Safety and effectiveness of risedronate in Paget's disease of bone: postmarketing surveillance study in Japan.

Introduction: We conducted an all-case postmarketing surveillance study between 2008 and 2017 to evaluate the safety and effectiveness of risedronate for Paget's disease of bone (PDB) in Japan.

Material and methods: This study registered all patients who received once-daily risedronate 17.5 mg for the treatment of PDB and collected data over a 48-week follow-up period per treatment cycle for each patient.

Results: The safety analysis set included 184 patients (mean age, 63.7 years), 81 (44.0%) of whom previously received a bisphosphonate. Of them, 41 (22.3%) experienced 72 adverse drug reactions (ADRs), and 8 (4.3%) experienced 14 serious ADRs. Common ADRs included gastrointestinal disorders (20 patients, 10.9%) and hypocalcemia (6 patients, 3.3%). The effectiveness analysis set included 182 patients, 124 of whom completed only one treatment cycle and 58 of whom completed multiple treatment cycles. The proportions of patients who normalized serum alkaline phosphatase (ALP) concentration were 71.1% (113/159 patients) and 67.3% (33/49 patients) for the first and second treatment cycles, respectively. The relapse rate according to ALP levels after the end of treatment for the first cycle was 5.0% (95% confidence interval [CI] = 2.1-11.5) at 24 weeks and 12.9% (95% CI = 7.5-21.7) at 40 weeks. Regarding pain relief, the achievement rates were 70.0% (49/70 patients) and 30.8% (4/13 patients) for the first and second treatment cycles, respectively.

Conclusion: To conclude, risedronate 17.5 mg/day is safe and effective for treating patients with PDB in daily practice.