Science News - April 21, 2012

Throat therapy

Scientists seek a
cough remedy that
really delivers relief

By Laura Beil Each year more than 26 million people in the United States go to a doctor complaining about a cough. Most have colds and will just have to wait it out. Other people cough because they have allergies, asthma, bronchitis, pneumonia or even cancer. In rare instances, there is no known culprit — a person simply starts coughing and can’t stop.

a viral infection such as the common
cold (green) can lead to irritated and
inflamed airways—and a nasty cough.

the last few years have yielded significant insights into cough science, encouraging more researchers and pharmaceutical companies to have a look. (Given how much money is spent on cough suppressants, pharmaceutical companies recognize that a better, safer syrup would be a blockbuster.)

Studies so far have found molecular on-and-off cough switches on the surface of the respiratory tract, although none have yet led to new cough medicines. New findings also show that coughing is a complicated event that shares some of the same neural circuitry with other basic body functions, like pain and temperature sensitivity. And brain scans are revealing a neural network for coughing that goes beyond a mindless impulse.

“It’s been a remarkable decade,” says Brendan Canning, a pulmonologist at the Johns Hopkins Asthma and Allergy Center in Baltimore. In 2005, a new scientific journal, called Cough, was launched in response to a sudden burst of interest in the field.

Current cough syrups also have the potential to be addictive, which makes policy makers and doctors hesitant to rely on them. Prescription drug abuse with opiates has become a national epidemic in the United States, and some lawmakers have moved to ban the sale of over-the-counter cough syrups to minors to prevent teens from getting high on dextromethorphan.

A new approach to cough treatment could more directly act in the airways or could still target the brain, but without such widespread side effects. But here’s the tricky part: Coughing is the body’s mechanism for defending its lungs, so a medicine can’t work too well for the body’s own good.

“There’s a devastating need for new drugs,” Dicpinigaitis says.

People plagued with constant coughing get so desperate for relief, he says, that he occasionally walks into his New York office and sees suitcases in the waiting room from out-of-state patients who have Googled him and come for a visit. “Most cough is acute cough associated with the common cold,” he says. “But in a subgroup of those folks, the cold comes and goes, but the cough comes and stays.” Some of his patients have spent more than a decade watching their sleep and social lives dwindle from too much coughing.

A new cough remedy might be easier to find if coughing were an easier thing to study. Rats and mice, the standard models in medical research, don’t cough the way people do. Even animals that do readily cough go quiet when placed under anesthesia, just like people. When an awake volunteer in an MRI scanner coughs, it’s challenging to keep the person still enough to get a good image of the brain.