IC50: 2 nM (PTH).

Trabecular bone calcium and dry weight of the distal femur increased significantly in Teriparatide-treated animals. The increase in trabecular calcium compared with vehicle control occurred as early as 1 week after initiation of treatment with a 35% and 45% increase, respectively, for 10 μg/kg and 40 μg/kg Teriparatide. Similar results were observed for trabecular dry weight. After 4 weeks of treatment with 10 mg/kg or 40 mg/kg Teriparatide, trabecular calcium increased significantly by 70% and 123%, respectively, compared with the vehicle and by 73%.
The 4-week Teriparatide administration increase the pore ratio, number, and density as well as the cortical area, thickness, and bone mineral content (BMC), without significant influencing the volumetric bone mineral density (BMD). The 4-week Teriparatide administration + 8-week vehicle administration decrease the pore ratio, number, and density as well as the cortical area and thickness, compared with the 4-week Teriparatide administration, but the pore ratio, cortical area, and thickness are still higher compared with the 12-week vehicle administration. The 4-week Teriparatide administration + 8-week higherdose IBN administration increase the cortical area, thickness, BMC, and volumetric BMD and decrease the pore ratio, but not the pore number or density, compared with the 4-week Teriparatide administration + 8-week vehicle administration.