A 72-year-old woman with severe osteoporosis and two prior vertebral compression fractures is started on teriparatide. Its mechanism of action is:
- A Inhibition of osteoclast-mediated bone resorption
- B Stimulation of osteoblast-mediated bone formation ✓
- C Enhancement of intestinal calcium absorption
- D Reduction of renal calcium excretion
Correct answer: B. Stimulation of osteoblast-mediated bone formation
Explanation
Teriparatide is recombinant parathyroid hormone (1-34) and is the only anabolic agent approved for osteoporosis. Intermittent PTH exposure stimulates osteoblast activity and new bone formation. Bisphosphonates and denosumab inhibit osteoclast-mediated resorption. While PTH can indirectly affect calcium handling, its therapeutic effect in osteoporosis is through bone formation.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
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Written and medically reviewed by the StethoPrep medical team.