Lect 1

• The esophagus and cranial portion of the stomach are parts of the GI tract.
• The buccal mucosa is used in polymer patches and feline oral sprays.
• The cornified epithelium of the buccal mucosa is a effective barrier that decreases the chance of drug absorption.
• The stomach's acidity and motility create a hostile environment for drugs and promote the absorption father down the tract.
• The GI tract presents an important degree of heterogeneity relative to morphology and physiology.
• The surface mucus of the stomach may be a barrier for some drugs.
• The main role of the GI tract is digestion and nutrient absorption.
• The stomach's simple mucosa lining allows absorption.
• The anatomy and physiology of the GI tract can vary dramatically between species, and sometimes even within the same species.
• The oral cavity includes the sublingual area, which is a route for systemic drug administration, such as Nitroglycerin.
• The recommended textbooks for the course include Small Animal Clinical Pharmacology & Therapeutics, Second Edition, by Dawn Merton Boothe, and Veterinary Anesthesia and Analgesia: The Fifth Edition of Lumb and Jones, by Kurt A. Grimm, Leigh A. Lamont, William J. Tranquilli, Stephen A. Greene, and Sheilah A. Robertson.
• Other recommended textbooks for the course include Veterinary Pharmacology and Therapeutics, Tenth Edition, by Jim E. Riviere and Mark G. Papich, Handbook of Veterinary Pharmacology, Second Edition, by Walter H. Hsu, and Plumb’s Veterinary Drug Handbook, Tenth Edition, by James A. Budde and Dawn M. McCluskey.
• The course also includes recommended resources such as NCBI Pubmed, a scientific literature database, books, and pictures.
• Pharmacokinetics (PK) is the study of the time course of drug fate in the body.
• The degree of the pharmacologic response is related to the drug concentration at the tissue (receptor).
• Drugs move through the body by four mechanisms: bulk flow, passive diffusion, carrier-mediated transport, and endocytosis or pinocytosis.
• Drug therapy aims to induce a desired pharmacologic response.
• Most drugs are characterized by a molecular weight (MW) < 350 Da, falling within the molecular weight range 200 - 1000 Da.
• A drug is a molecule that interacts with specific molecular components of an organism to produce biochemical and physiologic changes/effects.
• Drugs can be classified as chemicals that can affect living processes, intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease in people or animals, and are administered as such rather than released by physiological mechanisms.
• The drug movement across cell membranes (transmembrane diffusion) depends on the following host and drug factors: Passive diffusion is the most common method by which compounds move through the body.
• Bulk flow is the movement across the fenestrated capillaries of the body from plasma to tissue, dependent on the concentration of drug dissolved in the plasma or tissue fluid, and is not affected by the chemical nature of the drug.
• Drug effect on the body is governed by four physiological processes: Absorption, Distribution, Metabolism, and Excretion, also known as ADME.
• Pharmacogenetics is the study of genetic determinants of response to drug therapy.
• Drug movements largely, but not exclusively depend on passive diffusion of the drug.
• The route of administration is generally based on physicochemical properties of the drug, formulation to be used, therapeutic indications, pathophysiology of the disease, and target species.
• Absorption is the movement of drug from the site of administration into the systemic circulation (blood or plasma).
• Bioavailability is the concept of how much of a drug reaches the tissue site after administration.
• The processes that govern the movement of drugs across lipid-based biological membranes are important and regulate drug movement.
• The manufacturer’s recommendations should always be followed carefully.
• Oral (Gastrointestinal) drug absorption has advantages of being the safest, easiest to administer, economical, and may require the drug to be mixed in the food to facilitate administration.
• Drug therapy involves pharmacologic response, drug concentration at the tissue (receptor), selection of routes of administration, and drug movement.
• Enteral administration is the most common route of drug administration but less frequently used parenteral administration is occasionally used.
• Drug concentrations at the tissue site are approximated by measuring “plasma drug concentrations” (PDCs).
• Disadvantages of oral (Gastrointestinal) drug absorption include the acidic environment of stomach and digestive enzymes that may destroy the drug, inactivation of the drug by bacterial enzymes in ruminants, irritation of the GI mucosa by some drugs, alteration of drug absorption due to the presence of food, and some drugs are extensively metabolized by the GI mucosa and the liver (first-pass metabolism).
• Intraperitoneal, Subcutaneous, Intramuscular, Oral transmucosal, Oral Transdermal are routes of administration.
• The patient's condition or healthy status is a factor in the use of unconventional systemic routes.
• The bioavailability is determined by comparing plasma levels of a drug after a particular route of administration with the levels achieved by IV administration.
• Bioavailability ( F ) is the percentage of an administered dose of drug that reaches systemic circulation.
• Drugs are often administered orally with the intent of absorption occurring through the mucosa of the mouth.