Efficacy of intermittent low dose alendronate in Thai postmenopausal osteoporosis

Alendronate has been proven to be effective in the prevention and treatment of postmenopausal osteoporosis with the recommended daily dose of 10 mg. However, a constraining requirement for dosing limited its general acceptance in treatment. Since alendronate is potent and has a long half-life, weekly administration of alendronate in lower total doses might be safer and more convenient. The purpose of this study was to determine the efficacy of low dose once-weekly 20 mg alendronate in Thai postmenopausal women with osteoporosis. Thirty-nine postmenopausal women with osteoporosis received alendronate 20 mg once a week plus 750 mg elemental calcium daily. Bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at baseline and 6 and 12 months after treatment. Serum C-terminal telopeptide of type I collagen (CTx-I) was measured by electrochemiluminescence immunoassay at baseline and 3 months after treatment. By the end of 1 year, once weekly 20 mg alendronate significantly increased vertebral BMD (+6.2%, p < 0.001 vs baseline) from baseline whereas there was a reduction of 60.7% in serum CTx-I at 3 months. However, the BMD at femur did not increase significantly (+0.64%). Conclusion. Low-dose intermittent once-weekly 20 mg alendronate was effective, cost saving and had a good safety profile in increasing vertebral BMD and stabilizing BMD at the femoral neck in postmenopausal osteoporosis.