When a congressional committee holds a hearing next Wednesday, the subject will be the safety of the diabetes drug Avandia and whether federal drug regulators have paid close enough attention to its potential risks.
But for one witness who has been summoned to appear, Dr. John B. Buse, a nationally noted diabetes specialist, the subject could take a slightly different turn: whether he was the target of an effort by the drug's maker, GlaxoSmithKline, to silence his longstanding criticism of Avandia.
The drug, used for Type 2 diabetes, is one of the company's best-selling products, generating more than $3 billion in sales last year.
Congressional investigators are looking into what they called "very serious" claims that Avandia's maker "silenced one or more medical professionals who attempted to speak out about the potential for cardiovascular problems with Avandia," according to a letter last week from the Senate Finance Committee to Glaxo.
Glaxo denied that it sought to stifle scientific discussion of its drug. Karen Lightfoot, a spokeswoman for the panel that will conduct the hearing, the House Oversight and Government Reform Committee, declined to discuss Buse's coming testimony.
Buse also declined to discuss his testimony. But a friend, a University of Michigan diabetes expert, Dr. Charles F. Burant, said that Buse had been troubled by pressure he had received from Glaxo several years ago relating to his criticism .