PTH, Alendronate and Osteoporosis
Is It Better To Take PTH Together With Alendronate to Treat Osteoporosis?
What is the Problem and what is known about it so far?
Osteoporosis is a disease in which the strength of bones is reduced. This weakening of bone makes them more likely to break. There are more than 20 million people in the United States who suffer from this disease. Although most of the bone breaks occur in women, three out of every ten occur in men.
New medicines are now available to treat osteoporosis such as parathyroid hormone (PTH) and alendronate. Because these medications work in separate ways, researchers wanted to find out if they are more effective when taken together rather than by themselves.
Why did the researchers do this particular study?
To compare the effects of PTH alone, alendronate alone, and the two medicines combined, in men with osteoporosis.
Who was studied?
83 men with ages ranging from 46-85 were studied. All the men had below normal bone density, which is a sign of osteoporosis.
How was the study done?
The men were randomly assigned (placed by chance) to 1 of 3 groups. The first group received alendronate alone. The second group received PTH alone. In both the first and the second group the medicines were taken for 2.5 years. The third group received alendronate alone for the first 6 months and then both alendronate and PTH for the next 2 years. Two devices that can take special pictures of bone were used at the start of the study and every 6 months thereafter to see how the bone density was affected by the different medicines.
What did the researchers find?
Bone density of the thighbone and the spine was increased more in the men who took PTH alone than in the other two groups. Adding alendronate to PTH medicine actually lowered the ability of PTH to increase bone density in the spine and thighbone.
What were the limitations of the study?
The dose of PTH given to the men was higher than the currently approved dose for patient use. Currently approved doses of PTH when combined with alendronate may further reduce the effectiveness of PTH. Because PTH was started 6 months after alendronate in the combined group, different effects might be seen if PTH and alendronate were started at the same time. Although this study only included men, other studies have shown similar finding in women with osteoporosis. PTH treatment is costly and requires daily injections.
What are the implications of the study?
In middle-aged and older men with osteoporosis, alendronate impairs the ability of PTH to increase bone density. PTH alone appears to be more effective in treating osteoporosis in the spine and thighbone than alendronate alone. Additional studies are needed before a combination of PTH and alendronate can be recommended to patients. Because of cost and need for daily injections, PTH treatment should be mostly used in persons with severe osteoporosis.
Summarized by Andrew Tinsley, College of Medicine, University of Vermont.
Summarized from "The Effects of Parathyroid Hormone, Alendronate, or Both in Men with Osteoposis" Finkelstein, Joel S. et al. The New England Journal of Medicine, September 25, 2003, Volume 349, Issue 13, Pages 1216-1226.
