Shares of Pfizer rose 7.7% after a U.S. court ruling blocked generic competition until 2011 for the cholesterol drug Lipitor, the world’s best-selling prescription medicine.

U.S. District Judge Joseph J. Farnan Jr. said on Friday that a version of the drug by India’s Ranbaxy Laboratories would infringe Pfizer’s patents, and he also upheld the validity of the two patents. Judge Farnan issued his ruling after the close of regular trading in America, following a non-jury trial in Wilmington, Del., that ended in December 2004.

The win, the second patent victory this year for a major pharmaceutical company, lifted shares of other American and European drugmakers as investors grow more confident that the companies can defend their products against generic rivals. Lipitor generated almost $11 billion in worldwide sales last year for Pfizer, the world’s biggest drugmaker, or about 20% of its total revenue.

“It’s good for the industry that we see the courts willing to respect patent rights. I hope this becomes a wake-up call for Congress and the administration, recognizing that this is a threat to American investors and American jobs,” the chief executive, Hank McKinnell, said in an interview yesterday. “This was a huge win for Pfizer.”

The ruling will encourage the company to continue investing in potential added uses of the medicine, Pfizer said.

“The legal victory represents a significant reduction in the risk profile of the company,” a Friedman Billings Ramsey analyst, David Moskowitz, wrote in a note to clients yesterday. “The company’s fending off of this major threat is likely to lift sentiment for the entire large-cap pharmaceutical group through the remainder of 2005.”

Eli Lilly & Co. in April won a court ruling that bars generic competition to its best-selling Zyprexa schizophrenia treatment until 2011.

Shares of Pfizer rose $1.74 to $24.32 as of 4:01 p.m. in New York Stock Exchange composite trading, after rising as much as 12% earlier, the biggest gain in at least 25 years.

They had dropped 16% this year through Friday. The company’s shares rose 10.3% on October 21, 1987.

Shares of drugmakers Merck & Co., Lilly, and Bristol-Myers Squibb Co. also soared. Merck increased $2.24, or 7.5%, to $32.25, Bristol-Myers rose 47 cents, or 2.1%, to $22.49 and Lilly increased 93 cents, or 1.6%, to $57.59. Bristol-Myers is facing a patent challenge to its Plavix blood-thinner medicine.

Shares of AstraZeneca, which is facing patent challenges to its Nexium ulcer drug and Seroquel for schizophrenia, gained as much as 4.3%. Shares of Paris-based Sanofi-Aventis, which is facing patent lawsuits over its two best-selling medicines, increased as much as 4%.