As the pharma world continues to digest data from the JUPITER study on AstraZeneca’s Crestor, the firm’s chief executive is taking a cautious line on what effect it will have on sales of the cholesterol blockbuster.

In a teleconference with reporters, David Brennan said it is too early to predict how the data from the landmark study, which demonstrated a dramatic risk reduction of cardiovascular death in people with low to normal cholesterol levels, will affect sales of Crestor (rosuvastatin). He noted that there has been “a flurry of estimates” from analysts about the commercial impact of JUPITER, “some of them pretty bullish” but “I would urge caution when forecasting the speed of such changes".

The initial response to the study has been that it will transform the way statins are prescribed, ie to people with normal levels of cholesterol. Mr Brennan did add that it is "reasonable to think" the data will be considered when the American College of Cardiology and other such bodies update their treatment guidelines for heart disease next year.

However he stressed that AstraZeneca will not promote Crestor for use as a preventative in healthy patients who are at risk of heart problems until it obtains approval. The company will submit the findings of JUPITER to regulators on both sides of the Atlantic in the first half of 2009.

Mr Brennan also noted that the benefits of Crestor shown in the study, which for example demonstrated that the combined risk of heart attack, stroke or CV death was reduced by 47%, does not necessarily extend to similar cholesterol drugs. "We know all statins are not created equal," he added.

Dresdner Kleinwort analyst Tim Franklin issued a research note saying that while some doctors may opt to prescribe generic statins as a preventative, many will now choose to use Crestor on the basis of JUPITER. He added that “the surprising level of risk reduction observed with Crestor compared to previous statin studies also tells us that it is not always possible to extrapolate from one product to another or from one set of data to another quite so easily".

Although Mr Brennan is being cautious about sales forecasts for Crestor, which had third-quarter revenues of $922 million (up 28%), analysts seem convinced about the positive effect of the study. Morgan Stanley says they could reach as much as $8 billion in 2014, while UBS is predicting sales of at least $7 billion in 2012.