials using DAA in coinfection show that treatment response rates are similar to those obtained in HCV monoinfection. Thus, HIV should no longer be considered as a "special" population, as long as antiretroviral therapy is given and drug interactions are taken into account. Envisioning HCV eradication from the HIV population faces major challenges ahead, including identification of the large number of undiagnosed individuals, and ensuring wide access to the best but often expensive HCV medications. This article forms part of a symposium in Antiviral Research on "Hepatitis C: next steps toward global eradication".

Hepatic safety and tolerability of raltegravir among HIV patients coinfected with hepatitis B and/or C

BACKGROUND

Potential liver toxicity is an important consideration for antiretroviral selection among patients coinfected with HIV and viral hepatitis (B and/or C). We sought to describe the hepatic safety profile of raltegravir in this population.

METHODS

Using data from HIV clinical cohorts at Johns Hopkins University and the University of North Carolina at Chapel Hill, we evaluated factors associated with liver enzyme elevations (LEEs) and calculated adverse event incidence rates for patients initiated on raltegravir-containing regimens prior to 1 January 2010. LEEs were graded according to Division of AIDS definitions.

RESULTS

During the study period, 456 patients received raltegravir - of whom 36% were hepatitis-coinfected (138 HCV, 17 HBV, 11 HBV+HCV). Coinfected patients were more likely to have baseline abnormal LEEs and developed severe (grade 3-4) LEEs at a rate 3.4× that of HIV-monoinfected patients (95% CI 1.28, 9.61). Among all participants, the incidence rate for first occurrence of severe LEEs was 5 per 100 person-years (95% CI 3, 7). In adjusted analyses, coinfected patients had a 2.7-fold increased hazard of severe LEEs (95% CI 1.03, 7.04). 60% of severe abnormalities occurred within 6 months after starting raltegravir; the drug was discontinued in 3 (1.3%) coinfected patients and 18 (6.2%) monoinfected patients.

CONCLUSIONS

Compared with HIV-monoinfected patients, those with HIV-hepatitis coinfection are at increased hazard of developing LEEs on raltegravir, at a level similar to other antiretrovirals. Severe events were uncommon, rarely leading to raltegravir discontinuation. With appropriate monitoring, raltegravir-based therapy is safe in hepatitis-coinfected patients.

Strategies for assignment of HIV-HCV genotype-1-coinfected patients to either dual-therapy or direct-acting antiviral agent-based triple-therapy

BACKGROUND

The aim of this study was to evaluate strategies for assignment of HIV-HCV genotype-1-coinfected patients (HIV-HCV-GT1) to either dual-therapy or direct-acting antiviral agent (DAA)-based triple-therapy.

METHODS

A total of 148 treatment-naive HIV-HCV-GT1 who received antiviral therapy with pegylated interferon/ribavirin were included in this multinational, retrospective analysis. Patients with rapid virological response (RVR) were treated for 48 weeks, while patients without RVR received either 48 or 72 weeks of treatment. IL28B rs12979860 (IL28B) non-C/C, advanced liver fibrosis and high HCV RNA were considered as established risk factors for treatment failure.

RESULTS

A trend toward higher sustained virological response (SVR) rates in patients with IL28B C/C (65% [37/57] versus 51% [40/79]; P=0.097) was observed. Higher SVR rates were observed in patients without advanced liver fibrosis (61% [47/77] versus 42% [22/52]); P=0.036) and without high HCV RNA (73% [35/48] versus 49% [49/100]; P=0.006), as well as in patients with RVR (90% [35/39] versus 45% [49/109]; P<0.001). SVR rates varied statistically significantly between the risk factors for treatment failure subgroups (86% [6/7] versus 69% [34/49] versus 48% [21/44] versus 20% [4/20] for zero, one, two and three risk factors, respectively; P<0.001). In patients without RVR, higher rates of SVR were observed in those treated for 72 weeks (62% [23/37]), when compared to patients treated for 48 weeks (36% [26/72]; P=0.01).

CONCLUSIONS

RVR had an excellent positive predictive value for the response to dual-therapy in HIV-HCV-GT1, emphasizing the utility of a lead-in phase for assigning these patients to dual-therapy or DAA-based triple-therapy. The use of an IL28B-guided approach was suboptimal, while a combination of established baseline predictors may provide guidance for individual treatment decisions prior to the initiation of antiviral therapy. However, the extension of treatment duration to 72 weeks in HIV-HCV-GT1 without RVR should be strongly considered if triple-therapy is not available.

Update on Hepatitis C Virus and HIV Coinfection

Chronic hepatitis C virus (HCV) infection has historically been difficult to treat in the HIV-infected population, owing to generally poor responses to interferon-based therapies. The recent rapid development of directly acting antiviral agents (DAAs) against HCV has the potential to revolutionize treatment of this infection in the HIV population by improving tolerability and outcome, and, ultimately, reducing the significant burden of liver-related morbidity and mortality in this population. Clinical trials to address the safety and efficacy of novel DAAs in the HCV/HIV coinfected population are ongoing, and show much promise. The rapidity of current drug discovery in the field of HCV is both impressive and daunting for clinicians who will have to master these drugs. Going forward, the inclusion of individuals from this large and growing patient population in clinical trials will be of paramount importance.

Update on HIV/HCV coinfection

Liver disease is currently one of the leading causes of hospitalization and death in HIV-positive individuals. Coinfection with the hepatitis C virus (HCV) is a major contributor to this trend. Besides hepatic damage, which is enhanced in the presence of HIV-associated immunosuppression, HCV may contribute to disease in coinfected individuals by potentiating immune activation and chronic inflammation, which ultimately account for an increased risk of cardiovascular events, kidney disease, and cancers in this population. Fortunately, hepatitis C therapeutics has entered a revolutionary era in which we hope that most patients treated with the new oral direct-acting antivirals (DAA) will be cured. However, many challenges preclude envisioning a prompt elimination of HCV from the coinfected population. Issues that should be addressed include the following: (1) rising incidence of acute hepatitis C in men who have sex with men, and expansion/recrudescence of injection drug use in some settings/regions; (2) adverse drug interactions between antiretrovirals and DAA; and (3) high cost of DAA, which may lead many to defer or fail to access appropriate therapy.

Role of ritonavir in the drug interactions between telaprevir and ritonavir-boosted atazanavir

BACKGROUND

Detrimental bidirectional pharmacokinetic interactions have been observed when telaprevir (TVR) and ritonavir (RTV)-boosted human immunodeficiency virus (HIV) protease inhibitors are coadministered in healthy volunteers. Our aim was to evaluate the role of RTV in the bidirectional TVR and atazanavir (ATV) interactions.

METHOD

An open-label, sequential study was carried out in hepatitis C virus (HCV)/HIV-coinfected patients on a RTV-boosted ATV-based (ATVr) antiretroviral regimen (300/100 mg every 24 hours) and triple therapy for chronic C hepatitis genotype 1 (TVR, 1125 mg every 12 hours, pegylated interferon-alpha and ribavirin). Pharmacokinetic profiles were acquired before and after switching from ATVr to unboosted ATV (200 mg every 12 hours). The plasma levels of both drugs were determined by liquid chromatography coupled with mass spectrometry. Pharmacokinetic parameters were calculated by noncompartmental analysis and compared by geometric mean ratios and their 90% confidence intervals.

RESULTS

Fourteen white HCV/HIV-coinfected males were enrolled in this study. After RTV was withdrawn, the TVR AUC(0-12) (area under the concentration-time curve), maximum concentration (C(max)), and minimum concentration (C(min)) values increased by 19% (7%-30%), 12% (0.9%-29%), and 18% (2%-34%), respectively, without any changes in the TVR terminal half-life. The ATV AUC(0-12), C(max), and C(min) values were 39% (13%-66%), 19% (8%-59%), and 48% (1%-96%) higher, respectively, with a significantly shorter terminal half-life (22.6 hours vs 10.4 hours).

CONCLUSIONS

RTV is responsible for the adverse interactions that occur when TVR and ATVr are administered together, possibly by influencing either the absorption phase or first-pass metabolism of TVR. The boost effect of TVR on ATV exposure is higher than on RTV, despite its shorter terminal half-life. The coadministration of TVR and unboosted ATV results in increased exposure of both drugs compared with their coadministration with RTV.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov: NCT01818856. European Medicines Agency EudraCT no. 2012-002515-25.

Drug-drug interactions during antiviral therapy for chronic hepatitis C

The emergence of direct-acting antiviral agents (DAAs) for HCV infection represents a major advance in treatment. The NS3 protease inhibitors, boceprevir and telaprevir, were the first DAAs to receive regulatory approval. When combined with PEG-IFN and ribavirin, these agents increase rates of sustained virologic response in HCV genotype 1 to ∼70%. However, this treatment regimen is associated with several toxicities. In addition, both boceprevir and telaprevir are substrates for and inhibitors of the drug transporter P-glycoprotein and the cytochrome P450 enzyme 3A4 and are, therefore, prone to clinically relevant drug interactions. Several new DAAs for HCV are in late stages of clinical development and are likely to be approved in the near future. These include the protease inhibitors, simeprevir and faldaprevir, the NS5A inhibitor, daclatasvir, and the nucleotide polymerase inhibitor, sofosbuvir. Herein, we review the clinical pharmacology and drug interactions of boceprevir, telaprevir and these investigational DAAs. Although boceprevir and telaprevir are involved in many interactions, these interactions are manageable if health-care providers proactively identify and adjust treatments. Emerging DAAs seem to have a reduced potential for drug interactions, which will facilitate their use in the treatment of HCV.

The importance of drug-drug interactions in the DAA era

With the licensing of the direct acting antivirals telaprevir and boceprevir the topic of drug-drug interactions has come to the forefront. These first generation hepatitis C virus protease inhibitors are metabolized by and inhibit the key drug metabolizing enzyme CYP3A4, which means that knowledge of drug-drug interactions has become an essential component of the evaluation of a patient starting triple therapy. The number of potential co-medications means that many drugs will be used in hepatitis C virus patients where there are no pharmacokinetic study data. Here we have to use the data that are available and seek to extrapolate to unstudied drugs using key principles of clinical pharmacology (disposition characteristics, concentration-effect relationships, therapeutic window) in order to give some guidance for management of patients. This is a rapidly moving area in hepatitis C therapy, both in terms of understanding the drug interaction profile of telaprevir and boceprevir, interaction mechanisms that sometimes appear counterintuitive and that may involve enzymes other than CYP3A4 or transporters, but then seeking to understand the interaction potential of the next wave of drugs that will soon be with us.

[Pharmacokinetic interactions of telaprevir with other drugs]

Telaprevir is a new direct-acting antiviral drug for the treatment of hepatitis C virus (HCV) infection and is both a substrate and an inhibitor of cytochrome P450 (CYP450) isoenzymes. With the introduction of this new drug, assessment of drug-drug interactions has become a key factor in the evaluation of patients under treatment for HCV infection. During the treatment of this infection, many patients require other drugs to mitigate the adverse effects of anti-HCV drugs and to control other comorbidities. Moreover, most patients coinfected with HIV and HCV require antiretroviral therapy during treatment for HCV. Physicians should therefore be familiar with the pharmacokinetic properties of direct-acting antivirals for HCV treatment and their potential drug-drug interactions. The present article reviews the available information to date on the interactions of telaprevir with other drugs and provides recommendations for daily clinical practice.