Which osteoanabolic agent is a sclerostin inhibitor used to increase bone formation?

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

Answer: (A)

Sclerostin acts as a brake on bone formation by inhibiting the Wnt/β-catenin signaling pathway in osteoblasts. Blocking this inhibitor releases the brake and ramps up bone formation, which is the hallmark of an osteoanabolic approach. Romosozumab is a monoclonal antibody that binds sclerostin, preventing it from dampening Wnt signaling. This leads to increased osteoblast activity and bone formation, with a favorable net gain in bone mass as formation is boosted and resorption is not strongly promoted.

Other options work through different mechanisms: teriparatide is a parathyroid hormone analog that stimulates bone formation but does so via PTH receptor signaling rather than inhibiting sclerostin; alendronate is a bisphosphonate that primarily reduces bone resorption; denosumab blocks RANKL to prevent osteoclast formation, also focusing on antiresorptive effects.