New Canadian study casts doubts on safety of Avandia

GlaxoSmithKline’s Avandia is once again surrounded by controversy. A new study on Tuesday revealed some fresh results that cast doubt on the safety of the controversial Avandia (rosiglitazone) medication which is intended to keep diabetic patients’ sugar levels at bay.

It has been already established in an earlier study that the widely-used diabetes medicine Avandia can cause heart attacks and death. Now, the new study has also found evidence that diabetic patients consuming this widely used drug are at elevated risks of developing heart attack and death.

However, GlaxoSmithKline, better known as GSK and Glaxo, does not agree with the recent findings.

In May this year, a study conducted by researchers at the Cleveland Clinic suggested that diabetic patients taking Avandia may now have to shift to some substitute drug as the diabetes drug intended to keep sugar levels at bay may in fact doubles the cardiovascular diseases in takers. That study was published in the New England Journal of Medicine.

The recent study by Canadian scientists drew the similar links between GSK’s diabetes drug Avandia and heart risks. Results of new clinical trials again suggest that several diabetes drugs, especially GlaxoSmithKline's Avandia can cause heart attacks, congestive heart failure and death.

The new study, published on Tuesday in The Journal of the American Medical Association, concludes that older people treated with Glaxo’s Avandia and Takeda Pharmaceutical’s Actos may be at increased risk of heart attacks and death.

Rosiglitazone maleate, marketed by London-based Glaxo as Avandia, is a drug that reduces glucose (sugar) level in the blood by increasing the level of insulin. It belongs to the antibiotic drug class called "thiazolidinediones” and is used to treat type II diabetes, which harms the body's ability to control blood sugar and can lead to heart disease, lindness and early death. The type II diabetes is a serious and debilitating disease that becomes progressively more common with age and obesity.

Takeda’s Actos (pioglitazone) is another member from this class. The thiazolidinediones affects a gene called PPAR-gamma and helps the body to use insulin more effectively.

To reach their findings, Dr. Lorraine Lipscombe of the Institute for Clinical Evaluative Sciences in Toronto and colleagues analyzed drug use and health outcomes for 159,000 people age 65 and older treated for Type 2 diabetes in the government-run health system that provides medical care to all people in Ontario.

In their study, the researchers evaluated the risks of congestive heart failure, heart attack and all-cause death associated with the use of Avandia and Actos compared to other diabetes drugs.

After following the study subjects for nearly four years, Dr. Lipscombe and his fellow researchers found 60% increased risk of congestive heart failure, 40 % higher risk of heart attack and 29 % higher risk of overall death among the patients who were treated with Avandia alone. However, the researchers did not notice an elevated risk for any of these for Actos.

"These findings provide evidence from a real-world setting and support data from clinical trials that the harms of thiazolidinediones may outweigh their benefits, even in patients without obvious...cardiovascular disease," the researchers reported.

Avandia has been allowed by the Food and Drug Administration’s safety advisory panel to remain on the market, but does come with a stronger label warning. The US health agency FDA ruled last month that GSK’s blockbuster diabetes drug Avandia must now carry a "black box" label warning that says the drug could cause chest pain or heart attacks.

Avandia’s original black box warning advised the drug could cause or exacerbate congestive heart failure in some patients. Now, the existing black box warning on Avandia adds a new language advising caution in prescribing the drug to diabetics who already have heart disease or are at high risk of suffering a heart attack.