Chapter 11 Gastrointestinal Drugs Copyright  ©  2011 Delmar, Cengage Learning
Basic Anatomy and Physiology <ul><li>The term  gastrointestinal (GI) tract  describes a long, muscular tube that begins at...
Control Mechanisms of the GI Tract <ul><li>One control mechanism of the GI tract is the autonomic nervous system (parasymp...
Gastrointestinal Disorders <ul><li>Among the most common complains in veterinary medicine </li></ul><ul><li>Underlying cau...
Drugs Affecting the GI Tract <ul><li>Antisialogues </li></ul><ul><ul><li>Drugs that decrease salivary flow </li></ul></ul>...
Drugs Affecting the GI Tract <ul><li>Antidiarrheals </li></ul><ul><ul><li>Drugs that decrease peristalsis, thereby allowin...
Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Anticholinergics are used to treat tenem...
Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Protectants/adsorbents coat inflamed int...
Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Opiate-related agents control diarrhea b...
Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Probiotics seed the GI tract with benefi...
Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>A theory regarding the development of di...
Drugs Affecting the GI Tract <ul><li>Laxatives </li></ul><ul><ul><li>A laxative loosens the bowel contents and encourages ...
Drugs Affecting the GI Tract <ul><li>Types of Laxatives </li></ul><ul><ul><li>Osmotic </li></ul></ul><ul><ul><ul><li>Pull ...
Drugs Affecting the GI Tract <ul><li>Types of Laxatives (cont.) </li></ul><ul><ul><li>Stimulant </li></ul></ul><ul><ul><ul...
Drugs Affecting the GI Tract <ul><li>Types of Laxatives (cont.) </li></ul><ul><ul><li>Bulk-forming </li></ul></ul><ul><ul>...
Drugs Affecting the GI Tract <ul><li>Types of Laxatives (cont.) </li></ul><ul><ul><li>Emollients </li></ul></ul><ul><ul><u...
Drugs Affecting the GI Tract <ul><li>Antiemetics </li></ul><ul><ul><li>Drugs that control vomiting that help alleviate dis...
Drugs Affecting the GI Tract <ul><li>Vomiting has many causes including: </li></ul><ul><ul><li>Viral and bacterial infecti...
Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Phenothiazine derivatives </li></ul></ul><u...
Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Antihistamines </li></ul></ul><ul><ul><ul><...
Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Anticholinergics </li></ul></ul><ul><ul><ul...
Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Procainamide derivatives </li></ul></ul><ul...
Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Serotonin receptor antagonists </li></ul></...
Drugs Affecting the GI Tract <ul><li>Neurokinin receptor antagonists </li></ul><ul><ul><li>Work on NK1 receptors located i...
Drugs Affecting the GI Tract <ul><li>Emetics </li></ul><ul><ul><li>Drugs that induce vomiting </li></ul></ul><ul><ul><li>U...
Drugs Affecting the GI Tract <ul><li>Emetics (cont.) </li></ul><ul><ul><li>Can be centrally acting (working on the CRTZ) o...
Drugs Affecting the GI Tract <ul><li>Antiulcer drugs </li></ul><ul><ul><li>Help prevent the formation of ulcers </li></ul>...
Drugs Affecting the GI Tract <ul><li>Antiulcer drugs (cont.) </li></ul><ul><ul><li>Antacids </li></ul></ul><ul><ul><ul><li...
Drugs Affecting the GI Tract <ul><li>Antiulcer drugs (cont.) </li></ul><ul><ul><li>Histamine-2 receptor antagonists </li><...
Drugs Affecting the GI Tract <ul><li>Antiulcer drugs (cont.) </li></ul><ul><ul><li>Prostaglandin analogs </li></ul></ul><u...
Drugs Affecting the GI Tract <ul><li>Antifoaming drugs </li></ul><ul><ul><li>Reduce or prevent the formation of foam </li>...
Drugs Affecting the GI Tract <ul><li>Prokinetic agents </li></ul><ul><ul><li>Increase the motility of parts of the GI trac...
Drugs Affecting the GI Tract <ul><li>Prokinetic agents (cont.) </li></ul><ul><ul><li>Dopaminergic agents stimulate gastroe...
Drugs Affecting the GI Tract <ul><li>Enzyme supplements </li></ul><ul><ul><li>Pancreatic enzymes must be supplemented in t...
Drugs Affecting the GI Tract Appetite Altering Drugs <ul><li>Serotonin antagonist antihistamines </li></ul><ul><ul><li>Pro...
Drugs Affecting the GI Tract Appetite Altering Drugs <ul><li>Glucocorticoids </li></ul><ul><ul><li>Stimulate steroid-induc...
Drugs Affecting the GI Tract Appetite Altering Drugs <ul><li>Progestins </li></ul><ul><ul><li>Used to stimulate appetite a...
Dental Prophylaxis and Treatment <ul><li>Refer to Table 11-1 in your textbook </li></ul>Copyright  ©  2011 Delmar, Cengage...
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11. gastrointestinal drugs

  1. 1. Chapter 11 Gastrointestinal Drugs Copyright © 2011 Delmar, Cengage Learning
  2. 2. Basic Anatomy and Physiology <ul><li>The term gastrointestinal (GI) tract describes a long, muscular tube that begins at the mouth and ends at the anus. </li></ul><ul><li>Structures: </li></ul><ul><ul><li>Oral cavity </li></ul></ul><ul><ul><li>Esophagus </li></ul></ul><ul><ul><li>Stomach </li></ul></ul><ul><ul><li>Small intestine </li></ul></ul><ul><ul><li>Large intestine </li></ul></ul><ul><li>Structures vary from monogastric animals with simple stomachs to ruminant animals with multichambered forestomachs </li></ul>Copyright © 2011 Delmar, Cengage Learning
  3. 3. Control Mechanisms of the GI Tract <ul><li>One control mechanism of the GI tract is the autonomic nervous system (parasympathetic and sympathetic branches) </li></ul><ul><li>Parasympathetic stimulation increases intestinal motility, increases GI secretions, and relaxes sphincters </li></ul><ul><ul><li>Cholinergic drugs simulate these actions </li></ul></ul><ul><ul><li>Anticholinergic drugs inhibit these actions </li></ul></ul><ul><li>Sympathetic stimulation decreases intestinal motility, decreases GI secretions, and inhibits the action of sphincters </li></ul><ul><ul><li>Sympathetic nerves simulate these actions </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  4. 4. Gastrointestinal Disorders <ul><li>Among the most common complains in veterinary medicine </li></ul><ul><li>Underlying causes include: </li></ul><ul><ul><li>Infectious sources, dietary excess, adverse drug effects, systemic disease </li></ul></ul><ul><li>These disorders result in clinical signs such as: </li></ul><ul><ul><li>Diarrhea, constipation, vomiting, bloat, ulcer development, or pain </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  5. 5. Drugs Affecting the GI Tract <ul><li>Antisialogues </li></ul><ul><ul><li>Drugs that decrease salivary flow </li></ul></ul><ul><ul><li>Used to limit the flow of excess saliva, which often occurs secondary to anesthetic drug use </li></ul></ul><ul><ul><ul><li>Examples include anticholinergics such as glycopyrrolate and atropine </li></ul></ul></ul><ul><ul><ul><li>These drugs can also affect peristalsis because they are also used to treat vomiting, diarrhea, and excess gastric secretion </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  6. 6. Drugs Affecting the GI Tract <ul><li>Antidiarrheals </li></ul><ul><ul><li>Drugs that decrease peristalsis, thereby allowing fluid absorption from the intestinal contents </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><ul><ul><li>Anticholinergics </li></ul></ul></ul><ul><ul><ul><li>Protectants/adsorbents </li></ul></ul></ul><ul><ul><ul><li>Opiate-related agents </li></ul></ul></ul><ul><ul><ul><li>Probiotics </li></ul></ul></ul><ul><ul><ul><li>Metronidazole </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  7. 7. Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Anticholinergics are used to treat tenemus and vomiting </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><ul><ul><li>Atropine </li></ul></ul></ul><ul><ul><ul><li>Aminopentamide </li></ul></ul></ul><ul><ul><ul><li>Isopropamide </li></ul></ul></ul><ul><ul><ul><li>Propantheline </li></ul></ul></ul><ul><ul><ul><li>Methscopolamine </li></ul></ul></ul><ul><ul><li>Side effects include dry mucous membranes, urine retention, tachycardia, and constipation </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  8. 8. Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Protectants/adsorbents coat inflamed intestinal mucosa with a protective layer (protectants) or bind bacteria and/or digestive enzymes and/or toxins to protect intestinal mucosa from damaging effects (adsorbents) </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><ul><ul><li>Bismuth subsalicylate (bismuth + aspirin-like product) </li></ul></ul></ul><ul><ul><ul><li>Kaolin/pectin </li></ul></ul></ul><ul><ul><ul><li>Activated charcoal </li></ul></ul></ul><ul><ul><li>Side effects include constipation </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  9. 9. Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Opiate-related agents control diarrhea by decreasing both intestinal secretions and the flow of feces and increasing segmental contractions </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><ul><ul><li>Diphenoxylate </li></ul></ul></ul><ul><ul><ul><li>Loperamide </li></ul></ul></ul><ul><ul><ul><li>Paregoric </li></ul></ul></ul><ul><ul><li>Side effects include CNS depression, ileus, urine retention, bloat, and constipation </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  10. 10. Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>Probiotics seed the GI tract with beneficial bacteria; use is based on the theory that some forms of diarrhea are caused by disruption of the normal bacterial flora of the GI tract </li></ul></ul><ul><ul><li>Must be refrigerated to maintain the viability of the bacteria </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><ul><ul><li>Plain yogurt with active cultures </li></ul></ul></ul><ul><ul><ul><li>Variety of trade-name products </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  11. 11. Drugs Affecting the GI Tract <ul><li>Antidiarrheals (cont.) </li></ul><ul><ul><li>A theory regarding the development of diarrhea is that anaerobic bacteria may increase due to disruption of normal GI flora </li></ul></ul><ul><ul><li>One way to treat this is to use an antibiotic effective against anaerobic bacteria </li></ul></ul><ul><ul><li>Metronidazole is an example of an antibiotic used to treat diarrhea </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  12. 12. Drugs Affecting the GI Tract <ul><li>Laxatives </li></ul><ul><ul><li>A laxative loosens the bowel contents and encourages evacuation of stool </li></ul></ul><ul><ul><li>Laxatives help animals evacuate without excessive straining; treat chronic constipation from nondietary causes and movable intestinal blockages; and evacuate the GI tract before surgery, radiography, or diagnostic procedures </li></ul></ul><ul><ul><li>Cathartics are harsher laxatives; purgatives are harsh cathartics </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  13. 13. Drugs Affecting the GI Tract <ul><li>Types of Laxatives </li></ul><ul><ul><li>Osmotic </li></ul></ul><ul><ul><ul><li>Pull water into the colon and increase water content in the feces, thereby increasing bulk and stimulating peristalsis </li></ul></ul></ul><ul><ul><ul><li>Are salts or saline product that may cause electrolyte imbalances if absorbed systemically </li></ul></ul></ul><ul><ul><ul><li>Examples include: lactulose, sodium phosphate with sodium biphosphate, magnesium sulfate, magnesium hydroxide </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  14. 14. Drugs Affecting the GI Tract <ul><li>Types of Laxatives (cont.) </li></ul><ul><ul><li>Stimulant </li></ul></ul><ul><ul><ul><li>Increase peristalsis by chemically irritating sensory nerve endings in the intestinal mucosa </li></ul></ul></ul><ul><ul><ul><li>Many are absorbed systemically and cause a variety of side effects </li></ul></ul></ul><ul><ul><ul><li>Examples include bisacodyl, phenolphthalein, and castor oil </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  15. 15. Drugs Affecting the GI Tract <ul><li>Types of Laxatives (cont.) </li></ul><ul><ul><li>Bulk-forming </li></ul></ul><ul><ul><ul><li>Substances that absorb water into the intestine, increase fecal bulk, and stimulate peristalsis, resulting in large, soft stool production (which tends to look normal) </li></ul></ul></ul><ul><ul><ul><li>Are not systemically absorbed, so side effects are rare </li></ul></ul></ul><ul><ul><ul><li>Examples include psyllium hydrophilic mucilloid, polycarbophil,and bran </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  16. 16. Drugs Affecting the GI Tract <ul><li>Types of Laxatives (cont.) </li></ul><ul><ul><li>Emollients </li></ul></ul><ul><ul><ul><li>Can be stool softeners (reduce stool surface tension and reduce water absorption through the colon), lubricants (facilitate the passage of fecal material, increasing water retention in stool), or fecal wetting agents (detergent-like drugs that permit easier penetration and mixing of fats and fluid with the fecal mass) </li></ul></ul></ul><ul><ul><ul><li>Examples include docusate sodium, docusate calcium, docusate potassium, and petroleum products </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  17. 17. Drugs Affecting the GI Tract <ul><li>Antiemetics </li></ul><ul><ul><li>Drugs that control vomiting that help alleviate discomfort and help control electrolyte balance </li></ul></ul><ul><ul><li>Most are given parenterally, as the patient may vomit the medication before it can be absorbed through the GI tract </li></ul></ul><ul><ul><li>Examples: </li></ul></ul><ul><ul><ul><li>Phenothiazine derivatives </li></ul></ul></ul><ul><ul><ul><li>Antihistamines </li></ul></ul></ul><ul><ul><ul><li>Anticholinergics </li></ul></ul></ul><ul><ul><ul><li>Procainamide derivatives </li></ul></ul></ul><ul><ul><ul><li>Serotonin receptor antagonists </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  18. 18. Drugs Affecting the GI Tract <ul><li>Vomiting has many causes including: </li></ul><ul><ul><li>Viral and bacterial infections, dietary indiscretion, food intolerance, surgery, pain, or other drugs </li></ul></ul><ul><li>The vomiting center of the brain have many inputs that tell it to activate including: </li></ul><ul><ul><li>Equilibrium changes in the ear, responses due to pain or fear, intracranial pressure changes, vagus nerve stimulation in the GI tract, and activity in the chemoreceptor trigger zone </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  19. 19. Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Phenothiazine derivatives </li></ul></ul><ul><ul><ul><li>Inhibit dopamine in the chemoreceptor trigger zone, thus decreasing the stimulation to vomit </li></ul></ul></ul><ul><ul><ul><li>Side effects include hypotension and sedation </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Acepromazine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Chlorpromazine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Prochlorperazine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Perphenazine </li></ul></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  20. 20. Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Antihistamines </li></ul></ul><ul><ul><ul><li>Controls vomiting when the vomiting is due to motion sickness, vaccine reactions, or inner ear problems </li></ul></ul></ul><ul><ul><ul><li>Work by blocking input from the vestibular system to the CRTZ </li></ul></ul></ul><ul><ul><ul><li>A side effect is sedation </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Trimethobenzamide </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Dimenhydrinate </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Diphenhydramine </li></ul></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  21. 21. Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Anticholinergics </li></ul></ul><ul><ul><ul><li>Block acetylcholine peripherally, which decreases intestinal motility and secretions </li></ul></ul></ul><ul><ul><ul><li>May decrease gastric emptying (which may increase the tendency to vomit) </li></ul></ul></ul><ul><ul><ul><li>Side effects include dry mouth, constipation, urinary retention, and tachycardia </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Aminopentamide </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Atropine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Propantheline </li></ul></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  22. 22. Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Procainamide derivatives </li></ul></ul><ul><ul><ul><li>Work centrally by blocking the CRTZ and peripherally by speeding gastric emptying, strengthening cardiac sphincter tone, and increasing the force of gastric contractions </li></ul></ul></ul><ul><ul><ul><li>Should not be used in animals with GI obstructions, GI perforation, or GI hemorrhage </li></ul></ul></ul><ul><ul><ul><li>An example used in veterinary medicine is metoclopramide </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  23. 23. Drugs Affecting the GI Tract <ul><li>Antiemetics (cont.) </li></ul><ul><ul><li>Serotonin receptor antagonists </li></ul></ul><ul><ul><ul><li>Work selectively on 5-HT 3 receptors, which are located peripherally and centrally </li></ul></ul></ul><ul><ul><ul><li>Work on the theory that some chemicals cause vomiting because they increase serotonin release from small intestinal cells </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Ondansetron </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Dolasetron </li></ul></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  24. 24. Drugs Affecting the GI Tract <ul><li>Neurokinin receptor antagonists </li></ul><ul><ul><li>Work on NK1 receptors located in the center of the brain </li></ul></ul><ul><ul><li>Work by inhibiting substance P, the key neurotransmitter involved in vomiting </li></ul></ul><ul><li>Maropitant citrate </li></ul><ul><ul><li>Used to prevent acute vomiting and motion sickness </li></ul></ul><ul><ul><li>Side effects include: </li></ul></ul><ul><ul><ul><li>Pain at the injection site, pre-travel vomiting and hypersalivation, and diarrhea </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  25. 25. Drugs Affecting the GI Tract <ul><li>Emetics </li></ul><ul><ul><li>Drugs that induce vomiting </li></ul></ul><ul><ul><li>Used in the treatment of poisoning and drug overdose </li></ul></ul><ul><ul><li>Vomiting should not be induced if caustic substances have been ingested </li></ul></ul><ul><ul><ul><li>Always check with poison control prior to inducing vomiting </li></ul></ul></ul><ul><ul><li>Activated charcoal is given if emesis is contraindicated (it absorbs many chemicals and drugs in the upper GI tract) </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  26. 26. Drugs Affecting the GI Tract <ul><li>Emetics (cont.) </li></ul><ul><ul><li>Can be centrally acting (working on the CRTZ) or peripherally acting (working on receptors locally) </li></ul></ul><ul><ul><li>Centrally acting </li></ul></ul><ul><ul><ul><li>Apomorphine </li></ul></ul></ul><ul><ul><ul><li>Xylazine </li></ul></ul></ul><ul><ul><li>Peripherally acting </li></ul></ul><ul><ul><ul><li>Ipecac syrup </li></ul></ul></ul><ul><ul><ul><li>Home remedies </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  27. 27. Drugs Affecting the GI Tract <ul><li>Antiulcer drugs </li></ul><ul><ul><li>Help prevent the formation of ulcers </li></ul></ul><ul><ul><li>Categories include </li></ul></ul><ul><ul><ul><li>Antacids </li></ul></ul></ul><ul><ul><ul><li>Histamine-2 receptor antagonists </li></ul></ul></ul><ul><ul><ul><li>Mucosal protective drugs </li></ul></ul></ul><ul><ul><ul><li>Prostaglandin analogs </li></ul></ul></ul><ul><ul><ul><li>Proton pump inhibitors </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  28. 28. Drugs Affecting the GI Tract <ul><li>Antiulcer drugs (cont.) </li></ul><ul><ul><li>Antacids </li></ul></ul><ul><ul><ul><li>Promote ulcer healing by neutralizing HCl and reducing pepsin activity </li></ul></ul></ul><ul><ul><ul><li>Interact with other drugs </li></ul></ul></ul><ul><ul><ul><ul><li>By adsorption or binding the other drugs </li></ul></ul></ul></ul><ul><ul><ul><ul><li>By increasing stomach pH </li></ul></ul></ul></ul><ul><ul><ul><ul><li>By increasing urinary pH </li></ul></ul></ul></ul><ul><ul><ul><li>May be systemic or nonsystemic </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Systemic: sodium bicarbonate, calcium carbonate </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Nonsystemic: magnesium hydroxide, aluminum/magnesium hydroxide, aluminum hydroxide </li></ul></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  29. 29. Drugs Affecting the GI Tract <ul><li>Antiulcer drugs (cont.) </li></ul><ul><ul><li>Histamine-2 receptor antagonists </li></ul></ul><ul><ul><ul><li>Prevent acid reflux by competitively blocking the H 2 receptors of the parietal cells in the stomach, thus reducing gastric acid secretion </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Cimetidine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Ranitidine </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Famotidine </li></ul></ul></ul></ul><ul><ul><li>Mucosal protective drugs </li></ul></ul><ul><ul><ul><li>Combine with protein to form an adherent substance that covers the ulcer and protects it from stomach acid and pepsin </li></ul></ul></ul><ul><ul><ul><li>An example is sucralfate </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  30. 30. Drugs Affecting the GI Tract <ul><li>Antiulcer drugs (cont.) </li></ul><ul><ul><li>Prostaglandin analogs </li></ul></ul><ul><ul><ul><li>Suppress gastric secretions and increase mucus production in the GI tract </li></ul></ul></ul><ul><ul><ul><li>An example is misoprostol, which is usually given to animals taking NSAIDs </li></ul></ul></ul><ul><ul><li>Proton pump inhibitors </li></ul></ul><ul><ul><ul><li>Bind irreversibly to the H + -K + -ATPase enzyme on the surface of parietal cells of the stomach; this inhibits hydrogen ion transport into the stomach so that it cannot secrete HCl </li></ul></ul></ul><ul><ul><ul><li>Examples: </li></ul></ul></ul><ul><ul><ul><ul><li>Omeprazole </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Lansoprazole </li></ul></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  31. 31. Drugs Affecting the GI Tract <ul><li>Antifoaming drugs </li></ul><ul><ul><li>Reduce or prevent the formation of foam </li></ul></ul><ul><ul><li>Used in ruminants, whose rumens are subject to acute frothy bloat </li></ul></ul><ul><ul><li>Make this foam less stable, breaking it up to promote gas release through belching </li></ul></ul><ul><ul><li>Administered as solutions by stomach tube directly into the forestomach </li></ul></ul><ul><ul><li>Examples include poloxalene and polymerized methyl silicone </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  32. 32. Drugs Affecting the GI Tract <ul><li>Prokinetic agents </li></ul><ul><ul><li>Increase the motility of parts of the GI tract to enhance movement of material through it </li></ul></ul><ul><ul><li>Types of prokinetic agents are parasympathomimetics, dopaminergic antagonists, and serotonergic agents </li></ul></ul><ul><ul><li>Parasympathomimetic agents include </li></ul></ul><ul><ul><ul><li>Acetylcholinesterase inhibitors, which compete with ACh for acetylcholinesterase, resulting in increased intestinal tone and salivation </li></ul></ul></ul><ul><ul><ul><ul><li>An example is neostigmine </li></ul></ul></ul></ul><ul><ul><ul><li>Cholinergics, which make a precursor to acetylcholine </li></ul></ul></ul><ul><ul><ul><ul><li>An example is dexpanthenol </li></ul></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  33. 33. Drugs Affecting the GI Tract <ul><li>Prokinetic agents (cont.) </li></ul><ul><ul><li>Dopaminergic agents stimulate gastroesophageal sphincter, stomach, and intestinal motility by sensitizing tissues to the action of the neurotransmitter ACh </li></ul></ul><ul><ul><ul><li>Examples include metoclopramide and domeridone </li></ul></ul></ul><ul><ul><li>Serotonergic agents stimulate motility of the gastroesophageal sphincter, stomach, small intestine, and colon </li></ul></ul><ul><ul><ul><li>An example is cisapride </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  34. 34. Drugs Affecting the GI Tract <ul><li>Enzyme supplements </li></ul><ul><ul><li>Pancreatic enzymes must be supplemented in the diet when the pancreas is not functioning properly (as in pancreatic exocrine insufficiency) </li></ul></ul><ul><ul><li>Pancrealipase contains primarily lipase, but also contains amylase and protease </li></ul></ul><ul><ul><li>Can be irritating to the skin on contact and to nasal passages upon inhalation </li></ul></ul><ul><ul><ul><li>• Refer to Table 11-1 in your textbook </li></ul></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  35. 35. Drugs Affecting the GI Tract Appetite Altering Drugs <ul><li>Serotonin antagonist antihistamines </li></ul><ul><ul><li>Promote appetite by inhibition at the serotoninergic receptors which control satiety </li></ul></ul><ul><ul><li>Side effects include sedation and dry mouth </li></ul></ul><ul><li>Benzodiazepines </li></ul><ul><ul><li>Effective appetite stimulants in cats but not dogs </li></ul></ul><ul><ul><li>Side effects include sedation and ataxia </li></ul></ul><ul><li>Tetracyclic antidepressants </li></ul><ul><ul><li>Stimulate appetite by antagonizing alpha2-receptors </li></ul></ul><ul><ul><li>Side effects include sedation, vocalization </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  36. 36. Drugs Affecting the GI Tract Appetite Altering Drugs <ul><li>Glucocorticoids </li></ul><ul><ul><li>Stimulate steroid-induced euphoria which stimulates appetite </li></ul></ul><ul><ul><li>Side effects include polydipsia, polyuria, dull haircoat, weight gain, and behavioral changes </li></ul></ul><ul><li>Anabolic steroids </li></ul><ul><ul><li>Stimulate hematopoiesis, appetite, and weight gain </li></ul></ul><ul><ul><li>Side effects include hepatotoxicity, masculinization, and early closure of growth plate in young animals </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  37. 37. Drugs Affecting the GI Tract Appetite Altering Drugs <ul><li>Progestins </li></ul><ul><ul><li>Used to stimulate appetite and promote weight gain in anorectic cats and dogs </li></ul></ul><ul><ul><li>Side effects include behavioral changes, endometritis, and mammary enlargement </li></ul></ul><ul><li>Dirlotapide </li></ul><ul><ul><li>Drug for management of obesity in dogs </li></ul></ul><ul><ul><li>Side effects include vomiting, diarrhea, lethargy, and anorexia </li></ul></ul>Copyright © 2011 Delmar, Cengage Learning
  38. 38. Dental Prophylaxis and Treatment <ul><li>Refer to Table 11-1 in your textbook </li></ul>Copyright © 2011 Delmar, Cengage Learning
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