What Is a Calcitonin Receptor?

Calcitonin is a polypeptide hormone involved in the bone metabolism of calcium agents. It was discovered by Copp et al in 1961. In 1961 Kumar and Foster and others further proved that calcitonin in mammals originated from the thyroid gland, but fish calcitonin was produced in the parotid glands behind it. All calcitonins are similar in structure, with a single chain and 32 amino acids in different arrangement order. The arrangement order of amino acids depends on the species, and their functions are basically similar. Fish calcitonin binds mammalian calcitonin receptors more than mammalian calcitonin. For this reason, the current clinical applications are fish calcitonin.

Chinese name: Calcitonin
Foreign name: calcitonin
Alias: Dense calcium

Whether prescription drugs: prescription
Dosage form: Injection
Whether to include health insurance: Yes

Calcitonin Pharmacology and Application

Calcitonin has an acute inhibitory effect on osteoclasts cells and can reduce the amount of calcium from the bone to the blood in the body. Patients or experimental animals with an increased bone turnover rate have significantly decreased plasma calcium after calcitonin injection, but adults with normal bone turnover rate have no such response. Fish calcitonin increases the excretion of sodium, calcium, and phosphorus in the urine, but the aforementioned effect of human calcitonin is slight. The main role of calcitonin is in the "calcium stress period", such as child growth period, women's pregnancy, lactation and so on. During this period, serum calcitonin was significantly increased, which played a role in promoting bone development and protecting bones. Women's postmenopausal bone loss increases, and the related phenomenon is that blood calcium and blood calcitonin levels are reduced. The application of calcitonin treatment can reduce this type of bone loss. In addition to inhibiting bone resorption, calcitonin also has a good effect on the symptoms of bone pain caused by many bone metabolic diseases, but its mechanism of action is not fully understood at present.

The role of calcitonin is mainly to reduce blood calcium through the regulation of bones, kidneys and the gastrointestinal tract.

(1) Effect on bone marrow Bone culture in vitro proves that calcitonin inhibits bone resorption, and also inhibits autolysis of bone, which reduces the release of calcium from bone marrow, and at the same time, bones continuously take in calcium from plasma, leading to lower blood calcium and calcium It can also inhibit the dissolution and transfer of bone salt, inhibit the decomposition of bone matrix, increase the rate of bone turnover, increase the excretion of urinary calcium and urinary phosphorus, and cause hypocalcemia or hypophosphatemia. The effect of reducing blood calcium in the body is short-lived, and calcitonin can counteract the effect of parathyroid hormone on the bone marrow.

(2) The effect on the kidney can inhibit the reabsorption of calcium, phosphorus, and sodium by the renal tubules, thereby increasing their excretion in the urine, but it has little effect on potassium and hydrogen.

(3) The effect on the gastrointestinal tract can inhibit the intestinal transport of calcium and the secretion of gastric acid, gastrin, and melanin.

Oral calcitonin rapidly degrades in gastric juice. The blood concentration reached a peak about 0.5 to 1 hour after intramuscular or subcutaneous injection, and disappeared from the blood after 12 hours. The half-life is about 10 minutes, and the elimination rate is 8.4 ± 1.1 mg / Kg per minute. The bioavailability of nasal spray administration is approximately 50% of that by injection.

Calcitonin usage

1. Deformative osteitis: It can relieve bone pain, X-ray and histology can be improved. The usage method is to subcutaneously or intramuscularly once every other day or three times weekly intramuscularly, 50 ~ 100 units each time, 12 weeks later. Bone pain was reduced and disappeared in 3 to 6 months.

2. Senile osteoporosis: The bone resorption disorder of this disease can be treated with calcitonin, which is injected subcutaneously or intramuscularly 3 times a week, each time 50 ~ 100 units.

3. Hypercalcemia: Hypercalcemia of bone metastatic tumors after treatment with this product; generally only reduce blood calcium and urine calcium, most of bone pain does not reduce. For acute treatment of hypercalcemia crisis, intravenous infusion, 50 ~ 10 units / Kg per day, added to 500 mL of physiological saline, slowly instilled, finished in 6 hours, or divided into the above 2 to 4 slow intravenous Drip. Hypercalcemia caused by vitamin D poisoning is better for children than adults. For hyperparathyroidism, parathyroid cancer and hyperthyroidism caused by hyperthyroidism, the starting dose is 4 units / kg every 12 hours, subcutaneously or intramuscularly. If the effect is not good, increase the dose appropriately.

4. Painful neurotrophy: subcutaneous or intramuscular injection, 100 IU per day for 2 to 4 weeks, and then 100 IU each time, 3 times a week for more than 6 weeks. Intranasal administration of 200 IU daily, divided into 2 to 4 times for 2 to 4 weeks, and then 200 IU each time, 3 times a week for more than 6 weeks.

5. Others: Oral calcitonin can directly inhibit gastric wall cells from secreting gastric acid, which has a therapeutic effect on stomach and duodenal ulcers. Can also be used for hyperphosphatemia and early diagnosis of medullary thyroid cancer.

Calcitonin Note

1. Cannot be used in early and late postmenopausal osteoporosis with conventional estrogen / calcium combination therapy;

2. Nausea, vomiting, diarrhea, loss of appetite, heartburn, headache, dizziness, gait instability, hyponatremia, local pain, elevated serum aminotransferase, etc .; occasional abdominal pain, thirst, hand and foot convulsions, Tinnitus, asthma attacks, sweating, numbness of the fingers, polyuria, and chills, etc., may temporarily reduce the dose of the drug if necessary.

3. This pharmaceutical peptide preparation may cause shock. Therefore, patients with allergies should be consulted in detail, pay attention to observation, if symptoms occur, the drug should be discontinued and appropriate treatment should be given. Rare local or systemic allergic reactions should be discontinued when rashes and urticaria occur. Use with caution in patients with allergies, bronchial asthma, or patients with a previous history.

4. In animal experiments, one year after subcutaneous injection of large doses in rats, the incidence of pituitary tumors is increased, so it should not be used for a long time.

5. Animal reproduction research proves that this product cannot pass through the placenta and has no teratogenic effect, but there is no data on the effect on pregnant women. This product can enter breast milk, women should avoid using it during lactation.

6. For children lacking long-term experience in using this product, the treatment period should not exceed several weeks.

7. Long-term use of this product can appear antibodies, but usually does not affect the efficacy of the drug. In addition, long-term medication also shows that the drug fails, that is, the phenomenon of "escape". This may be due to the saturation of the receptor binding site of the drug, which has nothing to do with the production of antibodies. After stopping the medication, the treatment response of calcitonin can recover.