A fixed-dose combination supplement containing elemental calcium (as calcium carbonate) and cholecalciferol (Vitamin D3). It is primarily used for the prevention and treatment of calcium and vitamin D deficiencies. Calcium is essential for bone mineralization, muscle contraction, nerve transmission, and blood coagulation. Vitamin D3 enhances intestinal absorption of calcium and phosphate, regulates bone remodeling, and supports immune function. This low-dose combination is often used for maintenance therapy or in populations with mild deficiency.
Adult: One tablet/capsule once or twice daily, as directed by physician. Typically 1-2 tablets daily. Should be taken with meals for better absorption of calcium carbonate.
Note: Take orally with or immediately after a meal to enhance calcium absorption and reduce gastric upset. Swallow whole with a full glass of water. Do not take within 2 hours of other medications (e.g., tetracyclines, bisphosphonates, levothyroxine) to avoid binding interactions. Can be taken in the morning or evening.
The combination works synergistically. Calcium provides the essential cation for physiological processes. Vitamin D3 (after activation to calcitriol) acts as a hormone that binds to the Vitamin D Receptor (VDR) in the intestines, bones, and kidneys. This complex regulates gene expression, increasing the synthesis of calcium-binding proteins (e.g., calbindin) in enterocytes, enhancing active transcellular calcium absorption. It also promotes renal reabsorption of calcium and phosphate and, in conjunction with PTH, stimulates bone resorption to mobilize calcium when needed.
Pregnancy: Category A (Indian/old FDA) / Category C (US FDA for high doses). This dose is generally considered safe. Calcium and Vitamin D requirements increase during pregnancy. Use under medical supervision. Essential for fetal skeletal development.
Driving: No effect on driving ability.
| Thiazide Diuretics (e.g., Hydrochlorothiazide) | Reduce renal calcium excretion, increasing risk of hypercalcemia. | Major |
| Oral Bisphosphonates (e.g., Alendronate) | Calcium supplements interfere with absorption. Administer at least 2 hours apart. | Moderate |
| Levothyroxine | Calcium carbonate can decrease levothyroxine absorption. Administer 4-6 hours apart. | Moderate |
| Oral Tetracycline/Quinolone Antibiotics | Calcium binds to these drugs, reducing their absorption and efficacy. | Moderate |
| Corticosteroids (e.g., Prednisolone) | Reduce calcium absorption and increase excretion, potentially reducing efficacy. | Moderate |
| Orlistat | May reduce absorption of fat-soluble Vitamin D3. | Moderate |
| Cardiac Glycosides (Digoxin) | Hypercalcemia potentiates digoxin toxicity, risk of arrhythmias. | Major |
| Phenytoin, Phenobarbital, Carbamazepine | Induce hepatic CYP450 enzymes, increasing metabolism of vitamin D3 to inactive metabolites, reducing efficacy. | Moderate |
Same composition (Calcium (100mg) + Vitamin D3 (200IU)), different brands: