Federal regulators have extended its approval to AstraZeneca permitting it to market its cholesterol pill Crestor as a precautionary measure against heart attack and stroke in patients with healthy cholesterol levels.

The approval was granted on the basis of data obtained for a nearly 18,000-patient study funded by AstraZeneca and called Jupiter.

The Food and Drug Administration cleared Crestor for a millions of US patients who traditionally have not been candidates for cholesterol-lowering drugs.

Crestor was able to fetch FDA approval for lowering the risk of heart attacks, strokes, bypass operations and artery-clearing procedures in people with high levels of C-reactive protein (CRP) plus at least one other risk factor.

The study involved testing Crestor in contrast with a placebo in middle-aged people with healthy cholesterol, but high CRP. It suggested the major cardiovascular problems’ rate to be 1.6 percent for patients treated with Crestor compared with 2.8 percent with a placebo, the FDA revealed.

On Monday, the FDA said doctors "must interpret the results of the Jupiter trial with caution". The findings "do not support the use of Crestor in all patients with elevated (CRP)", the agency said.

The approval is speculated to boost sales of the drug; however industry analysts cite the size of the opportunity is unpredictable because of the looming arrival of cheaper generic versions of Pfizer Inc's rival Lipitor in late 2011.