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COMMENT ON CLASSIFICATION. There are many ways to classify drugs for asthma and COPD (chronic obstructive pulmonary disease). The classification offered here is based on their mechanism of action in improving the basic problem (which is airway obstruction) and by their route of administration (oral or pill form, by inhalation, or by injection).
Our lungs contain many branching airways that deliver fresh air to the blood. The phrase "drugs for asthma and COPD" means drugs that help open up the airways when they become narrowed due to disease. Other drugs may be used in people with asthma and COPD, such as antibiotics for infection, but they are not used to directly "open up" the airways.
When it comes to drugs for "opening up" the airways, all available medications can be classified by one of two basic mechanisms of action: bronchodilation and anti-inflammatory.
Bronchodilators "dilate" or open up the bronchi, which are the larger airways delivering air inside the lungs. They do this by acting on smooth muscle in the walls of the bronchi. Anti-inflammatory drugs, by contrast, act to decrease the inflammation inside the airways; in this case "inflammation" means fluid and cellular debri that tends to clog up the airways of people with asthma and COPD.
There are three types of bronchodilators and three types of anti-inflammatory drugs used in asthma and COPD, based on their specific biochemical mechanism of action. Thus, for example, there are three separate biochemical mechanisms by which drugs can lead to bronchodilation.
So far this seems like a simple classification, but complexity arises because, within each of these 6 types, drugs can be given by different routes (e.g., orally with a pill; inhalation with a spray; by injection into the tissues or directly into the vein) and similar drugs can be used for different purposes.
For example, while most bronchodilators of the "Beta-adrenergic" mechanism are given by the inhalation, and are used mainly for immediate relief of symptoms, at least one drug of this type (Salmeterol, brand name Serevent) is used to prevent symptoms from occurring, not to provide immediate relief.
The situation with anti-inflammatory drugs is even more complicated. Steroids (also known as corticosteroids) are powerful anti-asthma drugs that work by reducing airway inflammation. However, they only provide relief of symptoms when taken in pill form or when injected into the muscle or directly into the vein. When steroids are inhaled, they don't provide sufficient dose to relieve symptoms; instead, the low dose of inhaled steroids is used mainly to prevent a worsening of symptoms, or to improve mild symptoms over the long term (days).
Another class of anti-inflammatory drugs, called mediator-release inhibitors (brand names Cromolyn and Tilade), also doesn't provide quick relief of symptoms; the two drugs in this group are used mainly as preventive medication, i.e., to prevent symptoms from worsening or from occurring in the first place.
The newest of the three classes of anti-inflammatory drugs, the anti-leukotrienes (single drug currently available has brand name Accolate), also doesn't provide any quick relief, but may help to control asthma symptoms over the long term. (Interestingly, Accolate is the first truly new asthma drug - based on mechanism of action - to be available in over 25 years.)
How is the patient to sort all this out? It's not easy, particularly since there is far from universal agreement among physicians about how to best use asthma drugs. A patient with asthma symptoms could go to three different physicians and end up with three different regimens, with three different levels of effectiveness.
A rule of thumb is that the sicker the asthmatic or COPD patient, the more likely he or she will need (and benefit by) steroids, either in pill form or systemically (injected into the muscle or vein). Steroids will usually be prescribed along with a quick-acting bronchodilator, usually given by inhalation. In my opinion, the other two classes of anti-inflammatory drugs, as well as all inhaled steroids, should not be relied on to provide quick relief to a suffering asthmatic.
Of the drugs listed below, only Primatene mist (a short acting, inhaled bronchdilator) is sold over the counter in the U.S. All others are by prescription only. Primatene is a very short acting drug, and while it can provide some immediate relief, it does not provide any anti- inflammatory activity. Thus it is imperative that any suffering asthmatic or COPD patient get under the care of a physician who is knowledgeable about the available medications and how to manage flareups of asthma and COPD.
One other point needs to be made about COPD, or chronic obstructive pulmonary disease. COPD is found mainly in long term smokers. The term COPD comprises two similar conditions, chronic bronchitis and emphysema. It is usually not important to distinguish whether a person has mainly chronic bronchitis or emphysema; physicians routinely use "COPD" to cover either one or both.
What is important is to recognize that symptoms of a flare up of COPD (e.g., cough, shortness of breath, wheezing, chest congestion) can be identical to symptoms from asthma, so the same drugs listed below are used in both conditions: asthma (which itself is not due to smoking) and COPD (usually due to smoking). There is very little, if any, difference in the use of these drugs in treating symptomatic COPD and asthma patients.
----> Inhaled. All act within about 15 minutes, except salmeterol.
----> Subcutaneous (epinephrine, terbutaline)
----> Oral (albuterol, terbutaline, ephedrine)
----> BETA-ADRENERGIC AGENTS ARE NOT USED INTRAVENOUSLY IN ADULTS
2. Methyl xanthines
----> Oral (caffeine, theophylline [many brands], oxtriphylline [Choledyl])
----> Intravenous (aminophylline)
----> THEOPHYLLINE AND OTHER TYPES OF METHYL XANTHINES ARE NOT USED BY INHALATION
----> Inhaled form only (atropine, ipratropium bromide [Atrovent])
----> NOT AVAILABLE IN ORAL OR PILL FORM
----> Inhaled; not used for quick relief.
----> Oral (prednisone, prednisolone, methylprednisolone [Medrol, Medrol DosePak], dexamethasone)
----> Intramuscular (methylprednisolone [Depo-Medrol])
----> Intravenous (hydrocortisone [SoluCortef], methylprednisolone [SoluMedrol], dexamethasone)
----> Inhaled only (cromolyn sodium [Intal], nedocromil sodium [Tilade])
NOTE: Both drugs are used only for prophylaxis of asthma, not for treatment of the acute attack or for the symptomatic patient.
----> THESE TWO DRUGS DRUGS ARE NOT AVAILABLE IN ORAL FORM
----> Oral. There are three drugs in this class: e first drugs of this group are zafirlukast, a "leukotriene-receptor-blocking drug" and zileuton, a drug which blocks the formation of leukotriene. Their trade names are,
----> ANTI-LEUKOTRIENE DRUGS ARE NOT USED BY INHALATION