NEW YORK (AP) -- The fight for market share in the world's largest drug category is about to intensify as a new cholesterol-lowering medicine called Vytorin joins the pack that includes Lipitor, Zocor and Crestor.

The introduction of Vytorin -- expected to win Food and Drug Administration approval later this month -- is likely to ignite a pricing and advertising battle.

Vytorin, a combination of two other cholesterol drugs, Zocor and Zetia, has been shown in studies to lower cholesterol better than market leader Lipitor. Zocor is from the class of drugs known as statins, and lowers cholesterol by cutting its production in the liver. Zetia, meanwhile, limits the absorption of cholesterol in the intestines.

The new drug, manufactured and marketed by a joint venture between Merck & Co. Inc. and Schering-Plough Corp., is expected to provide tough competition for Pfizer Inc.'s Lipitor, which dominates the market with a 55 percent share of prescriptions and 49 percent of sales.

It's also likely to have a big impact on Crestor, a statin introduced last September that has fought Lipitor with studies demonstrating Crestor's superior cholesterol-lowering ability. There have been concerns about the drug's safety, however.

"Vytorin is in an enviable position. It has best-in-class efficacy without the safety hangups," said Tim Anderson, an analyst at Prudential Securities. He predicts Vytorin sales will hit $3.4 billion by 2008.

Vytorin, made by Merck/Schering-Plough Pharmaceuticals, is launching at a time when growth has slowed in the cholesterol-lowering market. Last year, combined sales of cholesterol-lowering medicines rose 11 percent to $13.85 billion, according to research firm IMS Health. That followed an increase of 14 percent in 2002, 21 percent in 2001 and 26 percent in 2000.

Analysts believe the recent stagnation may be a result of patients having to pay higher insurance copayments for their drugs.

But there are signs the market is gathering some momentum, with sales up 13 percent in the first five months of this year. Analysts suggest heavy advertising by AstraZeneca PLC to promote Crestor helped boost revenues.

Vytorin's expected approval coincides with the release last week of new guidelines that call for people who have had heart attacks or who are at high risk for heart disease to lower their LDL, or bad cholesterol, to 70 instead of 100 as previously recommended. The guidelines were released by the National Cholesterol Education Program, an initiative of the National Heart, Lung and Blood Institute, one of the National Institutes of Health.

Analysts expect the guidelines to help increase the market for cholesterol drugs.

There certainly is room for growth -- while an estimated 37 million Americans could benefit from the drugs, only around 14 million take them.

But individual drugs have had their own problems. Some doctors and analysts suggest that sales of Zetia, made by Merck/Schering-Plough, were curtailed because it is prescribed along with a statin to further lower cholesterol, and many patients didn't want to pay for two drugs. Zetia sales reached $469 million last year.

"Cholesterol drugs aren't like insulin," said Richard Evans, an analyst at Sanford C. Bernstein. "It's not like if you don't' take them you are immediately going to die."

That's why doctors and analysts agree that pricing will be a major factor in Vytorin's success as insurers grow ever more vigilant about restraining drug prices. Lipitor is $2.58 or $3.75 a pill, depending on the dose. Crestor is $2.23 a pill for all doses.

Adam Schechter, vice president and general manager of the joint venture, wouldn't comment on Vytorin's price, but analysts expect it to be less expensive than Lipitor. However, they say it will likely cost more than Crestor because Vytorin doesn't have similar safety concerns.

Still, the pricing war may not begin until 2006 when Merck's Zocor loses patent protection, opening the way for cheaper generics.

While Merck/Schering-Plough Pharmaceuticals prepares to launch Vytorin, the other drug makers are trying to keep their own cholesterol medicines competitive. AstraZeneca, for example, is fighting claims that Crestor is unsafe.

Crestor's launch was delayed by a year because the FDA demanded additional studies because of safety concerns. In March, Dr. Sidney Wolf, director of Public Citizen Health Group petitioned the FDA to ban Crestor because it had been linked to kidney failure and damage and rhabdomyolsis, a rare potentially fatal, muscle-destroying condition.

Wolf had a letter published in the prestigious British medical journal, The Lancet, outlining the dangers of Crestor. And European regulators recently changed Crestor's label to stress that patients on the highest dose of the drug be monitored carefully. Concerns about rhabdomyolsis rise with higher doses of statins.

AstraZeneca spokeswoman Rachel Bloom-Baglin says Crestor is safe and that Wolf is distributing misleading information.

Still, Wolf's allegations are affecting Crestor. Dr. Christie Ballatyne, director of the Center for Cardiovascular Disease Prevention at Methodist DeBakey Heart Center & Baylor College of Medicine, said some of his patients have read stories about Wolf's claims and don't want the drug.

Ballatyne welcomes the addition of Vytorin because he says it gives him three power cholesterol-lowering drugs to treat patients. But he said in the end price is an important factor.

"Price is always an issue when it comes to managed care," Ballatyne said.

Pfizer, meanwhile, is looking to defend its market share. Dr. Gary Palmer, Pfizer's vice president of cardiovascular medicine, said Vytorin would have an impact on sales of rival drugs, but he said it would take more than just studies attesting to its cholesterol-lowering abilities to dent Lipitor's leadership position.

Palmer said Pfizer "has a tidal wave of data" showing Lipitor also cut heart attacks and strokes.

Copyright 2004 The Associated Press. All rights reserved.