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Nucleoside reverse transcriptase
inhibitors (NRTIs) are medicines that slow the ability of the
hepatitis B virus (HBV) to multiply in the body. They
are taken as pills once a day for at least a year, and usually much longer.
Entecavir is also available as a liquid that you swallow.
Adefovir, entecavir, telbivudine, and tenofovir are approved by the U.S. Food and
Drug Administration (FDA) for use in adults. Lamivudine is approved for use by
adults and by children ages 2 to 17.
NRTIs are used to treat long-term
(chronic) HBV infection in adults and children who are at risk for liver
disease. The American Association for the Study of Liver Disease has made
recommendations on who should receive treatment for
chronic hepatitis B based on the presence of hepatitis B
antigens in your blood, the level of
hepatitis B virus DNA (HBV DNA) in your blood, and the
levels of the liver
enzyme alanine aminotransferase (ALT).1
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. NRTIs work in
most of the people who take them, but
relapse (the virus starts to multiply again) is common
after a medicine is stopped, so you may have to take the medicine for a long
Some studies of
entecavir show that it works better than lamivudine or
adefovir.3, 4, 5
Adefovir is effective against HBV infections that have
become resistant to lamivudine.1 A study showed that treatment with
adefovir worked better for some people with chronic hepatitis B if the medicine
was taken for 144 weeks than if it was taken for only 48 weeks.6
Tenofovir is effective at reducing the amount of hepatitis B virus in the body.7
hepatitis B virus may develop
resistance to some of the NRTIs:1
All medicines have side effects. But many people don't feel the side effects, or they are able to deal with them. Ask your pharmacist about the side effects of each medicine you take. Side effects are also listed in the information that comes with your medicine.
Here are some important things to think about:
Call 911 or other emergency services right away if you have:
Call your doctor if you:
Common side effects of these medicines include:
Adefovir and tenofovir may harm your kidneys if you are at risk for or
have a kidney problem.
See Drug Reference for a full list of side effects. (Drug
Reference is not available in all systems.)
It is important to talk to your doctor about
all the medicines and herbal remedies you are taking. These may affect how well
your medicine for chronic hepatitis B works.
After treatment with
any type of NRTI is stopped, your infection may come back (relapse), and you
may need to start taking the same or a different medicine
There have been some studies combining lamivudine
with peginterferon. The studies have had different results about how well
combining these medicines works compared to using only one medicine.9, 10
Adefovir may affect how well medicines for
Medicine is one of the many tools your doctor has to treat a health problem. Taking medicine as your doctor suggests will improve your health and may prevent future problems. If you don't take your medicines properly, you may be putting your health (and perhaps your life) at risk.
There are many reasons why people have trouble taking their medicine. But in most cases, there is something you can do. For suggestions on how to work around common problems, see the topic Taking Medicines as Prescribed.
If you are pregnant, breast-feeding, or planning to get pregnant, do not use any medicines unless your doctor tells you to. Some medicines can harm your baby. This includes prescription and over-the-counter medicines, vitamins, herbs, and supplements. And make sure that all your doctors know that you are pregnant, breast-feeding, or planning to get pregnant.
Follow-up care is a key part of your treatment and safety. Be sure to make and go to all appointments, and call your doctor if you are having problems. It's also a good idea to know your test results and keep a list of the medicines you take.
Complete the new medication information form (PDF)new medication information form (PDF)(What is a PDF document?) to help you understand this medication.
Lok SFL, McMahon BJ (2009). Chronic Hepatitis B: Update 2009. Available online: http://www.aasld.org/practiceguidelines/Documents/Bookmarked%20Practice%20Guidelines/Chronic_Hep_B_Update_2009%208_24_2009.pdf.
Hadziyannis SJ, et al. (2003). Adefovir dipivoxil for
the treatment of hepatitis B e antigen-negative chronic hepatitis B.
New England Journal of Medicine, 348(9):
Chang T-T, et al. (2006). A comparison of
entecavir and lamivudine for HBeAg-positive chronic hepatitis B.
New England Journal of Medicine, 354(10):
Lai C-L, et al. (2006). Entecavir versus
lamivudine for patients with HBeAg-negative chronic hepatitis B.
New England Journal of Medicine, 354(10):
Leung N, et al. (2009). Early hepatitis B
virus DNA reduction in hepatitis B e antigen-positive patients with chronic
hepatitis B: A randomized international study of entecavir versus adefovir.
Hepatology, 49(1): 72–79.
Hadziyannis, SJ, et al. (2005). Long-term therapy with
adefovir dipivoxil for HBeAg-negative chronic hepatitis B. New England Journal of Medicine, 352(26): 2673–2681.
Reynaud L, et al. (2009). Tenofovir and its potential in the treatment of hepatitis B virus. Therapeutics and Clinical Risk Management, 5(1): 177–185.
Hann H-W, et al. (2008). Tenofovir (TDF) has stronger antiviral effect than adefovir (ADV) against lamivudine (LAM)-resistant hepatitis B virus (HBV). Hepatology International, 2(2): 244–249.
Chan HLY, et al. (2005). A randomized, controlled
trial of combination therapy for chronic hepatitis B: Comparing pegylated
interferon alfa-2b and lamivudine with lamivudine alone. Annals of Internal Medicine, 142(4): 240–250.
Janssen, H (2005). Pegylated interferon alfa-2b alone
or in combination with lamivudine for HBeAg-positive chronic hepatitis B: A
randomised trial. Lancet, 365(9454):
October 29, 2012
Kathleen Romito, MD - Family Medicine & W. Thomas London, MD - Hepatology
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