What are bisphosphonates and how do they treat osteoporosis?

Bisphosphonates like alendronate, risedronate, and zoledronic acid are first-line medications for osteoporosis that work by inhibiting osteoclast activity, reducing bone resorption, and increasing bone mineral density. Oral bisphosphonates must be taken first thing in the morning on an empty stomach with a full glass of plain water, and the patient must remain upright for at least 30 minutes to prevent esophageal erosion and ulceration. Long-term use beyond five years is associated with rare but serious adverse effects including osteonecrosis of the jaw and atypical femoral fractures.