Parathyroid hormone shots can be given for up to two years to build stronger bones in women with osteoporosis, but bone density increases further when followed by treatment with Merck & Co.’s drug Fosamax, according to a study released Wednesday.
Doctors are still struggling for the best way to use the various drugs designed to ward off the brittle bone disease that is estimated to affect 8 million women in the United States.
A team led by Dennis Black of the University of California, San Francisco, found that the bones of women who had received the parathyroid hormone shots began to weaken if the treatment was followed by a placebo instead of Fosamax.
The study, published in this week’s New England Journal of Medicine, found a 31 percent increase in the density of spine bones for patients who received Fosamax after the hormone shots compared to a 14 percent gain for those on the placebo.
The study about Fosamax, also known as alendronate, comprised 238 women from New York, Pittsburgh, Minneapolis and Bangor, Maine.
Preventing further bone loss
Fosamax, an antiresorptive therapy, works by slowing the body’s natural process of destroying old bones, while parathyroid hormone — supplied in this case by NPS Pharmaceuticals Inc. — increases the rate of new bone formation.
“If antiresorptive therapy does not follow parathyroid hormone therapy, much of the skeletal gain in bone mineral density with parathyroid hormone is lost,” Black’s team concluded in the study.
When the women took Fosamax at the same time as their hormone shots, the study showed there was little additional benefit.
In a smaller study in this week’s Journal, a research team led by Felicia Cosman from Helen Hayes Hospital in West Haverstraw, N.Y., concluded that giving the hormone treatment in three-month cycles, followed by three-month respites, was just as effective as daily injections.
Since the hormone treatment costs about $10,000 per year, it could mean a significant costs savings to patients, Cosman told Reuters.
She said her team tried giving the hormone treatment in three-month bursts because the drug seems most effective during the first three months. All 126 women involved in the study were also taking Fosamax during the 15 months of treatment.
“If you give it a little rest, you still get a comparable boost in bone formation (during the second three-month cycle),” said Cosman.
The hormone does carry a risk of side effects such as dizziness, leg cramps, mild nausea, and aches and pains in the muscles and joints, she said, adding that the injections are better tolerated than some oral medications for osteoporosis.
The parathyroid hormone in the Cosman study was synthesized by Bachem, but it was chemically similar to Eli Lilly & Co.’s drug Forteo.