Adefovir has been approved by the US Food and Drug Administration (FDA) for the treatment of chronic hepatitis B.
Tradenamed Hepsera, adefovir is a nucleotide analogue and slows the progression of chronic hepatitis B by inhibiting viral replication. FDA approval is based upon two double-blind placebo-controlled trials. At week 48, 53% of patients receiving adefovir in one study and 63% in the other showed significant improvement in the liver inflammation caused by hepatitis B compared to 25% and 35% of patients receiving the placebo. An improvement in fibrosis (liver scarring) was also observed in people receiving adefovir which also showed itself to be effective against strains of hepatitis B resistant to 3TC.
Side effects of adefovir include kidney toxicities and a short-term worsening of hepatitis B infection.
Originally developed as an anti-HIV drug, adefovir was investigated for treatment of chronic hepatitis B after it was found that the doses used to treat HIV caused severe kidney toxicities. The 10mg dose of adefovir used to treat hepatitis B has been shown to be much less likely to cause kidney problems.