The primary objective of this pilot study is to estimate the percent change from baseline at Week 4, Month 6 in NTX bone turnover marker for a monthly 150mg dose of risedronate administered for 6 months and a loading dose regimen of risedronate over a 6 month treatment period both compared to a 5 mg daily dose of risedronate for 6 months

The secondary objectives are :

• To estimate the percent change from baseline at specified visits other than Week 4, Month 6 in NTX for the monthly 150 mg dose of risedronate administered for 6 months and the loading dose regimen of risedronate over a 6 month treatment period both compared to the 5 mg daily dose of risedronate.
• To estimate the percent change from baseline at all specified visits in serum CTX and bone specific alkaline phosphatase for the monthly 150 mg dose of risedronate administered for 6 months and the loading dose regimen of risedronate over a 6 month treatment period both compared to the 5 mg daily of risedronate.
• To estimate the percent change from baseline at Month 6 in lumbar spine BMD for the monthly 150 mg dose of risedronate administered for 6 months and the loading dose regimen of risedronate over a 6 month treatment period both compared to the 5 mg daily dose of risedronate.
• To evaluate the safety of the risedronate 150 mg monthly and the loading dose regimen.

Inclusion Criteria:

• ambulatory women,postmenopausal >= 5 years

• have lumbar spine baseline BMD within the following criterion :

  • Hologic: <= 0.827 g/cm2 or
  • Lunar: <= 0.942 g/cm2 or
  • Norland: <= 0.768 g/cm2

• be in general good health as determined by medical history, physical examination and laboratory tests

Exclusion Criteria:

• serum 25-OH vitamin D level <= 12 ng/ml

• history of osteomalacia

• history of active hyperparathyroidism or hyperthyroidism

• hypocalcemia or hypercalcemia from any cause

• depot injection >10,000 IU Vitamin D in the past 9 months prior to starting the investigational product

• use of Vitamin D supplementation within 3 months prior to starting the investigational product

• use of any of the following medications within a specified number of months prior to starting the investigational product :

  • any bisphosphonate.
  • use of any fluoride with the exception of fluoride use for oral hygiene
  • strontium
  • other bone active agents
  • subcutaneous estrogen implant
  • oral or parenteral glucocorticoids
  • anabolic steroids
  • estrogen or estrogen-related drugs, except for low dose vaginal creams
  • progestogen
  • calcitonin, calcitriol, or calcifediol

• any allergic or abnormal reaction to bisphosphonates

• creatinine clearance < 30 ml/min