1. Clinical Overview
Strontium ranelate is a dual-action bone agent used for the treatment of severe osteoporosis in postmenopausal women and in adult men at high risk of fracture. It is a strontium salt of ranelic acid. Its unique mechanism involves simultaneously increasing bone formation and decreasing bone resorption, leading to improved bone mass and strength. In the Indian context, it is a second-line agent, typically reserved for patients with severe osteoporosis who are intolerant to or have contraindications for first-line therapies like bisphosphonates.
| Onset | Duration | Bioavailability |
|---|---|---|
| Biochemical markers of bone resorption (e.g., serum CTX) decrease within 4 weeks. Significant increases in Bone Mineral Density (BMD) are typically observed after 3-6 months of treatment. | The therapeutic effect on BMD and fracture risk reduction is sustained with continuous daily therapy. Effects on bone turnover markers are maintained as long as treatment continues. | Approximately 25% (range 19-27%) of an oral dose is absorbed. Absorption is reduced by food, milk, and calcium-containing products. |
2. Mechanism of Action
Strontium ranelate exerts a dual mode of action on bone metabolism. The strontium cation (Sr2+) is the active moiety. It is incorporated into the bone matrix by exchanging with calcium in the hydroxyapatite crystal. This incorporation is believed to modulate the activity of bone cells.
3. Indications & Uses
- Treatment of severe postmenopausal osteoporosis to reduce the risk of vertebral and hip fractures.
- Treatment of severe osteoporosis in adult men at high risk of fracture.
4. Dosage & Administration
Adult Dosage: 2 gm (one sachet) orally, once daily.
Administration: Take at bedtime, preferably at least 2 hours after eating. The granules from the sachet must be suspended in a glass of plain water (not milk, tea, coffee, or carbonated drinks). Stir and drink immediately. Do not take with food, milk, or calcium-containing products as they severely reduce absorption. Patients should remain in an upright position (sitting or standing) for at least 30 minutes after intake to reduce esophageal irritation.
5. Side Effects
Common side effects may include:
- Nausea
- Diarrhea
- Headache
- Dermatitis/Eczema
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Oral Tetracyclines (e.g., Doxycycline) and Quinolones (e.g., Ciprofloxacin) | Strontium forms insoluble complexes in the gut, reducing absorption of both drugs. A minimum 2-hour interval is required. | Major |
| Oral Calcium Supplements and Antacids containing divalent cations (Al, Mg, Ca) | Severely reduce the absorption of strontium ranelate. Must be taken at least 2 hours apart. | Major |
| Oral Bisphosphonates (e.g., Alendronate) | Potential pharmacodynamic antagonism. Not recommended for concomitant use. | Moderate |
| Warfarin | No pharmacokinetic interaction. However, caution advised due to potential increased VTE risk with strontium. | Moderate |
7. Patient Counselling
- DO take the medicine at bedtime, at least 2 hours after your last meal or snack.
- DO mix the granules in a full glass of plain water only. Drink it immediately.
- DO remain sitting or standing upright for at least 30 minutes after taking the dose.
- DO NOT take with food, milk, tea, coffee, or carbonated drinks.
- DO NOT take calcium supplements or antacids within 2 hours of taking strontium ranelate.
- DO inform all your doctors and dentists that you are taking this medicine.
8. Toxicology & Storage
Overdose: Acute overdose may lead to nausea, vomiting, diarrhea, and headache. Chronic overdose could theoretically lead to 'strontium rickets' or osteomalacia due to excessive substitution of calcium in bone, impairing mineralization.
Storage: Store below 30°C in a cool, dry place, protected from light and moisture. Keep the sachets in the original outer carton. Keep out of reach and sight of children.