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.
