1. Clinical Overview
A fixed-dose combination supplement primarily indicated for the prevention and treatment of calcium and vitamin D deficiencies, and vitamin B12 deficiency, particularly in the context of osteoporosis, osteomalacia, and nutritional deficiencies. The combination addresses bone health, neuromuscular function, and hematopoiesis synergistically.
| Onset | Duration | Bioavailability |
|---|---|---|
| Calcium: Rapid (hours). Vitamin D3: 2-4 weeks for measurable biochemical changes. Methylcobalamin: Variable, from days to weeks for hematological response. | Calcium: 4-6 hours. Vitamin D3: 15-20 days (due to storage in fat and muscle). Methylcobalamin: Weeks to months (due to hepatic storage). | Calcium (as carbonate): ~30% (dose-dependent, decreases with higher doses). Vitamin D3 (Cholecalciferol): ~60-90% from oral solution, lower from solid forms. Methylcobalamin: ~1-5% via passive diffusion; significantly higher with intrinsic factor-mediated active transport in the ileum. |
2. Mechanism of Action
This combination works via three distinct but complementary pathways. Calcium provides the essential mineral for bone mineralization, blood coagulation, and muscle contraction. Vitamin D3 enhances intestinal absorption of calcium and phosphate, promotes bone remodeling, and regulates immune function. Methylcobalamin acts as a cofactor for methionine synthase (homocysteine metabolism) and L-methylmalonyl-CoA mutase (myelin synthesis), crucial for neurological health and red blood cell formation.
3. Indications & Uses
- Prevention and treatment of calcium and vitamin D deficiency
- Osteoporosis (as an adjunct to specific therapy)
- Osteomalacia/Rickets
- Nutritional vitamin B12 deficiency (maintenance phase)
- Prophylaxis in individuals with malabsorption syndromes (e.g., post-gastrectomy, Crohn's disease)
4. Dosage & Administration
Adult Dosage: One tablet/capsule once daily or as directed by the physician. For weekly Vitamin D3 dosing: One tablet/capsule once per week, often taken with a meal for better absorption of fat-soluble Vitamin D3.
Administration: Take with or immediately after a meal to enhance calcium absorption and reduce gastric irritation. Swallow whole with a full glass of water. For weekly dosing, choose a fixed day (e.g., every Sunday). Do not take within 2 hours of iron supplements, tetracyclines, or fluoroquinolones.
5. Side Effects
Common side effects may include:
- Constipation
- Abdominal discomfort or bloating
- Nausea
- Headache
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Thiazide Diuretics (e.g., Hydrochlorothiazide) | Increased risk of hypercalcemia due to reduced renal calcium excretion. | Major |
| Digoxin | Hypercalcemia potentiates digitalis toxicity, leading to serious cardiac arrhythmias. | Major |
| Oral Bisphosphonates (e.g., Alendronate) | Calcium supplements can interfere with absorption. Administer at least 2 hours apart. | Moderate |
| Levothyroxine | Calcium carbonate can decrease its absorption. Administer at least 4 hours apart. | Moderate |
| Corticosteroids (e.g., Prednisolone) | Reduce calcium absorption and antagonize vitamin D action. | Moderate |
| Orlistat, Cholestyramine | May reduce absorption of fat-soluble Vitamin D3. | Moderate |
| Proton Pump Inhibitors (e.g., Omeprazole) | Long-term use may impair calcium carbonate absorption (requires acidic environment) and B12 absorption. | Moderate |
| Phenytoin, Phenobarbital | Increase metabolism of Vitamin D3, reducing its efficacy. | Moderate |
7. Patient Counselling
- DO take with food for better absorption and to avoid stomach upset.
- DO maintain adequate fluid intake (2-3 liters/day) to reduce risk of kidney stones.
- DO inform your doctor if you are taking any other medicines, especially for heart, bones, or thyroid.
- DON'T take with high-fiber cereals or spinach at the same meal.
- DON'T take within 2-3 hours of other medicines without consulting your pharmacist.
- DON'T crush or chew the tablet unless it is specifically a chewable formulation.
8. Toxicology & Storage
Overdose: Primarily due to hypercalcemia and hypervitaminosis D: Nausea, vomiting, anorexia, constipation, abdominal pain, polyuria, polydipsia, dehydration, lethargy, confusion, psychosis, cardiac arrhythmias, renal failure, nephrocalcinosis.
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.