Pfizer, the world’s biggest drugs company, said quarterly net profit leapt 50 percent as it halved production costs, predicting a strong but challenging outlook.

Net profit soared to 3.34 billion dollars in the three months to September 26 from 2.24 billion dollars a year earlier, it said.

Net earnings per share rose 55.2 percent to 45 cents. Stripping out one-off items, “adjusted” earnings per share rose 15 percent to 55 cents, one cent better than industry analysts generally predicted.

Sales rose 3.9 percent to 12.83 billion dollars.

Revenue was boosted by blockbuster drugs such as the world’s best-selling medicine, anti-cholesterol drug Lipitor, and arthritis pain drugs Celebrex and Bextra. Viagra still commanded 70 percent of the market for its type of Erectile dysfunctionmedication.

Production costs were sliced 50 percent to 1.64 billion dollars.

“We continue to generate strong earnings growth in 2004 in spite of continuing pricing pressure; new branded competition; new generic competition from the loss of patent exclusivity; difficult political, legal, and regulatory environments; and the effects of less favorable than expected foreign-exchange rates,” chairman and chief executive Hank McKinnell said in a statement.

“These challenges are being addressed. And, while we expect these issues to temper revenue and income growth in 2005, Pfizer’s long-term prospects remain strong.”

Pfizer predicted 2004 adjusted earnings per share of 2.12 to 2.14 dollars a share and net earnings per share of 1.58 to 1.60 dollars.

The group said it to save about 3.5 billion dollars in costs this year because of a 2003 merger with Pharmacia.

It was too early to predict the 2005 results, Pfizer said.

The group warned, however, that it expected a “substantial impact” from the loss of exclusive rights over four major drugs, Diflucan, Neurontin, Accupril, and Zithromax, with 2004 sales of more than five billion dollars.

Pfizer had announced Monday it would sponsor a clinical study into how its Celebrex medication affects patients at high risk for heart disease.

On September 30, rival pharmaceutical Merck announced a global withdrawal of its blockbuster arthritis drug Vioxx after a study showed it increased the risk for strokes and heart attacks.

But Pfizer said a recent Federal Drugs Administration-sponsored analysis of 1.4 million patients, and in additional clinical studies where patients have been treated for up to four years, patients using Celebrex showed no increased risk of “cardiac events.”