Usage
Calcitonin is primarily prescribed for the following medical conditions:
- Paget’s Disease of Bone: A chronic bone disorder characterized by excessive bone breakdown and disorganized bone formation. Calcitonin helps to regulate bone turnover, reducing bone pain and other symptoms.
- Postmenopausal Osteoporosis: Calcitonin can help slow bone loss in women after menopause, reducing the risk of fractures.
- Hypercalcemia: A condition marked by elevated calcium levels in the blood. Calcitonin helps lower blood calcium levels.
Pharmacological Classification: Calcitonin is classified as an antiresorptive agent, specifically a calcitonin.
Mechanism of Action: Calcitonin primarily works by inhibiting osteoclast activity. Osteoclasts are cells responsible for breaking down bone tissue. By suppressing their activity, calcitonin reduces bone resorption and helps stabilize bone metabolism.
Alternate Names
- Calcitonin-salmon (synthetic form commonly used)
- Miacalcin (brand name)
- Fortical (brand name)
How It Works
Pharmacodynamics: Calcitonin binds to calcitonin receptors on osteoclasts, directly inhibiting their bone-resorbing activity. This leads to a decrease in serum calcium levels and a reduction in bone turnover markers. Calcitonin also increases renal excretion of calcium, phosphate, and other electrolytes.
Pharmacokinetics:
- Absorption: Well absorbed after subcutaneous (SC) or intramuscular (IM) injection. Nasal spray absorption is variable.
- Metabolism: Metabolized primarily in the kidneys.
- Elimination: Primarily renal excretion.
Mode of Action: Calcitonin interacts with specific receptors on the surface of osteoclasts. This binding triggers intracellular signaling cascades that reduce osteoclast activity and promote their apoptosis (programmed cell death).
Elimination Pathways: Primarily eliminated through renal excretion.
Dosage
Standard Dosage
Adults:
- Paget’s Disease: 100 IU SC/IM daily or 50 IU twice daily. Maintenance: 50-100 IU every 1-3 days. Nasal spray: 200 IU daily, alternating nostrils.
- Postmenopausal Osteoporosis: 100 IU SC/IM every other day. Nasal spray: 200 IU daily, alternating nostrils.
- Hypercalcemia: Initial dose: 4 IU/kg SC/IM every 12 hours. May increase to 8 IU/kg every 12 hours, or up to 8 IU/kg every 6 hours in severe cases.
Children: Use and dosage must be determined by a doctor, considering the potential risks to bone growth and development. Calcitonin is generally not recommended for pediatric use.
Special Cases:
- Elderly Patients: No specific dose adjustments based on age are required. However, careful monitoring for side effects is recommended.
- Patients with Renal Impairment: Dosage adjustment may be necessary in patients with severe renal impairment due to decreased clearance.
- Patients with Hepatic Dysfunction: No specific dose adjustments are necessary.
- Patients with Comorbid Conditions: Monitor carefully for interactions with other medications or underlying medical conditions.
Clinical Use Cases
- The clinical use cases primarily revolve around the treatment of Paget’s disease, postmenopausal osteoporosis, and hypercalcemia.
- Calcitonin is not typically used in settings like intubation, surgical procedures, mechanical ventilation, ICU care, or emergency situations outside of hypercalcemic crisis management.
Dosage Adjustments
Dose adjustments may be necessary based on patient response, renal function, and other individual factors. Monitor serum calcium levels, bone turnover markers, and potential side effects to guide dose adjustments.
Side Effects
Common Side Effects:
- Nausea
- Vomiting
- Flushing
- Injection site reactions (pain, redness, swelling)
- Nasal irritation (with nasal spray)
Rare but Serious Side Effects:
- Allergic reactions (including anaphylaxis)
- Hypocalcemia (low blood calcium)
Long-Term Effects:
- Increased risk of malignancies with prolonged use (especially with nasal spray)
Adverse Drug Reactions (ADR):
- Anaphylaxis
- Severe hypocalcemia
Contraindications
- Hypersensitivity to calcitonin-salmon
- Hypocalcemia
Drug Interactions
- Lithium: Calcitonin may reduce lithium levels.
- Cardiac glycosides (e.g., digoxin): Dosage adjustments may be needed.
- Calcium channel blockers: Dosage adjustments may be needed.
- Bisphosphonates: Additive calcium-lowering effect possible.
Pregnancy and Breastfeeding
- Pregnancy: Limited data available. Use only if clearly needed and potential benefit outweighs risk.
- Breastfeeding: Calcitonin is present in breast milk, but infant absorption is likely limited. Not recommended during breastfeeding.
Drug Profile Summary
- Mechanism of Action: Inhibits osteoclast activity, reduces bone resorption, and increases renal calcium excretion.
- Side Effects: Nausea, vomiting, flushing, injection site reactions, nasal irritation, allergic reactions, hypocalcemia.
- Contraindications: Hypersensitivity, hypocalcemia.
- Drug Interactions: Lithium, cardiac glycosides, calcium channel blockers, bisphosphonates.
- Pregnancy & Breastfeeding: Use with caution; not recommended during breastfeeding.
- Dosage: Varies depending on condition; see Dosage section.
- Monitoring Parameters: Serum calcium levels, bone turnover markers.
Popular Combinations
Calcitonin is sometimes used in combination with calcium and vitamin D supplementation, particularly in the treatment of osteoporosis.
Precautions
- Perform skin testing before initiating therapy in patients with suspected hypersensitivity.
- Monitor for allergic reactions, especially during initial doses.
- Monitor serum calcium levels periodically.
- Limit treatment duration to minimize the risk of malignancies.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Calcitonin?
A: The dosage depends on the condition being treated. Refer to the Dosage section for specific recommendations.
Q2: What are the common side effects of Calcitonin?
A: Common side effects include nausea, vomiting, flushing, and injection site reactions.
Q3: How does Calcitonin work in Paget’s disease?
A: It slows the excessive bone breakdown and remodeling characteristic of Paget’s disease, reducing bone pain and other symptoms.
Q4: Can Calcitonin be used during pregnancy?
A: Limited data are available regarding pregnancy. Use only if the potential benefit outweighs the risk.
Q5: Is Calcitonin safe for breastfeeding mothers?
A: Calcitonin is present in human milk, although infant absorption may be limited. The drug is generally not recommended during breastfeeding.
Q6: What are the long-term risks associated with Calcitonin use?
A: Long-term use, particularly with the nasal spray formulation, has been associated with an increased risk of malignancies.
Q7: What are the contraindications for Calcitonin?
A: Calcitonin is contraindicated in patients with hypersensitivity to the drug and in those with hypocalcemia.
Q8: How should Calcitonin be administered?
A: Calcitonin can be administered subcutaneously, intramuscularly, intravenously, or intranasally (as a spray), depending on the formulation and indication.
Q9: Does Calcitonin interact with any other medications?
A: Yes, calcitonin can interact with lithium, cardiac glycosides, calcium channel blockers, and bisphosphonates.
