1. Clinical Overview
A fixed-dose combination supplement containing elemental calcium (as carbonate/salt) and cholecalciferol (Vitamin D3). It is a cornerstone therapy for the prevention and treatment of calcium and vitamin D deficiencies, which are highly prevalent in the Indian population due to dietary habits, skin pigmentation, and limited sun exposure. The combination is synergistic, as Vitamin D3 enhances the intestinal absorption of calcium.
| Onset | Duration | Bioavailability |
|---|---|---|
| Calcium: Rapid, within hours for acute hypocalcemia. Vitamin D3: Slower, therapeutic serum levels of 25-hydroxyvitamin D may take 2-3 months of regular supplementation. | Calcium: 4-6 hours post-dose. Vitamin D3: Long-acting, with a half-life of approximately 15 days, providing sustained metabolic effects. | Calcium: Highly variable (15-45%), dependent on gastric pH, dietary factors, and Vitamin D status. Vitamin D3: Well absorbed (approx. 80%) from the small intestine with dietary fats. |
2. Mechanism of Action
This combination works synergistically. Calcium provides the essential mineral for bone mineralization, neuromuscular function, and cellular signaling. Vitamin D3 (after activation to calcitriol) acts as a hormone that increases intestinal absorption of calcium and phosphate from the gut, promotes renal reabsorption of calcium, and regulates bone remodeling in conjunction with parathyroid hormone (PTH).
3. Indications & Uses
- Prevention and treatment of calcium and Vitamin D deficiency
- Adjunctive therapy in osteoporosis (postmenopausal and senile)
- Management of osteomalacia and rickets
- Supportive therapy in hypoparathyroidism
4. Dosage & Administration
Adult Dosage: One tablet daily, or as directed by the physician. Typically taken with a meal.
Administration: Take the tablet with or immediately after a meal to enhance calcium absorption and reduce gastric discomfort. Swallow whole with a full glass of water. Do not take with high-oxalate foods (spinach, sweet potatoes) or high-fiber meals at the same time, as they can reduce absorption. Maintain adequate hydration.
5. Side Effects
Common side effects may include:
- Constipation
- Abdominal discomfort or bloating
- Nausea
- Flatulence
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Bisphosphonates (e.g., Alendronate) | Calcium can significantly reduce absorption of bisphosphonates. Administer at least 2 hours apart. | Major |
| Levothyroxine | Calcium carbonate can decrease levothyroxine absorption. Administer at least 4-6 hours apart. | Major |
| Quinolone/Tetracycline Antibiotics | Calcium chelates these antibiotics, reducing their efficacy. Administer 2-3 hours before or 4-6 hours after calcium. | Major |
| Digoxin | Hypercalcemia potentiates digoxin toxicity, increasing risk of arrhythmias. Monitor serum calcium and digoxin levels. | Major |
| Thiazide Diuretics (e.g., Hydrochlorothiazide) | Reduce calcium excretion, increasing risk of hypercalcemia. Monitor serum calcium. | Moderate |
| Corticosteroids (e.g., Prednisolone) | Reduce calcium absorption and increase excretion, potentially negating the supplement's benefit. | Moderate |
| Orlistat, Bile Acid Sequestrants | May reduce absorption of fat-soluble Vitamin D3. | Moderate |
7. Patient Counselling
- DO take with a meal for better absorption and to minimize stomach upset.
- DO maintain adequate fluid intake throughout the day.
- DO inform your doctor about all other medications and supplements you are taking.
- DON'T take more than the recommended dose.
- DON'T take it at the same time as iron supplements, thyroid medication, or certain antibiotics (space them by 2-4 hours).
- DON'T take with large amounts of high-fiber or high-oxalate foods.
8. Toxicology & Storage
Overdose: Acute: Nausea, vomiting, anorexia, constipation, abdominal pain, polyuria, polydipsia, dehydration, confusion, lethargy. Chronic: Hypercalcemia, hypercalciuria, nephrocalcinosis, renal stones, renal impairment, vascular and soft tissue calcification.
Storage: Store in a cool, dry place, below 30°C. Protect from light and moisture. Keep the container tightly closed. Keep out of reach of children.