Effects of teriparatide on serum calcium in postmenopausal women with osteoporosis previously treated with raloxifene or alendronate

The effect of teriparatide (20 mu g/day) on serum calcium was examined in postmenopausal women previously treated with alendronate or raloxifene. Women previously treated with alendronate or raloxifene who added teriparatide or switched to teriparatide did not have clinically meaningful increases in mean predose serum calcium. Introduction The effects of a 6-month treatment with teriparatide (20 mu g/day; rhPTH(1-34), TPTD) on serum calcium (Ca) was examined in a prospective study of postmenopausal women previously treated with alendronate (70 mg/week or 10 mg/day [ALN] or raloxifene 60 mg/d [RLX]) for >= 18 months. Methods Women continued their usual ALN or RLX during a 2-month antiresorptive phase. Women previously treated with ALN were randomized to add TPTD (n=52) or switch to TPTD (n=50) and women previously treated with RLX were randomized to add TPTD (n=47) or switch to TPTD (n= 49). All were to take at least 500 mg/day of elemental Ca and 400-800 IU/day of vitamin D. Results Predose mean serum Ca did not significantly change in groups adding TPTD to either RLX or ALN treatment. In patients who switched from RLX or ALN to TPTD, mean serum Ca increased by 0.05 mmol/L and 0.04 mmol/L respectively. Only 1 patient had the predefined calcium endpoint of serum calcium > 2.76 mmol/L (11 mg/dL) at more than one visit. Conclusions Women previously treated with ALN or RLX who added TPTD or switched to TPTD did not have clinically meaningful increases in mean predose serum Ca.