General Information

Forteo is a synthetic form of parathyroid hormone (PTH), which is naturally found in the body. The synthetic hormone is to be given by subcutaneous injection for the treatment of osteoporosis in men and post-menopausal women who are at high risk for a fracture.

Forteo is supplied in a disposable pen device that can be used for up to 28 days to give once-daily self-administered injections. Forteo is available in a 20 microgram (mcg) dose and should be taken for a period of up to 24 months.

Clinical Results

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.

Mechanism of Action

Forteo [teriparatide (rDNA origin) injection] contains recombinant human parathyroid hormone (1-34), [rhPTH(1-34)], which has an identical sequence to the 34 N-terminal amino acids (the biologically active region) of the 84-amino acid human parathyroid hormone. Studies have shown that PTH acts on bone building cells called osteoblasts to stimulate new bone growth and improve bone density. Unlike agents already in use that prevent further bone loss (such as estrogen and bisphosphonate), synthetic PTH may have the potential to replace depleted bone stores.