Identify a drug that is a nucleotide analog used for Hepatitis B.

Adefovir is a nucleotide analog that is specifically indicated for the treatment of Hepatitis B. As a nucleotide reverse transcriptase inhibitor, it works by interfering with the viral DNA synthesis necessary for Hepatitis B replication. Its structure mimics that of natural nucleotides, allowing it to be incorporated into the viral DNA, which effectively disrupts the viral replication process.

Tenofovir is also a nucleotide analog and is used for Hepatitis B, but adefovir is more directly associated with the question. Sofosbuvir is a nucleoside analog primarily used for Hepatitis C treatment, and lamivudine, while it is a nucleoside analog effective against Hepatitis B, is not classified as a nucleotide. Therefore, adefovir is the most appropriate choice for a drug that is a nucleotide analog specifically used for Hepatitis B.