Ranbaxy Laboratories, the Indian unit of Japan's Daiichi Sankyo, yesterday recalled some batches of its generic version of cholesterol-lowering drug Lipitor from the US market after finding small glass particles in some lots of Atorvastatin, the generic name for Pfizer's blockbuster drug Lipitor.

Ranbaxy's US subsidiary, Ranbaxy Pharmaceuticals Inc, is recalling certain select lot numbers of Atorvastatin calcium tablets of 10mg, 20mg, and 40mg dosage strengths, packaged in 90's and 500 count bottles. The recall does not affect the 80mg strength dosage.

Ranbaxy, the Indian unit of Japan's Daiichi Sankyo said that the voluntary recall would cause a temporary supply disruption, but it expects to resume shipments after conducting an internal probe within two weeks.

The company did not reveal how it discovered the problem nor did it report any injuries or deaths tied to the recalled product.

Ranbaxy was the first to market the generic version of Lipitor late last year after Pfizer lost Lipitor's US patent protection on 30 November 2011, and Ranbaxy was given rights to 180 days of marketing exclusivity by the US Food and Drug Administration (FDA) for being the first to file for a generic equivalent.

Ranbaxy and US-based Watson Pharmaceuticals, which had been authorised by Pfizer to sell a generic version of Lipitor, were the two companies that had exclusive rights to sell the generic version of Lipitor for six months in the US.

Watson did not require FDA approval since it has tied up with Pfizer for selling the drug under a royalty-payment scheme.

The recall will benefit five other manufacturers in the US including Watson and Pfizer since Ranbaxy holds around 44 per cent Atorvastatin market share in the US.

Ranbaxy has recently been targeted by the FDA over its manufacturing practices and quality controls at several plants in India and the US.

It has also been hauled up by the FDA for falsifying data and test results in approved and pending drug applications, which could lead to defective products.

In January, the US Department of Justice obtained a decree from a federal judge banning Ranbaxy from producing some generic drugs, but not the generic version of Lipitor in the US market until it corrects the problems at its plants.