Respiratory system drugs

Drugs of the respiratory system are mainly used to treat lung conditions such as asthma and chronic obstructive pulmonary disease (COPD). They include the following.

Beta 2 agonists: These drugs are sympathetic agonists that activate beta 2 receptors in the airways. This relaxes smooth muscle in the bronchi and causes bronchodilation. They include:

Short-acting agonists such as albuterol (also called salbutamol) (Ventolin, Proventil HFA, ProAir) and terbutaline (Brethine, Bricanyl)
Long-acting agonists such as salmeterol (Serevent Diskus), vilanterol (available only in combination inhalers such as Breo Ellipta and Trelegy Ellipta), and formoterol (Perforomist, Foradil Aerolizer)

Some medications are available in combination, for example fluticasone with salmeterol (Advair Diskus, Advair HFA).

Only quick-acting beta 2 agonists such as albuterol are effective for controlling acute asthma.

Adverse effects include tremors, tachycardia, headache, dizziness, and sore throat. Salmeterol can increase the risk of severe asthma attacks and death and can increase blood sugar levels.

Corticosteroids: Corticosteroids are anti-inflammatory drugs. They reduce secretions and mucosal inflammation and decrease the severity and frequency of asthma attacks.

Adverse effects include oral candidiasis, cough, adrenal suppression, osteoporosis, growth suppression, peptic ulcers, myopathy, hypertension, and Cushing’s syndrome.

After using an inhaled corticosteroid, the mouth should be rinsed with water to reduce local side effects such as throat irritation, hoarseness, and thrush (candidal infection of the throat).

Corticosteroids used in asthma and COPD include budesonide (Pulmicort Flexhaler), beclomethasone (Qvar Redihaler, Beclovent), fluticasone (Flovent HFA), triamcinolone (Aristocort), prednisolone (Flo-Pred, Millipred, PredForte), methylprednisolone (Medrol), and prednisone (Rayos, Deltasone, Sterapred).

Some popular corticosteroid combinations include Breo Ellipta (fluticasone and vilanterol) and Dulera (formoterol and mometasone).

Theophylline: Theophylline (Theo-24, Elixophyllin) is a methylxanthine that inhibits the enzyme phosphodiesterase. This prevents the breakdown of cAMP, leading to increased cAMP and bronchodilation.

Adverse effects include tachycardia, arrhythmias, sudden death, nervousness, insomnia, tremors, seizures, and gastric upset. It has a narrow therapeutic index, so drug levels need to be monitored regularly.

Muscarinic antagonists: Muscarinic antagonists used in respiratory diseases include ipratropium (Atrovent, Atrovent HFA) and tiotropium (Spiriva HandiHaler, Spiriva Respimat). They block muscarinic receptors in the airways, which decreases bronchoconstriction and mucosal secretion.

Adverse effects include dry mouth, throat irritation, urinary retention, tachycardia, delirium, and blurred vision.

Cromolyn and nedocromil: These drugs inhibit the release of inflammatory mediators from mast cells and suppress leukocyte chemotaxis, which suppresses inflammation. They are used to prevent asthma, including exercise-induced and allergen-induced bronchoconstriction. For asthma, cromolyn is given by nebulizer as a generic inhalation solution. The oral concentrate (Gastrocrom) is used for mastocytosis, not asthma.

These drugs are generally well tolerated, with minor adverse effects including cough, unpleasant taste, dermatitis, and muscle inflammation (myositis).

Zileuton: Zileuton (Zyflo) inhibits the enzyme 5 lipoxygenase, which is used in the synthesis of inflammatory mediators called leukotrienes.

Adverse effects include headache, nausea, gastric upset, myalgia, and vasculitis. Serious liver damage may occur.

Leukotriene modifiers: These drugs antagonize the action of leukotrienes on the airways by blocking leukotriene receptors.

Adverse effects are similar to zileuton and include headache, nausea, gastric upset, myalgia, and vasculitis. Serious liver damage may occur.

They include montelukast (Singulair) and zafirlukast (Accolate).

Monoclonal antibodies: Monoclonal antibodies are synthetic antibodies, and each type binds to only one antigen. They are included in the drug group known as biologics and have varied uses in the diagnosis and treatment of diseases.

Monoclonal antibodies used in the treatment of asthma include omalizumab (Xolair), tezepelumab (Tezspire), dupilumab (Dupixent), benralizumab (FASENRA), mepolizumab (NUCALA), and reslizumab (CINQAIR).

Common adverse effects include sore throat, joint pain, rash, and back pain. Additional adverse effects include worm infestation with tezepelumab and nosebleeds and ear infections with omalizumab.

Live attenuated vaccines (such as measles and rotavirus) must be avoided when taking tezepelumab.

Benralizumab, dupilumab, and mepolizumab are also interleukin inhibitors.

Beta 2 agonists

Activate beta 2 receptors → relax bronchial smooth muscle → bronchodilation
Short-acting: albuterol/salbutamol, terbutaline; only these effective for acute asthma attacks
Long-acting: salmeterol, vilanterol, formoterol; often combined with corticosteroids (e.g., Advair)
Adverse effects: tremors, tachycardia, headache, dizziness, sore throat
- Salmeterol: increased risk of severe attacks/death, raises blood sugar

Corticosteroids

Anti-inflammatory; reduce secretions, mucosal inflammation, attack frequency/severity
Examples: budesonide, beclomethasone, fluticasone, triamcinolone, prednisolone, methylprednisolone, prednisone
Combinations: Breo Ellipta, Dulera
Adverse effects: oral candidiasis, cough, adrenal suppression, osteoporosis, growth suppression, peptic ulcers, myopathy, hypertension, Cushing’s syndrome
Rinse mouth with water after inhaled use to prevent thrush/throat irritation

Theophylline

Methylxanthine; inhibits phosphodiesterase → increases cAMP → bronchodilation
Narrow therapeutic index → requires regular drug level monitoring
Adverse effects: tachycardia, arrhythmias, sudden death, nervousness, insomnia, tremors, seizures, gastric upset

Muscarinic antagonists

Block muscarinic receptors → decrease bronchoconstriction and mucosal secretion
Examples: ipratropium, tiotropium
Adverse effects: dry mouth, throat irritation, urinary retention, tachycardia, delirium, blurred vision

Cromolyn and nedocromil

Inhibit mast cell mediator release; suppress leukocyte chemotaxis and inflammation
Used to prevent asthma (exercise-/allergen-induced); cromolyn given via nebulizer
- Oral cromolyn (Gastrocrom) used for mastocytosis, not asthma
Well tolerated; adverse effects: cough, unpleasant taste, dermatitis, myositis

Zileuton

Inhibits 5-lipoxygenase enzyme → blocks leukotriene synthesis
Adverse effects: headache, nausea, gastric upset, myalgia, vasculitis
Risk of serious liver damage

Leukotriene modifiers

Block leukotriene receptors → antagonize leukotriene action on airways
Examples: montelukast, zafirlukast
Adverse effects similar to zileuton: headache, nausea, gastric upset, myalgia, vasculitis, possible liver damage

Monoclonal antibodies

Synthetic, antigen-specific antibodies; classified as biologics
Examples: omalizumab, tezepelumab, dupilumab, benralizumab, mepolizumab, reslizumab
Common adverse effects: sore throat, joint pain, rash, back pain
- Tezepelumab: worm infestation risk; avoid live vaccines
- Omalizumab: nosebleeds, ear infections
Benralizumab, dupilumab, mepolizumab also act as interleukin inhibitors

Respiratory system drugs

Drugs of the respiratory system are mainly used to treat lung conditions such as asthma and chronic obstructive pulmonary disease (COPD). They include the following.

Beta 2 agonists: These drugs are sympathetic agonists that activate beta 2 receptors in the airways. This relaxes smooth muscle in the bronchi and causes bronchodilation. They include:

Short-acting agonists such as albuterol (also called salbutamol) (Ventolin, Proventil HFA, ProAir) and terbutaline (Brethine, Bricanyl)
Long-acting agonists such as salmeterol (Serevent Diskus), vilanterol (available only in combination inhalers such as Breo Ellipta and Trelegy Ellipta), and formoterol (Perforomist, Foradil Aerolizer)