Teriparatide (Forteo®)

Teriparatide is Food and Drug Administration (FDA)-approved to reduce risk of fracture in those with osteoporosis. This medicine works like the natural hormone called parathyroid hormone. When taken by once-daily injection, this medicine causes bone forming cells to lay down new bone, resulting in substantial improvement of bone density and strength such that bones are much less likely to fracture with minor trauma, such as a fall on ice.

The dose of teriparatide is 20 micrograms of the medicine, injected once daily into the fatty tissue under the skin of the abdomen or thigh. This is identical to the manner in which patients who have diabetes give themselves insulin shots. The medicine is dispensed in an injection pen that contains 28 daily doses, along with 28 needles that need to be changed before each shot.

Teriparatide can cause nausea or stomach upset, and can raise the blood level of calcium. While unusual, leg cramps or dizziness may occur.

Teriparatide has been shown to cause bone cancer in one strain of rat. No cases of these bone tumors have occurred in patients on teriparatide.

Forteo typically increases bone density in the spine by 10 percent and in the hip by 5 percent over 18 months. The risk of fractures typically is substantially reduced from Forteo, although not fully eliminated.

After two of three months of using teriparatide we typically recommend checking a morning calcium level before that day’s shot to be sure the blood calcium level is normal. Repeat bone density testing to assess the effect of the medication usually is done one to two years after starting the medication.

Teriparatide is FDA-approved only for two years of use. After that two-year treatment period, we usually recommend another medication, such as alendronate (Fosamax®) or risedronate (Actonel®), to preserve the gains from teriparatide.

It is critically important that those using teriparatide get adequate amounts of calcium and vitamin D through their diet or supplements. Inadequate amounts of daily calcium or vitamin D may blunt the benefit of these medicines.

Always remember to put the cap back on the needle after use.