Information about Dasabuvir
Viekira Pak is a combination of oral antiviral agents that is used to treat chronic hepatitis C, genotype 1.
Liver safety of Dasabuvir
This combination has been associated with a low rate of serum enzyme elevations during therapy, and has been reported to cause rare cases of clinically apparent liver injury with jaundice and may result in hepatic decompensation in some patients with preexisting cirrhosis.
History of Dasabuvir
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 and well tolerated therapy without use of interferon and with treatment courses of 8, 12 or 24 weeks only.
Mechanism of action of Dasabuvir
Viekira Pak (vee kee' rah pak) is the commercial name for a combination of oral, direct acting antiviral agents used to treat chronic hepatitis C associated with HCV genotype 1. The hepatitis C virus (HCV) encodes several nonstructural (NS) polypeptides that are essential for its replication: NS3/4 that has protease and helicase activities, NS5A that is a membrane bound polypeptide that is essential in the creation of the replicative complex, and NS5B an HCV specific, RNA-dependent, RNA polymerase. These polypeptides are effective targets for antiviral therapy of hepatitis C. Viekira Pak is a combination paritaprevir (par’ i ta’ pre veer: formerly ABT-450) which is a potent HCV NS3/4 protease inhibitor, ombitasvir (om bit’ as veer: ABT-267) an NS5A replication complex inhibitor, and dasabuvir (da sa’ bue veer: ABT-333) a nonnucleoside HCV RNA polymerase [NS5B] inhibitor. Paritaprevir is metabolized by CYP 3A4 and is typically given in combination with low doses of ritonavir, an inhibitor of CYP 3A4, to achieve higher and more prolonged drug levels which allow for once daily dosing. In cell culture and in humans infected with HCV, each of the agents has potent activity against HCV, but development of antiviral resistance rapidly arises with continued exposure. The combination of several direct acting agents with different molecular targets allows for a sustained viral suppression while avoiding antiviral resistance.
Clinical use of Dasabuvir
The combination of these three agents (and ritonavir) with and without ribavirin (an antiviral nucleoside analogue with activity against HCV) has been shown to be very effective in suppressing HCV replication in patients infected with HCV genotype 1, and to result in a sustained virological response (SVR) and eradication of HCV in more than 90% of patients when given for 12 weeks or more.
FDA approval information for Dasabuvir
Viekira Pak was approved for use in the United States in 2015, the second all-oral antiviral combination to receive approval for chronic hepatitis C. It is available as two tablets, one being the fixed combination of ombitasvir (12.5 mg), paritaprevir (75 mg) and ritonavir (100 mg) which is given once daily, and the other being dasabuvir (250 mg) which is given twice daily with meals.
Dosage and administration for Dasabuvir
Ribavirin (if a part of the combination therapy as is recommended for genotype 1a and for patients with cirrhosis) is available in tablets of 200 mg and is given twice daily for a total dose of 1,000 mg (if body weight is <75 kg) or 1,200 mg (if body weight ≥75 kg). Current indications for Viekira Pak (the combination of dasabuvir, ombitasvir and paritaprevir with ritonavir: D-O-P/r) are limited to patients with HCV genotype 1. The combination of just ombitasvir and paritaprevir with ritonavir (O-P/r) is also available under the commercial name Technive and is approved for use in combination with ribavirin in patients with chronic hepatitis C, genotype 4, without cirrhosis. Side effects of Viekira Pak and Technive are uncommon, but are generally mild and can include nausea, itching, rash, cough and insomnia. When given with ribavirin, side effects are greater, but are largely due to the hemolysis, nasal congestion and skin reactions that are common with that agent.
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