MONDAY, Dec. 11, 2006 (HealthDay News) -- Despite the death of Pfizer's new cholesterol drug, researchers say they are not abandoning their quest to find ways to prevent heart disease by raising levels of "good" cholesterol.
Reducing LDL, or "bad" cholesterol, has been the main focus of cardiology in recent years, but boosting its counterpart, HDL, also has a salutary effect.
Indeed, Pfizer was intending to market the new drug with Lipitor, a cholesterol-lowering statin that happens to be the world's best-selling drug. But the development of the drug, torcetrapib, was hurriedly shut down on Dec. 2 because of an unexpected number of deaths and cardiovascular problems in patients participating in clinical trials. Pfizer, the world's largest drug maker, had already poured $800 million into the venture.
Increasing HDL lowers event rates, while lowering LDL cholesterol does the same, explained Dr. Robert Myerburg, a professor of medicine and physiology at the University of Miami's Miller School of Medicine. "That's pretty well-established. There's good supporting data, and the rationale is there."
"It's a valid strategy," added Dr. Daniel Fisher, a clinical assistant professor of medicine at New York University School of Medicine in New York City.
While HDL is not as important as LDL in controlling heart disease, it's still a player, experts say.
"There are six major factors that we've designated that are vastly important in the prevention and control of heart disease, and HDL has never made that cut," explained Dr. Gerald Fletcher, a spokesman for the American Heart Association and a professor of medicine at the Mayo Clinic College of Medicine, in Jacksonville, Fla. "HDL has never been established as that important compared to LDL, but it's certainly important."
Other drugs that are similar to torcetrapib are currently in various stages of development, but it's not clear if the problems that cropped up with torcetrapib will reappear with those medications.
"We don't know the class effect or the potency of the drugs," Myerburg stated. "And we don't know how much added benefit they will provide to the person taking multiple drugs."
In the meantime, doctors and patients already have Niaspan, an extended-release version of niacin. Niaspan is less potent than torcetrapib.
"Niaspan also raises HDL but to a lesser extent," Fisher said. "It's not even in the same ballpark."
And because Niaspan also lowers LDL, it's hard to tease out what's causing the good. "Which is a major player in improving event rates?" Myerburg asked. "We don't know where the benefit is coming from."
And Niaspan, which works by a completely different mechanism than torcetrapib, causes uncomfortable skin flushing that can prompt some patients to discontinue taking their medication. A government-sponsored trial is currently looking at how Niaspan works in combination with statins.
Drugs called fibrates can also boost good cholesterol but, in combination with statins, can have undesirable muscle and liver effects, Fisher said.
Statins themselves raise HDL as well, but to a much lesser extent than either Niaspan or torcetrapib.
There are other things patients can do that don't involve taking another pill, experts added.
"A regular, dedicated exercise program will elevate HDL, but it has to be a long-term thing," Fletcher said.
Visit the American Heart Association for more on cholesterol.