Calcitonin (Salmon) is a synthetic polypeptide hormone identical to salmon calcitonin. It acts as a potent inhibitor of osteoclastic bone resorption, leading to a rapid decrease in serum calcium levels. It is used primarily for the treatment of postmenopausal osteoporosis, Paget's disease of bone, and hypercalcemia. In the Indian context, it is a second-line or adjunctive therapy, especially where bisphosphonates are contraindicated or not tolerated.
Adult: Postmenopausal Osteoporosis: SC/IM: 100 IU daily or every other day. Nasal: 200 IU (one spray) daily in one nostril. Paget's Disease: SC/IM: 100 IU daily initially, maintenance 50 IU daily or 50-100 IU every other day. Hypercalcemia: SC/IM: 4 IU/kg every 12 hours; may increase to 8 IU/kg every 12 hours if response inadequate.
Note: Parenteral: Rotate subcutaneous or intramuscular injection sites (thigh, abdomen). Nasal: Use one spray per day in alternating nostrils. Prime nasal spray before first use. Patient should be sitting upright, not tilt head back. Avoid blowing nose immediately after.
Calcitonin binds directly and with high affinity to specific calcitonin receptors (CTRs) on osteoclasts. This binding activates adenylate cyclase and increases intracellular cAMP. The increased cAMP inhibits osteoclast motility and ruffled border formation, leading to a rapid and potent inhibition of bone resorption. It also promotes renal excretion of calcium, phosphate, sodium, and magnesium.
Pregnancy: Category C (US FDA). Animal studies have shown fetal effects. Use only if potential benefit justifies potential risk to the fetus. Not recommended.
Driving: May cause dizziness and flushing. Patients should not drive or operate machinery until they know how the medicine affects them.
| Bisphosphonates (e.g., Alendronate, Zoledronic acid) | Additive hypocalcemic effect. Monitor serum calcium closely. | Moderate |
| Loop Diuretics (e.g., Furosemide) | May reduce the hypocalcemic effect of calcitonin. | Moderate |
| Lithium | Calcitonin may decrease serum lithium levels; monitor lithium levels. | Moderate |
| Calcium and Vitamin D Supplements | May antagonize the hypocalcemic effect. Space administration if used for osteoporosis. | Mild |
Same composition (Calcitonin (Salmon) (200IU)), different brands: