[Alendronate in postmenopausal women with osteopenia and osteoporosis: effects on bone mineral density during treatment and after withdrawal].

OBJECTIVE: To determine the efficacy of alendronate (Fosamax) administration and withdrawal on the bone mineral density (BMD) in postmenopausal women with osteopenia and osteoporosis.

METHODS: Alendronate (10 mg) and calcium carbonate (containing calcium 500 mg) were administered daily to 25 Chinese menopausal women with osteopenia and osteoporosis for 6 months and to 15 women for 12 months. After the withdrawal of alendronate, calcium carbonate was administered continuously. Follow-up was made three times for the 6-month group: before treatment, 6 months after treatment, and 13 +/- 4 months (6 - 24 months) after aldoronate withdrawal, and was made four times for the 12-month group: before treatment, 6 months and 12 months after treatment, and 23 +/- 7 months (14 - 36 months) after alendronate withdrawal to determine the BMD of lumbar spine 2 approximately 4, neck of femur, Wards triangle, and greater trochanter and blood alkaline phosphatase (ALP).

RESULTS: Compared to the baseline value, the BMD in lumbar spine and hip increased significantly 6 months after treatment in 6-month group, with the BMD in lumbar spine 2 - 4 increased by 5.3% (P < 0.001). In the 6 month group, no significant decline was found in the BMD in lumbar spine and hip 13 +/- 4 months after alendronate withdrawal, the BMD in greater trochanter even increased further compared with that 6 months after treatment. In the 12-month group, the BMD significantly increased except in the Wards triangle after 6 months' treatment with an increase by 4.2% in lumbar spine 2 - 4 (P < 0.001). After 12 months' treatment the increment of BMD in lumbar spine 2 - 4 was 6.1% (P < 0.001) and the BMD of the hip remained unchanged. 23 +/- 7 months after the alendronte withdrawal the values of BMD in lumbar spine and hip were almost the same as that 12 months after treatment.

CONCLUSION: Alendronate increases the BMD in spine and hip, especially in lumbar spine. The skeletal benefits are maintained for at least 13 - 23 months in spine and hip after withdrawal of alendrenate.