BMJ: More Bad News for Avandia and its Link with Cardiac Events

March 21, 2011

A new study has found Avandia to be associated with significantly higher odds of congestive heart failure, heart attack, and death compared with Actos.

The diabetes drug Avandia (rosiglitazone, GlaxoSmithKline) has already been suspended in Europe and is available in the US and Canada on a restricted basis. A new study has found the drug to be associated with significantly higher odds of congestive heart failure, heart attack, and death compared with Actos (pioglitazone, Takeda Pharmaceuticals).

The meta-analysis, published March 17 in the British Medical Journal, analyzed the results of 16 studies involving 810,000 patients (429,000 on Avandia and 381,000 on Actos). Most patients were more than 60 years old, according a news report on CardiovascularBusiness.com.

Yoon Kong Loke, MD, senior lecturer in clinical pharmacology at the University of East Anglia in Norwich, England, and colleagues noted that both drugs, which help to control blood sugar levels in patients with type 2 diabetes, are known to increase the risk of heart failure. However, they said, “It is unclear whether there are clinically important differences in their cardiac safety.”

Compared with Actos, Avandia was associated with a modest but statistically significant increased risk of heart attack (16%), congestive heart failure (23%), and mortality (14%).

In certain groups of patients with type 2 diabetes, this may lead to 170 excess heart attacks, 649 excess cases of heart failure and 431 excess deaths for every 100,000 patients who receive Avandia rather than Actos.

“The consistency in the magnitude of increased risk for the different cardiac outcomes, as well as mortality, indicates that this is unlikely to be a chance finding,” the researchers concluded.

They also noted the large number of patients as a strength of the study and the “absence of substantial statistical heterogeneity, which suggests that the risk is maintained across most populations and is unaffected by geographical variations.”

Loke and colleagues said their study has important implications, especially since there are about 3.8 million prescriptions for Avandia dispensed annually in the US.

The precise biological mechanisms responsible for the differences in cardiovascular risk and mortality between the two drugs are uncertain, according to the study.

However, it is known that Avandia causes greater elevations of triglycerides and LDL-C levels than Actos does. Actos also has shown some potential benefit in preventing progression of atherosclerosis, whereas Avandia has not. In addition, Avandia leads to more fluid retention, which may explain its greater risk of congestive heart failure.

In an accompanying BMJ editorial, Victor Montori, MD, and Nilay Shah, MD, from the Mayo Clinic in Rochester, Minn., argued that the Avandia story “says much about how health care has become less about promoting patients’ interests, alleviating illness, promoting function and independence, and curing disease, and much more about promoting other interests, including those of the drug industry.”

When the FDA restricted the drug rather than suspend its use, the agency’s explanation was that it “trusted clinicians and patients to balance the risks and benefits of this agent in the few patients for which the alternatives seemed less desirable or safe.” Montori and Shah said that research should be undertaken to “understand what occurs when drugs are left on the market with strong warnings.”