Effects of risedronate on bone turnover markers in osteoporotic postmenopausal women: comparison of two protocols of treatment.

AIM: Bisphosphonates are powerful agents able to prevent bone loss. The objective of the study was to evaluate the efficacy and tolerability of risedronate once a week (35 mg) compared with risedronate 5 mg once daily in women with osteoporosis. METHODS: A randomized, double-blind, active-controlled study enrolled 102 postmenopausal women aged 66.5 + 7.5 years with osteoporotic fractures. All women received risedronate during 6 months. Group 1 (G1, n=51) received risedronate 5 mg once daily and group 2 (G2, n=51) received 35 mg once a week. Serum alkaline phosphatase (ALP), bone alkaline phosphatase (bone ALP), serum C-terminal telopeptide of type I collagen (CTX) were measured at baseline, 3 months and 6 months after treatment in the two groups. RESULTS: We noted no significant difference in markers between women of the 2 groups. After 3 months, bone ALP and CTX decreased (respectively -22.1% and -47.6%) in the 2 groups with no significant difference between them. After 6 months study, bone ALP and CTX decreased respectively by -46.5% and -62.9% with no statistically significant difference between study groups for bone markers. CONCLUSION: Our study found that treatment with once weekly risedronate 35 mg is able to decrease CTX and bone ALP compared with risedronate 5 mg once daily, in postmenopausal women with osteoporotic fractures. We didn't find adverse events with the 35 mg once-a-week dose group compared to the once-daily dose group. Based on these results, the effects of risedronate 35 mg once a week are similar in efficacy to daily dosing and may lead less adverse events than once-a-month dose. This therapeutic protocol may provide an alternative for patients who prefer once-a-week oral dosing.