Asthma in Adults

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. They are used alone only for patients with mild and intermittent asthma. Patients with more severe cases should use them in combination with other agents.

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. Studies have indicated that levalbuterol is as effective as albuterol with fewer side effects. Xopenex is administered with a nebulizer and is available without preservatives. (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 agents, then patients should discuss corticosteroids or other drugs to treat underlying inflammation.

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, particularly in people with existing heart conditions. Such patients face an increased risk for sudden death from cardiac related causes. This risk is higher with oral or nebulized agents, but there have also been reports of heart attacks and angina in some patients using inhaled beta2-agonists.

Beta2-agonists have serious interactions with certain other drugs, such as beta-blockers, and patients should tell the physician about any other medications they are taking. Individuals with diabetes, existing heart disease, high blood pressure, hyperthyroidism, an enlarged prostate, or a history of seizures should take these drugs with caution.

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 beta 2-agonists may reduce the effect of short-acting forms.

Its a major concern that patients who perceive beta2-agonists as being less effective may overuse them. Overdose can be serious and in rare cases even life-threatening, particularly in patients with heart disease.

Theophylline and Similar Agents

Theophylline. Theophylline (Theo-Dur, Theolair, Slo-Phyllin, Slo-bid, Constant-T, Respbid) relaxes the muscles around the bronchioles and also stimulates breathing. One study reported that it 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, 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:

• Chronic smokers metabolize theophylline much more quickly and require higher doses of the drug than nonsmokers; prolonged-release versions are helpful for such people.
• Too much caffeine can increase the concentration of this drug and the amount of time it stays in the body.
• Theophylline also interacts with many other drugs that are taken for other common medical conditions, including asthma. Caution should be exercised if beta2-agonists and theophylline are used together.
• Theophylline should not be taken by anyone who has a peptic ulcer and should be taken with caution by the elderly and by individuals with heart disease, liver disease, hypertension, seizure disorders, or congestive heart failure. Of special note, people with heart conditions who take theophylline orally face an increased risk for sudden death from heart-related causes.

Xanthines. Drugs similar to theophylline called xanthines, such as doxofylline, may prove to be effective bronchodilators without the adverse effects on the heart that theophylline and beta2-agonists have. More research is needed.

Anticholinergic Agents

Inhaled ipratropium bromide (Atrovent) acts as a bronchodilator over time. Ipratropium bromide alone is only modestly beneficial for acute asthma attacks. In fact, the drug is not approved specifically for asthma. It may, however, have benefits in certain cases:

• It may be useful for certain older asthma patients who also have emphysema or chronic bronchitis.
• A combination with a beta2-agonist might be helpful for patients who do not initially respond to treatment with a beta2-agonist alone.