Dry spell is over: New research into coughs and treatments

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At Monell Chemical Senses Center, fellow Janina Steubert and psychologist Paul Wise study taste’s role in suppressing coughs.(David Swanson / Staff Photographer)

Like many children the world over, Ian Paul's 4-year-old daughter does not love the taste of her cough medicine.

But unlike many children's medicines, hers is kept in the pantry. It's honey, and it may actually work.

Paul, a physician researcher at Pennsylvania State University, conducted one of two studies that have found that a spoonful of honey - that old home remedy - can help get your hacking kid through the night.

Not everyone in the medical community is convinced about honey's cough-suppressing powers, plus it is not recommended for children younger than 12 months because of the slight chance of infant botulism. But the bigger story is that after decades of relative inactivity, scientists are vigorously studying the cough and new medicines to treat it.

It's a radical idea in a field that hasn't come up with a new active ingredient since the 1950s. Americans spend hundreds of millions of dollars a year on cough syrups for which there is little evidence of effectiveness, at least at doses deemed to be safe. Now, various trials are under way, along with a broad range of preliminary research, on how the nervous system is involved in triggering coughs.

For example, some scientists, including one at Philadelphia's Monell Chemical Senses Center, induce coughs by having people inhale a vapor that contains an extract from chili peppers.

Such research is long overdue, said Paul, who also conducted a 2010 study that found another old cough remedy, vapor rub, to be effective.

"There's not a new drug on the market in 50 years for the most common symptom that there is," Paul said.

The reasons for this pharmaceutical dry spell are many, but a big one is simply that the cough is hard to study, said Brendan Canning, associate professor of medicine at the Johns Hopkins Asthma and Allergy Center.

To start with, the most common type of cough - the one caused by the common cold - eventually goes away by itself.

So, in addition to the usual research practice of determining if a drug's impact is due to pharmacology or to the placebo effect, researchers must also tease out whether patients are simply getting better on their own.

"You have kind of a moving target," said Peter Dicpinigaitis, director of the Montefiore Cough Center and professor at Albert Einstein College of Medicine in New York.

To test a potential medicine, researchers must try to study a sample of patients at roughly the same stage of illness. And with something so hard to measure, they need large numbers of patients to achieve useful statistical results - an expensive proposition, especially when the existing medicines already sell well, Dicpinigaitis said.

"There's no financial motivation" to find a more effective treatment, the cough specialist said.

Then there's the issue of how to measure a symptom that, to some extent, a person can control. Witness the sudden explosion of hacking in the audience after an orchestra stops playing, said Canning, the Hopkins researcher.

One way is to videotape patients and count their coughs, but because they are aware of being recorded, they may alter their behavior in response, Canning said. Another is to ask parents to estimate a child's cough frequency in a daily diary.

Only recently have researchers started to develop more objective measures: mobile electronic cough-counting devices that patients can wear.

Finally, any solution must be a partial one. Complete suppression of the cough reflex would be dangerous, as it is essential for clearing debris that could lead to aspiration pneumonia.

In Paul's honey study, published in 2007 in the Archives of Pediatrics and Adolescent Medicine, he and Penn State colleagues analyzed the effect of three treatments on 105 children with a cold-induced cough. The study was funded by the National Honey Board, but the board had no input in it, and Paul was able to publish the results whether positive or negative.

At random, some of the children were given a dose of buckwheat honey before bed, while others got a syrup containing a common anti-cough ingredient called dextromethorphan - made with a honey flavor so the kids couldn't tell the difference between that and real honey. A third group got no treatment at all.

Parents filled out surveys the day before and the day after, describing symptoms.

The results: Honey was significantly better than no treatment at reducing the number of coughs, whereas dextromethorphan was not. When honey and dextromethorphan were compared head to head, there was no significant difference.

Paul suspects that if he'd done a larger study, honey would have the edge. And in 2010, an Iranian study also suggested honey was effective.

Some area pediatricians are unconvinced, but are willing to present honey as an option to patients.

"There's no harm in trying it," said Paul Matz, a physician in the Mullica Hill office of Advocare Haddon Pediatric Group.

Some cough-suppressing drugs and cold remedies, on the other hand, can have dangerous side effects at high doses. In 2007, the Philadelphia Medical Examiner's Office reported that during a six-year period, at least eight infants and toddlers died partly because of an overdose of pseudoephedrine, a decongestant.

While honey may be safer, what makes it work?

One possibility is that honey is rich in antioxidants, Paul said. Another is that by coating the throat, it prevents the irritation of nerves that triggers cough, he said. Some scientists have hypothesized that its efficacy has something to do with the taste.

Scientists at Monell are among those testing the impact of the taste of various substances.

They induce coughs with the chili-pepper extract called capsaicin. Paul Wise, an experimental psychologist at Monell, demonstrated the process recently on postdoctoral fellow Janina Seubert. He directed her to place a plastic tube to her mouth and inhale the capsaicin mist.

Sure enough, she responded with a vigorous cough, cough. She stopped almost right away, but continued to feel the aftereffects.

"I still sort of have a tickle in my throat," Seubert said.

In his studies, Wise starts with a low concentration of capsaicin and increases it until the person coughs. Then he administers substances with various tastes to determine if they decrease a person's cough sensitivity - that is, if a greater concentration of capsaicin is needed to make them cough.

Some researchers question whether such methods are a perfect model for a cough due to illness, but the work has led to some provocative findings.

Using a similar method, British researchers reported they could inhibit coughs somewhat by administering a compound from a substance people find even tastier than honey: chocolate.

 


Researchers at the Monell Chemical Senses Center show how they trigger a cough by having someone inhale a vapor containing an extract from chili peppers. Go to

www.philly.com/cough


Contact staff writer Tom Avril

at 215-854-2430 or tavril@phillynews.com.