Adefovir and dipivoxil

Adefovir dipivoxil is the prodrug of adefovir, which competitively inhibits HBV DNA polymerase and results in chain termination after incorporation into the viral DNA. Adefovir has good oral bioavailability Dose reductions are required in renal dysfunction. Adefovir suppresses HBV replication and improves liver histology and fibrosis. However, serum HBV DNA reappears after cessation of therapy. Adefovir has activity against lamivudine-resistant strains of HBV. Nephrotoxicity is dose-limiting. Lactic acidosis and severe hepatomegaly with steatosis may also occur. Adefovir dipivoxil is a nucleotide analog that is phosphorylated to adefovir diphosphate , which is then incorporated into viral DNA. This leads to termination of further DNA synthesis and prevents viral replication. Adefovir is administered once a day and is excreted in urine, with 45 percent as the active compound. Clearance is influenced by renal function. Both decreased viral load and improved liver function have occurred in patients treated with adefovir. As with other agents, discontinuation of adefovir results in severe exacerbation of hepatitis in about 25 percent of patients. Adefovir does not seem to have significant drug interactions. The drug should be used cautiously in patients with existing renal dysfunction.