1. Clinical Overview
A fixed-dose combination of a potent bisphosphonate (Alendronic Acid) and a high-dose vitamin D supplement (Cholecalciferol). It is a first-line therapy for postmenopausal osteoporosis in India, designed to increase bone mineral density, reduce fracture risk, and correct/prevent vitamin D deficiency, which is highly prevalent in the Indian population. The once-weekly dosing regimen enhances compliance.
| Onset | Duration | Bioavailability |
|---|---|---|
| Biochemical markers of bone resorption (e.g., urinary N-telopeptide) decrease significantly within 1 month. Radiologically detectable increases in Bone Mineral Density (BMD) are typically observed after 6-12 months of continuous therapy. | The skeletal effects of alendronate are prolonged. After discontinuation, the anti-resorptive effect and BMD gains may persist for several years due to its binding to bone mineral. Vitamin D3 stores (in liver and fat) can last for several months. | Alendronic Acid: ~0.7% (fasting, with plain water). Reduced to near zero with food, coffee, or juice. Vitamin D3: ~60-90% from the gastrointestinal tract when taken with a fat-containing meal. |
2. Mechanism of Action
Alendronate inhibits osteoclast-mediated bone resorption. It is a pyrophosphate analogue that binds to hydroxyapatite crystals in bone, especially at sites of active resorption. Once internalized by osteoclasts, it inhibits the mevalonate pathway, preventing the prenylation of small GTPase signaling proteins (e.g., Ras, Rho, Rac). This disrupts the osteoclast's cytoskeleton, leading to apoptosis and reduced bone resorption. Vitamin D3 (Cholecalciferol) is a prohormone. It is converted to calcitriol, the active hormone that binds to the Vitamin D Receptor (VDR) in the intestine, bone, kidney, and parathyroid glands. This enhances intestinal absorption of calcium and phosphate, promotes bone mineralization, and suppresses parathyroid hormone (PTH) secretion.
3. Indications & Uses
- Treatment of postmenopausal osteoporosis (to increase bone mass, reduce fracture risk)
- Treatment of osteoporosis in men
- Prevention and treatment of glucocorticoid-induced osteoporosis (in patients initiating or on long-term glucocorticoid therapy, e.g., ≥7.5 mg prednisolone/day)
4. Dosage & Administration
Adult Dosage: One tablet (Alendronic Acid 70mg + Vitamin D3 5600 IU) once weekly.
Administration: 1. Take immediately upon rising for the day, at least 30 minutes before the first food, beverage (other than plain water), or other medication. 2. Swallow the tablet whole with a full glass (200-250 mL) of plain water only. 3. Do not suck, chew, or crush the tablet. 4. Remain fully upright (sitting or standing) for at least 30 minutes after taking the tablet. Do not lie down. 5. Do not eat or drink anything other than water during this 30-minute period. 6. Take calcium and/or other mineral supplements (e.g., iron, antacids) at a different time of day (at least 2-4 hours later).
5. Side Effects
Common side effects may include:
- Gastrointestinal: Abdominal pain, dyspepsia, nausea, constipation, diarrhea, flatulence
- Musculoskeletal: Bone, muscle, or joint pain (usually mild, transient)
- Neurological: Headache
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Calcium Supplements / Antacids (containing Ca, Mg, Al) | Severely reduce absorption of alendronate. Form insoluble complexes. | Major |
| Iron Supplements | Reduce absorption of alendronate. | Major |
| NSAIDs (e.g., Ibuprofen, Diclofenac) | Increased risk of gastrointestinal irritation and ulceration. | Moderate |
| Aminoglycosides (IV) | May have additive hypocalcemic effect. | Moderate |
| Thiazide Diuretics | May increase risk of hypercalcemia due to reduced calcium excretion. | Moderate |
| Corticosteroids (e.g., Prednisolone) | May antagonize bone-building effects; this combination is used for glucocorticoid-induced osteoporosis but requires monitoring. | Moderate |
| Cholestyramine / Orlistat / Mineral Oil | May reduce absorption of fat-soluble Vitamin D3. | Moderate |
| Anticonvulsants (Phenytoin, Carbamazepine, Phenobarbital) | Increase metabolism of Vitamin D3, potentially reducing its efficacy. | Moderate |
| Other Bisphosphonates (e.g., Risedronate, Ibandronate) | Additive effects and toxicity; concurrent use not recommended. | Major |
7. Patient Counselling
- DO take it first thing in the morning, on an empty stomach, with plain water only.
- DO remain upright (sitting/standing) for at least 30 minutes after taking it.
- DO take your calcium supplement (if prescribed) in the afternoon or evening, at least 4 hours apart.
- DO inform your dentist about this medication before any invasive dental procedure.
- DO NOT lie down after taking the tablet.
- DO NOT chew, crush, or suck the tablet.
- DO NOT take it with coffee, tea, juice, or mineral water.
- DO NOT take it with or shortly before/after food or other medicines.
8. Toxicology & Storage
Overdose: Alendronic Acid Overdose: Hypocalcemia, hypophosphatemia, upper GI adverse events (upset stomach, heartburn, esophagitis, gastritis, ulcer). Potential for renal impairment. Vitamin D3 Overdose: Hypercalcemia, hypercalciuria. Symptoms: Polyuria, polydipsia, anorexia, nausea, vomiting, weakness, fatigue, somnolence, confusion, nephrocalcinosis, renal impairment.
Storage: Store below 30°C. Protect from light and moisture. Keep the bottle tightly closed. Keep out of reach of children.