Effect of risedronate on biochemical marker of bone resorption in postmenopausal women with osteoporosis or osteopenia

Objective. The primary objective of the present study was to evaluate the effectiveness and adverse events of risedronate use in postmenopausal woman by measuring its effects on urinary crosslinked C-terminal telopeptides of type I collagen (CTx), a biochemical marker of bone resorption. Methods. One hundred osteoporotic (control and treatment) and 111 osteopenic (control and treatment) postmenopausal women, selected according to World Health Organization criteria, were included in the study. The treatment groups (osteopenic and osteoporotic) were given risedronate 35 mg once a week. The primary endpoint was mean percentage change in CTx from baseline to 6 months. The secondary endpoints included evaluation of the incidence of clinical or laboratory adverse events occurring during the 6-month study period. The least significant change (LSC), calculated from the within-subject variability in the two control groups, was used to define response. Results. Of the 211 women enrolled, 157 (74.4%) completed the study. After 6 months, urinary CTx levels were - 54.7% (range - 67% to - 48%) below baseline in the osteoporotic treatment group and - 66.7% (range - 74% to - 59%) below baseline in the osteopenic treatment group. Analysis of LSC showed that 89% of risedronate treatment groups were categorized as responders after 6 months of treatment. Conclusion. The study shows that osteoporotic and osteopenic women on risedronate treatment have statistically significant suppressed bone turnover and CTx can be useful to confirm this observation. The low withdrawal rate and adverse effects rate show that risedronate was well tolerated by the study population.