(organic chemistry, medicine) Any salt or ester of etidronic acid, but especially the sodium salt, which is used to reduce calcium loss from bones

plural of etidronate

(pharmacology) The phosphonic acid (1-hydroxy-1-phosphono-ethyl)phosphonic acid which inhibits the formation, growth, and dissolution of hydroxyapatite crystals and is administered orally in the treatment of some bone diseases (such as Paget's disease of bone).