WASHINGTON (AP) -- Shares of Cubist Pharmaceuticals fell Wednesday after regulators said an industrial chemical had been found in the company's antibiotic when used with a certain drug pump.
The Food and Drug Administration said significant levels of a chemical used to make rubber were found in the Cubicin that had been stored in Readymed drug pumps, manufactured by Cardinal Health. Cubicin, which is used to treat skin and blood infections, is the company's best-selling product with sales of $189.5 million in 2006.
Shares of Cubist Pharmaceuticals Inc. fell 58 cents, or 2.9 percent, to $19.53.
Lexington, Massachusetts-based Cubist notified doctors of the contaminant in an April 4 letter which FDA posted to its Web site Wednesday.
In the letter, the company recommended ''against using Readymed elastomeric infusion pumps with Cubicin until this issue has been addressed.''
Exposure to the rubber-making chemical has been shown to cause tumor growth in rats, according to the letter. Cubicin also said the contamination was present only in tests using Cardinal's pumps, not in those with rival I-Flow Corp.'s Eclipse pump.
''The clinical significance of this finding is unknown,'' the company states.
Shares of Cardinal Health Inc. fell 61 cents, or 1.1 percent, to $53.26.