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:
Some medications are available in combination, for example fluticasone with salmeterol (Advair Diskus).
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.
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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), methylprednisone (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 inflammation. They are used to prevent exercise-induced and allergen-induced asthma. The brand name is Gastrocrom (Cromolyn).
Adverse effects include 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.
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