Teriparatide (Forteo)

A synthetic 34-amino acid peptide analog of parathyroid hormone-related protein (PTHrP 1-34) that selectively activates the RG conformation of the PTH1 receptor. This receptor selectivity produces a more transient signaling response compared to teriparatide, favoring anabolic bone formation with less stimulation of bone resorption and calcium mobilization. Abaloparatide increases bone mineral density at both cortical and trabecular sites.

A 32-amino acid peptide hormone naturally produced by parafollicular C-cells of the thyroid gland. Calcitonin inhibits osteoclast-mediated bone resorption by binding to calcitonin receptors on osteoclasts, reducing their activity and number. Salmon calcitonin is approximately 40-50 times more potent than human calcitonin and has a longer half-life, making it the preferred therapeutic form.

A C-type natriuretic peptide (CNP) analog that acts as an agonist at the natriuretic peptide receptor B (NPR-B) on growth plate chondrocytes. Vosoritide counteracts the constitutively activated FGFR3 signaling that suppresses endochondral ossification in achondroplasia. By stimulating the NPR-B/cGMP/MAPK pathway, it antagonizes the growth-inhibitory FGFR3 signal and restores more normal linear bone growth.

PTH (1-34) analogs, including teriparatide and abaloparatide, are synthetic peptides corresponding to the 34 N-terminal amino acids of human parathyroid hormone. These agents bind to the PTH1 receptor on osteoblasts and osteocytes, stimulating bone formation through activation of intracellular signaling pathways including cyclic AMP and protein kinase A. Intermittent administration preferentially stimulates osteoblastic bone formation over osteoclastic resorption, increasing bone mass and reducing fracture risk. The anabolic effect distinguishes these agents from antiresorptive therapies such as bisphosphonates.