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Romosozumab Mechanism — SCE Rheumatology MCQ

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ModerateMetabolic Bone DiseaseRomosozumab MechanismSCE Rheumatology

A 72-year-old postmenopausal woman with severe osteoporosis and vertebral fragility fractures is prescribed romosozumab. Which option best describes its molecular target and effect on bone remodelling?

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Correct answer: D — A monoclonal antibody to sclerostin that increases bone formation and decreases bone resorption

Romosozumab is a humanised monoclonal antibody that binds and inhibits sclerostin, an osteocyte-derived inhibitor of canonical Wnt signalling. Sclerostin inhibition activates bone-lining cells, increases osteoblast matrix production and recruits osteoprogenitor cells, thereby increasing bone formation. It also alters osteoclast-regulatory mediators and decreases bone resorption, producing a characteristic dual effect. Option C describes denosumab, which inhibits RANKL. Option A describes raloxifene. Option E describes the principal pharmacological behaviour of bisphosphonates, while option B describes teriparatide or abaloparatide. Romosozumab is administered for 12 months; the UK SmPC recommends subsequent antiresorptive therapy to extend the skeletal benefit.

Reference: Electronic Medicines Compendium. EVENITY 105 mg solution for injection in pre-filled pen, Summary of Product Characteristics, sections 4.2 and 5.1. Updated 4 November 2024. https://www.medicines.org.uk/emc/product/10956/smpc