Jul 20, 2007

More Trouble for Avandia; Alternative Drugs Reviewed

Tara Dairman

It hasn’t been a very good year for Type 2 diabetes drug rosiglitazone (brand name Avandia). First, in December and January, studies came out linking the drug to an increased risk of bone fractures in women (see "Diabetes Drug Linked to Fracture Risk”). Then, in May, the drug made headlines when an analysis of multiple studies found a link between rosiglitazone and increased risk of heart attack (see "Type 2 Drug Avandia Linked to Increased Risk of Heart Attacks”). Now two more studies have been published, one of which links the drug to a slew of adverse effects and the other of which ties it to an increased risk of cancer in women.

The first study, published on July 18 in The Cochrane Library (the journal of an international, not-for-profit organization that reviews medical research), examined 18 past trials of rosiglitazone that involved more than 8,000 participants. The analysis, performed by researchers in Germany, concluded that rosiglitazone was not any more effective at lowering HbA1c levels than other oral diabetes drugs and did not provide any additional benefits in areas such as length of life, quality of life, or drug cost. What's more, its documented side effects included double the risk of edema (swelling), weight gain of up to 11 pounds, increased risk of cardiovascular disease (heart disease and stroke), and bone fractures in women.

This analysis was conducted independently of the review of multiple studies published in May that linked rosiglitazone with increased heart attack risk.

Another study published recently in the journal BMC Medicine looked at the relationship between the use of thiazolidinediones, the class of diabetes drugs to which rosiglitazone belongs, and the occurrence of cancer. Researchers interviewed a selection of about 1,000 people with diabetes about their health, including any history of cancer. They found that people who took thiazolidinediones had a 59% increased risk of cancer, even after they controlled for factors such as age, body-mass index, smoking, HbA1c level, other diabetes drugs used, and total number of prescription drugs used. After further analysis, the researchers found that rosiglitazone was associated with an 89% increased risk of cancer, whereas the risk associated with the other drug in the thiazolidinedione class, pioglitazone (Actos), was not statistically significant. They also found that the association with cancer was statistically significant only in women.

Meanwhile, a third study, published online on July 16 in the journal Annals of Internal Medicine, examined more than 200 published trials of various oral diabetes drugs and found that several older diabetes drugs are just as safe and effective as newer, more expensive diabetes drugs. For instance, metformin (brand name Glucophage and others), which is available generically, effectively lowers HbA1c levels without causing weight gain or hypoglycemia, and it also helps lower LDL, or bad, cholesterol levels. Thiazolidinediones rosiglitazone and pioglitazone, on the other hand, trigger weight gain and raise LDL cholesterol levels. Consumer Reports, which published a consumer guide to the study results, also recommended the sulfonylurea drugs glipizide (Amaryl) and glimepiride (Glucotrol) as "Best Buys" for safety, effectiveness, and value. You can read a summary of the guide here.

It is important to keep in mind that all diabetes drugs have side effects. Any changes in your drug regimen should be decided upon by you and your health-care provider based on your individual needs and medical history. In the case of rosiglitazone, additional studies have shown conflicting data about some of the drug's proposed side effects, and absolute risks associated with the drug are small. (For instance, in the review published in May, out of a group of nearly 28,000 study subjects there were 14 more heart attacks in people taking rosiglitazone than in those taking another drug or a placebo.) The FDA's advisers have scheduled a meeting on July 30 to discuss rosiglitazone's safety, and DiabetesSelfManagement.com will keep you posted with breaking news as this situation continues to evolve.

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