Medications currently approved for treatment of osteoporosis act by slowing the rate of bone loss and decreasing bone resorption. Teriparatide is a synthetic recombinant 34-amino-acid fragment of human parathyroid hormone. Teriparatide binds to the G protein PTH receptor and stimulates the action of osteoblasts, which are the cells responsible for bone formation. Thus the main difference between teriparatide and antiresorptive therapy for osteoporosis is that the former promotes the growth of new bone. In preclinical studies intermittent PTH has been associated with a significant increase in cancellous bone mass at several sites. Intermitent exposure to PTH for 4-6 weeks in ovariectomized animal models leads to increased cancelous bone thickness. Clinical trials have shown that teriparatide significantly increases bone density and reduces the incidence of vertebral and non-vertebral osteoporotic fractures in women with postmenopausal osteoporosis at high risk of fractures and increases bone density in men with either hypogonadal or idiopathic osteoporosis. It is administrated daily via subcutaneous injection, and has been associated with minimal side effects and no reported drug interactions. Therefore, teriparatide emerges as a completely new approach in the treatment of osteoporosis, directly stimulating new bone formation.
Parathyroid hormones; Teriparatide; Osteoporosis
