The effect of zoledronic acid on the markers for remodelled bone in Paget's disease

Background: The arrival of the biphosphonates signified an advance in the treatment of Pagets's disease of bone (PDB), but agents which are more efficacious and easier to use are needed to improve the complement of treatments. Zoledronic acid, a biphosphonate administered in the form of a single intravenous perfusion, could satisfy these requirements. Method: We administered a perfusion of 15 minutes in duration of 5 mg of zoledronic acid to patients with PDB. The principal criterion for evaluating efficacy was the rate of therapeutic response at 6 months and 12 months, defined as a normalisation of the levels of alkaline phosphatase (AP), of amino-terminal propeptide of procollagen type 1 (P1NP), as markers for formation, and of carboxy-terminal telopeptide of collagen type 1 (CTx) as marker for resorption. We also evaluated the response of AP, CTx and P1NP at 18 months and 24 months. Results: At 6 months and 12 months all the patients who received zoledronic acid presented a therapeutic response with normalisation of levels of AP, P1NP and CTx. The response was maintained at 18 and 24 months, although only one patient showed raised levels of AP at 24 months, coinciding with an elevation of hepatic gamma-glutamyl transpeptidase. Conclusions: A single perfusion of zoledronic acid produces a rapid, complete and sustained response in PDB.