Cyclical etidronate therapy in the prevention and treatment of corticosteroid-induced osteoporosis

Corticosteroids are a major cause of osteoporosis, resulting in significant morbidity. This review is an attempt to summarize a very complex field. The pathophysiology of corticosteroid-induced osteoporosis is still not well worked out and the outline provided is a summary of some of the theories expressed in the literature. In reviewing the clinical aspects, most of the trials reviewed involved mixed populations of patients with complicated systemic disorders of varying severity, confounded by a wide range of therapeutic agents. Often, as in rheumatoid arthritis, it is not possible to separate the effects of the primary disease from that of corticosteroids with regard to the bone injury. With these limitations in mind, corticosteroid-induced bone loss seems to be a result of a combination of a reduction in bone formation and an increase in bone resorption. Prevention and treatment of corticosteroid-induced osteoporosis has consisted of use of the lowest dose of corticosteroid, calcium, vitamin D and hormone replacement therapy in postmenopausal women. Recent advances with the bisphosphonates, in particular intermittent cyclic therapy with etidronate (ICT-etidronate), provide better evidence of treatment efficacy. Indeed the evidence for the use of ICT-etidronate for the prevention and treatment of corticosteroid-induced osteoporosis is far more compelling than is the evidence for hormone replacement therapy, calcium or vitamin D. We now have studies that demonstrate safe, effective and acceptable therapy for the prevention and treatment of corticosteroid-induced osteoporosis; hence all patients who might benefit should be offered treatment with etidronate.