So, yesterday, I talked about what asthma control is.
Today, and for the next two posts, I’m going to write about how you get and maintain asthma control. There are three pillars to getting good asthma control: Medicine, exercise, and trigger management. Today, I’m going to talk about medicine.
Most people with asthma need at least one maintenance medicine. Only the mildest of asthmatics can maintain control with just a rescue puffer. Maintenance or preventer meds are taken every day, usually twice a day, to help control asthma. There are several main classes of maintenance asthma medicines:
- Inhaled corticosteroids
- Inhaled non-steroidal anti-inflammatories
- Long-acting bronchodialators
- Leukotriene receptor antagonists
- Oral corticosteroids
- Humanized antibodies
Inhaled corticosteroids (abbreviated in papers as ICS) are finely-ground anti-inflammatory steroid that you inhale. They work by reducing the inflammation of your airways, making them less swollen and twitchy. They’re the single most common type of asthma maintenance med, and most people who are on other maintenance meds will be on one or more ICS drugs as well. They’re typically delivered either through a dry powder inhaler or through a metered dose inhaler. Sometimes, they’re delivered through a nebulizer. There are too many ICS drugs to list, but a list of common drugs in this class may be found here.
Inhaled non-steroidal anti-inflammatory drugs are an older class of asthma medicine, still used in those with steroid-resistant asthma or those who have a history of bad reactions to inhaled corticosteroids. They work by stabilizing mast cells and preventing the allergic reaction that leads to swelling, inflammation, and twitchy airways. There are two drugs in this class: cromolyn sodium and necromil sodium. They’re not used very often anymore because they’re inconvenient (you need to take them four times a day) and are held to be less safe than ICS and leukotriene receptor antagonists. Since MDIs stopped being produced in 2010 when the CFC propellant was banned, they can only be delivered through a nebulizer. This class has mostly been replaced by the leukotriene receptor antagonists discussed below.
Long-acting bronchodialators (abbreviated LABAs) are a class of drugs that works by binding to a receptor on the outside of the cell, which causes relaxation of the smooth muscle. In this way, they work exactly like asthma rescue medicines, but they last longer. This longer lasting action comes at a price: they usually aren’t fast acting, and so with one exception (formoterol), they can’t be used as asthma rescue medicines. They stop, reverse, and prevent bronchospasms. These medicines are not without risk: The benefit of LABAs to quality of life and asthma control must be weighed against a small but significantly increased risk of sudden, severe and life threatening asthma attacks. This increased risk is either greatly reduced or eliminated entirely (literature is contradictory on this point) in people who are taking inhaled corticosteroids, and therefore these medications are contraindicated in asthma patients who are not taking ICS therapy. What that means is that if you are asthmatic and your doctor has you on a LABA without an ICS, you should talk with your doctor about whether it’s a good idea.
Leukotriene receptor antagonists (abbreviated LRTAs) are a class of drugs that work by inhibiting the action of leukotrienes. In short, they stop allergic reactions before they begin. Common drugs in this class are montekulast, zafirlukast, and zileuton. LRTAs come with a warning for possible neuropsychiatric side effects, the effects of which can be delayed by several years. As such, LRTAs, like LABAs, are a class of drug that is approached with caution and only when a risk-benefit analysis indicates that the potential benefit outweighs the potential risk.
Methylxanthines (also called theophyllines) are a class of drug that is related to caffeine. They are stimulants, anti-inflammatories, and bronchodialators. They work by relaxing the airways and possibly by reducing the inflammation that causes asthma symptoms. There is also some evidence that theophylline might reverse steroid insensitivity in severe asthmatics. Theophylline has a relatively narrow therapeutic window, and when I was on it as a kid, I had to go for weekly blood tests to make sure it wasn’t building up in my system to toxic levels. Due to their side-effects and potential toxicity, theophyllines are only used in people whose asthma is very severe and uncontrolled. On a completely-unrelated-to-the-medicine note: theophylline syrup tastes absolutely terrible, and I learned to swallow pills at four so I wouldn’t have to take it anymore.
Antihistamines are drugs which prevent allergic reactions by either preventing the production of histamine or preventing the binding of histamine to its receptor. It is a broad class which includes many different sub-families but they all work by preventing the allergic reaction from completing by stopping the action of histamine on cells. This in turn prevents allergic inflammation and bronchospasm. Some people with allergic asthma (me included) have allergy medicines included for some asthma attacks (I’m supposed to take diphenhydramine if I think allergies might be playing a role in my asthma attack). There are far, far, far, far, far too many antihistamines to even try to list all of them, but a partial list of antihistamines may be found here.
Oral corticosteroids are the pill version of inhaled corticosteroids, and work in a similar manner, except throughout your whole body rather than just at your lungs. Due to systemic application, they come with a lot of very nasty side-effects, and the risk of side-effects increases as the length of time you’re on them increases. For this reason, doctors try to avoid treating people with oral steroids, and won’t prescribe them except for serious flares or for those who can’t control their asthma any other way.
Humanized antibodies represent the only class of asthma drug I’ve never been on. The only asthma drug in this class is Omalizumab. There is a not-unsubstantial risk of anaphylaxis associated with humanized antibody treatment, and for this reason, humanized antibody treatment is only prescribed to those with moderate to severe asthma that is unresponsive to steroid treatment. They work by blocking cell receptors that lead to serious allergic reactions, including severe allergic asthma and anaphylaxis. Xolair is also very expensive. Depending on dose, it can cost up to $2,000/mo.
For asthma treatment, doctors usually follow a stepwise approach to treatment: This means that asthma medicine is increased if you’re doing badly and if you’re doing well for more than six months, they will try reducing your medicine to see if you can manage on lower doses. This allows for the fact that asthma can change in severity and may actually get better over time, while allowing doctors to respond if your asthma control is lacking. Canadian Thoracic Society sets the guidelines for asthma treatment in Canada, while equivalent organizations set similar guidelines in other countries.