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