Antiasthmatic Drugs

views updated Jun 11 2018

Antiasthmatic Drugs

Definition

Antiasthmatic drugs are medicines that treat or prevent asthma attacks.

Purpose

For people with asthma, the simple act of breathing can be a struggle. Their airways become inflamed and blocked with mucus during asthma attacks, narrowing the opening through which air passes. This is not such a problem when the person breathes in, because the airways naturally expand when a person takes a breath. The real problem arises when the person with asthma tries to breathe out. The air cannot get out through the blocked airways, so it stays trapped in the lungs. With each new breath, the person can take in only a little more air, so breathing becomes shallow and takes more and more effort.

Asthma attacks can be caused by allergies to pollen, dust, pets or other things, but people without known allergies may also have asthma. Exercise, stress, intense emotions, exposure to cold, certain medicines and some medical conditions also can bring on attacks.

The two main approaches to dealing with asthma are avoiding substances and situations that trigger attacks and using medicines that treat or prevent the symptoms. With a combination of the two, most people with asthma can find relief and live normal lives.

KEY TERMS

Asthma— A disease in which the air passages of the lungs become inflamed and narrowed.

Inflammation— Pain, redness, swelling, and heat that usually develop in response to injury or illness.

Inhalant— Medicine that is breathed into the lungs.

Mucus— Thick fluid produced by the moist membranes that line many body cavities and structures.

Nebulizer— A device that turns liquid forms of medicine into a fine spray that can be inhaled.

Description

Three types of drugs are used in treating and preventing asthma attacks:

Bronchodilators relax the smooth muscles that line the airway. This makes the airways open wider, letting more air pass through them. These drugs are used mainly to relieve sudden asthma attacks or to prevent attacks that might come on after exercise. They may be taken by mouth, injected or inhaled. Bronchodilators may be taken in pill or liquid form, but normally are used as inhalers, which go directly to the lungs and result in fewer side effects.
Corticosteroids block the inflammation that narrows the airways. Used regularly, these drugs will help prevent asthma attacks. Those attacks that do occur will be less severe. However, corticosteroids cannot stop an attack that is already underway. These drugs may be taken by mouth, injected or inhaled.

Leukotriene modifiers (montelukast and zafirlukast) are a new type of drug that can be used in place of steroids, for older children or adults who have a mild degree of asthma that persists. They work by counteracting leukotrienes, which are substances released by white blood cells in the lung that cause the air passages to constrict and promote mucus secretion. Leukotriene modifiers also fight off some forms of rhinitis, an added bonus for people with asthma. However, they are not proven effective in fighting seasonal allergies.
Cromolyn also is taken regularly to prevent asthma attacks and may be used alone or with other asthma medicines. It cannot stop an attack that already has started. The drug works by preventing certain cells in the body from releasing substances that cause allergic reactions or asthma symptoms. One brand of this drug, Nasalcrom, comes in capsule and nasal spray forms and is used to treat hay fever and other allergies. The inhalation form of the drug, Intal, is used for asthma. It comes in aerosol canisters, in capsules that are inserted into an inhaler, and in liquid form that is used in a nebulizer.

Precautions

Using antiasthmatic drugs properly is important. Because bronchodilators provide quick relief, some people may be tempted to overuse them. However, with some kinds of bronchodilators, this can lead to serious and possibly life-threatening complications. In the long run, patients are better off using bronchodilators only as directed andalsousing corticosteroids, which eventually will reduce their need for bronchodilators. However, a 2004 Canadian study has questioned a standard practice of increasing steroids after asthma attacks or worsened symptoms. Also, research in 2004 showed that people with asthma who worked closely with their physicians to self-manage their asthma had fewer attacks, which reduces the need for bronchodilators. Carefully managing asthma also reduces visits to the emergency department and hospitalizations.

Corticosteroids are powerful drugs that may cause serious side effects when used over a long time. However, these problems are much less likely with the inhalant forms than with the oral and injected forms. While the oral and injected forms generally should be used only for one to two weeks, the inhalant forms may be used for long periods.

It is important to remember that leukotriene modifiers are used to prevent and manage asthma, not to stop an attack. A physician or pharmacist can advise patients on possible interactions with other drugs.

Patients who are using their antiasthmatic drugs correctly but feel their asthma is not under control should see their physicians. The physician can either increase the dose, switch to another medicine or add another medicine to the regimen. A 2004 survey showed that 70% of people with mild to moderate asthma were not taking the correct dose of asthma medication.

When used to prevent asthma attacks, cromolyn must be taken as directed every day. The drug may take as long as four weeks to start working. Unless told to do so by a physician, patients should not stop taking the drug just because it does not seem to be working. When symptoms do begin to improve, patients should continue taking all medicines that have been prescribed, unless a physician directs otherwise.

Side effects

Inhalant forms of antiasthmatic drugs may cause dryness or irritation in the throat, dry mouth, or an unpleasant taste in the mouth. To help prevent these problems, gargling and rinsing the mouth or taking a sip of water after each dose is recommended.

More serious side effects are not common when these medicines are used properly. However, anyone who has unusual or bothersome symptoms after taking an antiasthmatic drug should get in touch with a physician.

Interactions

A physician or pharmacist should be consulted before combining antiasthmatic drugs with any other prescription or nonprescription (over-the-counter) medicine.

Resources

PERIODICALS

"Many People With Asthma Arenót Taking the Right Amount of Medication." Obesity, Fitness & Wellness Week (September 25, 2004): 87.

"Study Calls Standard Asthma Management Into Doubt." Doctor (July 15, 2004): 4.

"What's New in: Asthma and Allergic Rhinitis." Pulse (September 20, 2004): 50.

Gale Encyclopedia of Medicine, 3rd ed. Ross-Flanigan, Nancy; Odle, Teresa

Antiasthmatic Drugs

views updated May 21 2018

Antiasthmatic drugs

Definition

Antiasthmatic drugs are medicines that treat or prevent asthma attacks.

Description

Three types of drugs are used in treating and preventing asthma attacks:

Bronchodilators relax the smooth muscles that line the airway. This makes the airways open wider, letting more air pass through them. These drugs are used mainly to relieve sudden asthma attacks or to prevent attacks that might come on after exercise . They may be taken by mouth, injected, or inhaled.
Corticosteroids block the inflammation that narrows the airways. Used regularly, these drugs help prevent asthma attacks. Those attacks that do occur will be less severe. However, corticosteroids cannot stop an attack that is already underway. These drugs may be taken by mouth, injected, or inhaled.
Cromolyn also is taken regularly to prevent asthma attacks and may be used alone or with other asthma medicines. It cannot stop an attack that already has started. The drug works by preventing certain cells in the body from releasing substances that cause allergic reactions or asthma symptoms. One brand of this drug, Nasalcrom, comes in capsule and nasal spray forms and is used to treat hay fever and other allergies . The inhalation form of the drug, Intal, is used for asthma. It comes in aerosol canisters, in capsules that are inserted into an inhaler, and in liquid form that is used in a nebulizer.

General use

All three types of drugs may be used in combination with each other.

Cromolyn is a common but not invariable first choice for children who have asthma. It reduces the frequency of asthmatic attacks and is suitable for long-term use. Cromolyn may not be needed when attacks are mild and infrequent.

Bronchodilators should be used to treat attacks once they begin. They may also be taken on a regular basis to prevent attacks.

Corticosteroids are valuable, but some have serious long-term side effects. Except in patients whose conditions cannot be managed with cromolyn and brochodilators, corticosteroids should be reserved for emergency room use. In patients who require ongoing use of steroids, alternate day dosing or inhalation of some of the newer corticosteroids may minimize the adverse effects of this class of drugs.

Precautions

Parents whose children are using their antiasthmatic drugs correctly but feel their asthma is not under control should see consult their child's physicians. The physician can either increase the dose, switch to another medicine, or add another medicine to the regimen.

Corticosteroids are powerful drugs that may cause serious side effects when used over the long term. However, these problems are much less likely with the inhalant forms than with the oral and injected forms. While the oral and injected forms generally should be used only for one to two weeks, the inhalant forms may be used for long periods.

Side effects

Inhalant forms of antiasthmatic drugs may cause dryness or irritation in the throat, dry mouth, or an unpleasant taste in the mouth. To help prevent these problems, patients can gargle and rinse the mouth or take a sip of water after each dose.

KEY TERMS

Asthma —A disease in which the air passages of the lungs become inflamed and narrowed, causing wheezing, coughing, and shortness of breath.

Inflammation —Pain, redness, swelling, and heat that develop in response to tissue irritation or injury. It usually is caused by the immune system's response to the body's contact with a foreign substance, such as an allergen or pathogen.

Inhalant —Medication that is breathed into the lungs.

Mucus —The thick fluid produced by the mucous membranes that line many body cavities and structures. It contains mucin, white blood cells, water, inorganic salts, and shed cells, and it serve to lubricate body parts and to trap particles of dirt or other contaminants.

Nebulizer —A device that turns liquid forms of medication into a fine spray that can be inhaled.

More serious side effects are not common when these medicines are used properly. However, parents whose children have unusual or bothersome symptoms after taking an antiasthmatic drug should get in touch with the child's physician.

Interactions

There are many drugs that are used in treatment of asthma. Interactions should be reviewed on an individual basis.

Drugs which decrease blood levels of aminophylline (which opens bronchial passages) and may require a dose increase are:

carbamazepine
isoprenolol
phenobarbital
phenytoin
rifampin

Parental concerns

All health professionals with responsibility for an asthmatic's drug therapy should have an up-to-date list of the drugs and doses being used by the child. Asthmatic children should wear a suitable identification bracelet with a list of drugs being used, in case of an emergency room admission. Children using inhalers should be knowledgeable on the use of these devices.

See also Asthma.

Resources

BOOKS

Beers, Mark H., and Robert Berkow, eds. The Merck Manual, 2nd home ed. West Point, PA: Merck & Co., 2004.

Mcevoy, Gerald, et al. AHFS Drug Information 2004. Bethesda, MD: American Society of Healthsystems Pharmacists, 2004.

Raskin, Lauren. Breathing Easy: Solutions in Pediatric Asthma. Washington, DC: Georgetown University, 2000.

Siberry, George K., and Robert Iannone, eds. The Harriet Lane Handbook, 15th ed. Philadelphia: Mosby Publishing, 2000.

PERIODICALS

Allen, D. B. "Systemic effects of inhaled corticosteroids in children." Current Opinion in Pediatrics 4 (August 16, 2004): 440–4.

Berger, W. E., and G. G. Shapiro. "The use of inhaled corticosteroids for persistent asthma in infants and young children." Annual Allergy Asthma Immunology 92 (April 2004): 387–99.