Respiratory system drugs

Drugs of the respiratory system are mainly used for the treatment of lung conditions like asthma and COPD or chronic obstructive pulmonary disease. They include the following.

Beta 2 agonists: These drugs are sympathetic agonists that activate the beta 2 receptor in the airways to cause relaxation of smooth muscle in the bronchi and bronchodilation. They include short-acting agonists like albuterol, also known as salbutamol (Ventolin, Proventil HFA, ProAir) and terbutaline (Brethine, Bricanyl), and long-acting drugs like salmeterol (Serevent Diskus, Advair HFA), vilanterol (Trelegy Ellipta) and formoterol (Perforomist, Foradil Aerolizer). Some medications are available in combination, e.g., fluticasone with salmeterol (Advair Diskus). Only quick-acting beta 2 agonists like albuterol are effective in 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 increase blood sugar levels.

Corticosteroids: Corticosteroids are anti-inflammatory, 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. The mouth should be rinsed with water after using inhaled corticosteroids, to avoid side effects such as throat irritation, hoarseness and thrush, or 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 hence 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, hence 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, decrease bronchoconstriction and mucosal secretion. Adverse effects include dry mouth, throat irritation, urinary retention, tachycardia, delirium and blurred vision.

Cromolyn and nedocromil: They inhibit the release of inflammatory mediators from mast cells and suppress inflammation. They are used to prevent exercise and allergen induced asthma. The brand name is Gastrocrom (Cromolyn). Adverse effects include cough, unpleasant taste, dermatitis and muscle inflammation or myositis.

Zileuton: Zileuton (Zyflo) inhibits the enzyme 5 lipoxygenase that 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: They 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 can only bind to one antigen. They are included in the drug group known as biologics. They have varied uses in 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. Adverse effects include worm infestation with tezepelumab and nosebleeds and ear infections with omalizumab. Live attenuated vaccines like measles, rotavirus, etc. must be avoided when taking tezepelumab. Benralizumab, dupilumab and mepolizumab are also interleukin inhibitors.