Agents that dilate the bronchi and bronchioles, decreasing resistance in the respiratory airway and increasing airflow to the lungs.
Bronchodilators can improve respiratory symptoms by reducing lung hyperinflation and improving inspiratory muscle efficiency.
Bronchodilators are separated into 2 major classes by the mechanisms of action and are the mainstay of COPD treatment.
Beta-2 agonists bind to beta-2 adrenergic receptors on airway smooth muscle cells, promoting bronchodilation and increasing ciliary beat frequency.
Muscarinic antagonists block M1 and M3 muscatinic receptors, preventing parasympathetic bronchoconstriction of airway smooth muscle and inhibiting goblet cell mucus secretion.
Although Oral bronchodilators are available, delivery through inhalation improves efficacy and decreases adverse effects.
Beta-2 agonist improve FEV1 and are available as short acting and long acting agents.
Beta agonists increase cyclic AMP and lower intracellular calcium concentrations resulting in relaxation of bronchial and tracheal smooth muscle, which relieves bronchospasm, reduces airway resistance, facilities mucous drainage and increases vital capacity.
Useful in obstructive lung diseases, of which asthma and chronic obstructive pulmonary disease are the most common conditions.
Use in bronchiolitis and bronchiectasis is controversial and is of unproven significance in restrictive lung diseases.
Bronchodilators are either short-acting or long-acting in nature.
Long acting bronchodilator therapy is the cornerstone management for most patients with COPD.
In some patients with mild disease, and few symptoms, short acting bronchodilators may suffice for symptom control, but in many cases they are used only as rescue medications.
Long-acting bronchodilators are indicated for patients with higher symptom burden, prior exacerbations or more severely impaired lung function in daily or twice daily preparations.
Both Long-acting beta 2 agonists (LABAs) such as formotero, vilanterol, olodadaterol, indacaterol, or aformoterol, and Long-acting muscarinic antagonists such as tiotropium, umeclidinium, glycopyrrolate, acidinium, or revefenacin reduce symptoms and decrease exacerbation risk.
Short-acting bronchodilators include short acting beta2-agonists, albuterol and levalalbuterol and short acting muscarinic antagonist ipratropium.
Short acting bronchodilators maybe used as needed alone or in combination for patients with limited symptoms or activity-specific dyspnea but are not appropriate as scheduled therapies for patients with a history of exacerbation or persistent symptoms
Short-acting medications provide quick, rescue, relief from acute bronchoconstriction, while long-acting bronchodilators help to control and prevent symptoms.
Three types of prescription bronchodilating drugs are β2-agonists, anticholinergics , and theophylline.
Short acting β2-agonists provide quick, temporary relief from asthma symptoms or bronchospasm episodes.
Short acting β2-agonists usually take effect within 20 minutes or less, and last from four to six hours.
These inhaled administered medications are utilized for treating sudden and severe or new asthma symptoms.
Short acting β2-agonists utilized 15 to 20 minutes ahead of time, can prevent asthma symptoms triggered by exercise or exposure to cold air.
Some short-acting β-agonists, such as salbutamol, are specific to the lungs; they are called β2-agonists and can relieve bronchospasms without unwanted cardiac (β1) side effects.
Frequent need to take short-acting β-agonists indicates uncontrolled asthma.
Short acting Beta 2 agonists include albuterol include side effects such as tachycardia, palpitations, tremors and hypokalemia.
Long-acting β2-agonists are long-term medications taken routinely in order to control and prevent bronchoconstriction.
Long-acting β2-agonists are not intended for fast relief, 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.
Long-acting β2-agonists include Salmeterol, Formoterol, and olodaterol.
Anti-cholinergics antagonize muscarinic receptors and block the effects of acetylcholine reducing airway constriction in mucus production.
Respiratory anticholinergic examples are tiotropium (Spiriva) and ipratropium bromide.
Short acting anti-cholinergics include ipratropium lasting 4 to 6 hours.
Long acting anticholinergics act for 12 hours and may last up to 24 hours with tiotropium.
Anti-cholinergics side effects include taste changes, dry mouth, and a slight increase in cardiovascular events.
Tiotropium is a long-acting, 24 hour, anticholinergic bronchodilator used in the management of chronic obstructive pulmonary disease (COPD).
Only available as an inhalant, ipratropium bromide is used in the treatment of asthma and COPD.
Respiratory anticholinergics will not stop an asthma attack already in progress, and has no effect on asthma symptoms when used alone, it is most often paired with a short-acting β2-agonist.
Respiratory anticholinergics are available in oral and injectable forms.
Theophylline is a long-acting bronchodilator that prevents asthma episodes.
Theophylline contains nonselective phosphodiesterase inhibitor properties and inhibits breakdown of cyclic AMP, but its mainmechanism of action remains unknown.
Theophylline available as oral or injectable agent, belongs to the chemical class methyl xanthines.
Utilized in severe cases of asthma.
Must be taken 1–4 times daily.
Monitoring plasma levels must be done as it causes smooth muscle relaxation n the lungs and is effective at doses that are near toxic with a narrow therapeutic window.
Many drugs interfere with theophylline and it’s clearance declines with aging.
Side effects of theophylline can include nausea, vomiting, diarrhea, stomach ache, headache, rapid or irregular heart beat, muscle cramps, nervousness and hyperactivity.
The presence of symptoms may indicate the need for an adjustment of theophylline medication.
Theophylline may promote GERD, by relaxing the lower esophageal sphincter muscle.
Some medications, such as seizure and ulcer medications and antibiotics containing erythromycin, 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.
Theophylline adverse reactions including with me is, grand mal seizures, sleep disturbances, nausea, headaches, and acid reflux.
Additionally some psychostimulant drugs that have an amphetamine like mode of action, such as amphetamine, methamphetamine, and cocaine, have bronchodilating effects and were used often for asthma due to the lack of effective β2-agonists for use as bronchodilator, but are now rarely, if ever, used medically for their bronchodilation effect.
Inhalation of bronchodilators is the pref2242ed route of administration associated with fewer adverse effects than oral treatment.