A randomized, double-blind comparison of risedronate and etidronate in the treatment of Paget's disease of bone. Paget's Risedronate/Etidronate Study Group.

PURPOSE: To compare the efficacy and tolerability of oral risedronate and etidronate for treatment of Paget's disease of bone.

PATIENTS AND METHODS: Patients from 12 centers in North America received risedronate 30 mg daily for 2 months (62 patients) or etidronate 400 mg daily for 6 months (61 patients) in a prospective, randomized, double-blind study. Serum alkaline phosphatase (the primary variable), serum bone-specific alkaline phosphatase, and urinary deoxypyridinoline concentrations were monitored for 12 to 18 months.

RESULTS: Serum alkaline phosphatase concentration normalized by month 12 in 73% of risedronate-treated patients, compared with 15% of those receiving etidronate (P <0.001). Median time to normalization was 91 days for risedronate-treated patients and >360 days for etidronate-treated patients (P <0.001); relapse rates were 3% in the risedronate group and 15% in the etidronate group (P <0.05). At month 18, 53% of the risedronate group and 14% of the etidronate group remained in biochemical remission. Urinary deoxypyridinoline normalized in 87% of patients on risedronate and 57% of patients receiving etidronate (P <0.01); serum bone-specific alkaline phosphatase normalized in 73% of patients on risedronate and 18% of patients on etidronate (P <0.001). Patients who had received etidronate previously had a blunted response to etidronate, but not to risedronate. Reductions in pain were statistically significant in the risedronate group, but not in the etidronate group. Both drugs were well tolerated.

CONCLUSION: Although etidronate is effective, risedronate offers a shorter duration of therapy, better and longer-lasting remission, significant reductions in pain, and provides additional remission in subjects who exhibited an incomplete response to previous etidronate treatment.