Osalmid is a potent inhibitor of ribonucleotide reductase small subunit M2 (RRM2) that potently inhibits HBV DNA and cccDNA synthesis in HepG2.2.15 cells. Osalmid inhibits RR (ribonucleotide reductase) activity in vivo, and exhibits synergistic effect with lamivudine on inactivation mutant HBV strain. Osalmid is a biliation activator (choleretic agent), but a mechanism of this activity remains unknown.