Concerns about the diabetes drug Avandia continue to mount in the wake of a recent study linking Avandia with accelerated bone loss and osteoporosis. In the report, published in the December 2007 issue of Nature Medicine, researchers from the Salk Institute in La Jolla, California report that rosiglitazone (Avandia) has been shown to interfere with the formation of new bone tissue in mice and warn that long-term use may speed up osteoporosis.
Bone tissue is constantly regenerated in a process known as bone remodeling. Bone remodeling utilizes two specialized cells – osteoclasts and osteoblasts – which work in unison to support bone integrity. Osteoclasts initiate the remodeling process by secreting an acid-like substance to dissolve old, weakened bone, leaving behind a series of small pits or cavities. Once this is complete, the osteoblasts move in to fill the cavities with a collagen mixture that hardens to form new bone.
Maintaining healthy bone mass depends on the body’s ability to maintain a state of equilibrium between bone destruction and bone replacement. When this balance is disrupted, as in the case with osteoporosis, bone remodeling is impaired, resulting in weakened, brittle bone.
The Salk researchers found that Avandia stimulates the production of osteoclasts that degrade bone tissue without an equivalent increase in activity by osteoblasts. What the US researchers have shown is that, in mice receiving the drug, the increased activity from osteoclasts throws the remodeling process out of equilibrium, ultimately tipping the balance towards bone loss.
Commenting on the findings, the researchers noted that, “These findings have potential clinical implications, as they suggest that long-term rosiglitazone usage in the treatment of Type 2 diabetes and insulin resistance may cause osteoporosis, owing to a combination of decreased bone formation and increased bone resorption.”
Despite growing concern over the wisdom of using Avandia for the treatment of diabetes, a number of potential benefits have turned up. Avandia has been shown to reduce cancer in several studies, and ironically its role in promoting osteoporosis may ultimately lead to new insight into the disorder.
Source: Diabetes Drug Avandia Could Weaken Bones. Dec. 2, 2007, Nature Medicine.
