Eli Lilly has quickly responded to claims that it played down health risks linked to its multi-billion dollar schizophrenia drug Zyprexa.

A New York Times article, which refers to "hundreds of internal Lilly documents and e-mail messages among top company managers" given to the newspaper by James Gottstein, a lawyer representing mentally ill patients, claims that Lilly executives kept important information from doctors about links between Zyprexa (olanzapine) and obesity and its tendency to raise blood sugar, risk factors for diabetes.

The NYT piece also claims that Lilly's own published data, which it told sales representatives to play down in conversations with doctors, showed 30% of patients taking Zyprexa gain 22lbs or more after a year on the treatment, with some reporting gains of 100lbs or more. It then goes on to list several examples from the documents, which cover 1995 to 2004, indicating Lilly's concern that Zyprexa sales would suffer if it was more forthright about the drug's risks.

For example, in 2000, a group of diabetes doctors that Lilly had retained to consider potential links between Zyprexa and diabetes warned the company that "unless we come clean on this, it could get much more serious than we might anticipate," according to an e-mail message from one Lilly manager to another.

The article cites an e-mail sent in November 1999 by Alan Breir, now Lilly’s chief medical officer and then chief scientist on the Zyprexa programme, which states that "olanzapine-associated weight gain and possible hyperglycemia is a major threat to the long-term success of this critically important molecule."

Lilly came straight out saying that "contrary to incorrect statements in the Times article," it has conducted more than 23 years of research on Zyprexa and in the ten years the drug has been on the market, "Lilly, government bodies such as the National Institute of Mental Health and competitors…have not found that Zyprexa causes diabetes."

The firm also notes that "from the day that Zyprexa was approved," the labelling identified the "potentially clinically-significant weight gain that was observed in more than half of all patients treated long-term with Zyprexa, as well as the diabetes-related adverse events observed in clinical trials."

'Illegal and selective disclosure' slammed

It also states that "the Times failed to mention that these leaked documents are a tiny fraction of the more than 11 million pages of documents provided by Lilly as part of the litigation process. They do not accurately portray Lilly’s conduct." Finally, the firm spoke of its concern that "this illegal and selective disclosure of incomplete information will cause unwarranted concern among patients that may cause them to stop taking their medication without consulting a physician."

Last year, Lilly agreed to pay $750 million to settle suits by 8,000 people who claimed they developed diabetes or other medical problems after taking Zyprexa and thousands more suits are pending, claimed the newspaper. Zyprexa is suffering from generic competition but it is still making a major contribution to Lilly's coffers with third-quarter sales reaching $1.12 billion.