Focus

Assessing safety and efficacy of sofosbuvir for the treatment of hepatitis C

INTRODUCTION

IFN-free regimens with direct antiviral agents (DAAs) against hepatitis C virus (HCV) are likely to greatly expand patients' access and response to hepatitis C therapy, while safety and tolerability of treatments seem substantially improved. Sofosbuvir (SOF), a NS5B nucleotide polymerase inhibitor with pan-genotypic activity and a high-barrier to resistance, has been approved by FDA and EMA in an all oral combination therapy for chronic hepatitis C with ribavirin (RBV) alone, or in combination with either pegylated interferon/RBV or other DAAs.

AREAS COVERED

This paper provides an overview of SOF-based therapy in chronic hepatitis C as it emerges from the published clinical trials. Data on special populations are included (i.e., decompensated patients, patients on liver transplant waiting lists, patients with renal impairment). The data has been analyzed according to the different HCV-genotypes and comprehensively covers both safety and efficacy treatment profiles.

EXPERT OPINION

Clinical trials have highlighted the safety and efficacy of SOF-based regimens, leading to the rapid approval of this therapy and its incorporation in the recommendations of the international societies on treatment of HCV infection. However, additional data are still needed to optimize both combination therapies' efficacy and duration in some categories of patients who have been under-represented in the registration trials.

Drug interactions with new hepatitis C oral drugs

INTRODUCTION

Chronic hepatitis C virus (HCV) infection has recently become a curable disease with antiviral therapy. The knowledge of drug interactions using direct-acting antivirals (DAA) may permit maximizing antiviral efficacy and avoiding drug-related toxicities. Ageing in the chronic hepatitis C population, along with added co-morbidities that require other medications, has increased the attention on drug interactions using DAA.

AREAS COVERED

This review provides an update of the most clinically significant pharmacokinetic and pharmacodynamic drug interactions occurring between currently available DAA and other medications. The review also revisits how drug interactions with DAA can be prevented and managed.

EXPERT OPINION

Interactions between DAA and other drugs are frequent in clinical practice. The most frequent drug interactions modify drug metabolism by inducing or inhibiting the cytochrome P450, leading to abnormal drug exposures. Through this mechanism HCV protease inhibitors, especially when co-formulated with ritonavir as pharmacoenhancer, and non-nucleoside HCV polymerase inhibitors interact with other medications. In contrast, NS5B nucleos(t)ide analog inhibitors (i.e., sofosbuvir) and some HCV NS5A inhibitors (i.e., ledipasvir), which do not or only marginally affect CYP450, are relatively free of significant pharmacokinetic interactions. However, exposure to HCV nucleos(t)ide analogs may be influenced by induction/inhibition of drug transporters (i.e., P-glycoprotein) as well as by pharmacodynamic interference with other nucleos(t)ide analogs used as antivirals or cancer drugs. Drug interactions for some NS5A inhibitors (i.e., daclatasvir) are generally moderate and can be managed with dose adjustments.