ROSIGLITAZONE AND PIOGLITAZONE
These medications are also called thiazolidinediones, TZDs, or
glitazones.
Working
These are insulin sensitizers: they work by making the tissues more sensitive to the effects
of insulin
They usually take a few days to work, so one should not expect glucose levels to fall for at
least a week or two. The medicine does depend on having enough insulin to be effective. In addition to their
glucose-lowering effect, thiazolidinediones lower triglycerides and free fatty acid levels and raise total
cholesterol, LDL cholesterol, and HDL cholesterol. Pioglitazone, when compared to rosiglitazone, is more
effective in lowering triglycerides and raising HDL cholesterol. It also does not raise LDL cholesterol as much
as rosiglitazone does. Since lipid abnormalities are associated with heart disease, it has been proposed that
the lipid changes seen with these drugs (especially pioglitazone) might be beneficial. In small research studies
these drugs have been shown to prevent the reblockage of coronary arteries after they have been opened with a
procedure called coronary angioplasty. These medicines also seem to help fatty liver, an important abnormality
found in many people with type 2 diabetes and which can lead to liver damage (cirrhosis of the
liver).
Side Effects
The main side effects of these medicines are weight gain and fluid
retention. The weight gain tends to be around the abdomen. Despite the weight gain, the glucose levels generally
fall. Fluid retention can cause ankle swelling, and in individuals with heart disease these medicines can cause
heart failure. (The symptoms of heart failure include swelling of the legs and shortness of breath on exertion.)
The fluid retention is more of a problem if you are also on insulin. A recent combined analysis of all people with
type 2 diabetes who were in clinical trials with rosiglitazone for more than six months suggested that individuals
on rosiglitazone had more heart attacks than those who were not taking the drug. This finding still requires
confirmation. Pioglitazone, on the other hand, does not seem to have this effect. Very rarely, these medicines can
cause swelling of the retina at the back of the eye and cause blurred vision. Stopping the medicine resolves this
side effect. The first medicine in this class was called troglitazone (Rezulin) and was withdrawn from clinical use
because it caused liver failure. This problem does not appear to occur with rosiglitazone and pioglitazone, In
experimental animals, these drugs increase bone turnover, and there are preliminary reports that they may
increase the risk of fractures in
women but not men.
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