Childhood Asthma : Medications: Bronchodilators, Cromolyn, Corticosteroids

by Food and Drug Administration (FDA)

(Page 2 of 3)

Medications

Medications for asthma have come a long way since the days of the ancient Egyptians, who treated the disease by administering camel or crocodile dung, or by burning herbs on a hot brick and having the asthma patient inhale the fumes. Or even, for that matter, since the days of the great 12th century physician and Jewish theologian Moses Maimonides, who prescribed — what else? — hot chicken soup.

Asthma can't be cured, but modern physicians have a powerful array of drugs to help prevent an attack or to relieve one that has already started. For some children, one medication will work; others need a combination of drugs. Most drugs fall in three major groups: bronchodilators, an anti-allergic mediator agent (cromolyn), and anti-inflammatory agents (corticosteroids).

Bronchodilators

These drugs dilate (open) the narrowed bronchial tubes, allowing oxygen to enter and carbon dioxide to exit the lungs more freely. Bronchodilators can be taken orally or inhaled in the form of an aerosol.

Theophylline, which relaxes the muscles surrounding the bronchial tubes, has been used as a bronchodilator in asthma therapy since 1922. The chemical was first isolated from cocoa in 1888, and is related to caffeine, whose bronchodilating effects were noted as early as 1698. The drug is usually taken orally in immediate-release or slow-release tablets, beads or capsules. It is used to treat occasional episodes and as a preventive medication for long-term use. In emergencies, it may be given intravenously.

Theophylline doses must be carefully adjusted and monitored, based on body weight and how quickly the child eliminates the drug from the body. Too high a dose may result in stomachaches, headaches, high blood pressure, anxiety seizures, and other side effects. But if the dose is too low, the drug is ineffective. Younger children break down theophylline more rapidly than do older children and adults, and thus require a higher dose of theophylline per kilogram (pound) of body weight. (For more on theophylline, see "Keeping Time to Circadian Rhythms" in this issue.)

Epinephrine (adrenalin) is another drug that opens up the bronchial tubes. Usually given by injection, epinephrine works fast. It may increase the heart rate and produce other side effects such as headache, jitteriness, anxiety, and sometimes nausea and vomiting.

Beta-adrenergics or beta-agonists, are epinephrine-like drugs that can be inhaled or taken orally in liquid or tablet form. Although not approved for use in children, epinephrine-like drugs are nevertheless prescribed by some physicians when, in their judgment, the benefit to the child outweighs the risks. Used to treat occasional attacks and as a preventive medication on a long-term basis, they are longer-acting and cause fewer side effects than epinephrine.

These drugs can be used in a device called a metered-dose inhaler, which delivers a specific amount of the drug directly to the bronchial tubes in the form of an aerosol spray. Very young children who can't master the inhaler can use a compressor-driven nebulizer, which sends a fine mist of the drug to the lungs through a mouthpiece or face mask, or they may take oral forms of adrenergic drugs.

To prevent exercise-induced asthma, inhaled adrenergic drugs should be used at least 15 minutes before exercise. Overuse of the inhaler can be dangerous, because it can cause irregular heartbeats, chest pain, and worsening of asthma. Overuse may also mean that the asthma is not under control.

Cromolyn

Unlike bronchodilators, which treat only symptoms, cromolyn treats the specific cause of asthma: airway hyper-reactivity and inflammation. Cromolyn makes airways less sensitive to factors that can trigger asthma episodes and, when an allergic reaction does occur, prevents the release of histamine from certain cells (mast) that cause bronchial tube inflammation.

Cromolyn is inhaled, either as a liquid in a metered-dose inhaler or from a nebulizer, or as a powder using a spinhaler, a propeller device specifically designed for cromolyn use. Cromolyn can be used as long-term preventive treatment. It can also be used to prevent an attack, especially before exercise or exposure to cold air or known allergens, but it is of no use when an asthma attack is under way. The drug has a few mild side effects, such as a bad taste in the mouth, throat irritation, and coughing from the powder.

Corticosteroids

Other drugs used to treat the disease rather than the symptoms are corticosteroids, which are related to cortisone, a hormone produced by the adrenal glands. (These steroids are not to be confused with anabolic steroids used by body builders.)

"Steroids have been, without question, the major advance in the treatment of asthma for the last 20 years," says Michael Kaliner, M.D., head of the Allergic Diseases Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health. "They cause inflammation of the airways to go away, and reduce airway irritability." They also decrease mucus production and swelling, and allow other medicines to work more effectively.

When taken by mouth for more than a week or two, however, they can produce severe side effects, including growth suppression in children, a characteristic "moon" face, bone thinning, acne, cataracts, increased blood pressure, increased blood sugar, and more.

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