Clodronate and osteoporosis.

Bisphosphonates are widely used in disorders associated with increased resorption of bone, particularly in Paget's disease of bone and the hypercalcaemia of malignancy. Their undoubted efficacy and relatively low toxicity makes them attractive candidates for the management of osteoporosis. The three bisphosphonates widely tested are etidronate, pamidronate and clodronate. Whereas pamidronate can only be given by intravenous infusion, clodronate may be given intravenously or by mouth. Unlike etidronate, even high doses of clodronate do not impair the mineralisation of bone, making it suitable for long-term use in osteoporosis. Clodronate has been shown to inhibit experimentally induced increases in bone resorption and in patients prevents bone loss at the menopause and during immobilisation. Short-term and long-term studies indicate that clodronate appears to stop bone loss at the lumbar spine in patients with vertebral osteoporosis. Long-term studies of the effects at the hip are not yet reported. The effects of clodronate on the frequency of osteoporotic fractures are not yet known and will demand well controlled long-term prospective studies.