Grazoprevir is a second generation NS3/4A protease inhibitor approved in the EU and the USA for the treatment of hepatitis C virus (HCV) genotypes 1 and 4 infections in adult patients in combination with elbasvir (C virus (HCV) NS5A inhibitor) as the fixed-dose combination product Zepatier with or without ribavirin. In phase III trials, 12 or 16 weeks of treatment with once-daily elbasvir/grazoprevir (fixed-dose tablet or as individual agents), taken with or without ribavirin, generally provided high rates of sustained virological response at 12 weeks (SVR12) in treatment-naive and -experienced adult patients with chronic HCV genotype 1a, 1b or 4 infection, including those with or without compensated cirrhosis, HIV co-infection, inherited blood disorders or chronic kidney disease or patients receiving opioid agonist therapy or of Japanese origin. Elbasvir/grazoprevir was generally well tolerated. Thus, elbasvir/grazoprevir, with or without ribavirin, represents an effective new option for the treatment of adults with chronic HCV genotype 1 and 4 infection, including a number of difficult-to-treat populations.

Narlaprevir (formerly SCH 900518), a NS3 protease inhibitor is being developed by R-Pharm for the treatment of a chronic hepatitis C (genotype 1). Narlaprevir is a potent inhibitor of hepatitis C virus (HCV) NS3 protease with a Ki of 7 ± 1 nM and a 90% inhibitory concentration (IC90) of ∼28 ng/ml for HCV genotype 1 replicon in vitro. Narlaprevir successfully passed extensive pre-clinical and clinical trials in Schering-Plough Research Institute (USA) and in a variety of clinical centers of Europe, USA and Russia. Based on clinical findings R-Pharm obtained a registration certificate for Arlansa (Narlaprevir) ЛП-003622 dd 12.05.2016 issued by Ministry of Healthcare of the Russian Federation.

Ciluprevir (BILN-2061) is a selective inhibitor of the HCV NS3 serine protease, which was developed by Boehringer Ingelheim for the treatment of hepatitis C infection. The drug was discontinued in phase II due to adverse events such as cardiac toxicity (demonstrated in animals). In the cell-based replicon assay, ciluprevir inhibited HCV RNA replication at low nanomolar levels. It had inhibitory rate constant (Ki) values of 0.3 and 0.66 nM for the NS3 proteases of HCV genotypes 1a and -1b, respectively.

Grazoprevir is a second generation NS3/4A protease inhibitor approved in the EU and the USA for the treatment of hepatitis C virus (HCV) genotypes 1 and 4 infections in adult patients in combination with elbasvir (C virus (HCV) NS5A inhibitor) as the fixed-dose combination product Zepatier with or without ribavirin. In phase III trials, 12 or 16 weeks of treatment with once-daily elbasvir/grazoprevir (fixed-dose tablet or as individual agents), taken with or without ribavirin, generally provided high rates of sustained virological response at 12 weeks (SVR12) in treatment-naive and -experienced adult patients with chronic HCV genotype 1a, 1b or 4 infection, including those with or without compensated cirrhosis, HIV co-infection, inherited blood disorders or chronic kidney disease or patients receiving opioid agonist therapy or of Japanese origin. Elbasvir/grazoprevir was generally well tolerated. Thus, elbasvir/grazoprevir, with or without ribavirin, represents an effective new option for the treatment of adults with chronic HCV genotype 1 and 4 infection, including a number of difficult-to-treat populations.