Adefovir (Hepsera) Therapy for Chronic Hepatitis B
Adefovir is a nucleotide analogue that received FDA approval for treatment of chronic hepatitis B in September 2002. The standard dose is one 10 mg pill each day. Studies have shown that treating HBeAg-patients for one year with adefovir results in an approximately 12 percent seroconversion rate (eradication of HBeAg and formation of HBeAb). And HBVDNA will drop to less than 400 copies/mL in approximately 21 percent of people. Significant improvement in liver inflammation and scarring (on liver biopsy specimens) has also been demonstrated. It appears that adefovir alone may be as effective as adefovir in combination with lamivudine. Efficacy has also been demonstrated as to HBeAg negative patients. Within this patient group after 48 weeks of therapy with adefovir, ALT levels normalize in approximately 72 percent of people, HBVDNA becomes nondetectable in 51 percent of people and inflammation and scarring of the liver improve in 64 percent of patients. For treatment of HBV, adefovir appears to have the same advantages over interferon as lamivudine. For example, adefovir treatment achieves results similar to lamivudine for both HBeAg positive and HBeAg negative (pre-core mutants) people. Furthermore, neither race nor hepatitis B genotype have a significant impact on the efficacy of adefovir.
A major advantage of adefovir over lamivudine is that adefovir does not lead to the development of drug-resistant mutations. Adefovir has the ability to eradicate HBV DNA in people who have developed lamivudine-resistant mutations. This applies even to those people who developed these mutations after liver transplantation.
Once treatment with adefovir is discontinued, most people will relapse. Thus, going forward, long-term adefovir treatment will probably become the standard of care. So far, studies of people using adefovir for approximately three years have not noted any adverse consequences such as drug-resistant HBV mutant formation, severe side effects or damage to other organs. The major side effect of adefovir is kidney damage, but this appears to be associated with dosages higher than 10 mg/day.
Lamivudine and Adefovir Combination Therapy
Studies combining lamivudine and adefovir are currently ongoing. Preliminary results appear promising. Patients who develop lamivudine-resistant HBV should not be treated with a combination of lamivudine and adefovir, but should discontinue lamivudine and be treated with adefovir alone.
All contents of this article are Copyright © Melissa Palmer, MD
Melissa Palmer, MD is the author of " Dr. Melissa Palmer's Guide of Hepatitis and Liver Disease". (Published 2004. Penguin Putnam).
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