Asthma Drug Might Help Fight Heart Failure

Clenbuterol may strengthen patients in lieu of transplant, early research shows

Amanda Gardner

Amanda Gardner

Published on April 21, 2006

FRIDAY, April 21, 2006 (HealthDay News) -- Body builders sometimes turn, illicitly, to the asthma drug clenbuterol to help them bulk up, but now researchers say the drug might also help heart failure patients stay strong without the need for heart transplant.

The first U.S. study of the drug found it was safe in a small number of heart failure patients. The drug was also found to increase skeletal muscle mass and strength, although there was no significant change in heart function.

The trial, which is a precursor to bigger trials, is an example of how far doctors will go to find solutions to the growing problem of heart failure.

And like many other avenues of research, the promise is still a faint one.

"We've learned the hard way that any pharmacological intervention in this very fragile group of patients needs to be studied very cautiously and thoroughly," cautioned Dr. Ann Bolger, a spokeswoman for the American Heart Association and professor of medicine at the University of California, San Francisco. "Something that looks to be positive early on may not still be positive later on."

The end step for many heart failure patients is a heart transplant. But with a worldwide shortage of organ donors, many patients have to survive on heart pumps. Is there a way to avoid both heart pumps and transplants? Possibly, the experts say.

"The idea is to one day develop strategies to promote cardiac recovery while patients are supported with a heart pump. That would obviate the need for heart transplants," said Dr. Simon Maybaum, medical director of the Center for Advanced Cardiac Therapy and the Cardiac Transplant and Assist Device Program at Montefiore Medical Center and Albert Einstein College of Medicine in New York City. "This is a growing area of research, and both novel pharmacological agents and cellular therapy [stem cells] will be studied. This research is crucial since because of the critical lack of organs for patients with end-stage heart failure."

Maybaum was lead author of the study, which was presented recently at a meeting of the International Society of Heart and Lung Transplantation in Madrid, Spain.

"We're looking for ways to make the transition off the pump and potentially go forward from there," Bolger added. "We need more tools to save lives."

Studies done by one British center found that clenbuterol resulted in significant improvement in cardiac function in patients with heart pumps awaiting heart transplants. In fact, the pumps could be taken out in more than half of the patients, meaning they no longer were in need of transplant. Those studies used doses 20 times those typically used by asthma patients and athletes.

Clenbuterol is not approved in the United States and, in fact, has a checkered history: Some people fell ill after eating livestock that had been treated with the drug.

Maybaum, however, managed to obtain permission from the U.S. Food and Drug Administration to conduct a small pilot study using high-dose clenbuterol.

There were two parts to the study: The first tested high-dose clenbuterol in heart pump patients. The second focused on whether the drug in lower doses would improve muscle function and quality of life in heart failure patients without heart pumps (those with milder heart failure). Seven patients completed the study.

Clenbuterol did increase skeletal muscle mass and strength, and was safe at the doses given -- 10 to 15 times that usually taken by asthmatics and athletes. There was no significant change in heart function. However, Maybaum pointed out that the study was not designed to look at this.

Data from the second part of the study is still blinded to researchers, and therefore not yet available.

The next step will be to conduct a multi-center trial in the United States to try to replicate the British findings with heart pump patients.

However, some experts voiced major concerns.

"Patients in heart failure have a pretty broad spectrum of responses to all kinds of therapies, so we have to be very careful. In some situations, this type of drug can be very dangerous with respect to arrhythmias, blood pressure changes and even stroke," Bolger said. "Medications that seem to give the heart an extra boost sometimes make patients feel better, but increase early mortality."

On the other hand, Bolger added, muscle-building strategies including physical fitness, have already been shown to benefit heart failure patients.

Even the study authors were cautious about the odds of success.

"Whenever there are such novel results which have the potential to dramatically affect such a difficult disease process, we go into the research with a mixture of excitement and skepticism," Maybaum acknowledged. "We're optimistic that we will find solution, but we're not sure which one will bear out. We will definitely live in an era where we will be able to repair the heart as opposed to replace it."

More information

For more on heart failure, head to the American Heart Association.

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