Which anabolic agent is a parathyroid hormone analog used in osteoporosis to upregulate osteoblast activity?

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

Answer: (B)

Intermittent stimulation of osteoblasts drives bone formation, which is the goal of anabolic therapies for osteoporosis. Teriparatide is a parathyroid hormone analog (PTH 1-34) given as a daily injection, and it directly promotes osteoblast activity and survival. This boosts bone formation, increases bone mineral density, and reduces fracture risk, especially in the spine. The effect relies on intermittent, not continuous, PTH exposure; continuous PTH would favor bone resorption, but the intermittent regimen shifts the balance toward formation. Teriparatide is used for a limited time (about two years) due to safety considerations. Other agents like denosumab and alendronate slow bone loss by inhibiting osteoclasts, while romosozumab stimulates bone formation via a different pathway, but none are parathyroid hormone analogs.