Currently Enrolling Trials
Forteo (teriparatide injection) - 2 indications
- for the treatment of post-menopausal women with osteoporosis at high risk for fracture, and to increase bone mass in men with primary or hypogonadal osteoporosis at high risk for fracture; approved in 2002
- for the treatment of adults with osteoporosis associated with sustained systemic glucocorticoid therapy at high risk for fracture; approved in 2009
Forteo is a synthetic form of parathyroid hormone (PTH), which is naturally found in the body.
Forteo is specifically indicated for:
- the treatment of postmenopausal women with osteoporosis at high risk for fracture or patients who have failed or are intolerant to other available osteoporosis therapy;
- increase of bone mass in men with primary or hypogonadal osteoporosis at high risk for fracture or patients who have failed or are intolerant to other available osteoporosis therapy;
- the treatment of men and women with osteoporosis associated with sustained systemic glucocorticoid therapy at high risk for fracture or patients who have failed or are intolerant to other available osteoporosis therapy
Forteo is supplied as an injection for subcutaneous administration into the thigh or abdomen. The recommended dosage is 20 mcg given subcutaneously once a day. Instruct patients to take supplemental calcium and vitamin D if daily dietary intake is inadequate. Use of Forteo for more than 2 years during a patient's lifetime should only be considered if a patient remains at or has returned to having a high risk for fracture.
Mechanism of Action
Endogenous 84-amino acid parathyroid hormone (PTH) is the primary regulator of calcium and phosphate metabolism in bone and kidney. Physiological actions of PTH include regulation of bone metabolism, renal tubular reabsorption of calcium and phosphate, and intestinal calcium absorption. The biological actions of PTH and teriparatide are mediated through binding to specific high-affinity cell-surface receptors. Teriparatide and the 34 N-terminal amino acids of PTH bind to these receptors with the same affinity and have the same physiological actions on bone and kidney. Teriparatide is not expected to accumulate in bone or other tissues.
The skeletal effects of teriparatide depend upon the pattern of systemic exposure. Once-daily administration of teriparatide stimulates new bone formation on trabecular and cortical (periosteal and/or endosteal) bone surfaces by preferential stimulation of osteoblastic activity over osteoclastic activity. In monkey studies, teriparatide improved trabecular microarchitecture and increased bone mass and strength by stimulating new bone formation in both cancellous and cortical bone. In humans, the anabolic effects of teriparatide manifest as an increase in skeletal mass, an increase in markers of bone formation and resorption, and an increase in bone strength. By contrast, continuous excess of endogenous PTH, as occurs in hyperparathyroidism, may be detrimental to the skeleton because bone resorption may be stimulated more than bone formation.
Adverse events associated with the use of Forteo (teriparatide) may include, but are not limited to, the following:
- Neck pain
- Angina pectoris
Indication 1 - post-menopausal women with osteoporosis at high risk for fracture, and to increase bone mass in men with primary or hypogonadal osteoporosis at high risk for fracture
The FDA's approval of Forteo was based on 24 clinical trials enrolling more than 2,800 postmenopausal women and men with osteoporosis. Phase III clinical trial data showed that Forteo stimulated new bone formation, lowered the risk of vertebral (spinal) fractures and increased bone mineral density (BMD) compared with placebo in postmenopausal women with osteoporosis during an average of 19 months of treatment. The data also showed that Forteo reduced the relative risk of spinal fractures by 65 percent (9.3 % absolute risk reduction), compared with placebo, and lowered the relative risk of nonspinal fractures overall (sites such as the wrist, ribs, hip, ankle/foot, etc.) by 53% (2.9% absolute risk reduction), compared with placebo.
In addition, Forteo also significantly increased spine BMD in postmenopausal women with osteoporosis beginning at three months of treatment. The data showed that 96% of women had an increase from baseline, with 72 percent achieving at least a 5 percent increase in spine BMD and 44% gaining 10 percent or more compared with placebo.
Indication 2 - adults with osteoporosis associated with sustained systemic glucocorticoid therapy at high risk for fracture
Because of differences in mechanism of action (anabolic vs. anti-resorptive) and lack of clarity regarding differences in BMD as an adequate predictor of fracture efficacy, data on the active comparator are not presented.
Effect on Bone Mineral Density (BMD).
In patients with glucocorticoid-induced osteoporosis, Forteo increased lumbar spine BMD compared with baseline at 3 months through 18 months of treatment. In patients treated with Forteo, the mean percent change in BMD from baseline to endpoint was 7.2% at the lumbar spine, 3.6% at the total hip, and 3.7% at the femoral neck (p <0.001 all sites).