Zoledronic acid - A review of its use in the management of bone metastases and hypercalcaemia of malignancy

Zoledronic acid (Zometa(R)(1)) is an effective inhibitor of osteoclast-mediated bone resorption. Zoledronic acid demonstrated efficacy in the reduction of skeletal-related events (SREs) in patients with multiple myeloma or bone metastases secondary to breast cancer, prostate cancer or other solid tumours, or hypercalcaemia of malignancy. I Zoledronic acid was effective in patients with multiple myeloma or metastatic breast cancer with osteolytic or mixed bone lesions. The proportion of patients who experienced an SRE was similar during 12 months of treatment with zoledronic acid 4mg or pamidronic acid 90mg, but significantly fewer patients receiving zoledronic acid required radiotherapy to bone. Furthermore, in patients with breast cancer and osteolytic lesions, median time to a first SRE was more than 4 months longer with zoledronic acid than with pamidronic acid. In the multiple event analysis in a 12-month extension study (total study duration was 25 months) in patients with breast cancer, zoledronic acid was superior to pamidronic acid, with an 18% reduction in the risk of experiencing an SRE. Both drugs were associated with a slight reduction in pain. Zoledronic acid 4mg, compared with placebo, significantly reduced the proportion of patients with prostate cancer bone metastases experiencing an SRE, particularly pathological fractures after 15 months' treatment. The drug also significantly delayed the onset of skeletal complications compared with placebo in patients with prostate cancer and other solid tumours including non-small cell lung cancer. When administered as a single 15-minute intravenous infusion, zoledronic acid 4mg was significantly more effective than pamidronic acid administered as a 2-hour infusion in the treatment of severe hypercalcaemia of malignancy, as assessed by complete responses measuring normalised serum calcium concentrations at day 10 after a single dose. Furthermore, zoledronic acid normalised serum calcium concentrations significantly faster than pamidronic acid, and the duration of response and median time to relapse were approximately twice as long in zoledronic acid recipients than in pamidronic acid recipients. Zoledronic acid is well tolerated and has a similar tolerability profile to pamidronic acid. The most commonly reported adverse events included flu-like symptoms (fever, arthralgias, myalgias and bone pain), fatigue, gastrointestinal reactions, anaemia, weakness, dyspnoea and oedema. Conclusion: In conjunction with antitumour therapy, zoledronic acid should be considered for routine use to reduce skeletal complications in patients with advanced malignancies involving bone. In patients with hypercalcaemia of malignancy, zoledronic acid is expected to become the treatment of choice.