Elcatonin is a physio-chemically stable calcitonin derivative in which the disulfide bond between cysteine residues at positions 1 and 7 of eel calcitonin has been replaced by an ethylene bond. The primary pharmacological effect of Elcatonin is its activity at specific osteoclast receptors, resulting in diminished osteoclast activity at extremely low concentrations. Elcatonin inhibits the bones autolysis and renal calcium, phosphorus, and sodium reabsorption thus keeps blood calcium at a normal level. In clinical settings, once-weekly intramuscular injection of elcatonin has been shown to significantly increase bone mineral density within 6 months and to alleviate post-fracture pain and improve Quality of life in osteoporosis