Teriparatide

Teriparatide (Forteo) is a recombinant form of parathyroid hormone, used in the treatment of some forms of osteoporosis. It is manufactured and marketed by Eli Lilly and Company.

Administration
Teriparatide is administered by injection once a day in the thigh or abdomen. The recommended dose is 20 μg per day.

Uses
Teriparatide has an ongoing clinical trial to evaluate its effectiveness in treating the symptoms of osteogenesis imperfecta.

Teriparatide should not be prescribed for patients who are at increased risks for osteosarcoma. This includes those with Paget's Disease of bone or unexplained elevations of serum alkaline phosphate, open epiphysis, or prior radiation therapy involving the skeleton.

Side Effects
The main risk of teriparatide is an increased risk of osteosarcoma, at least as seen in rat studies. Because of this risk, it is typically used as second line therapy and even then for no more than two years.

Mechanism of action
Teriparatide is the 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, and to date only, FDA approved agent for the treatment of osteoporosis that stimulates new bone formation.

FDA approval
Teriparatide was approved by the 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.