Risedronate sodium is a pyridinyl bisphosphonate that acts as a potent antiresorptive agent. It is a third-generation nitrogen-containing bisphosphonate specifically indicated for the treatment and prevention of osteoporosis in postmenopausal women and glucocorticoid-induced osteoporosis. It inhibits osteoclast-mediated bone resorption, leading to a net increase in bone mineral density (BMD) and a reduction in fracture risk. The 35mg dose is formulated as a delayed-release tablet for once-weekly oral administration, designed to improve upper GI tolerability.
Adult: For Postmenopausal Osteoporosis (Treatment & Prevention) & Glucocorticoid-Induced Osteoporosis: One 35mg delayed-release tablet orally, once a week.
Note: DELAYED-RELEASE 35mg TABLET: Must be taken in the morning immediately after breakfast. Swallow the tablet whole with a full glass of plain water (at least 120 ml). Do NOT crush, chew, or suck the tablet. Do NOT take while lying down or reclining. After taking the tablet, remain upright (sitting, standing, or walking) for at least 30 minutes. Do NOT eat or drink anything other than plain water for at least 30 minutes after taking the tablet. Do NOT take at bedtime or before rising for the day.
Risedronate has a high affinity for hydroxyapatite crystals in bone. It is selectively taken up by and adsorbed to the bone surface at sites of active bone resorption. It is internalized by osteoclasts during the resorption process. Inside the osteoclast, it inhibits the enzyme farnesyl pyrophosphate synthase (FPPS) in the mevalonate pathway.
Pregnancy: Pregnancy Category C (US FDA). Not indicated for use in women of childbearing potential. Bisphosphonates are incorporated into the maternal skeleton and can be released for years. Potential for fetal harm in animals. Use only if potential benefit justifies potential risk to the fetus.
Driving: No known effects. However, dizziness or musculoskeletal pain, though uncommon, could impair ability.
| Calcium Supplements / Antacids (containing Ca, Mg, Al, Fe) | Severely impair absorption of risedronate. | Major. Administer at a different time of day (at least 2-4 hours apart). |
| NSAIDs (e.g., Ibuprofen, Diclofenac) | May increase risk of gastrointestinal irritation and ulceration. | Moderate. Use with caution. |
| Aminoglycosides (e.g., Gentamicin) | May have additive hypocalcemic effect. | Moderate. Monitor serum calcium. |
| Loop Diuretics (e.g., Furosemide) | May increase risk of hypocalcemia. | Moderate. |
| PPIs (e.g., Omeprazole) | Theoretically may reduce efficacy of delayed-release risedronate (which requires an acidic environment for release). However, clinical significance is debated. Immediate-release risedronate absorption is not affected. | Moderate. Consider monitoring BMD response. |