Older osteoporosis drugs, known as antiresorptives, treated osteoporosis by slowing or stopping bone loss. They did this by blocking the action of osteoclasts, a type of cell that removes cells from the bone. Forteo, however, stimulates the formation of new bone by increasing the number and action of bone-forming cells, called osteoblasts.
Research on Forteo for Osteoporosis
In clinical studies upon which the FDA based their approval, Forteo was shown to increase bone mineral density at the spine and hip in men and post-menopausal women who took 20 mcg of the drug each day, along with calcium and vitamin D supplements. The study also showed that the risk of fractures in post-menopausal women decreased 65% for spinal fractures and 53% for all other fractures caused by osteoporosis.
Risks of Forteo
Forteo is not without risk. During animal studies, rats were found to have an increased risk of developing osteosarcoma, a rare but deadly cancer of the bone. No human subjects in the study developed osteosarcoma, but the drug is not recommended for patients who are at increased risk for this cancer, including patients with Paget's disease of bone or unexplained elevations of alkaline phosphatase, children or growing adults, or those who have had prior radiation therapy involving the skeleton.
Additionally, patients with bone metastases or a history of skeletal malignancies, and those with metabolic bone diseases other than osteoporosis, should not take Forteo.
Calcium blood levels should be checked prior to prescribing and, if elevated, Forteo should not be prescribed, as it may further increase calcium levels.
Side effects reported from the use of the drug included mild nausea, dizziness and leg cramps.
