Elcatonin is a Calcitonin derivative which is transformed from eel's calcitonin by changing the S-S bond into the stable C-N bond. It inhibits the absorption and autolysis of bones, thus leads to blood calcium descending. In addition, it inhibits the bone salts dissolving and transferring and promotes the excretion of calcium and phosphorus in urine. Meanwhile, it inhibits renal tubules reabsorbing calcium, phosphorus and sodium and keeps blood calcium at normal level. It is mainly used for remitting or eliminating the pain caused by Osteoporosis.