Scientists at Johns Hopkins have found that individuals who have the misfortune to be allergic to cats can find welcome relief and protection from symptoms in one of a new class of drugs already known to help other asthmatics.

Results of the Hopkins research published in the April issue of the Journal of Allergy and Clinical Immunology show that zafirlukast not only prevents wheezing and shortness of breath but also the itchy, runny, swollen noses triggered by allergens in cat dander.

"This drug has the added advantage of providing some relief for the nose as well as the chest," says Robert Wood, associate professor of pediatrics. "It's especially appealing because it is not a steroid and is given in pill form."

Zafirlukast is one of a relatively new class of asthma medicines known as leukotriene antagonists. These drugs block chemicals released by lung cells that are responsible for allergy symptoms. Because the drug has been very successful in treating asthma in adults and children, Hopkins researchers tested its potential to stop allergic reactions to cats.

The researchers enlisted 18 individuals with cat allergies and randomly assigned them to receive one week each of zafirlukast or placebo. Subjects volunteered to endure a one-hour stay in a specially designed "cat challenge room." This carpeted room, home to a couple of house cats, contained bedding that was shaken right before a study volunteer entered the habitat. "The room provides an extremely intense cat exposure, 10 to 100 times the level of allergens you would find in the home," Wood says.

While in the cat challenge room, the volunteers scored, on a scale of 1 to 3, the severity of their symptoms every five minutes. Researchers also tested the individuals' pulmonary function every 15 minutes and measured swelling in the back of the nose.

Zafirlukast significantly reduced the number of lung and nasal allergic symptoms individuals experienced when exposed to cats. Three of the 18 subjects had mild adverse effects such as diarrhea, nausea and mouth dryness during treatment with the drug.

"In some people, this drug was dramatically effective, and people don't have to rely on using their inhalers," Wood says.

Allergy is the most widespread chronic condition in the world, and sensitivity to animals is one of the most common causes of allergy. More people are allergic to cats than dogs, and in the United States, cat allergies affect between 5 percent and 10 percent of the population.

Other Hopkins authors of the study are Wanda Phipatanakul, Peyton Eggleston and Mary Kay Conover-Walker from the Division of Allergy and Immunology, Department of Pediatrics, at the School of Medicine, and Jana Kesavanathan from the Division of Environmental Health Sciences at the School of Public Health. The study was funded by Astra-Zeneca Pharmaceuticals, makers of the drug, and by the National Institutes of Health.