Chapter 9 Respiratory System Drugs Copyright © 2011 Delmar, Cengage Learning

Basic Anatomy and Physiology The respiratory system is the body system that brings oxygen from the air into the body for delivery via the blood to cells Respiration is the exchange of gases between the atmosphere and the cells of the body Ventilation is the bringing in of fresh air Copyright © 2011 Delmar, Cengage Learning

Basic Anatomy and Physiology Copyright © 2011 Delmar, Cengage Learning

Respiratory Conditions Respiratory conditions are categorized into upper and lower respiratory conditions –Upper respiratory conditions in animals are mainly caused by infectious agents that produce clinical signs such as congestion and coughs –Lower respiratory conditions in animals include asthma, bronchitis, pneumonia, and chronic obstructive pulmonary disease (COPD) COPD in horses is commonly called “heaves” Copyright © 2011 Delmar, Cengage Learning

Respiratory Drugs Expectorants –Increase the flow of respiratory secretions to allow material to be coughed up from the lungs –Increase the fluidity of mucus –An example is guaifenesin Copyright © 2011 Delmar, Cengage Learning

Respiratory Drugs Mucolytics –Decrease the viscosity or thickness of respiratory secretions –An example is acetylcysteine (also used to treat acetaminophen toxicity) Copyright © 2011 Delmar, Cengage Learning

Respiratory Drugs Antitussives –Suppress coughs –May be centrally acting or locally acting –Centrally acting antitussives include butorphanol, hydrocodone, codeine, dextromethorphan, and trimeprazine (in a combination product) Copyright © 2011 Delmar, Cengage Learning

Respiratory Drugs Decongestants –Decrease the congestion of nasal passages by reducing swelling –Examples include phenylephrine and pseudoephedrine Copyright © 2011 Delmar, Cengage Learning

Respiratory Drugs Bronchodilators –Widen the lumen of the bronchi and counteract bronchoconstriction –Examples include cholinergic blocking agents (anticholinergics such as aminopentamide, atropine, and glycopyrrolate), beta-2-adrenergic agonists (such as epinephrine, isoproterenol, terbutaline, and albuterol), and methylxanthines (such as aminophylline and theophylline) Copyright © 2011 Delmar, Cengage Learning

Respiratory Drugs Antihistamines –Block the effects of histamine –Antihistamine drug names usually end with – amine –Side effects include CNS depression and anticholinergic effects such as dry mouth –Examples include diphenhydramine and chlorpheniramine Copyright © 2011 Delmar, Cengage Learning

Respiratory Drugs Respiratory stimulants –Stimulate the animal to increase its respirations –Examples include naloxone (usually used to stimulate respiration following narcotic overdose) and yohimbine (used to reverse xylazine administration or overdose) Copyright © 2011 Delmar, Cengage Learning

Asthma Drugs Glucocorticoids: –anti-inflammatory drugs administered orally or by inhalation –Orally used to treat feline asthma –Inhaled used to decrease swollen and narrowed airways by decreasing inflammation –There are fewer side effects with inhaled glucocorticoids than with oral ones Bronchodilators: –Used in addition to glucocorticoids in the treatment of feline asthma –Side effects include tracheal or bronchial irritation Copyright © 2011 Delmar, Cengage Learning

Asthma Drugs Methylxanthines: –Another group of bronchodilators used in the treatment of feline asthma –Have a narrow therapeutic index Cyclosporin: –A fungal derived protein useful in the allergic response in feline asthma –Side effects include nephrotoxicity and vomiting Copyright © 2011 Delmar, Cengage Learning

Chronic Obstructive Pulmonary Disease (COPD) Drugs Is treated by using some forms of medication and keeping good management practices: –Keeping horses outside as much as possible –Reducing dust –Storing hay in a dry place –Improving ventilation in horse stables Copyright © 2011 Delmar, Cengage Learning

Chronic Obstructive Pulmonary Disease (COPD) Drugs Glucocorticoids help decrease smooth muscle contraction, suppress inflammation, and reduce mucus production Inhaled glucocorticoids are used to decrease swollen and narrow airways Bronchodilators relax the smooth muscles of the airways –Can also be combined with other anti-inflammatory drugs Copyright © 2011 Delmar, Cengage Learning