Hepatitis C drugs are given as combinations. Interferon-free direct-acting
antiviral treatment consists of drugs of two or three different types. Each
type of drug is designed to interrupt a different stage in the life cycle of
HCV. By targeting different stages, a treatment combination has a better chance
of stopping the production of new viruses. If one type of drug is used
hepatitis C viruses are highly likely to develop resistance to it. If two or
more types of drugs are used, it is much more difficult for viruses to emerge
which are resistant to both drugs. Direct-acting antivirals target three
different parts of the HCV life cycle to stop the production of new viruses:
- Protease
inhibitors such as paritaprevir (part of Viekirax & Exviera) glecaprevir
(part of Maviret), grazoprevir (part of Zepatier) and
voxilaprevir (part of Vosevi).
- NS5A
inhibitors such as ledipasvir (part of Harvoni), pibrentasvir (part
of Maviret) daclatasvir (Daklinza), velpatasvir (part of Epclusa)
and elbasvir (part of Zepatier).
- NS5B
polymerase inhibitors: sofosbuvir (Sovaldi, also in Harvoni and
Epclusa).
- NS5B
non-nucleoside inhibitors: dasabuvir (part of Viekirax).
Ribavirin
Ribavirin is an antiviral drug and is taken daily in tablet form. As an
individual medication, ribavirin has almost no effect on hepatitis C viruses.
When combined with interferon, however, it enhances the effect of interferon,
improving the chances of curing hepatitis C. Ribavirin also improves the effect
of some direct-acting antiviral combinations in people who have hepatitis C
that is harder to cure, such as people with advanced cirrhosis and those with
post-liver transplant recurrence of hepatitis C.
Interferon
Interferon is a substance produced by the body when viruses or bacteria
enter the body. Using interferon as a treatment stimulates the body’s natural
immune defences. Interferon can be injected to stimulate an immune response.
Pegylated interferon alpha is used in the treatment of hepatitis C. It has a
type of protective coating, which prevents it being broken down too quickly in
the body. This helps to maintain constant levels of interferon, improving the
chances of successful treatment. Pegylated interferon is rarely used nowadays
in the treatment of hepatitis C because
direct-acting antivirals are better tolerated, more effective and cure most
people after 8-12 weeks of treatment.