Kos Pharmaceuticals Inc.'s Niaspan is the only U.S.-marketed drug to prevent heart disease by boosting "good" cholesterol. Soon there may be a lot of company.

Niaspan is the first of what doctors, drugmakers and investors say may be the next multibillion-dollar generation of medicines for fighting heart disease. By raising blood levels of HDL, the so-called beneficial form of cholesterol, researchers say they can lower a patient's risk of developing clogged arteries, heart attacks and strokes.

Drugs such as Pfizer Inc.'s Lipitor that lower the "bad" kind of cholesterol already are transforming efforts to prevent heart attacks. These statin drugs, as they are known, generate $20 billion annually. U.S. research cardiologists, who say patients at high risk of heart disease need even more help, now are turning to Niaspan and a half-dozen HDL medicines being tested.

"If the '90s were the decade of the statins, this is the decade of the HDL" raising drugs, said Allen Taylor, director of cardiovascular research at Walter Reed Army Medical Center in Washington.

Sales of Niaspan jumped 37 percent in the first nine months of this year to $311 million. The company's stock doubled in the past 12 months.

Prescriptions for Niaspan may increase as drugmakers present new patient studies testing whether boosting HDL, short for high-density lipoprotein, lowers heart-disease risk. Next year, Pfizer will finish a large study of its experimental HDL-raising drug, torcetrapib.

"Right now Kos is the only player in town," said RBC Capital Markets analyst Ken Trbovich in Denver, who has an "outperform" rating on Kos and doesn't own any shares. With Pfizer publishing new HDL research, "it's simply affirming what Kos has been telling doctors," Trbovich said.

Kos started selling Niaspan in the U.S. five years ago with a 90-person sales force, said Chief Executive Officer Adrian Adams. Through a marketing partnership with Takeda Pharmaceutical Co., Japan's largest drugmaker, almost 2,000 sales representatives now are pitching the importance of HDL boosting to doctors.

Kos, founded in 1988, created Niaspan by reformulating niacin, a type of vitamin B. Niacin assists in the functioning of the digestive system and had been known for years to lower bad cholesterol, increase HDL and reduce triglycerides, another damaging fatty protein in the blood.

The reformulated version doesn't have side effects, such as liver damage, associated with the high doses of niacin needed to affect blood fat levels.

It wasn't until 1998 that heart researchers got the first proof that raising HDL levels can save lives. A study found that Warner-Lambert Co.'s drug Lopid, which works in part by increasing HDL, cut the risk of heart attacks and dying from cardiovascular disease by 22 percent.

That study, later confirmed by more research, found that to prevent heart disease, the amount of HDL in a person's blood should register at 60 or higher. Readings below 45 for men and 55 for women increase disease risk, doctors say.

Lopid, acquired by Pfizer when it purchased Warner-Lambert in 2000, is little prescribed because of side effects including potentially fatal muscle damage that can occur when used with other drugs, including statins. The drug is still available and generic versions are sold under the chemical name gemfibrozil.

Researchers speculate that HDL plays a key role in picking up the dangerous, fatty lipids from the arteries and ferrying them to the liver for disposal.

The premise still isn't fully proven. Unlike bad cholesterol, which comes in one form, there are a variety of types of HDL cholesterol and increasing the levels of only some varieties may help counter disease, said Christopher Cannon, a cardiologist at Brigham and Women's Hospital in Boston.

"To be honest, the first step we are looking for is proof of principle that raising HDL by any means is good," he said. "There are different ways of raising HDL and different types. That gives another layer of complexity to the HDL story."