Alendronate is a medication commonly prescribed to treat and prevent osteoporosis in postmenopausal women and to increase bone mass in men with osteoporosis. It belongs to a class of drugs known as bisphosphonates, which work by inhibiting osteoclast activity—the cells responsible for breaking down bone tissue. By slowing bone loss, alendronate helps maintain bone strength, reducing the risk of fractures, particularly in the spine and hip. Alendronate must be taken on an empty stomach with a full glass of water, and patients should remain upright for at least 30 minutes afterward to prevent irritation or damage to the esophagus.