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Information about Telaprevir
Telaprevir is an oral, direct acting hepatitis C virus (HCV) protease inhibitor that is used in combination with other antiviral agents in the treatment of chronic hepatitis C, genotype 1.
Liver safety of Telaprevir
Telaprevir has not been linked to instances of acute liver injury during therapy, but has been linked to cases of severe cutaneous reactions such as DRESS and Stevens Johnson syndrome which can be associated with mild hepatic injury. In addition, when combined with peginterferon and ribavirin, telaprevir has been associated with cases of hepatic decompensation in patients with preexisting cirrhosis.
Mechanism of action of Telaprevir
The hepatitis C virus is a small RNA virus that is a major cause of chronic hepatitis, cirrhosis and hepatocellular carcinoma in the United States as well as worldwide. Various approaches to antiviral therapy of chronic hepatitis C have been developed, starting in the 1980s with interferon alfa which was replaced in the 1990s by long acting forms of interferon (peginterferon), to which was added the oral nucleoside analogue, ribavirin. Between 2010 and 2015, several potent oral, direct acting anti-HCV agents were developed and combinations of these found to have marked activity against the virus, allowing for highly effective therapy without use of interferon with treatment courses of 12 to 24 weeks only. These direct acting agents included HCV protease (NS3/4) inhibitors, structural replication complex (NS5A) inhibitors and the HCV RNA polymerase (NS5B) inhibitors. The HCV protease inhibitors block the activity of the viral encoded protease that is essential in the posttranslational modification of the viral polypeptide, cleaving it into a series of structural and nonstructural (NS: enzyme) regions. The HCV proteases that have been developed are polypeptide-like molecules, modified amino acids that that resemble the specific amino acid sequence that the protease cleaves and act as competitive inhibitors of the protease enzyme. At least four HCV protease inhibitors (all having the suffix: -previrs) have been approved for use in the United States: boceprevir , telaprevir , simeprevir  and paritaprevir .
Telaprevir (tel a' pre vir) was one of the first HCV specific protease inhibitors developed as therapy of chronic hepatitis C. Like other HCV protease inhibitors, telaprevir blocks the activity of the viral encoded protease (HCV nonstructural [NS] region 3/4) that is essential in the posttranslational modification of the viral polypeptide that is cleaved into a series of structural and nonstructural (enzyme) regions. When used by itself, telaprevir results in rapid inhibition of HCV RNA levels, but resistance develops rapidly in a high proportion of patients. When combined with peginterferon and ribavirin, it was shown to provide a sustained inhibition of HCV RNA with a low rate of antiviral resistance. Triple therapy with telaprevir, peginterferon and ribavirin, when given for 44 to 48 weeks, increased the sustained virological response (SVR) rate from 40% to 50% (peginterferon and ribavirin alone) to 70% to 85% in patients with genotype 1.
FDA approval information for Telaprevir
Telaprevir was approved for use in the United States in 2011 for patients with chronic hepatitis C, genotype 1, to be used in combination with peginterferon and ribavirin. Since that time, telaprevir has been replaced by more potent and better tolerated oral antiviral agents that can be given in combination without peginterferon. For these reasons, telaprevir was withdrawn by the sponsor in 2015. Telaprevir was previously available under the brand name Incivek (formerly VX950) as tablets of 375 mg. The recommended dose was 750 mg three times daily for the first 12 of the 24 or 48 weeks of combination therapy.
Side effects of Telaprevir
The side effects of telaprevir were difficult to separate from those of peginterferon and ribavirin, but the triple therapy was associated with a higher rate of many side effects, including anemia, fatigue, itching, rash, anal pruritus and burning and gastrointestinal upset. rash was particularly common with telaprevir therapy occurring in at least half of patients and occasionally being associated with DRESS or Stevens Johnson syndrome.
The following are drugs for Hepatitis C:
HCV NS5A Inhibitors
HCV NS5B (Polymerase) Inhibitors
HCV Protease Inhibitors
- Asunaprevir, Boceprevir, Glecaprevir, Grazoprevir, Paritaprevir, Simeprevir, Telaprevir, Voxilaprevir