Adefovir dipivoxil-induced development of osteomalacia and Fanconi syndrome during the treatment of hepatitis B virus (HBV)-related cirrhosis

Adefovir dipivoxil is a nucleotide analog reverse transcriptase inhibitor used to treat adult patients affected by HBeAg-positive and HBeAg-negative chronic hepatitis B and with clinical evidence of lamivudine-resistant hepatitis B virus (HBV). Adefovir administered at a dosage of 10 mg/day is generally well tolerated, even if renal toxicity, type Fanconi syndrome, was reported during long-term treatments. We report a case of osteomalacia with Fanconi syndrome and pathologic fracture of the femur related to long-time (67 months) adefovir treatment (10 mg/day) in a patient with compensated hepatitis B virus (HBV) cirrhosis (Child 5A) and with a previous normal renal function (estimated Glomerular Filtration Rate before adefovir = 78.26 ml/min/1.73 m(2); during adefovir treatment = 57.38 ml/min/1.73 m(2)). The patient was switched to entecavir at a dose of 1 mg/day, with both suppression of viremia and improvement of osteomalacia and Fanconi syndrome; the patient's follow-up is still ongoing after 22 months.