Novel bisphosphonate cyclic acetal compounds are disclosed, as well as methods of preparing the compounds, pharmaceutical compositions including the compounds, and administration of the compounds in methods of treating bone metabolism disorders, such as abnormal calcium and phosphate metabolism.新規のビスホスホネート環状アセタール化合物が開示され、該化合物、該化合物を含む薬学的組成物の調製方法、ならびに異常なカルシウムおよびリン酸の代謝等の骨代謝疾患を治療する方法における該化合物の投与方法も開示される。【選択図】図1