more than the incidence in the population over 60 years old (0.4 in 100,000). Mechanism of action Teriparatide is a portion of human parathyroid hormone (PTH), amino acid sequence 1 through 34, of the complete molecule (containing 84 amino acids). Endogenous PTH is the primary regulator of calcium and phosphate metabolism in bone and kidney. PTH increases serum calcium, partially accomplishing this by increasing bone resorption. Thus, chronically elevated PTH will deplete bone stores. However, intermittent exposure to PTH will activate osteoblasts more than osteoclasts. Thus, once-daily injections of teriparatide have a net effect of stimulating new bone formation leading to increased bone mineral density. Teriparatide is the first FDA approved agent for the treatment of osteoporosis that stimulates new bone formation. Society and culture Legal status Teriparatide was approved by the US Food and Drug Administration (FDA) on 26 November 2002, for the treatment of osteoporosis in men and postmenopausal women who are at high risk for having a fracture. The drug is also approved to increase bone mass in men with primary or hypogonadal osteoporosis who are at high risk for fracture. In October 2019, the US FDA approved a recombinant teriparatide product, Teriparatide Injection (previously referred to as PF708 and Bonsity) from Pfenex Inc. Teriparatide Injection is the first FDA approved proposed therapeutic equivalent candidate to Forteo. Biosimilars Recombinant teriparatide is sold by Eli Lilly and Company under the brand name Forteo/Forsteo. On 11 June 2020, Alvogen, Inc, Pfenex Inc.'s commercialization partner, launched teriparatide injection (Bonsity) in the United States. Teriparatide injection was developed by Pfenex Inc and approved by the US Food and Drug Administration (FDA) in October 2019. Teriparatide injection is pharmaceutically equivalent to Forteo (that is, has the same active ingredient in the same strength, dosage form and route of administration) and has been shown to have comparable bioavailability. These characteristics allowed the product to be approved under a 505(b)(2) NDA for which Forteo was the reference drug. It may provide a lower-cost teriparatide option for increasing bone density in patients at high risk for fracture, and is FDA-approved for the same indications as Forteo, which means it can be used for the same patients as Forteo, including new patients and those currently responding to treatment. Teriparatide was approved for medical use in the European Union in June 2003. A synthetic teriparatide from Teva Generics has been authorized for marketing in the European Union.