Bristol-Myers Squibb Co. (BMY) and Sanofi-Aventis SA (SNY) recalled about 64 million tablets of hypertension drug Avalide because a manufacturing problem could affect the drug's efficacy.

It is the second significant recall of Avalide in recent months. In September, Bristol and Sanofi recalled about 60 million tablets.

The recall affects certain lots of Avalide sold in the U.S., Puerto Rico, Canada, Mexico and Argentina. Bristol said Avalide sales for the first nine months of 2010 in the affected markets were about $310 million.

Bristol said it issued the recall as a precautionary measure because it discovered that certain batches of the drug contained an active ingredient--known as irbesartan--that was less soluble than expected. Solubility refers to the drug's ability to dissolve in stomach acid.

"We can't exclude the possibility that it might affect efficacy," said Bristol spokeswoman Laura Hortas.

Bristol co-markets Avalide and another hypertension drug, Avapro, with Sanofi-Aventis under a longstanding partnership. Avapro contains irbesartan, while Avalide is a combination of irbesartan and hydrochlorothiazide. The drugs are designed to lower high blood pressure.

Until Bristol resumes supply of Avalide, patients can take Avapro and hydrochlorothiazide as separate drugs, Bristol said. The company will make vouchers available to help defray the cost of hydrochlorothiazide. A Bristol website says the vouchers should allow most patients to obtain both medications for $20 a month.

Bristol advised patients to contact their pharmacy or health-care provider regarding the recall.

The Avalide recall is the latest in a string of product recalls in the drug industry due to manufacturing-quality problems. Johnson & Johnson (JNJ) has issued a series of recalls of over-the-counter medicines including Tylenol, and Pfizer has recalled some lots of its Lipitor cholesterol medication.

For Bristol, the recalls raise more questions about its manufacturing processes. In August, the U.S. Food and Drug Administration sent Bristol a warning letter saying that an agency inspection of a Bristol manufacturing plant in Manati, Puerto Rico, found various violations of manufacturing standards, including inadequate safeguards against contamination.

The latest Avalide recall was reported Thursday by Reuters.

Bristol shares fell 16 cents to $25.74, while Sanofi's American depositary shares were off 34 cents at $34.09.

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