Pharmacology
Summary
The mechanisms of drugs used to treat osteoporosis work through the regulation of bone resorption, a process that transfers calcium and phosphate from the bone into the serum, thereby stabilizing or increasing bone mineral density. Bisphosphonates, such as alendronate and zoledronate, are the preferred initial treatments for osteoporosis due to their efficacy, cost-effectiveness, and long-term safety. They function by binding to hydroxyapatite on bony surfaces and preventing bone resorption.
Additionally, Selective Estrogen Receptor Modulators (SERMs) like raloxifene have tissue-specific behavior that can imitate or antagonize the effects of estrogen. Likewise, denosumab, a human monoclonal antibody against RANKL, has been shown to inhibit bone resorption and is as effective as bisphosphonates in the treatment of postmenopausal osteoporosis. Lastly, calcitonin is a peptide hormone that works by lowering serum calcium and phosphate, thereby controlling osteoclasts and reducing bone resorption.
Lesson Outline
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FAQs
Bisphosphonates are a class of drugs that inhibit osteoclast-mediated bone resorption, which essentially slows down the process of bone loss. They bind to hydroxyapatite-binding sites on bony surfaces undergoing resorption and, when taken up by osteoclasts, interfere with their function and survival, thus allowing for greater bone density and reducing the risk of fractures in osteoporosis patients.
Denosumab is a human monoclonal antibody used as a treatment for postmenopausal osteoporosis. It works by specifically targeting RANKL (Receptor Activator of Nuclear factor Kappa-B Ligand), a vital protein for the formation, function and survival of osteoclasts, which are the cells responsible for bone resorption. By inhibiting RANKL, denosumab reduces bone resorption, increases bone density, and as a result, lowers the risk of fractures.
Raloxifene is a Selective Estrogen Receptor Modulator (SERM) that mimics the effect of estrogen on bone tissue. It aids in maintaining bone density by decreasing bone resorption, and is used primarily in the prevention and treatment of osteoporosis in postmenopausal women. Unlike estrogen, raloxifene does not stimulate the endometrium or breast tissue, and is therefore less likely to cause cancer in these tissues.
Calcitonin is a hormone involved in calcium and bone metabolism. It slows down the activity of osteoclasts, thus decreasing the rate of bone resorption. In the context of osteoporosis treatment, synthetic calcitonin is used to help increase spinal bone density and alleviate pain associated with bone fractures. However, it is usually prescribed when other treatments are not suitable, as it is less effective than other available treatments for osteoporosis.
Paget's disease is a chronic disorder that can result in enlarged and misshapen bones due to abnormal bone destruction and regrowth, resulting in dense, fragile, and abnormal bone. Bisphosphonates are the primary treatment for Paget's disease as they help slow bone turnover, thereby alleviating symptoms and promoting the restoration of normal bone structure. Specifically, they inhibit the osteoclast-mediated bone resorption, which is typically overactive in Paget's disease, which helps to reduce bone pain and improve quality of life.
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