Risedronate and pamidronate treatment in the clinical management of patients with severe Paget's disease of bone and acquired resistance to bisphosphonates.

The aim of this study was to evaluate the efficacy and safety of risedronate and pamidronate in 30 patients (mean age = 57.86 +/- 8.90 years) with severe Paget's disease of bone (PDB), showing acquired resistance to intravenous (IV) clodronate treatment. Fifteen patients were treated with oral risedronate (30 mg/day for 8 weeks). Treatment was repeated in patients without evidence of PDB remission [total alkaline phosphatase (tALP) serum levels in the normal range] at day 120. Fifteen patients were treated with IV pamidronate (30 mg/day for 3 days). Pamidronate treatment (60 mg/day for 3 days) was repeated in patients without evidence of PDB remission at day 120. At day 60, a significant decrease in tALP serum levels was obtained in all pagetic patients. At day 360, 13 (86.6%) patients treated with risedronate achieved PDB remission, 9 patients during the initial treatment and 4 after retreatment. Two patients showed a significant decrease in tALP serum levels without clinical remission after two risedronate treatments. At the same time, 12 (80%) patients treated with pamidronate achieved PDB remission, 6 patients during the first treatment and 6 after retreatment. Three patients showed a significant decrease in tALP serum levels but no clinical remission after two pamidronate courses. Two of these patients showed a relapse during the study. The incidence of minor side effects and transient hyperparathyroidism related to bisphosphonate treatment was significantly lower after risedronate therapy. In patients with resistant PDB, oral risedronate therapy has comparable efficacy to IV pamidronate with a lower incidence of treatment-related side effects.