A bronchodilator or broncholytic (although the latter occasionally includes

secretory 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classica ...

inhibition as well) is a substance that dilates the

bronchi A bronchus is a passage or airway in the lower respiratory tract that conducts air into the lungs. The first or primary bronchi pronounced (BRAN-KAI) to branch from the trachea at the carina are the right main bronchus and the left main bronchus. ...

and

bronchiole The bronchioles or bronchioli (pronounced ''bron-kee-oh-lee'') are the smaller branches of the bronchial airways in the lower respiratory tract. They include the terminal bronchioles, and finally the respiratory bronchioles that mark the start ...

s, decreasing resistance in the respiratory airway and increasing airflow to the

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...

s. Bronchodilators may be originating naturally within the body, or they may be

medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...

s administered for the treatment of breathing difficulties, usually in the form of

inhaler An inhaler (also known as a puffer, pump or allergy spray) is a medical device used for delivering medicines into the lungs through the work of a person's breathing. This allows medicines to be delivered to and absorbed in the lungs, which prov ...

s. They are most useful in

obstructive lung disease Obstructive lung disease is a category of respiratory disease characterized by airway obstruction. Many obstructive diseases of the lung result from narrowing (obstruction) of the smaller bronchi and larger bronchioles, often because of excessiv ...

s, of which

asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...

and

chronic obstructive pulmonary disease Chronic obstructive pulmonary disease (COPD) is a type of progressive lung disease characterized by long-term respiratory symptoms and airflow limitation. The main symptoms include shortness of breath and a cough, which may or may not produce ...

are the most common conditions. Although this remains somewhat controversial, they might be useful in bronchiolitis and

bronchiectasis Bronchiectasis is a disease in which there is permanent enlargement of parts of the airways of the lung. Symptoms typically include a chronic cough with mucus production. Other symptoms include shortness of breath, coughing up blood, and chest ...

. They are often prescribed but of unproven significance in

restrictive lung disease Restrictive lung diseases are a category of extrapulmonary, pleural, or parenchymal respiratory diseases that restrict lung expansion, resulting in a decreased lung volume, an increased work of breathing, and inadequate ventilation and/or oxygena ...

s. Bronchodilators are either short-acting or long-acting. Short-acting medications provide quick or "rescue" relief from acute

bronchoconstriction Bronchoconstriction is the constriction of the airways in the lungs due to the tightening of surrounding smooth muscle, with consequent coughing, wheezing, and shortness of breath. Causes The condition has a number of causes, the most common be ...

. Long-acting bronchodilators help to control and prevent symptoms. The three types of prescription bronchodilating drugs are

beta2-adrenergic agonist Beta2-adrenergic agonists, also known as adrenergic β2 receptor agonists, are a class of drugs that act on the β2 adrenergic receptor. Like other β adrenergic agonists, they cause smooth muscle relaxation. β2 adrenergic agonists' effect ...

s (short- and long-acting),

anticholinergics Anticholinergics (anticholinergic agents) are substances that block the action of the neurotransmitter called acetylcholine (ACh) at synapses in the central and peripheral nervous system. These agents inhibit the parasympathetic nervous sys ...

(short- and long-acting), and

theophylline Theophylline, also known as 1,3-dimethylxanthine, is a phosphodiesterase inhibiting drug used in therapy for respiratory diseases such as chronic obstructive pulmonary disease (COPD) and asthma under a variety of brand names. As a member of the ...

(long-acting).

Short-acting β₂-adrenergic agonists

These are quick-relief or "rescue" medications that provide quick, temporary relief from asthma symptoms or flare-ups. These medications usually take effect within 20 minutes or less, and can last from four to six hours. These inhaled medications are best for treating sudden and severe or new asthma symptoms. Taken 15 to 20 minutes ahead of time, these medications can also prevent asthma symptoms triggered by exercise or exposure to cold air. Some short-acting β-agonists, such as

salbutamol Salbutamol, also known as albuterol and sold under the brand name Ventolin among others, is a medication that opens up the medium and large airways in the lungs. It is a short-acting β2 adrenergic receptor agonist which works by causing rel ...

, are specific to the lungs; they are called β₂-adrenergic agonists and can relieve bronchospasms without unwanted

cardiac The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...

side effects of nonspecific β-agonists (for example,

ephedrine Ephedrine is a central nervous system (CNS) stimulant that is often used to prevent low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment. It is of unclear benefit in ...

epinephrine Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...

). Patients who regularly or frequently need to take a short-acting β₂-adrenergic agonist should consult their doctor, as such usage indicates uncontrolled asthma, and their routine medications may need adjustment.

Long-acting β₂-adrenergic agonists

These are long-term medications taken routinely in order to control and prevent bronchoconstriction. They are not intended for fast relief. These medications may take longer to begin working, but relieve airway constriction for up to 12 hours. Commonly taken twice a day with an anti-inflammatory medication, they maintain open airways and prevent asthma symptoms, particularly at night. Salmeterol and formoterol are examples of these.

Anticholinergics

Some examples of anticholinergics are tiotropium (Spiriva) and

ipratropium bromide Ipratropium bromide, sold under the trade name Atrovent among others, is a type of anticholinergic (SAMA: short acting muscarinic antagonist) medication which opens up the medium and large airways in the lungs. It is used to treat the symptom ...

. Tiotropium is a long-acting, 24-hour, anticholinergic bronchodilator used in the management of

(COPD). Only available as an inhalant, ipratropium bromide is used in the treatment of asthma and COPD. As a short-acting anticholinergic, it improves lung function and reduces the risk of exacerbation in people with symptomatic asthma. However, it will not stop an asthma attack already in progress. Because it has no effect on asthma symptoms when used alone, it is most often paired with a short-acting β₂-adrenergic agonist. While it is considered a relief or rescue medication, it can take a full hour to begin working. For this reason, it plays a secondary role in acute asthma treatment. Dry throat is the most common side effect. If the medication gets in contact with the eyes, it may cause blurred vision for a brief time. The use of anticholinergics in combination with short-acting β₂-adrenergic agonists has been shown to reduce hospital admissions in children and adults with acute asthma exacerbations.

Other

Available in oral and injectable form,

is a long-acting bronchodilator that prevents asthma episodes. It belongs to the chemical class methylxanthines (along with caffeine). It is prescribed in severe cases of asthma or those that are difficult to control. It must be taken 1–4 times daily, and doses cannot be missed. Blood tests are required to monitor therapy and to indicate when dosage adjustment is necessary. Side effects can include nausea, vomiting, diarrhea, stomach or headache, rapid or irregular heart beat, muscle cramps, nervous or jittery feelings, and hyperactivity. These symptoms may signal the need for an adjustment in medication. It may promote

acid reflux Gastroesophageal reflux disease (GERD) or gastro-oesophageal reflux disease (GORD) is one of the upper gastrointestinal chronic diseases where stomach content persistently and regularly flows up into the esophagus, resulting in symptoms and/ ...

, also known as GERD, by relaxing the lower esophageal sphincter muscle. Some medications, such as seizure and ulcer medications and antibiotics containing

erythromycin Erythromycin is an antibiotic used for the treatment of a number of bacterial infections. This includes respiratory tract infections, skin infections, chlamydia infections, pelvic inflammatory disease, and syphilis. It may also be used durin ...

, can interfere with the way theophylline works. Coffee, tea, colas, cigarette-smoking, and viral illnesses can all affect the action of theophylline and change its effectiveness. A physician should monitor dosage levels to meet each patient's profile and needs. Additionally some

psychostimulant Stimulants (also often referred to as psychostimulants or colloquially as uppers) is an overarching term that covers many drugs including those that increase activity of the central nervous system and the body, drugs that are pleasurable and inv ...

drugs that have an amphetamine like mode of action, such as

amphetamine Amphetamine (contracted from alpha- methylphenethylamine) is a strong central nervous system (CNS) stimulant that is used in the treatment of attention deficit hyperactivity disorder (ADHD), narcolepsy, and obesity. It is also commonly used ...

methamphetamine Methamphetamine (contracted from ) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disorder and obesity. Methamp ...

, and

cocaine Cocaine (from , from , ultimately from Quechua: ''kúka'') is a central nervous system (CNS) stimulant mainly used recreationally for its euphoric effects. It is primarily obtained from the leaves of two Coca species native to South Am ...

, have bronchodilating effects and were used often for

due to the lack of effective β₂-adrenergic agonists for use as bronchodilator, but are now rarely, if ever, used medically for their bronchodilatory effects.

Common bronchodilators

The bronchodilators are divided into short- and long-acting groups. Short-acting bronchodilators are used for relief of bronchoconstriction, while long-acting bronchodilators are predominantly used for prevention. Short-acting bronchodilators include: *

Salbutamol Salbutamol, also known as albuterol and sold under the brand name Ventolin among others, is a medication that opens up the medium and large airways in the lungs. It is a short-acting β2 adrenergic receptor agonist which works by causing rel ...

/albuterol (Proventil or Ventolin) * Levosalbutamol/levalbuterol (Xopenex) * Pirbuterol (Maxair) *

Epinephrine Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands and ...

(Primatene Mist) *

Racemic Epinephrine Epinephrine, also known as adrenaline, is a medication and hormone. As a medication, it is used to treat several conditions, including anaphylaxis, cardiac arrest, asthma, and superficial bleeding. Inhaled epinephrine may be used to improve t ...

(Asthmanefrin, Primatene Mist Replacement) *

Ephedrine Ephedrine is a central nervous system (CNS) stimulant that is often used to prevent low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment. It is of unclear benefit in ...

(Bronkaid) *

Terbutaline Terbutaline, sold under the brand names Bricanyl and Marex among others, is a β2 adrenergic receptor agonist, used as a "reliever" inhaler in the management of asthma symptoms and as a tocolytic (anti-contraction medication) to delay preterm ...

Long-acting bronchodilators include * Salmeterol (Serevent or Seretide) *

Clenbuterol Clenbuterol is a sympathomimetic amine used by sufferers of breathing disorders as a decongestant and bronchodilator. People with chronic breathing disorders such as asthma use this as a bronchodilator to make breathing easier. It is most commonl ...

(Spiropent) * Formoterol * Bambuterol *

Indacaterol Indacaterol is an ultra-long-acting beta-adrenoceptor agonist developed by Novartis. It needs to be taken only once a day, unlike the related drugs formoterol and salmeterol. It is licensed only for the treatment of chronic obstructive pulmonar ...

Experimental bronchodilator

From among 6000 compounds that relax the smooth muscle cells of the lungs' airways and open up the airways in asthmatic lung tissues, researchers have identified a drug called TSG12. TSG12 is a specific transgelin-2 (TG2)-agonist that relaxes airway smooth muscle cells and reduces asthmatic pulmonary resistance. The authors claim that "TSG12 is both non-toxic and more effective in reducing pulmonary resistance than current bronchodilators and could be a promising therapeutic approach for treating asthma without losing effectiveness over time."

References

External links

Drug information
{{Respiratory physiology Respiratory physiology Respiratory therapy Pulmonary function testing

Short-acting β2-adrenergic agonists

Long-acting β2-adrenergic agonists