To determine the effect and safety of menatetrenone on treatment of postmenopausal osteoporosis comparing with alfacalcidol.

Inclusion criteria :

• Postmenopausal women with menopause duration more than 5 years and with age between 45-75 years old (menopausal age ≥40), or if hysterectomy operated before natural menopause, the age of women between 60-75 years old.
• Subject with BMD (L2-4 or neck of femur) being more than 2 Standard Deviation (SD) below the young female adult mean (According to the standard of each center)
• BMI between 18 kg/m2-30 kg/m2.
• The anatomic structure of lumbar spine must be available for Dual-energy X-ray Absorptiometry (DEXA) examination, patient with serious scoliosis, bone trauma or sequela after orthopedics surgery, which makes BMD measurement difficult, should be excluded
• Subject who have given informed consent prior to participation in the trial and who undertake to comply with the protocol.

Exclusion Criteria

• Subject with conditions that are considered to effect osteoporosis, such as clear definite diabetes mellitus, rheumatoid arthritis, rheumatoid arthritis, hyperparathyroidism or other bone metabolic diseases.
• Subjects who have received treatment with active-type vitamin D3 preparation, other vitamin D preparations (>1000IU per day）, calcitonin, corticosteroid hormone, androgen, estrogen, other hormone, vitamin K preparation, in the 3 months prior to inanition of this study; Subjects who have received treatment with bisphosphonate preparation or Sodium Fluoride in the 1 year prior to inanition of this study; Subjects who have received treatment with Selective Estrogen Receptor Modulator (SERM) in the 6 months prior to inanition of this study
• Concurrent serious renal disease, hepatic disease, uncontrolled hypertension （≥150/100mmHg）, symptomatic ischemic heart disease, cerebral infarction or arteriosclerosis obliterans.
• Cancer history within 5 years.
• Subjects who take antacid containing aluminum in the preparation, warfarin or thrombolytic agents.
• Subject with any known abnormality in laboratory tests, which is deemed to be clinically significant by the investigator, which include:
• Serum alkaline phosphatace (ALP) > upper normal limit 10% (calculated according to the range of normal values of each center);
• Glutamic Oxalacetic Transaminase (AST)/ Glutamic Pyruvic Transaminase (ALT) > upper normal limit 50％(calculated according to the range of normal values of each center);
• Serum creatinine >1.5mg/dL (133μmol/L);
• Blood-fasting sugar ≥ 7mmol/L (126mg/L)
• Inability of subject to return for scheduled visits or to comply with any other aspect of the protocol.
• Subject who, in the opinion of the investigator, are poor medical candidates or pose any other risk for therapy with an investigational drug.

Safety Population