Asthma in Children and Adolescents

Description

Medications

Beta2-agonists do not reduce inflammation or airway responsiveness but serve as bronchodilators, relaxing and opening constricted airways during an acute asthma attack. A short-acting inhaled beta2-agonist, taken as needed, is often the only medication used by children with chronic mild asthma.

Asthma is a disease in which inflammation of the airways causes airflow into and out of the lungs to be restricted. When an asthma attack occurs, mucus production is increased, muscles of the bronchial tree become tight, and the lining of the air passages swells, reducing airflow and producing the characteristic wheezing sound.

Specific short-acting beta2-agonists include the following:

• Albuterol (Proventil, Ventolin), called salbutamol outside the U.S., is the standard short-acting beta2-agonist in America. Other similar beta2-agonists are isoproterenol (Isuprel, Norisodrine, Medihaler-Iso), metaproterenol (Alupent, Metaprel), pirbuterol (Maxair), terbutaline (Brethine, Brethaire, Bricanyl), and bitolterol (Tornalate). Isoetharine (Bronkometer, Bronkosol is available in nebulizers.
• Newer beta2-agonists, including levalbuterol (Xopenex), have more specific actions than the standard agents. Xopenex is administered with a nebulizer and studies have indicated that it is as effective as albuterol with fewer side effects. (It is very expensive, however.)

Short-acting bronchodilators are generally administered through inhalation and are effective for three to six hours. They relieve the symptoms of acute attacks, but they do not control the underlying inflammation. If asthma continues to worsen with the use of these

Side Effects of Beta2-Agonists. Side effects of all beta2-agonists include the following:

• Anxiety.
• Tremor.
• Restlessness.
• Headache.
• Patients may experience fast and irregular heartbeats. A physician should be notified immediately if such side effects occur.
• These drugs should be taken with caution by children with diabetes or a history of seizures.
• Beta2-agonists have serious interactions with certain drugs and parents should tell the physician about any other medications their child is taking.

Loss of Effectiveness and Overdose. There has been some concern that both short-acting beta2-agonists become less effective when taken regularly over time, increasing the risk for overuse. Over time some patients may become tolerant to many effects of short-acting beta2-agonists. The degree to which this affects the airways is uncertain. In some studies, the duration of action has declined but the peak effect appears to be preserved, making these drugs still useful for acute attacks. Regular use of long-acting beta2-agonists may increase the chances of a reduced effect from the short-acting forms.

Other Bronchodilators

Theophylline. Theophylline (Theo-Dur, Theolair, Slo-Phyllin, Slo-bid, Constant-T, Respbid) is a mild to moderate bronchodilator that has been used to treat childhood asthma for more than 30 years. It is useful for treating nocturnal asthma and may also have anti-inflammatory qualities even in low doses.

Available in tablet, liquid, and injectable forms, some theophylline sustained-release tablets and capsules have a long duration of action and can therefore be taken once or twice a day with good results.

It does have some problems, however. Side effects include changes in behavior, mood, and memory. If theophylline is not taken exactly as prescribed, an overdose can easily occur. Toxicity causes the following symptoms: nausea, vomiting, headache, insomnia, and, in rare cases, disturbances in heart rhythm and convulsions. A physician should be contacted immediately if any of these side effects occur.

The risks for these adverse effects are small if the drug is taken exactly as prescribed but the following precautions should be noted:

• Infants tend to metabolize the drug extremely slowly and, therefore, should receive very low doses.
• By the time asthmatic children reach one year old, however, they metabolize the drug faster than adults. There is a risk, therefore, of toxic effects.
• Fever and certain antibiotics may slow down the rate at which theophylline is eliminated from the body. In such cases, the doctor may want to reduce the dosage of theophylline.

If a child is taking theophylline on an ongoing basis, the doctor should monitor the drug level at the start of therapy and at regular intervals thereafter.