A 65-year-old woman with severe osteoporosis (T-score -3.5) and multiple vertebral fractures is started on teriparatide. The mechanism of action of teriparatide is best described as:
- A Inhibition of osteoclast-mediated bone resorption via induction of osteoclast apoptosis
- B Neutralization of RANKL to prevent osteoclast differentiation and activation
- C Stimulation of osteoblast activity and bone formation through intermittent PTH receptor activation ✓
- D Inhibition of sclerostin to simultaneously increase bone formation and decrease resorption
Correct answer: C. Stimulation of osteoblast activity and bone formation through intermittent PTH receptor activation
Explanation
Teriparatide is recombinant PTH (1-34). Intermittent low-dose PTH exposure preferentially stimulates osteoblast activity and net bone formation. Continuous PTH elevation (as in hyperparathyroidism) stimulates resorption. Option A describes bisphosphonates. Option B describes denosumab. Option D describes romosozumab.
Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.
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