|Teriparatide (brand name Forteo) is a medication
for osteoporosis treatment that works in a novel way. Unlike other bone drugs, it works are a biochemical level to cause new bone to be formed.
Teriparatide has been FDA approved to treat osteoporosis in postmenopausal
women and in men with hypogonadal or idiopathic osteoporosis who
are at high risk for fracture.
It is also approved for glucocorticoid-induced osteoporosis and has recently been recognized as the preferred treatment for
Osteoporosis-related fractures are a serious problem for older
people. It is often a hip fracture that leads to decline in the
health of the elderly. A third of all hip fractures occur in men,
and almost 38% of those men will die in the following year. Osteoporosis
in men is underdiagnosed. Generally defined as the thinning of
bone tissue and decrease in density, osteoporosis is the most
common type of bone disease.
The other treatments for osteoporosis are medications that
prevent bone resorption. Bisphosphonates alendronate (Fosamax)
and risedronate (Actonel) are oral medications. Other treatments
include salmon calcitonin (Miacalsin) which is available as a
nasal spray or injection. Raloxifene (Evista) is a selective estrogen
receptor modulator. By preventing bone resorption, these medications
are used to prevent bone loss.
Teriparatide is a synthetic form of the naturally occuring parathyroid
hormone. Unlike other osteoporosis drugs, it actually causes bone
density to increase. In the body, parathyroid hormone is released
by the parathyroid glands in the neck (behine the thyroid glands)
and is an important regulator in the bloodstream's levels of calcium
and phosphorus. Laboratory tests can determine the level of this
hormone in the blood.
The most important endpoint for treatment with any of these drugs
is prevention of fractures, especially hip and vertebral fractures. A recent scientific study suggested teriparatide could be useful for treatment of osteoarthritis. The medicine may promote the formation of new cartilage tissue, which other arthritis treatments do not. It was a small study and more work will be needed before teriparatide starts to be used for arthritis regularly.
Bone metabolism is a complex process. Bone remodels throughout
a person’s life, so that there is new bone being made along with
bone resorption. Among the substances that affect bone metabolism
are vitamin D, calcium, estrogen, testosterone, and parathyroid
hormone which regulates the calcium and bone formation in the
body. Other external factors influence bone metabolism and increase
the risk of osteoporosis, including prolonged use of corticosteroids,
alcoholism, smoking, and in men, hypogonadism.
Early trials of teriparatide leading to its FDA approval were
completed separately for men and women. Evaluation of drugs for
osteoporosis are complicated by the difficulty of knowing how
severe the bone loss is, and also because treatment is needed
not just to prevent thinning bone but to definitively protect
One randomized trial of postmenopausal women who had already
fractured vertebra compared teriparatide at either 20 or 40 micrograms
per day with placebo. After about 19 months, 14% of the women
taking placebo had new vertebral fractures, as compared with 5%
of the women taking 20 micrograms of teriparatide and 4% of the
women taking 40 micrograms. There were also a statistically significant
lower number of non-vertebral fractures in the teriparatide treated
group. 20 micrograms of teriparatide increased spine and hip bone
mineral density. However, this study had to be terminated because
1.6% of the women taking 40 micrograms of teriparatide and 0.2%
of those taking 20 micrograms developed significant increases
in serum calcium, the amount of calcium in the blood, which can
Another trial compared 40 micrograms of teriparatide to alendronate.
After about 14 months later, bone density increased more in the
spine and femoral neck (part of the hip) in the patients treated
with teriparatide. Bone density in the wrist decreased with teriparatide.
Fewer patients treated with teriparatide suffered nonvertebral
A randomized trial using teriparatide to treat men with osteoporosis
(half of whom had low testosterone levels) showed that teriparatide
doses of both 20 micrograms and 40 micrograms increased bone density
in the lumbar spine and the femoral neck. In this study bone density
in the wrist decreased.