Respiratory Drugs

Respiratory system mediates gas exchange between external environment and blood.

Drug Class	*Mechanism*	*Examples*	*Side effects*
Antitussive: for cough with cold or minor irritation.	Usually combined with aspirin or acetaminophen. Opiate drugs suppress cough reflex by central inhibitory effect. Non-opioid work by inhibiting irritant effects of histamine or by local anesthetic action on the respiratory epithelium.	Codeine, hydrocodone	Sedation, dizziness, GI upset.
Decongestants: Mucosal discharge, allergies	Alpha-1 agonists: bind ot receptors located on blood vessels and stimulate casoconstriction hence drying up mucosal vasculature.	Ephedrine, epinephrine	Headache, dizziness, nervousness, nausea. Prolonged use causes more adverse effects.
Antihistamines: for sedation and treatment of allergies	Histamine is endogenous chemical involved in normal regulation of physiological functions eg gastric secretions and hypersensitivity reactions. It works by exerting effect on two receptors H1 (found in vascular, GI track and respiratory tissue) and H2 (responsible for gastric secretions, can cause peptic ulcers). Antihistamines block the receptors.	Azatadine, clemastine (Tavist), tefenadine (Seldane)	Sedation, fatigue, dizziness, GI stress etc.
Mucolytics and expectorants: used in colds and pneumonia or chronic bronchitis.	Mucolytics attempt to decrease viscosity of respiratory secretions. Expectorants facilitate production and ejection of mucus.	Acetylcysteine (Mucosil)- inhalation drug.	GI irritation

*Drug Class*	*Mechanism*	*Examples*	*Side effects*
Beta-adrenergic Agonists	Relax the bronchiole smooth muscle hence prevent obstruction. Usually delivered by inhalation	Albuterol, epinephrine, ephedrine	Bronchial irritation. Other effects depend on route of administration.
Xanthine derivatives	Work by causing bronchodilation by inhibition of Ca ion release or prostaglandin inhibition. It may also increases respiratory muscle strength, accelerates mucociliary transport, decreases pulmonary artery pressure etc.	Theophylline, dyphylline	Toxicity, early signs are nausea, confusion, irritability etc. Serious side effects may be cardiac arrhythmias or seizures.
Anticholinergic drugs	Block the muscarinic receptors to cause bronchoconstriction (not the first choice of drugs)	Atropine	Dry mouth, constipation, urinary retention, confusion etc.
Coricosteroids: most effective for asthma.	Control the inflammation mediated bronchospasm by inhibiting the the production of prostaglandins and leukitrienes.	Flunisolide	Osteoporosis, skin breakdown, muscle wasting, aggravationof diabetes and hypertionsion.
Cromolyn Sodium: prevent bronchospasm with asthma	Prevents bronchoconsitriction by inhibiting release of inflammatory mediators like histamine and leukotrienes.	Carmolyn sodium	Irritation of upper respiratory passages.

Asthma is characterized by bronchial smooth muscle spasm, airway inflammation and mucous plugging of the airways. In some cases triggers for asthma attack are well defined eg pollen, dust, chemicals etc. Other factors may include exercise, cold, stress etc.

Cause: airway inflammation seems to be the initiating factor. Cells like the macrophages, neutrophils etc cause release of inflammatory chemicals like the prostaglandins, leukotrienes, histamine etc.

Treatment and Management: has been bronchodilators (eg beta agonists) and coriticosteroids. Patients should try and recognize the triggers for their asthma and consequently avoid them.

Hereditory disease affecting all major exocrine glands resulting in thick viscous secretions. These secretions cause obstruction in major ducts of glands and organs. Respiratory problems like pneumonia, bronchiectasis, pulmonary fibrosis and pulmonary infections are very common.

Treatment: bronchodilators and mucolytic/expectorant drugs help unplug the mucous. Infections can be treated by antibiotics. Breathing exercises etc also help.