Pfizer (NYSE: PFE) has recalled about 19,000 bottles of its Lipitor tablets after an “uncharacteristic odor” was reported in a bottle of the blockbuster cholesterol drug

This is the fourth such recall for Lipitor since August over similar “odor” problems -- the company has now recalled a total of 360,000 bottles.

Pfizer has said the bottles which contain the tablets were supplied by an outside manufacturer, and added that health consequences appear to be minimal.

The unpleasant odor has been attributed to 2,4,6-tribromoanisole, a chemical which is also used as a wood preservative.

Pfizer has a very rigorous quality and compliance program that includes a highly sensitive surveillance system, which has enabled Pfizer to quickly detect and respond to the odor-related issue, the company said. Our market actions reflect the rigor of our quality control system and a commitment to act rapidly and in the best interest of our customers.

Lipitor is the top-selling prescription drug in the U.S., racking up $7.5 billion in sales last year.