Feb. 14, 2003 -- A drug used to treat asthma may also calm the wheezing and coughing associated with a lung condition common among babies known as respiratory syncytial virus (RSV). New research shows Singulair (montelukast) eased symptoms and helped infants recover from some of the lingering lung and other breathing problems that frequently follow RSV.
According to the American Academy of Pediatrics (AAP), RSV is the most common cause of lower respiratory tract infections in children and is the leading cause of hospitalization for babies under 1 year old. More than 125,000 infants with RSV are hospitalized each year and about 2% die.
Babies become infected with RSV by the time they reach age 2. In most healthy infants, the virus causes only cold-like symptoms such as cough, fever, and runny nose. But in certain, high-risk infants, such as those born prematurely or with lung disease, RSV can cause serious complications and require hospitalization.
Researchers say many infants who are hospitalized with RSV continue to suffer from wheeze and other asthma-like symptoms long after they are discharged.
"We don't know if these symptoms are actually due to the RSV, asthma, or something else in these children," researcher Hans Bisgaard, MD, professor of pediatrics at Copenhagen University Hospital tells WebMD.
Some studies have suggested that babies who suffer from post-RSV wheeze and cough are more likely to develop asthma later in childhood, but that link isn't clear.
But researchers do know that during serious RSV cases infants release substances known as leukotrienes in the lungs, which are thought to contribute to the dangerous inflammation that occurs.
"This drug [Singulair] blocks leukotrienes," says Bisgaard. "And since we know leukotrienes are one of the mediators of post-RSV wheeze, we decided to target them. Just like taking an antihistamine for hay fever blocks the mediator that causes those symptoms."
Researchers compared the effects of daily treatment with a 5 mg chewable tablet of Singulair with placebo in 116 infants who were hospitalized for RSV. The treatment began within seven days after the start of RSV symptoms and lasted for 28 days.
The results appear in the Feb. 1 issue of American Journal of Respiratory and Critical Care Medicine.
Babies who were treated with the drug were symptom-free on six (22%) of the 28 days and nights compared with only one (4%) among those who received the placebo. Daytime coughing was also significantly reduced among the treated infants.
In addition, a worsening of symptoms requiring withdrawal from the study or hospitalization occurred in only four of the infants on Singulair versus 10 of those on the placebo, and these exacerbations were significantly delayed in the treated infants.
Experts say these findings clear the way for further studies into the long-term effectiveness of these types of drugs on RSV-related wheeze and cough, as well as new ways of fighting RSV itself.
Robert Welliver, MD, professor of pediatrics in the division of infectious diseases at the Women's and Children's Hospital of Buffalo, says this is only the first attempt to use this class of drugs to treat RSV-related complications. And he suspects there might be a much broader application for them.
"In this study, they only looked at treating infants after they left the hospital, but this might be treating the wrong end of the illness," says Welliver. "What if you take high-risk kids and put them on these drugs to prevent hospitalization? There is a high percentage of kids with [RSV] who had been in the doctor's office a day or two before they were hospitalized."
Giving these children a leukotriene-inhibitor early on, Welliver says, might prevent some of the inflammation from occurring in the first place.
Joe Spahn, MD, a pediatrician at National Jewish Medical and Research Center, agrees that much more study is needed.
This study found only a modest benefit from using Singulair, but Spahn says RSV-related wheeze involves a very complicated set of variables that no one really fully understands yet.
He says some people think using inhaled steroids, which are also frequently used to prevent asthma attacks, might work in treating this condition. But Spahn says there are just as many studies that say they work as say they don't.
"We don't have a very good therapy to treat this condition, so it's better than what we have,"
Spahn tells WebMD. "This is a start."