The human body continuously removes old bone and forms new bone tissue. In osteoporosis, bone breakdown occurs faster than bone formation, leading to gradual bone loss and making bones thin and fragile. This condition is especially common in postmenopausal women. Many patients remain asymptomatic and may not be aware of the disease, but it significantly increases the risk of fractures, particularly in the spine, hips, and wrists.
Risedronate has a strong affinity for hydroxyapatite crystals in bone and acts as an antiresorptive agent. At the cellular level, it inhibits osteoclast activity. Although osteoclasts continue to attach to the bone surface normally, their bone resorption activity is significantly reduced. Calcium suppresses parathyroid hormone (PTH) secretion and reduces bone turnover. Elevated PTH levels are associated with age-related bone loss, particularly in cortical bone, while increased bone turnover itself is an independent risk factor for fractures.