This study aims to prove non-inferiority of the efficacy of Masibone S (alendronate sodium trihydrate 70mg, oral solution) on the treatment of postmenopausal osteoporosis compared to the efficacy of Fosamax (alendronate sodium 70mg, oral tablet). The effect of Masibone S and Fosamax on bone mineral density in postmenopausal women with osteoporosis will be compared and analyzed. This study included a total 170 patients (85 per subgroup) for multi-center, randomized, open-label, parallel clinical trial. The drugs will be maintained for a total of 48 weeks. The primary endpoint is the difference of bone mineral density change at lumbar spine measured by DEXA between two groups.

Inclusion Criteria:

1. postmenopausal women ≥50 years old

2. osteoporosis - BMD T-score ≤-2.5 at lumbar spine, femoral neck, or total hip within previous 24 weeks

   - BMD T-score -1.0~-2.5 at lumbar spine, femoral neck, or total hip within previous 24 weeks and history of osteoporotic fractures - BMD T-score -1.0~-2.5 at lumbar spine, femoral neck, or total hip within previous 24 weeks and FRAX MOF >20% or HF >3%

3. Those who voluntarily agree in written form to participate in the clinical trial after hearing the explanation of this clinical trial and those who do not have any of exclusion criteria

Exclusion Criteria:

1. Patient with history of drugs that affect bone mineral density - bisphosphonate, denosumab, teriparatide, romosozumab within one year - calcitonin or analogues, calcimimetics within previous 12 weeks - strontium or fluoride for treating osteoporosis at any time in the past
2. Patients with history of osteonecrosis of jaw, osteonecrosis of external ear canal, or atypical femoral fracture
3. Patients with history of invasive dental procedure (tooth extraction, implant, oral surgery etc) within previous 24 weeks or patients who plan for invasive dental procedure during the clinical trial period
4. Patients with risk of aspiration (esophageal disorders such as esophageal stricture, achalasia or patients who can not sit or stand for more than 30 minutes)
5. Patients with severe renal dysfunction (eGFR by MDRD <30 ml/min/1.73m2 or on dialysis) or liver dysfunction (AST or ALT ≥x3 upper limit of normal reference range)
6. Patients who are under treatment or plan for treatment due to solid tumor or hematologic malignancy
7. Patients with secondary osteoporosis (persistent systemic steroid use, uncontrolled hyperthyroidism, primary hyperparathyroidism)
8. Hypocalcemia (albumin-corrected calcium <2.1mmol/L) or vitamin D deficiency (25OHD <10ng/mL) during screening
9. Patients with known allergic reaction, hypersensitivity, or intolerance to bisphosphonate and other components of intervention drugs during screening (including latex allergy and hereditary fructose intolerance)
10. Patients who the examiner considers not eligible for clinical trials

postmenopausal women