TRENTON, N.J. — India’s largest maker of generic drugs won approval late Wednesday to sell a generic version of cholesterol blockbuster Lipitor. The world’s top-selling drug ever lost U.S. patent protection earlier in the day.

The U.S. Food and Drug Administration said it granted Ranbaxy Laboratories approval to sell a generic version of Pfizer ’s Lipitor, called atorvastatin calcium. The last-minute decision ended widespread speculation over the outcome of a delay caused by long-standing manufacturing issues at some Ranbaxy factories.

Ranbaxy confirmed the approval in a statement issued late Wednesday night, noting Lipitor generated $7.9 billion in U.S. sales in the 12 months through September. Ranbaxy spokesman Chuck Caprariello said shipments would begin immediately.

Analysts, pharmacists and others had been watching closely to see whether Ranbaxy would be able to get its generic on the market by the time the patent expired for Lipitor.

That’s because quality problems at some Ranbaxy factories, dating to 2006, had led the FDA to block shipments of many of its generic drugs to this country and to hold up approval of any new Ranbaxy drugs.

According to FDA spokeswoman Sandy Walsh, Ranbaxy will be manufacturing the pills under a partnership with Ohm Laboratories in Ohm’s New Brunswick, N.J., facility.