Usage
- Medical Conditions: Calcium + Vitamin D3 is prescribed for the prevention and treatment of hypocalcemia, vitamin D deficiency, rickets in children, osteomalacia in adults, and osteoporosis. It’s also used as an adjunct therapy in patients with established osteoporosis receiving specific treatments like bisphosphonates. Patients with inadequate calcium intake (<700mg per day) or confirmed hypocalcemia should be advised on dietary measures for correction.
- Pharmacological Classification: Vitamin and mineral supplement, calcium supplement, vitamin D supplement.
- Mechanism of Action: Calcium is essential for bone mineralization, nerve conduction, muscle contraction, and various enzymatic reactions. Vitamin D3 facilitates calcium absorption from the gastrointestinal tract and regulates calcium and phosphate homeostasis.
Alternate Names
- Calcium carbonate + Cholecalciferol
- Calcium citrate + Cholecalciferol
- Several Brand names are available, such as Caltrate, Os-Cal, Oysco, Citracal, Calcichew-D3, AdCal D3.
How It Works
- Pharmacodynamics: Calcium strengthens bones and supports neuromuscular function. Vitamin D3 modulates calcium and phosphate absorption, bone metabolism, and immune function.
- Pharmacokinetics:
- Absorption: Calcium absorption is enhanced by vitamin D3 and occurs primarily in the duodenum and proximal jejunum. The absorption of calcium citrate doesn’t depend on stomach acid.
- Metabolism: Vitamin D3 is converted to its active form, calcitriol (1,25-dihydroxyvitamin D3), in the liver and kidneys.
- Elimination: Calcium is excreted mainly through the kidneys and feces. Vitamin D metabolites are excreted primarily in bile.
- Mode of Action: Vitamin D3 binds to the vitamin D receptor, a nuclear receptor, modulating gene transcription related to calcium and phosphate transport and metabolism.
Dosage
Standard Dosage
Adults:
- Prevention: 1000 mg calcium and 400-800 IU vitamin D3 daily for ages 19-50, or 10 mcg of vitamin D3 combined with at least 1000 mg of calcium daily.
- Treatment of Deficiency: Dosages vary depending on the severity of the deficiency. Commonly, 1000-1300 mg of elemental calcium and 400-800 IU of vitamin D3 are prescribed. Higher doses of vitamin D3 may be needed to achieve target serum 25(OH)D concentrations.
- Over 50 Years of Age: 1200 mg calcium and 800-1000 IU vitamin D3 daily.
- Post-Thyroidectomy: 3g of calcium/day for 2 weeks is standard.
- Split doses, about 4 hours apart.
Children:
- Dosages are based on age and health condition and should be determined by a pediatrician. Starting at age one, the RDA is 700 mg/day.
- Pediatric Safety Considerations: Monitor calcium levels to prevent hypercalcemia.
Special Cases:
- Elderly Patients: Ensure adequate vitamin D intake (800-1000 IU) due to decreased skin synthesis and potential malabsorption. Patients >70 years of age: Calcium 1300 mg/day.
- Patients with Renal Impairment: Use with caution. Monitor serum calcium and phosphorus levels.
- Patients with Hepatic Dysfunction: Monitor vitamin D levels and adjust dose as needed. Calcidiol is available for patients with liver disease if hydroxylation is impaired.
- Patients with Comorbid Conditions: Individualized dosing is based on underlying health conditions.
Clinical Use Cases
- Intubation, Surgical Procedures, Mechanical Ventilation, Intensive Care Unit (ICU) Use: Dosages are adjusted based on patient-specific factors and monitored regularly. Doses of up to 540,000 IU have been studied.
- Emergency Situations: IV calcium gluconate is administered for severe hypocalcemia with tetany or seizures, followed by oral supplementation.
Side Effects
Common Side Effects:
- Constipation
- Bloating
- Gas
- Nausea, abdominal pain
Rare but Serious Side Effects:
- Hypercalcemia (symptoms include anorexia, thirst, nausea, vomiting, muscle weakness)
Contraindications
- Hypercalcemia
- Hypercalciuria
- Hypophosphatemia
- Nephrolithiasis
- Hypervitaminosis D
- Severe renal impairment
Drug Interactions
- Tetracyclines, quinolones, oral bisphosphonates (reduced absorption)
- Corticosteroids (reduced calcium absorption)
- Thiazide diuretics (increased risk of hypercalcemia)
- Cardiac glycosides (effect potentiated by hypercalcemia)
- Erlotinib (reduced efficacy)
- Paricalcitol (increased risk of hypercalcemia)
- Enzyme-inducing antiepileptics (increased vitamin D metabolism)
- Aluminum products (risk of fatal encephalopathy in patients with renal failure)
- Iron or thyroid hormone supplements (take at different times of day than calcium)
Pregnancy and Breastfeeding
- Generally considered safe during pregnancy and breastfeeding at recommended doses (1000 mg calcium and 600 IU vitamin D3).
- Breastfed infants should receive 400 IU vitamin D daily.
Drug Profile Summary
- Mechanism of Action: Calcium is crucial for bone health and neuromuscular function. Vitamin D enhances calcium absorption.
- Side Effects: Constipation, bloating, hypercalcemia.
- Contraindications: Hypercalcemia, hypervitaminosis D, severe renal impairment.
- Drug Interactions: Several drug interactions, including tetracyclines, corticosteroids, and thiazide diuretics.
- Pregnancy & Breastfeeding: Generally safe at recommended doses.
- Dosage: Adult doses are outlined in the “Dosage” section.
- Monitoring Parameters: Serum calcium, phosphorus, 25(OH)D, PTH, creatinine.
Popular Combinations
- Calcium + Vitamin D3 is often combined in a single formulation for convenience and efficacy.
Precautions
- Screen patients for allergies, metabolic disorders, and organ dysfunction.
- **Specific Populations:**
- **Pregnant Women:** Monitor calcium levels; avoid excessive doses.
- **Breastfeeding Mothers:** Ensure infant vitamin D supplementation.
- **Children & Elderly:** Adjust doses as appropriate.
- **Lifestyle Considerations:** Alcohol and smoking can negatively impact bone health.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Calcium + Vitamin D3?
A: Adults: 1000 mg calcium and 400-800 IU vitamin D3 daily for ages 19-50, or 10 mcg of vitamin D3 combined with at least 1000 mg of calcium daily. Older adults generally require higher vitamin D doses (800-1000 IU daily).
Q2: What are the signs and symptoms of vitamin D deficiency?
A: Fatigue, bone pain, muscle weakness, increased risk of fractures.
Q3: Can Calcium + Vitamin D3 be taken with other medications?
A: Yes, but certain medications can interact, refer to the “Drug Interactions” section for specific interactions.
Q4: What are the common side effects of Calcium + Vitamin D3?
A: Constipation, bloating, and gas.
Q5: Who should not take Calcium + Vitamin D3?
A: Individuals with hypercalcemia, hypervitaminosis D, or severe renal impairment should avoid it.
Q6: How is vitamin D deficiency diagnosed?
A: A blood test measuring 25-hydroxyvitamin D levels is used to diagnose vitamin D deficiency.
Q7: What are the benefits of taking Calcium + Vitamin D3?
A: It supports bone health, prevents osteoporosis, and improves calcium absorption.
Q8: Can Calcium + Vitamin D3 be taken during pregnancy?
A: Yes, at recommended dosages.
Q9: What should I do if I miss a dose?
A: Take the missed dose as soon as you remember, unless it is close to the next scheduled dose. Do not double the dose.
Q10: Can I take a large dose of Vitamin D every few weeks or months, or is it better to take it daily?
A: Daily dosing is recommended for absorption. While some studies use weekly or bolus administration, the efficacy of this in all clinical situations has yet to be proven.
