Adefovir dipivoxil-associated thrombocytopenia in a patient with chronic hepatitis B.

A 56-year-old male patient received adefovir dipivoxil (10 mg/day) for chronic hepatitis B resistant to lamivudine. On the fifth week of treatment, the platelet count dropped to 26 x 10(3) mm(-3); anti-platelet antibodies were detectable in serum. The drug was discontinued and the platelet count improved spontaneously. A re-challenge with adefovir caused a new episode of thrombocytopenia, again after a five-week treatment period. To date, thrombocytopenia has not been described after adefovir therapy for chronic hepatitis B and seems to be a rare event.