Interferons for chronic hepatitis B

Examples

Generic Name	Brand Name
interferon alfa-2b	Intron A
pegylated interferon alfa-2a (peginterferon)	Pegasys

How It Works

Interferon is a man-made copy of a protein that your body makes in response to infection. It helps the immune system fight disease and may slow or stop the growth of the hepatitis B virus in your body.

Interferon is given as a shot 3 times a week. A slow release form of interferon, pegylated interferon (also known as peginterferon), is given as a shot once a week. Peginterferon is used more often than interferon to treat hepatitis B. Treatment with interferons can last 4 months to 1 year.

Why It Is Used

Interferons are used to treat long-term (chronic) HBV infection in adults and children who are at risk for liver disease. The Canadian Association for the Study of the Liver has made recommendations on who should receive treatment for hepatitis B based on the presence of hepatitis B antigen in your blood, the level of hepatitis B virus DNA (HBV DNA) in your blood, and the levels of your liver enzymes.¹

Treatment with interferons is not recommended if you are using illegal drugs or drinking too much alcohol. It is also not recommended if you have had an organ transplant or if you have advanced liver scarring (cirrhosis).

Interferons can cause or aggravate mental problems. Tell your doctor if you have a history of depression, suicidal thoughts, anxiety, drug or alcohol abuse, or mental illness.

How Well It Works

It is important to weigh the benefits of treatment against the risks. Treatment for HBV infection is considered successful if blood tests show that the virus is no longer multiplying in the body, if liver enzyme levels return to normal, and if liver damage (such as inflammation and scarring) improves.

The success of interferon treatment for hepatitis B depends on how treatment success is defined. Relapse—when the virus starts to multiply again—is common after treatment is stopped. Interferons stop the growth of the virus over the long term in about 35% of people who use them.² Recent studies suggest that peginterferon works a little better than interferon.^{3, 4}

Interferons work best for people who have high levels of liver enzymes and in whom the virus is multiplying. They are also more likely to work in people who have a strong immune system, who have had hepatitis for a short amount of time, and who became infected after childhood.⁵

Side Effects

Interferons have common side effects, including:

• Headaches and muscle aches.
• Fatigue.
• Fever.
• Hair loss.
• Depression and other mental health problems.
• A decrease in platelets (cells that cause blood to clot).
• A decrease in white blood cells.

Rare side effects include:

• Thyroid problems.
• Confusion.
• Too much protein in your urine, which may mean that you are having kidney problems.
• Heart problems.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

• Interferons have several advantages over other medicines used to treat chronic hepatitis B:
  • Drug resistance has not developed with interferon use. Resistance has developed with the use of other medicines to treat chronic HBV. Drug resistance occurs when viruses change over time and can no longer be killed by medicines that killed them in the past.
  • Treatment is done for a shorter length of time than treatment with other HBV medicines. For example, treatment with an interferon may last for 12 to 48 weeks, while treatment with a nucleoside reverse transcriptase inhibitor (NRTI) usually lasts for years.
  • Peginterferon has to be given only once a week. Interferon has to be given 3 times a week.
• interferons have some potential disadvantages compared to other medicines used to treat chronic hepatitis B:
  • Peginterferon was approved by Health Canada in 2005 to treat chronic hepatitis B, so its long-term effects are not yet known. But peginterferon has been used to treat chronic hepatitis C since 2002.
  • Interferons are expensive, but you usually take them for just 4 to 12 months. Other medicines may need to be taken for longer periods of time.
  • They must be given as injections (shots).
  • Interferons are more likely to cause side effects than are other medicines used to treat hepatitis B.
  • Experts do not know if interferons are safe for pregnant women. They are not considered safe for women who are breast-feeding.

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Author:	Douglas Dana Maria G. Essig, MS, ELS	Last Updated: February 8, 2008
Medical Review:	Anne C. Poinier, MD - Internal Medicine Kathleen Romito, MD - Family Medicine W. Thomas London, MD - Hepatology Jerome B. Simon, MD, FRCPC, FACP - Gastroenterology
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