PRIMED-S: Update on Asthma

By Susan Easter

FT. LAUDERDALE, FL -- February 18, 2003 -- New technology and knowledge have given rise to effective treatments to control and relieve asthma symptoms, according to Christopher H. Fanta, MD, Director of the Partners Asthma Center and an associate professor of medicine at Harvard Medical School, Boston, Massachusetts.

Dr. Fanta discussed the current state of asthma treatment here February 15^th at the Pri-Med South Conference.

In his update on asthma treatment, Dr. Fanta reviewed the defining features and correlated therapeutic developments to evolving treatment concepts of the past few decades.

Unique features of asthma are reversible airway obstruction, non-specific bronchial hyper-responsiveness and inflammation of airways.

During the 1970s, a pathogenic understanding of asthma evolved. Adverse effects were common with treatments and, in some cases, control of asthma worsened with treatment. The risk of death or near-death due to asthma was reported to have increased and accelerated decline of lung function was observed in some patients.

In the following decade, studies on bronchial samples found dramatic and persistent changes in the bronchial wall, including the presence of eosinophils and lymphocytes. In addition, researchers noticed that epithelial cells were stripped off the bronchial wall.

Based on this pathophysiology, treatments focused on reducing inflammation. Common therapies of the 1980s included inhaled corticosteroids, mast cell stabilizers and leukotrienes. Attempts were also made to reduce exposure to allergens to reduce asthma symptoms and severity of attacks.

By the 1990s, investigators identified the stages of asthma severity. In 1991, the Expert Panel Report characterized symptoms as mild, moderate or severe. By 1997, the Expert Panel Report II further differentiated the stages as mild intermittent asthma, mild persistent asthma, moderate persistent asthma, and severe persistent asthma.

An additional type of asthma identified was exercise-induced asthma, in which exercise is the major trigger of cooling and drying of bronchial mucosa. Pre-treatment with beta-blockers and/or mast cell stabilizers were found to prevent these symptoms. Researchers also found that it can be helpful to take peak flow measurements to monitor the disease.

More recently, therapies were developed that are based on offering various potencies of inhaled steroids. New delivery devices include ozone-safe propellants and dry powder inhalers. For patients with mild asthma, once-daily dosing is now available.

Dr. Fanta cautioned that practitioners must be aware of potential adverse effects of inhaled steroid use. Dose-dependent loss of bone density has been observed in a three-year study of 109 premenopausal women treated with triamcinolone, and he recommended periodic bone density scans.

While not as effective as inhaled steroids, leukotrienes alone or in combination provide potent and sustained action on asthma symptoms. They are effective in patients who have aspirin sensitive asthma, Dr. Fanta said.

Current asthma treatments are aimed at controlling or relieving symptoms. Relieving agents are fast-acting and work well for moderate to severe persistent asthma. These treatments effectively control nocturnal symptoms. Salmeterol can be particularly effective when used in combination with inhaled corticosteroids. A single dose is effective for at least 12 hours. Controlling agents are anti-inflammatories that are inhaled and long acting.

Asthma treatments continue to evolve, Dr. Fanta said. New technology and knowledge have given rise to anti-IgE monoclonal antibodies, interleukin and adhesion molecule antagonists, he concluded.