Visual Impairment With The Diabetes Drugs Rosiglitazone (Avandia) And Rosiglitazone With Metformin (Avandamet)

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Visual Impairment With The Diabetes Drugs Rosiglitazone (Avandia) And

Rosiglitazone With Metformin (Avandamet)

http://www.worstpills.org/member/ealert.cfm?ea_id=35

On Dec. 19, 2005, the Canadian drug regulator, Health Canada, issued a

warning about the possibility of visual impairment with the use of the

diabetes drugs rosiglitazone (AVANDIA) and the combination of

rosiglitazone with another diabetes drug, metformin (AVANDAMET). The

U.S. Food and Drug Administration (FDA) followed with a similar warning

on Jan. 5, 2006. The number of reports of vision impairment was not

disclosed in the warnings from either Health Canada or the FDA.

Rosiglitazone and the combination of the drug with metformin, Avandamet,

accounted for more than 10.6 million prescriptions dispensed in the U.S.

in 2004.

The full text of Canadian warning can be found on the Internet. The FDA

warning is also available online.

http://www.fda.gov/medwatch/safety/2006/safety06.htm#Avandia

Rosiglitazone was approved by the FDA in May 1999 to be used in addition

to diet and exercise to improve blood sugar control in patients with

type-2 diabetes mellitus, or non-insulin-dependent diabetes. Patients

who require insulin injections are termed type-1 diabetes. Rosiglitazone

belongs to the family of diabetes drugs known as thiazolidinediones, or

glitazones. Pioglitazone (ACTOS) is the only other glitazone currently

available on the U.S. market. Troglitazone (REZULIN), the original

member of the this family, was withdrawn from the market in March 2000

because of liver toxicity (see Worst Pills, Best Pills News April 2000).

We have previously urged against use of rosiglitazone or pioglitazone

(see the 2005 edition of Worst Pills, Best Pills, or our web site,

www.worstpills.org), especially in patients with heart failure (see

Worst Pills, Best Pills News, September 2003).

The drug-induced vision abnormality that concerns U.S. and Canadian

regulators is known as macular edema. The macula of the eye is the

central portion of the retina, a small area rich in structures called

cones. Cones are specialized nerve endings that detect color and upon

which daytime vision depends. Edema refers to fluid retention and

swelling. The swelling of the retina that can result from rosiglitazone

appears to be due to fluid leaking from blood vessels within the macula.

As macular edema progresses, blurring occurs in the middle or just to

the side of the central visual field. Visual loss from macular edema can

progress over a period of months and make it impossible to focus clearly.

Macular edema in common in diabetes. The lifetime risk for diabetics to

develop macular edema is about 10 percent . The condition is closely

associated with the degree of diabetic retinal disease (retinopathy).

High blood pressure and fluid retention also increase the pressure

within small blood vessels, called capillaries. The increased pressure

drives fluid from within the vessels into the retina. A common cause of

fluid retention in diabetes is kidney disease.

What You Can Do

If you experience visual deterioration while taking rosiglitazone or the

combination of rosiglitazone with metformin, report this potential

adverse drug reaction to your physician as soon as possible.

If you have developed visual problems such as macular edema that may be

related to your diabetes, you should not take rosiglitazone or

rosiglitazone with metformin. If you are currently taking either of

these drugs, ask your physician about other treatment options.

--

ne Holden, MS, RD < fivestar@... >

" Ask the Parkinson Dietitian " http://www.parkinson.org/

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