Long-term treatment with calcitonin in osteoporosis.

Many studies have shown that calcitonin has beneficial effects on the clinical and biological disturbances of diseases characterized by an excessive bone remodelling. Several controlled clinical studies have shown that long-term calcitonin treatment, given by parenteral or intranasal routes, exerts a beneficial positive effect on bone mass and bone turnover in established postmenopausal osteoporosis. Calcitonin therapy is particularly indicated for patients with high turnover osteoporosis where results show a net gain of bone mineral in the axial skeleton and a slowing of bone loss in the appendicular bones. Recently, calcitonin was shown to induce a significant reduction in postmenopausal osteoporotic vertebral fractures. Due to receptor down-regulation a resistance to the hormone may occur after 12-18 months of continuous treatment. Reported results of long-term calcitonin treatment demonstrated that it is possible to delay or to avoid the "resistance" to calcitonin by the cyclical or discontinued administration of the hormone.