May 21, 2007
Analysis: GlaxoSmithKline's Avandia raises cardiovascular risks, shares fall
by Daniel Beaulieu
Results from a meta-analysis published in the NEJM suggest that GlaxoSmithKline's diabetes drug Avandia (rosiglitazone) increases the risk of heart attack by 43 percent and the risk of cardiovascular death by 64 percent compared with placebo or other treatment regimens. The drugmaker, which said it "strongly disagrees" with the findings, saw its shares fall as much as 8 percent on the news.
As part of the analysis, researchers examined 42 studies of Avandia involving 15 560 patients who received the drug and 12 283 patients who were treated with regimens that did not include GlaxoSmithKline's compound. There were a total of 158 heart attacks and 61 deaths from cardiovascular causes in patients involved in the studies. The study authors suggested that the cardiovascular deaths could have resulted from chance.
"The results of this analysis raise serious concerns about the cardiovascular safety" of Avandia, remarked Steven Nissen, lead author and chairman of cardiology at the Cleveland Clinic. "Unfortunately, [Avandia] appears to increase, rather than decrease, the most serious complication of diabetes, heart disease." Nonetheless, Nissen cautioned that the study was limited because it did not include access to original data.
In response, GlaxoSmithKline stated that it "strongly disagrees with the conclusions reached in the NEJM article, which are based on incomplete evidence and a methodology that the author admits has significant limitations." Lawson McCartney, head of the drugmaker's diabetes drug development, stated that the company is not seeing anything like the cardiovascular issues reported in the NEJM article. The drugmaker added that "the totality of data show that Avandia has a comparable cardiovascular profile to other oral antidiabetic medicines" and noted that the company believes the drug's benefits outweigh its risks when used appropriately.
The FDA, which issued a safety alert for Avandia on Monday, noted that while it is aware of "a potential safety issue" associated with the compound, the agency indicated that it has no immediate plans to take action because of "contradictory evidence" about the drug's safety. In the statement the FDA said its analyses of all available data are "ongoing" and it has not yet confirmed the "clinical significance of the reported increased risk in the context of other studies." Robert Meyer, a supervisory medical officer at the FDA's drug evaluation office, stated that "we don't have a clear regulatory or clinical advice message as of today."
In an editorial accompanying the study, Bruce Psaty and Curt Furberg questioned the rationale of prescribing Avandia, in light of the findings. The authors noted that when the product was approved, "evidence was at best mixed" on its benefit, adding that if the data represent "a valid estimate of the risk of cardiovascular events, [then Avandia] represents a major failure of the drug-use and drug-approval process in the US." The compound had sales of $3 billion in 2006.
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