Indian pharmaceutical major, Ranbaxy Laboratories, which is a unit of Japan's Daiichi Sankyo, has said that it has resumed the production of the drug substance for its Atorvastatin cholesterol lowering drug in United States.

The Atorvastatin drug, which is the generic version of Pfizer's Lipitor, controls a dominant market share in the market and earns high margins for the company. The company had recalled batches of Atorvastatin in November 2012 saying that it could contain small glass particles measuring less than 1mm in size. Ranbaxy had said that the recall in the US was voluntary and included 10mg, 20mg and 40mg dosage strengths, packaged in 90s and 500 count bottles and it did not affect tablets in 80mg strength in the company.

"We are working with the US Food and Drugs Administration and have identified and implemented multiple corrective and preventive actions. As a part of the first step in initiating the manufacturing process to resume supplies to the US market, we have commenced the production of the drug substance for our Atorvastatin product," Ranbaxy said in filing with the stock exchanges.

The US FDA had earlier banned the shipments from some of Ranbaxy's manufacturing plants due to issues relating to US laws. The company agreed to make necessary changes to its plants and also appointed an independent regulator earlier this year and secured an approval from the US authorities to supply dugs in the US.

The shares of the company increased 3.8 per cent and were trading at Rs 429.40 on the National Stock Exchange.