http://www.med.upenn.edu/gastro/documents/ClinLiverDisHBVandinterferon.pdf
IFN has been used in the treatment of chronic hepatitis B for many years.
IFN exerts an antiviral effect on HBV infection through two mechanisms
[19]. First, IFN has a direct antiviral effect, inhibiting synthesis of viral
DNA and activating antiviral enzymes. Second, IFN exaggerates the cellular
immune response against hepatocytes infected with HBV by increasing the
expression of class I histocompatibility antigens and by stimulating the activity
of helper T lymphocytes and natural killer lymphocytes. Thus, IFN
induces an early reduction of HBV replication (reflected by a reduction of
HBV DNA in serum) and a late (about 2 months later) increase in serum
alanine aminotransferase (ALT) levels. Many controlled studies of IFN in
patients who have chronic hepatitis B have been reported. In these studies,
using various regimens, mean virologic response rate was 37% versus 17%,
the mean rate of HBeAg loss was 33% versus 12%, and the rate of hepatitis
B surface antigen (HbsAg) loss was 8% versus 2% in the interferon-treated
groups versus the placebo groups (Fig. 1) [5]. A dosage of 5 million units
(MU) to 10 MU, three times per week for 4 to 6 months, combines good
efficacy with satisfactory tolerance [4].
One drug used to treat hepatitis B is pegylated interferon (brand name Pegasys). Interferon, administered in a weekly injection,strengthens your immune system
to help it fight the hepatitis B virus (HBV).
Doctors may prescribe interferon for 48 weeks if your alanine aminotransferase (or ALT) level is above normal. This means your immune system is actively fighting
the HBV infection in your liver. When your immune system attacks your HBV-infected liver cells, the damaged cells release ALT.
Interferon works best when your ALT levels are elevated, and your viral load is low.
So, when your ALT level is elevated, doctors may prescribe interferon to help the immune system fight off HBV.
HBeAg-positive patients:
In clinical trials, about 27 to 32% of people who have the “e” antigen (HBeAg positive) were able to get rid of the HBeAg and develop the “e” antibody after interferon treatment, and 39% achieved normal ALT levels.
HBeAg-negative patients:
About 63% of these patients achieved undetectable viral load (HBV DNA) and 38% achieved normal ALT levels.
Remember.............
• If you have HBeAg, interferon can lower your viral load to
undetectable levels 25% of the time, and produce normal ALT
levels in 39% of patients.
• If you have HBeAg-negative hepatitis B, interferon can produce
undetectable viral load 63% of the time and normal ALT levels
38% of the time.
• Studies suggest that patients with HBV genotypes A and B
respond better to interferon than other genotypes.
• Interferon is an expensive drug, but it only has to be taken for 48
weeks.
• The immune system must be fighting the hepatitis B infection
(indicated by high ALT levels) for interferon to work.
• In some people, interferon causes fatigue and moderate to
severe depression.