African-Americans may need a bigger dose of asthma medications in order to keep their asthma under control, according to a new study.

Researchers found that African-Americans required a higher dose of glucocorticoids (search), a class of steroid drugs used to treat asthma.

Airway inflammation plays a critical role in asthma (search), and steroids are considered the most effective therapy to suppress the inflammation which triggers asthma.

Lymphocytes (search) — white blood cells which release chemicals needed to activate the immune system — contribute to airway inflammation, airflow restriction and difficulty in breathing in asthma.

"Regardless of asthma status or severity, African-Americans in our study required higher doses of a glucocorticoid than Caucasians to inhibit proliferation of these inflammatory cells," says researcher Ronina A. Covar, MD, of the National Jewish Medical and Research Center (search) in Denver in a news release. "This observation suggests that African-Americans may have an inherent predisposition that affects their ability to respond to certain medications at recommended doses."

Researchers say the finding may help explain why African-Americans are about four times more likely to be hospitalized or die due to asthma than Caucasians.

African-Americans Respond to Asthma Drug Differently

In the study, which appears in the February issue of Chest, researchers tested blood samples from 395 patients with asthma (27 percent African-Americans) and 202 patients without asthma (52 percent African-Americans) to see how they responded to treatment with glucocorticoids.

The results showed that among a group of African-American and Caucasian asthma patients with similar degrees of airflow restriction, the African-American patients required higher doses of the glucocorticoid medication to suppress lymphocytes.

This difference in drug response between African-Americans and Caucasians was also found among people without asthma.

Covar says that a suboptimal response to asthma medications may contribute to poor asthma control and, therefore, higher rates of asthma-related complications and death among African-Americans.

"These patients whose asthma is not adequately controlled on usual medication doses may benefit from a higher dose or the addition of other controller medications," says Covar.

By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCE: Federico, M. Chest, February 2005; vol 127: 571-578. News release, American College of Chest Physicians.