Continuous and cyclical clodronate therapies and bone density in postmenopausal bone loss.

OBJECTIVE

To evaluate the effectiveness of different clodronate regimens in postmenopausal osteoporosis.

METHODS

In groups of 20, 60 women were randomly assigned to one of three treatments: oral calcium, 1000 mg/day; oral calcium plus oral clodronate, 400 mg/day; oral calcium plus oral clodronate, 400 mg/day for 30 days, followed by a 60-day period of calcium supplement alone. This last regimen was repeated four times in the 12-month study period.

RESULTS

Patients who received calcium alone showed a decline in spinal bone mass, both after 6 and 12 months (P < .03 and P < .005, respectively); femoral density in this group also decreased after 6 and 12 months (P < .002 and P < .05, respectively). On the other hand, both clodronate-treated groups had increased levels of lumbar bone mass compared with controls, both after 6 and 12 months of therapy. However, at the end of the study, patients treated with cyclical clodronate had higher spinal bone mass compared with those treated continuously (3.32 +/- 0.71 versus 0.43 +/- 0.89%, P < .02). After 6 months, femoral bone density was significantly higher both in subjects treated with clodronate, both cyclically and continuously (P < .01), compared with controls. Continuous clodronate treatment resulted in a clear fall in biochemical indices of bone resorption, together with a consequent decrease in osteocalcin at 6 (P < .02) and 12 months (P < .003) and a significant increase in parathyroid hormone after 12 months (P < .001) of therapy.

CONCLUSION

One-year treatment with clodronate induces a gain in bone mass, especially in the spine. The continuous regimen does not result in any further benefit in lumbar bone density over the cyclical one, probably because of a greater suppression of bone turnover.