What are bronchodilators, and how do they work?
Bronchodilators are medications that open (dilate) the airways (bronchial
tubes) of the lung by relaxing bronchial muscles and allow people who have
difficulty breathing to breath better. Bronchodilators are used for treating:
-
Asthma -
Chronic obstructive pulmonary disease (COPD -
Allergic reactions - Related conditions that cause breathing problems
Asthma is a breathing problem resulting from narrowing of the airways that
allow air to move in and out of the lungs. These airways become narrowed from
the accumulation of mucus, spasm of the muscles that surround these airways
(bronchospasm), or swelling of the lining of the airways. Airway narrowing leads
to symptoms of asthma which include:
- Shortness of breath
- Wheezing
- A cough
- Congestion
Do I need a prescription for bronchodilators?
- Yes. Bronchodilators approved for treating asthma and other respiratory conditions
are prescription products. - Over the counter (OTC), homeopathic, or herbal
products often promoted for treating asthma are not approved by the FDA and they
are not considered effective by many doctors.
What are the uses for bronchodilators?
The bronchodilators listed in this article are used for managing bronchospasm
due to asthma, reactive airway disease, and exercise-induced asthma.
- Short-acting beta-adrenergic bronchodilators and ipratropium work quickly and
are used for acute management of asthma episodes. - Long-acting beta-adrenergic
bronchodilators, tiotropium, and theophylline are used daily and long-term for
preventing asthma attacks or reducing the frequency of symptoms.
What types of bronchodilators are available to treat asthma?
The three types of bronchodilators used for treating asthma
are; 1) beta-adrenergic bronchodilators; 2) anticholinergic bronchodilators; and
3)
xanthine derivatives.
- Beta-adrenergic bronchodilators dilate bronchial airways by relaxing the
muscles that surround the airways. Beta-adrenergic bronchodilators are beta-2
agonists. These medications stimulate beta-2 receptors on the smooth muscle
cells that line the airways, causing these muscle cells to relax, thus, opening
airways. - Anticholinergic bronchodilators block the effect of acetylcholine on airways
and nasal passages. Acetylcholine is a chemical that nerves use to communicate
with muscle cells. In asthma, cholinergic nerves going to the lungs cause
narrowing of the airways by stimulating muscles surrounding the airways to
contract. The "anticholinergic" effect of anticholinergic bronchodilators blocks
the effect of cholinergic nerves, causing the muscles to relax and airways to
dilate. - Xanthine derivatives open airways by relaxing the smooth muscles in the walls
of the airways and they also suppress the response of the airways to stimuli.
The mechanism of action of xanthines is not fully understood. Xanthine
derivatives may dilate bronchi by blocking the action of phosphodiesterase (PDE)
enzymes which ultimately leads to increased concentration of chemicals that
dilate bronchial airways.
List of short-acting and long-acting bronchodilators, anticholinergic bronchodilators, and xanthine derivatives
Short-acting beta-adrenergic bronchodilator inhalers available in the US
- albuterol (AccuNeb, Proair HFA, Proventil HFA, Ventolin HFA)
- levalbuterol (Xopenex HFA)
- epinephrine injection
Long-acting beta-adrenergic bronchodilator asthma inhalers available in the
US
- salmeterol (Servant Diskus)
- formoterol (Perforomist)
Anticholinergic bronchodilators available in the US
- ipratropium (Atrovent HFA)
- tiotropium (Spiriva Respimat)
Examples of xanthine derivatives available in the US
- theophylline (Theo 24, Elixophyllin, Uniphyl)
- aminophylline
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What are the side effects of bronchodilators?
Side effects of bronchodilators vary depending on the type of bronchodilator.
Beta-adrenergic bronchodilators side effects
Common side effects of beta-adrenergic bronchodilators include:
- Migraine headaches
- Non-migraine headaches
- Nausea
- Stomach upset
- Flu-like symptoms
- Cold symptoms
- Ear infections (otitis media)
- Bronchitis
- Cough
Other side effects of beta-adrenergic bronchodilators include:
- Allergic reactions (rash, hives, itching)
- Nervousness
- Tremor
- Wheezing
- Increased sputum
- Shortness of breath
Possible serious side effects of beta-adrenergic bronchodilators include:
- Bronchospasm (worsening of asthma)
- Serious allergic reactions (anaphylaxis)
- Low potassium
- Abnormal heart rhythm (palpitations)
- Fast heart rate
- Elevated blood pressure
- Chest pain
Anticholinergic bronchodilators side effects
Common side effects of anticholinergic bronchodilators include:
Other side effects of anticholinergic bronchodilators include:
- Rash
- Itching
- Flu-like symptoms
- Indigestion
- Back pain
- Sinusitis
- Bronchitis
Possible serious side effects of anticholinergic bronchodilators include:
- Life-threatening bronchospasms
- Serious allergic reactions involving the closure of the airways.
- Worsening symptoms of benign prostatic hyperplasia
- Worsening symptoms of narrow-angle glaucoma
Xanthines side effects
Common side effects of xanthines include:
- Nausea
- Vomiting
- Diarrhea
- Headaches
- Irritability
- Flushing
- Palpitations
Other side effects of xanthines include:
Possible serious side effects of xanthines include:
- Seizures
- Shock
- Heart arrhythmias
- Hypotension
- Exfoliative dermatitis
QUESTION
Asthma is a chronic respiratory disease.
See Answer
Which drugs or supplements interact with bronchodilators?
Drug interactions of beta-adrenergic bronchodilators
- Tricyclic antidepressants, for example, amitriptyline (Elavil, Endep), and
monoamine oxidase inhibitors (MAOIs), for example, tranylcypromine, should not
be combined with beta-adrenergic bronchodilators because of their additive
effects on the vascular system (for example, increased blood pressure and/or
heart rate). A period of two weeks should elapse between treatment with
beta-adrenergic bronchodilators and tricyclic antidepressants or monoamine
oxidase inhibitors. - Use of beta-adrenergic bronchodilators with other stimulant medications is
discouraged because of their combined effects on heart rate, blood pressure, and
the potential for causing chest pain in patients with underlying coronary heart
disease. - Beta-blockers, for example, propranolol (Inderal, Inderal LA), block the
effect of beta-adrenergic bronchodilators and may induce bronchospasm in
asthmatics. - Beta-adrenergic bronchodilators may cause hypokalemia (low potassium).
Therefore, combining beta-adrenergic bronchodilators with loop diuretics, for
example, furosemide (Lasix), may increase the likelihood of hypokalemia.
Drug interactions of anticholinergic bronchodilators
- Use with other anticholinergic drugs (for example, atropine) may increase the
occurrence of side effects.
Drug interactions of xanthine bronchodilators
- Allopurinol (Zyloprim), cimetidine (Tagamet), ciprofloxacin (Cipro),
clarithromycin (Biaxin), itraconazole (Sporanox), ketoconazole, erythromycin,
oral contraceptives, fluvoxamine (Luvox), ephedrine, and propranolol (Inderal)
elevate theophylline blood levels and can lead to toxicity. Theophylline
toxicity causes nausea, vomiting, insomnia, seizures, agitation, and life-
threatening heart rhythm abnormalities. - St. John’s Wort, rifampin, and carbamazepine decrease levels of theophylline
and potentially its effect by increasing its elimination. - Theophylline may decrease levels and the effect of carbamazepine by
increasing its elimination. Theophylline is metabolized mainly by the liver and
dosages should be reduced in patients with liver dysfunction. On the other hand,
theophylline is generally metabolized more rapidly in smokers (both tobacco and
marijuana) and higher dosages may be required.
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Are bronchodilators safe to use during pregnancy or while breastfeeding?
Beta-adrenergic bronchodilators
- Beta-adrenergic bronchodilators are used for treating children. However,
there are no adequate studies of beta-adrenergic bronchodilator use during
pregnancy. Some reports indicate that albuterol sulfate may cause congenital
defects when used during pregnancy. - It's not known whether beta-adrenergic bronchodilators are excreted in breast
milk.
Anticholinergics
- The safety of anticholinergic bronchodilators in pregnant women or nursing
mothers has not been adequately evaluated.
Xanthine bronchodilators
- Xanthine bronchodilators have not been adequately studied in pregnant women.
Theophylline is excreted in breast milk and may cause mild side effects such as
irritability in the infant. - The risks to the fetus or breast-feeding infant versus the risk to the woman should be considered before using bronchodilators in pregnant women; consultation with the patient’s OB/GYN doctor may be advisable.
Are there differences between bronchodilators?
Bronchodilators differ in their mechanism of action, how quickly they work,
and their duration of action, their uses, side effects, and how they are
administered. Beta-adrenergic bronchodilators are supplied as aerosols for
inhalation, powders for inhalation, solution for nebulization, syrup, and
tablets. Anticholinergic bronchodilators are supplied as solutions for
inhalation, powder for inhalation, and nebulized solution. Xanthines are
supplied as tablets, capsules, elixir, and solution for injection.