What is the role of calcitonin (calcitonin) in the body?

From the Guidelines

Calcitonin should be used as a second-line treatment for osteoporosis due to its weaker data compared to other options, and it is generally recommended for women with less serious osteoporosis who cannot tolerate other treatments. As a medication, calcitonin is primarily used to treat osteoporosis, Paget's disease of bone, and hypercalcemia. For osteoporosis treatment, salmon calcitonin is typically administered as a nasal spray at 200 IU once daily, alternating nostrils, or as an injection of 100 IU daily or every other day 1. The use of calcitonin has been studied extensively, with documented efficacy in the treatment of Paget’s disease, malignant osteolysis, and high-turnover osteoporosis, and it has also been shown to protect bone mass in conventional osteoporosis 1.

Some key points to consider when using calcitonin include:

• The development of the nasal route of administration has considerably improved patient acceptance, with excellent bioavailability and low toxicity 1
• Calcitonin acts by inhibiting osteoclast action, although it may also stimulate osteoblast function 1
• Common side effects include nasal irritation with the spray formulation, nausea, flushing, and allergic reactions
• Due to concerns about a possible small increased risk of cancer with long-term use, calcitonin is now generally considered a second-line treatment for osteoporosis when other therapies cannot be used or have failed 1

In terms of treatment duration, calcitonin is generally limited to short-term use for acute hypercalcemia and longer courses for bone disorders. The recommended dose for Paget's disease is usually 100 IU injected subcutaneously or intramuscularly daily. It is essential to weigh the benefits and risks of calcitonin treatment, considering the patient's individual needs and medical history. First-line therapy usually consists of bisphosphonates, and selection should be based on patient preference 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.

Main Mechanism of Action: Calcitonin acts primarily on bone by inhibiting bone resorption.

• Key Effects:
  • Inhibition of osteoclast function
  • Decrease in the rate of bone resorption
  • Decrease in the number of osteoclasts
  • Apparent decrease in osteoclast resorptive activity
  • Possible increase in osteoblastic activity and bone formation 2

From the Research

Calcitonin Overview

• Calcitonin is a hormone secreted by the C-cells of the thyroid gland in response to elevations of the plasma calcium level 3.
• It reduces bone resorption by inhibiting mature active osteoclasts and increases renal calcium excretion 3.
• Calcitonin is used in the management of postmenopausal osteoporosis, Paget's disease of bone, and malignancy-associated hypercalcemia 3.

Therapeutic Uses of Calcitonin

• Calcitonin has been shown to be effective in the treatment of Paget's disease, reducing bone pain and leading to radiological and histological improvement in bone 4, 5, 6.
• It is also used in the management of postmenopausal osteoporosis and osteoarthritis, although oral formulations have shown mixed results in clinical trials 3.
• Calcitonin has an analgesic action, possibly mediated through β-endorphins and the central modulation of pain perception, and may be useful in the management of osteoarthritis and rheumatoid arthritis 3.

Administration and Efficacy

• Traditional methods of calcitonin administration have been parenteral or intranasal, but oral formulations have been developed using different techniques 3.
• The efficacy of calcitonin can be affected by several factors, including the amount of water used to take the tablet, time of day, and proximity to intake of a meal 3.
• Salmon calcitonin is more potent than porcine calcitonin, and human calcitonin is intermediate in potency 4.
• Patients may experience side effects, including nausea and facial flushing, but these are generally mild and uncommon 4, 5.

Treatment of Paget's Disease

• Paget's disease of bone is a common bone disorder characterized by disorganized bone remodeling 7.
• Calcitonin is a valuable therapeutic agent in the treatment of Paget's disease, particularly in patients with osteolytic lesions 4.
• Bisphosphonates are the mainstay of treatment for Paget's disease, but patients who do not tolerate bisphosphonates can be treated with calcitonin 7.