Which osteoporosis medication is a sclerostin inhibitor used to increase bone formation, placed here to test alternative phrasing?

• A. Teriparatide
• B. Denosumab
• C. Romosozumab
• D. Alendronate

Answer: (C)

The main concept is how certain osteoporosis drugs promote bone formation by targeting the signaling that controls osteoblast activity. Sclerostin, produced by osteocytes, inhibits Wnt signaling, which is essential for osteoblasts to build bone. Blocking sclerostin releases this brake, boosting bone formation. Romosozumab is a monoclonal antibody that inhibits sclerostin, making it the drug in this list that directly increases bone formation via sclerostin blockade.

Teriparatide also increases bone formation but does so by stimulating the parathyroid receptor (PTH pathway), not by inhibiting sclerostin. Denosumab and alendronate primarily reduce bone resorption rather than increase formation.