Recent years have seen the introduction of new medical treatments for osteoporosis that have greatly reduced the rate of hip and spine fractures among older Americans. But drugs currently on the market work mainly by slowing the rate at which the bones become more fragile and vulnerable to breaks.
Soon however, those who suffer from osteoporosis may have a new drug - the first to actually stimulate the growth of bone cells. Within the year, the federal Food and Drug Administration is expected to approve a drug called Parathyroid Hormone, or PTH, the world's first osteoporosis drug that generates new bone cells.
"You're not going to cure every single fracture, but it will go a long way to reducing fractures that occur in people with severe cases of osteoporosis," says Dr. Felicia Cosman, an osteoporosis specialist and endocrinologist at Helen Hayes Hospital in West Haverstraw, New York, who also serves as clinical director of the National Osteoporosis Foundation. "It's very promising."
Cosman says preliminary studies have shown that PTH treatment in conjunction with estrogen therapy increases bone mass by 10 percent to 15 percent. By contrast, current drugs on the market stimulate bone mass by only an estimated 2 percent to 6 percent, and then only in the first year of use.
In a PTH study completed last year by Cosman, 52 women who had been on estrogen for at least one year were divided into two groups. The group that received PTH posted a 12.8 percent increase in bone mass in the spine and a 4.4 percent increase in bone mass of the hip. Additionally, that group retained nearly all the bone mass they had gained a year after they stopped taking the drug as long as they continued to receive estrogen therapy.
The main drawback so far, Cosman says, is that PTH must be injected daily for up to 18 months in order to see real improvement. After that time, the drug's use would be tapered off and patients might be switched to one of the older drugs.
While the FDA is still reviewing the drug, Cosman says, there appear to be few side effects associated with PTH, other than some minor nausea and soreness at the injection site. It is estimated that PTH will reduce the number of spine fractures from 500,000 to 250,000 cases annually and hip fractures from 300,000 to 150,000 cases.
These are the most common and debilitating injuries associated with the 8 million American women and 2 million men with osteoporosis. Spine fractures cause a deformation of the back, loss of height and extreme pain; hip fractures require major surgery, a long recovery and often lead to decreased mobility and other problems among the aged.
"You're not going to give PTH to a 52-year-old woman with mild osteoporosis," Cosman explains. "But for a 68-year-old woman who's been on other osteoporosis drugs for two years and has had fractures, this is going to be a big advance."
Scientists say bone growth is a complex procedure that consists of two stages -- bone resorption and bone formation. During resorption, special cells on the bone's surface dissolve bone tissue and create small cavities.
During bone formation, other cells fill the cavities with new bone tissue. In osteoporosis sufferers, the cycle is thrown out of whack and bone loss occurs without being replaced.
Currently Available Treatments
The five medications currently approved for osteoporosis by the FDA slow or stop the resorption cycle in the cells that causes the old bone to break down, but don't affect the reformation, which occurs at the same rate, says Lynn Chard-Petrinjak, a spokeswoman for the National Osteoporosis Foundation in Washington, D.C.
Each of these medications slows or stops bone loss and reduces fracture risk. Since the bone-dissolving process is slowed and the reformation process unaffected, patients on these medications may actually see a slight increase in bone density.
- The most potent of these drugs are alendronate (brand name: Fosamax) and risedronate (Actonel), which belong to a class of drugs called bisphosphonates. Alendronate is FDA-approved for treatment of osteoporosis in both men and women. Risedronate is approved for women, but it has yet to receive blanket approval for men. However, both drugs are FDA-approved for both sexes to treat a special type of steroid-induced osteoporosis that occurs in those who have taken prednisone or cortisone over a long period of time.
"If you can take one of the bisphosphonates, these drugs are the No. 1 treatment of choice for osteoporosis," Cosman says.
But all the FDA-approved drugs for osteoporosis have side effects, and some dugs appear to work better at a certain age or for patients with a specific medical history. The bisphosphonates are ideal, for example, for women in their mid-60s and beyond who have osteoporosis and are at risk for spine and hip fractures. However, their side effects can include upper gastrointestinal irritation and toxicity, leg cramps and general muscle pains.
Patients taking alendronate must also follow a strict regimen for ingesting the drug each week. The pill must be taken on an empty stomach, no earlier than 35 minutes before eating breakfast or even drinking coffee or tea, and requires the patient to sit upright and not lie down for an hour, because it can cause esophagal burning or ulceration if not digested properly.
- A third drug, raloxifene (Evista), belongs to a class of drugs called "selective estrogen receptor modulators," which bind to the estrogen molecules and halt bone loss. For women 55 to 60, raloxifene, which reduces the risk of spine fractures and also may reduce the risk of breast cancer, is a good choice, says Cosman, who adds that women in this age group don't need to worry so much about hip fractures, which tend to occur later in life.
Side effects of raloxifene can include menopausal symptoms such as hot flashes and blood clots in the veins of the leg, which must be treated with a blood thinner. While blood clots are rare in the normal population, Cosman says that because of the risk, she would not prescribe Raloxifene for people who are immobilized or have other diseases.
- One of the older drugs, calcitonin (Miacalcin), is a naturally occurring ormone that regulates calcium and bone metabolism. In women five years or more past menopause, calcitonin slows or stops bone loss and may relieve the pain of fractures, although it is not as potent as some of the newer drugs and is considered part of the second line of defense against osteoporosis, Cosman says.
It has been available by injection for 25 years and in 1995 became available as a nasal spray, which makes it extremely easy to administer. Side effects are rare and include allergic reaction, runny nose and congestion.
Men and Osteoporosis
While women are more prone to osteoporosis because their bones tend to be smaller to begin with, 2 million men also suffer from the disease. Doctors say their ailments often go undiagnosed because of the perception that osteoporosis is a women's disease.
In men, the most common therapy is testosterone replacement therapy the male analog to estrogen replacement therapy. Alendronate and risedronate have also been FDA-approved for men suffering from steroid-induced osteoporosis. While other drugs aren't specifically approved for men, mainly because the testing has focused on women, some doctors prescribe other osteoporosis drugs such as calcitonin off-label for men.
Non-Drug Treatments for Osteoporosis
In addition to drug therapy, there are several non-drug treatments that may also help osteoporosis. One that holds promise, says Cosman, is a semi-invasive technique called vertebroplasty, in which people with painful fractures caused by osteoporosis can receive injections of cement into the vertebra. This has been shown to reduce pain dramatically.
"That's a procedure you're going to read a lot about in the next year or two," Cosman predicts. While vertebroplasty is still experimental and has not yet been subjected to a randomized, clinical trial, doctors around the country are already doing the procedure, Cosman says.
Lastly, several firms now manufacture hip pads or hip protectors that are available at local surgical supply stores and work much the way shin guards do for soccer players. The pads lessen the impact of falls and can prevent hip fractures, but are not very popular because of added warmth and thickness which wearers find uncomfortable, Cosman says.
Nonetheless, "We're looking at a world of dramatically increasing options," says Cosman. "Anyone with osteoporosis should be on medical therapy. Calcium and vitamin D and exercise can prevent some bone loss, but they're not enough to stop it. If you have low bone mass at menopause, we recommend medical treatment."
Denise Hamilton is a Southern California-based journalist who writes a column for the Los Angeles Times' Health section. She also writes for Apria.com, New Times Los Angeles and other publications. Her book "The Jasmine Trade" will be published in July 2001.
