BISPHOSPHONATES AND THE TREATMENT OF BONE-DISEASE IN THE ELDERLY

Recognition of the way in which naturally occurring pyrophosphate affe cts bone metabolism has stimulated the development of a whole series o f related compounds, the bisphosphonates. Although the precise mechani sm of action of these compounds remains incompletely understood, they have been proven profoundly effective in clinical practice and already constitute a major advance in the therapy of conditions characterised by excessive bone resorption. Serious adverse effects are rare; howev er, mineralisation problems are a concern, particularly with etidronat e. The reduction in bone turnover during prolonged treatment for osteo porosis is also a concern but as yet of uncertain clinical importance. The wide variation in potency of different bisphosphonates in inhibit ing the resorption, mineralisation and turnover of bone will increasin gly determine which agents are used in various clinical situations. Bi sphosphonates are the treatment of choice in Pager's disease and hyper calcaemia of malignancy. They also appear to have potential to alter t he course of metastatic bony disease; although the magnitude and clini cal importance of any such effect remains unclear. Bisphosphonates sho w promise in the prevention and treatment of osteoporosis and increase bone mass in postmenopausal and steroid-induced osteoporosis. The eff ects of these drugs in other situations are less clear and the effects on fracture rates are not yet fully characterised. Optimal regimens h ave yet to be established but the long half-lives of these agents make s intermittent treatment a rational and convenient approach.