Respiratory System Drugs Overview

Respiratory System Drugs

• Respiration is the exchange of gases between the atmosphere and body cells. Ventilation brings fresh air into the body.
• Upper Respiratory Tract: Includes nares, nasal cavity, pharynx, and larynx, lined with cilia-containing epithelial cells. Cough receptors mainly in the pharynx and trachea suppress non-productive coughs. Diseases include congestion, sneezing, and coughing.
• Lower Respiratory Tract: Contains trachea, bronchi, bronchioles, and alveoli. Bronchioles have smooth muscle, and sympathetic stimulation leads to bronchodilation (relaxation) while parasympathetic stimulation causes bronchoconstriction (contraction). Alveoli produce surfactant, reducing surface tension to prevent collapse. Diseases include asthma, bronchitis, pneumonia, and recurrent airway obstruction (heaves) in horses.
• Respiratory Drugs:
  • Expectorants: Increase respiratory secretions, allowing easier removal of material, often increasing fluidity via Guaifenesin.
  • Adverse Effects: Mild decreases in blood pressure and increased heart rate.
• Mucolytics: Decrease viscosity of respiratory secretions; Acetylcysteine is used; Adverse effects include vomiting and chest tightness.
• Antitussives: Suppress coughs, central or locally acting on brain stem cough centers.
  • Central acting antitussives: Opioids (Butorphanol, Hydrocodone, Codeine) may cause respiratory depression.
  • Dextromethorphan: OTC cough medicine, chemically similar to cocaine; caution is warranted.
• Decongestants: Reduce nasal swelling; sprays, liquids, and oral forms. Include Phenylephrine & pseudoephedrine should be avoided in animals with hypertension or tachycardia.

Other Systems

• Asthma: A chronic inflammatory disease of the airways in felines. Inhaled allergens cause sudden smooth muscle contraction. Symptoms include wheezing, dry cough, open-mouth breathing, and dyspnea. Treatment involves glucocorticoids (for inflammation) and bronchodilators.
• Recurrent Airway Obstruction (ROA): Treatment involves keeping horses outdoors, reducing dust, maintaining dry hay storage, and improved stabling ventilation. Also important are glucocorticoids to reduce smooth muscle contraction, block inflammation, and increase mucus production.
• Infectious Tracheobronchitis (Kennel Cough): Caused by Bordetella bronchiseptica., characterized by non-productive hacking cough. Treatment often involves opioid drugs.
• Bovine Respiratory Disease: The most prevalent and costly bovine disease, it can be viral or bacterial with pneumonia being a problem. Often called shipping fever.

Hormonal and Reproductive Drugs

• Hormones act as messengers throughout the body, affecting cell activity in different parts of the body. Glands include pituitary, thyroid, parathyroid, adrenal, pancreas, thymus, pineal, and gonads.
• Negative and positive feedback loops regulate the endocrine system.
• Hormonal Drugs: Can be exogenous hormones or hormone-like preparations for replacement therapy, supplemental hormone therapy to treat hormone excess or deficiency in animals.

Blood Glucose Regulation

• Pancreas secretes insulin (promotes glucose uptake and use in cells) and glucagon (increases blood glucose levels by glycogen breakdown).
• Diabetes Mellitus: Insufficient insulin; characterized by high blood glucose, frequent urination and thirst, excess eating, weight loss, and cataracts in cases with chronic pancreatic dysfunction.
• Hypoglycemia: Low blood glucose levels; Treatment focuses on reducing symptoms, avoiding hypoglycemia, and addressing its root cause (eg. decreased exercise tolerance, dyspnea). Glucose curve monitoring is also very important.

Insulin Regulation & Other Treatments

• Types of insulin include ProZinc (recombinant) and Vetsulin (porcine zinc), used to regulate blood glucose in diabetic animals.
• Short-acting insulin starts working in 30-60 minutes and lasts 5-8 hours. Intermediate and long-acting are used for cases which require longer control. Ultra-long acting works gradually over several days.
• Oral hypoglycemic agents stimulate pancreatic beta cells to secrete insulin.
• Glipizide helps maintain or recover pancreatic beta cells function by inhibiting the kidneys' glucose reabsorption.
• Other important medications are included for different types of disorders such as poisoning, overdose, ulcers, etc. Specific details regarding the treatment for each case can be crucial for correct diagnosis and to avoid side effects.

Urinary System

• Kidneys filter through Glomerulus, Bowman's capsule, Proximal and Distal convoluted tubules, and collecting ducts. They affect blood pressure and osmotic pressure. The tubules filter certain substances as needed to maintain proper levels in the blood stream.
• Substances filtered include water, glucose, amino acids and ions. Wastes are also filtered and excreted.
• Disorders include urinary tract infections (UTIs), renal failure, urolithiasis, feline lower urinary tract disorders (FLUTD) and tumors.
• Treatments typically involve urinary acidifiers (for struvite, calcium oxalate, cystine, and ammonium urate uroliths), or urinary alkalinizers. Xanthine oxidase inhibitors decrease uric acid and ammonium-urate urolith formation. Additional support and management may be required for other urinary issues such as urinary incontinence.