Ranbaxy's U.S. subsidiary, Ranbaxy Pharmaceuticals Inc, said the recall affects certain lots of 10-, 20- and 40-milligram doses of the drug, known generically as atorvastatin calcium. The 80-milligram dosage is not affected.
The company is conducting an investigation which it expects will take two weeks. It did not report any injuries connected to the tainted pills and did not say how the problem was discovered.
The recall could cause shortages of the drug in the United States, analysts said. Ranbaxy, the first company to introduce generic Lipitor after Pfizer's patent expired in November 2011, controls about 60 per cent of the market, according Ross Muken, an analyst at ISI Group LLC.
"Given its dominant share of this high-volume drug, we are certain to see supply shortages over the next two weeks," Muken said. The near-term impact is likely to be felt most by retail pharmacies and more modestly by wholesalers, he added.
The recall is the latest in a series of manufacturing problems at Ranbaxy, which is operating under heightened scrutiny following a long-running dispute with the U.S. Food and Drug Administration (FDA).
In 2008 the FDA banned the company from importing about 30 drugs after it found manufacturing deficiencies at two of the company's facilities in India. In 2009 the U.S. government accused Ranbaxy of falsifying data used in drug applications.
Last December, Ranbaxy agreed to make changes to its manufacturing plants in the United States and India. And it said it would set aside $500 million to resolve any potential civil or criminal charges stemming from an investigation by the U.S. Department of Justice.
Under a proposed settlement earlier this year, Ranbaxy agreed to engage a third party to conduct a review of its facilities, implement procedures to ensure data integrity in its marketing applications, and ensure it meets good manufacturing practices.
During its first six months on the market, when it enjoyed marketing exclusivity, atorvastatin generated sales of nearly $600 million for Ranbaxy, according to Bhagwan Singh Chaudhary, a research associate at the brokerage IndiaNivesh.
"The (recall) will impact the company's credibility," said Chaudhary. "A recall suggests corrective measures suggested by the U.S. FDA are not being implemented."
Other drugmakers, including Indian rival Dr. Reddy's Laboratories Ltd, have launched their own versions of Lipitor, and the market has become more competitive.
In 2008, Japan's Daiichi Sankyo Co acquired a majority stake in Ranbaxy in a deal valued at $4.2 billion.
Shares of Ranbaxy, which is valued at $3.93 billion, fell 3.3 per cent to 496 rupees in Mumbai.
© Thomson Reuters 2012