Beta-arrestin-biased parathyroid hormone ligands: a new approach to the development of agents that stimulate bone formation.

Because daily treatment with parathyroid hormone (PTH) increases bone mass and decreases fracture risk, physicians use this agent to treat osteoporosis. However, PTH stimulates both bone-forming and bone-resorbing cells, complicating its clinical use. New results show that, in mice, a so-called biased agonist (PTH-betaarr) that selectively activates beta-arrestin -dependent signaling leads to PTH-induced trabecular bone formation without a simultaneous increase in bone resorption. This targeted approach may pave the way for future pharmacological developments in the treatment of osteoporosis.