FDA. US: The U.S. Food and Drug Administration today approved Natpara
(parathyroid hormone) to control hypocalcemia (low blood calcium
levels) in patients with hypoparathyroidism, a rare disease that affects
approximately 60,000 people in the United States.
Hypoparathyroidism
occurs when the body secretes abnormally low levels of parathyroid
hormone, which helps regulate calcium and phosphorus levels in the body.
Hypoparathyroidism
is caused by loss of function of the parathyroid glands and occurs most
commonly as a result of surgical removal of the parathyroid glands and
more rarely as a result of autoimmune or congenital diseases. Patients
with hypoparathyroidism can experience numbness, tingling, muscle
twitching, spasms or cramps, abnormal heart rhythm, and seizures as a
consequence of low blood calcium levels.
Hypoparathyroidism is
also associated with long-term complications such as kidney damage,
kidney stones, development of cataracts and calcification of soft
tissues.
Natpara, a hormonal injection administered once daily,
helps to regulate the body’s calcium levels. The FDA granted Natpara
orphan drug designation because it is intended to treat a rare disease.
“People
with hypoparathyroidism have limited treatment options and face
challenging symptoms that can severely impact their quality of life,”
said Jean-Marc Guettier, M.D., director of the Division of Metabolism
and Endocrinology Products in the FDA’s Center for Drug Evaluation and
Research. “This product offers an alternative to patients whose calcium
levels cannot be controlled on calcium supplementation and active forms
of vitamin D.”
The safety and effectiveness of Natpara were
evaluated in a clinical trial of 124 participants who were randomly
assigned to receive Natpara or a placebo. The trial was designed to
determine whether Natpara can be used as a substitute for, or be used to
help reduce the amount of, active forms of vitamin D or oral calcium
taken by participants.
Results showed 42 percent of Natpara-treated
participants achieved normal blood calcium levels on reduced doses of
calcium supplements and active forms of vitamin D, compared to three
percent of placebo-treated participants.
Natpara carries a boxed
warning that bone cancer (osteosarcoma) has been observed in rat studies
with Natpara. It is unknown whether Natpara causes osteosarcoma in
humans, but because of a potential risk of osteosarcoma, Natpara is only
recommended for use in patients whose hypocalcemia cannot be controlled
on calcium supplementation and active forms of vitamin D, and for whom
the potential benefits are considered to outweigh this potential risk.
Natpara is only available through a restricted program under a Risk
Evaluation and Mitigation Strategy (REMS).
The most common side
effects observed in Natpara-treated participants were sensations of
tingling, tickling, pricking, or burning of the skin (paraesthesia); low
blood calcium; headache; high blood calcium; and nausea.
Natpara is manufactured by NPS Pharmaceuticals, Inc., based in Bedminster, New Jersey.
The
FDA, an agency within the U.S. Department of Health and Human Services,
protects the public health by assuring the safety, effectiveness, and
security of human and veterinary drugs, vaccines and other biological
products for human use, and medical devices. The agency also is
responsible for the safety and security of our nation’s food supply,
cosmetics, dietary supplements, products that give off electronic
radiation, and for regulating tobacco products.