As expected, the label on GlaxoSmithKline’s Avandia will carry a black box warning that will carry additional information stating that the firm’s controversial type 2 diabetes drug may potentially increase the risk for heart attacks.

The US Food and Drug Administration says that GSK has agreed to add the new information which states that “a meta-analysis of 42 clinical studies…showed Avandia (rosiglitazone) to be associated with an increased risk of myocardial ischemic events such as angina or myocardial infarction." However the warning also notes that three other studies have "not confirmed or excluded this risk" and "in their entirety, the available data on the risk of myocardial ischemia are inconclusive”.

During the past year, the FDA said that it has “carefully weighed several complex sources of data, some which show conflicting results”, and has concluded that “there isn't enough evidence to indicate that the risks of heart attacks or death are different between Avandia and some other oral type 2 diabetes treatments”.

As a result, the agency has requested that GSK conduct a new long-term study in an effort to evaluate the potential cardiovascular risk of Avandia compared with an active control agent, most likely Takeda’s rival product Actos (pioglitazone). The study design will be prepared by next July and the study will be completed by 2014.

GSK says Avandia still 'valuable’
Avandia has had a torrid time ever since the aforementioned meta-analysis appeared in the New England Journal of Medicine raised concerns about cardiovascular risk and third-quarter sales of the drug sank 38% to £225 million. However the firm is keeping the faith as far as Avandia goes and its chief medical officer, Ronald Krall said that it “remains a valuable medicine for most patients with type 2 diabetes, and when used according to the labelling, has a well described and appropriate safety and effectiveness profile”.

Whether sales of Avandia will pick up again is a debatable point. Both GSK’s drug and Actos had their labels updated in August by the FDA which involved a boxed warning that it may "cause or worsen heart failure in certain patients". However this latest warning for Avandia refers to heart attacks, which may give Actos a further leg up in the battle for market share, though GSK can take some comfort from the fact that the FDA will ask makers of other diabetes drugs to note in their labels that they have not been proven to reduce cardiovascular risk.

All in all, this is pretty good news for GSK, according to analysts, but critics of the drug are not best pleased. Iowa Republican Senator Chuck Grassley said "The good news is, the FDA is taking action to better inform the public about a major safety issue with this popular diabetes drug. The bad news is, 2014 is a long time to wait for a more definitive review of the drug’s risks and benefits”.

He added that the case is a clear example of where “the views of the office that reviews drugs after they’re on the market must play second fiddle to the position of the FDA office that approved a drug for the market in the first place. The system is off balance, and that’s not good for public safety”. By Kevin Grogan