Pharmacological therapy of Paget's and other metabolic bone diseases

Paget's disease is a relatively common high-turnover metabolic bone disease that can serve as a model for osteoporosis and other metabolic bone diseases in investigation of therapeutic strategies to normalize bone turnover. Aims of treatment include rapid normalization of bone formation and resorption to prevent loss of mechanical integrity. Treatment will also reduce pain, while long-term maintenance of normal turnover may prevent long-term complications. Newer bisphosphonates have high antiresorptive potency and increased retention in bone, permitting a strategy of intermittent intravenous (IV) administration in achieving and maintaining normal bone turnover. In pivotal zoledronic acid Paget's disease trials, patients received a single 15-min IV infusion of zoledronic acid 5 mg (ZOL 5 mg) or risedronate 30 mg/day orally for 2 months. Treatment with ZOL 5 mg was associated with significant improvement in serum alkaline phosphatase, normalization in both the short and long term, and significant prolongation of biochemical therapeutic response in long-term follow-up. No changes in serum creatinine levels were observed with either treatment, and no clinically significant renal abnormalities were reported. Intermittent IV administration of potent bisphosphonates constitutes an intriguing strategy for treatment of Paget's disease and other metabolic bone diseases.