Introduction to the respiratory system and medications

The respiratory system exchanges oxygen (O${}_2$) and carbon dioxide (CO${}_2$) through two main processes:

• Inspiration (inhaling), which brings air into the lungs
• Expiration (exhaling), which moves air out of the lungs

It includes structures in the upper and lower respiratory tracts, such as the nose, trachea, bronchi, and lungs.

Asthma is a common respiratory disease caused by an abnormal allergic response. This response leads to inflammation and narrowing of the airways, which makes breathing more difficult. Several medication classes are used to treat asthma:

• Some are used as rescue medications for quick relief during an attack
• Others are used to prevent attacks and reduce their severity over time

Chronic obstructive pulmonary disease (COPD) includes chronic bronchitis and emphysema. These conditions cause long-term breathing problems.

An acute infection of the lung tissues is called pneumonia. Pneumonia is treated with antimicrobials tailored to the causative microorganism.

Table showing common drug classes and examples of the respiratory system

Drug class	Generic name	Brand name(s)	Primary use
Beta 2 agonists	Albuterol, salmeterol	Ventolin, Serevent Diskus	Asthma, COPD
Inhaled corticosteroids	Budesonide, fluticasone	Pulmicort Flexhaler, Flovent HFA	Asthma, COPD
Anticholinergics or muscarinic antagonists	Ipratropium, tiotropium	Atrovent, Spiriva Respimat	COPD
Leukotriene modifiers	Montelukast, zafirlukast	Singulair, Accolate	Asthma, allergies
Antihistamines	Diphenhydramine, cetirizine, loratidine	Benadryl, Zyrtec, Claritin	Allergies
Antitussives	Benzonatate, dextromethorphan	Tessalon, Delsym	Treatment of cough
Decongestants	Phenylephrine, pseudoephedrine	Sudafed	Treatment of nasal congestion