artificial peptide, 32 residues long formulated as a nasal spray.
Calcitonin inhibits bone resorption by osteoclasts (bone remodeling cells) and promotes bone formation by osteoblasts. This leads to a net increase in bone mass and a reduction in plasma calcium levels. It also promotes the renal excretion of ions such as calcium, phosphate, sodium, magnesium, and potassium by decreasing tubular reabsorption. In consequence, there is an increase in the jejunal secretion of water, sodium, potassium, and chloride.
Used in the treatment of symptomatic Paget's disease for patients unresponsive to alternate treatments or intolerant to such treatments. In addition, it is used in emergency situations when serum calcium levels must be decreased quickly until the underlying condition is identified. It can also be added to existing therapeutic regimens for hypercalcemia such as intravenous fluids and furosemide, oral phosphate or corticosteroids, or other agents. Calcitonin can be used in patients with azotemia and cases where intravenous fluids would be contraindicated due to limited cardiac reserves. Also for the treatment of post-menopausal osteoporosis in women more than 5 years post-menopause.
Calcitonin binds to the calcitonin receptor (found primarily in osteoclasts) which then enhances the production of vitamin D producing enzymes (25-hydroxyvitamine D-24-hydroxylase), leading to greater calcium retention and enhanced bone density. Binding of calcitonin to its receptor also activates adenylyl cyclase and the phosphatidyl-inositol-calcium pathway.