Effects of zoledronic acid in adults with osteogenesis imperfecta

BACKGROUND AND OBJECTIVE: Osteogenesis imperfecta (OI) is a genetic disorder that results in bone fragility. Several studies have demonstrated the effectiveness of bisphosphonate therapy. The aim of this study was to evaluate the effects of intravenous zoledronic acid on bone mineral density (BMD) and biochemical markers of bone turnover in adults with OI. MATERIAL AND METHODS: We carried out a prospective non-randomized study in patients with osteoporosis or severe osteopenia (T score < -2) related to OI and intolerance or contraindication to oral bisphosphonates. The patients were treated with a zoledronic acid infusion every 6 months. Densitometry was carried out annually. Calcium (Ca), phosphate (P), intact parathormone (PTH), 25 hydroxyvitamin D and biochemical markers of bone turnover [bone alkaline phosphatase (BAP), beta-cross-laps (CTX) and urinary deoxypyridoxine (DOP)] were measured every year. Adverse events and new fractures were registered. RESULTS: Ten patients (2 men and 8 women) were treated. Treatment increased BMD measured in the lumbar spine after 24 (0.738+/-0.141 vs 0.788+/-0.144 g/cm(2); p=0.048) and 36 months (0.720+/-0.139 vs 0.820+/-0.128; p=0.01). Significant increases in BMD were also observed after 24 months in the femoral neck (0.677+/-0.121 vs 0.703+/-0.122 g/cm(2); p<0.016). Serum Ca, P, BAP and CTX concentrations remained unchanged. PTH concentrations increased and vitamin D concentrations decreased after 36 months of treatment. DOP excretion decreased significantly after 24 months. Seven patients had mild influenza-like symptoms occurring within the first 24 h after the first infusion. No severe adverse events were observed. None of the patients had new fractures. CONCLUSION: Zoledronic acid seems to be a safe and effective treatment option in adults with osteoporosis related to OI.