Continuous vs. cyclical clodronate for osteoporosis - adapted from Obstetrics and Gynecology 1996;88

Author: Anne D. Walling
Date: Nov 15, 1996

Clodronate is a second-generation bisphosphonate that has shown the ability to induce substantial gains in bone mineral density when administered in a cyclical regimen in patients with osteoporosis. Because progressive gains in calcium balance and bone mass have been achieved with continuous use of related compounds, Giannini and colleagues compared the effectiveness of cyclical and continuous regimens for clodronate therapy.

Sixty postmenopausal women 48 to 70 years of age who had demonstrated significant loss of lumbar bone mass were randomly assigned to three treatment groups. All participants took 1,000 mg of oral calcium as a supplement to their normal diet. For 20 women, this was the only intervention. Another 20 women received 400 mg of clodronate daily throughout the study year. The third group of 20 women took 400 mg of clodronate cyclically for 30 days, followed by 60 days of calcium supplement alone, repeated over the one-year study period.

Biochemical markers of bone metabolism in urine and blood were measured at the beginning of the study and after six and 12 months. Bone mass was also measured at these intervals by dual x-ray absorptiometry. The three groups of women were comparable at the beginning of the study in age, height, weight, bone mineral density and time since menopause. Six women from the calcium-only group and three from each of the other groups did not complete the study.

Both groups of women receiving clodronate showed a significant increase in femoral bone density and lumbar bone mass, compared with women who received calcium alone. The women in the control group showed a decline in both femoral and lumbar bone mass. At six months, both treatment groups remained close to baseline values. At 12 months, those in the intermittently treated group had a higher percentage of change in spinal bone mineral density and spinal bone mass than those treated in the continuous regimen. The biochemical markers of bone metabolism in women taking continuous clodronate indicated a fall in bone resorption. None of the participants had serious side effects or adverse reactions to study medications.

The authors conclude that clodronate treatment for one year prevents progression of osteoporosis by inducing a gain in bone mass. The continuous regimen does not result in significant gains over cyclical regimens in spinal bone mass, but it may have an advantage in femoral bone density. They call for larger studies with longer follow-up to improve understanding of the optimal dosage regimens for these agents.

Giannini S, et al. Continuous and cyclical clodronate therapies and bone density in postmenopausal bone loss. Obstet Gynecol 1996;88:431-6.

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