From the Guidelines
Calcitonin should not be used as a first-line treatment for osteoporosis due to its high cost and limited availability in a convenient nasal spray form, as well as concerns about a possible small increased risk of cancer with long-term use. Calcitonin is a hormone produced by the thyroid gland that helps regulate calcium levels in the body by inhibiting bone resorption [ 1 ]. It is available as a medication in both nasal spray form and injectable form, typically used to treat conditions characterized by excessive bone breakdown such as Paget's disease, hypercalcemia, and osteoporosis. For osteoporosis treatment, the typical dosage is 200 IU daily as a nasal spray or 100 IU injected subcutaneously every other day.
Some key points to consider when evaluating the use of calcitonin include:
- Calcitonin prevents bone loss in postmenopausal women with osteoporosis and some randomized controlled trials have shown a decrease in vertebral fracture rate [ 1 ]
- Calcitonin given with calcium for six months in a randomized controlled cross-over study in women with primary biliary cirrhosis (PBC) with a z score of −2 did not affect the rate of bone loss compared with a control group treated with calcium alone [ 1 ]
- Calcitonin has to be given either subcutaneously or intramuscularly, which has limited its use, although an intranasal preparation may become available in the future [ 1 ]
- The cost of calcitonin is roughly eight times more expensive than alendronate and sixteen times more expensive than etidronate, making it a less attractive option for many patients [ 1 ]
Overall, while calcitonin may be a useful treatment option for certain patients with osteoporosis, its high cost, limited availability, and potential risks make it a second-line treatment option [ 1 ].
From the FDA Drug Label
CLINICAL PHARMACOLOGY Calcitonin acts primarily on bone, but direct renal effects and actions on the gastrointestinal tract are also recognized. The actions of calcitonin on bone and its role in normal human bone physiology are still not completely elucidated, although calcitonin receptors have been discovered in osteoclasts and osteoblasts. Single injections of calcitonin cause a marked transient inhibition of the ongoing bone resorptive process. With prolonged use, there is a persistent, smaller decrease in the rate of bone resorption Histologically, this is associated with a decreased number of osteoclasts and an apparent decrease in their resorptive activity.
The main action of calcitonin is on bone, where it:
- Inhibits bone resorption
- Decreases the number of osteoclasts and their resorptive activity
- May increase bone formation through increased osteoblastic activity 2 2
From the Research
Calcitonin Overview
- Calcitonin is a naturally occurring peptide that acts via specific receptors to strongly inhibit osteoclast function 3
- It has been used in the treatment of osteoporosis for many years, with the intranasal formulation being the most widely used due to its improved tolerability 3
Therapeutic Uses
- Calcitonin has been found to be useful in treating chronic back pain following vertebral fractures in spinal osteoporosis 4
- It can prevent bone loss and may be effective in preventing fractures 4
- Calcitonin has a direct analgesic effect on bone pain, making it clinically useful in improving pain from acute vertebral fractures of osteoporosis, Paget's disease, bone malignancies, and other sources of musculoskeletal pain 5
Efficacy and Safety
- Calcitonin has been shown to preserve or increase bone mineral density (BMD) and reduce the risk of vertebral fractures in osteoporosis 5
- The Prevent Recurrence of Osteoporotic Fractures (PROOF) study found that salmon calcitonin nasal spray at a dosage of 200 IU/day can reduce the risk of vertebral osteoporotic fractures by 33% 3, 6
- Side effects of calcitonin are generally mild and dose-related, including gastrointestinal, vascular, and dermatologic conditions 4
Administration and Bioavailability
- Calcitonin can be administered parenterally, intranasally, or potentially orally, although achieving adequate bioavailability remains a challenge 6, 7
- Nasal calcitonin is much better tolerated than injectable forms, with rare and generally negligible side effects 6
Current Status and Future Directions
- The use of calcitonin has declined in recent years due to the rise of bisphosphonates and monoclonal antibodies, as well as concerns about associations with cancer 7
- Despite this, calcitonin may still have a potential role in the management of fractures and other conditions, particularly in patients who cannot tolerate other treatments 7