Fosamax (alendronate sodium)

The following drug information is obtained from various newswires, published medical journal articles, and medical conference presentations.


Approval Status:

Approved on September 29, 1995

Specific Treatments:

Post-menopausal osteoporosis, Paget's disease of bone

General Information

Fosamax reduces the activity of the cells that cause bone loss and helps build healthy bone. It is the first nonhormonal medicine for women after menopause who have osteoporosis.

The FDA also cleared Fosamax for the treatment of Paget's disease of bone, a chronic disorder that affects up to 1.3 million Americans and may result in enlarged and deformed bones in one or more regions of the skeleton.

Clinical Results

The FDA clearance of Fosamax to treat osteoporosis is based on efficacy data from five clinical trials involving 1,827 postmenopausal women with osteoporosis in 16 countries who were followed for at least two years.

In clinical trials, Fosamax significantly increased bone mineral density (closely related to bone strength) at the spine (8.2%), hip (7.2%), and other sites. While the studies were not designed to detect fracture risk, further analysis supports that Fosamax reduced the number of women with new spinal fractures by nearly half (48%), reduced the total number of new spinal fractures by 63%, and reduced overall height loss by 35%. Women treated with Fosamax lost an average of 3 mm in height, compared with women on placebo who lost an average of 4.6 mm in height.

Side Effects

Side effects observed in clinical trials were generally mild. The most commonly reported drug-related side effects in subjects taking Fosamax were abdominal and musculoskeletal pain. Less frequently reported were other digestive disturbances such as nausea, heartburn, and irritation or pain of the esophagus.

Additional Information

Fosamax is indicated for the treatment of osteoporosis in postmenopausal women. Osteoporosis is a progressive disease of the skeleton caused by an imbalance in the body's bone-rebuilding cycle. Osteoporosis is characterized by low bone mass, which results in bones that are prone to fracture, or by the presence or history of an osteoporotic fracture. Bone mass is closely related to bone strength; the greater the bone mass, the stronger the bones and the less likely they are to fracture.

Osteoporosis affects more than 25 million Americans, 80 percent of them women. Each year, osteoporosis causes more than 1.3 million fractures, including 500,000 spinal fractures, 250,000 hip fractures, and 240,000 wrist fractures.

Bone is constantly being rebuilt (or remodeled) throughout life in a process in which old bone tissue is broken down (or resorbed) by cells called osteoclasts and replaced with new bone tissue by cells called osteoblasts. In healthy young adults, the overall rate of remodeling is usually in balance so that the amount of bone lost is about equal to the amount that is replaced.

However, after menopause, more bone is broken down than is replaced, causing bone loss to occur and bones to become weaker. This is due to a drop in the level of estrogen. In the first five years after menopause, women may lose as much as 25% of their bone mass. In fact, menopause is the single most important risk factor for osteoporosis in women.

In patients with Paget's disease of bone, excessive remodeling causes the bone to be enlarged but fragile, and may result in bone pain, deformities, fractures and in some cases, arthritis and neurological complications.

Merck estimates that the retail price for a daily dose of 10 mg will be between $1.65 and $1.80.