Veterinary gasteroenterolgy

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Veterinary gasteroenterolgy

  1. 1. Veterinary Gastroenterological pharmacology
  2. 2. Major Groups <ul><li>Appetite stimulants </li></ul><ul><li>Emetics </li></ul><ul><li>Antiemetics </li></ul><ul><li>Antiulcer drugs </li></ul><ul><li>Prokinetics </li></ul><ul><li>Drugs used in diarrhoea </li></ul><ul><li>Cathartics and laxatives </li></ul><ul><li>Ruminotorics </li></ul><ul><li>Antifoaming agents </li></ul><ul><li>Ruminoreticular antacids and acidifying agents </li></ul><ul><li>Ruminoreticular Motility </li></ul><ul><li>Drugs used in the treatment of colitis </li></ul>
  3. 3. Appetite stimulants <ul><li>B vitamin preparations </li></ul><ul><li>Glucocorticoids -prednisone </li></ul><ul><li>Anabolic steroids – Stanozolol </li></ul><ul><li>Benzodiazepines -in cats -Diazepam </li></ul><ul><li>Cyproheptadine- serotonin antagonist </li></ul><ul><li>Megestrol acetate -Progestin </li></ul>
  4. 4. Emetics <ul><li>Apomorphine </li></ul><ul><li>Xylazine </li></ul><ul><li>Syrup of ipecac </li></ul><ul><li>Hydrogen peroxide (3%) </li></ul><ul><li>Salt (1-3 tsp) in warm water or Large crystal of NaCl / Sod. carb. (washing soda ) </li></ul>
  5. 5. Antiemetics <ul><li>Phenothiazine tranquilizers </li></ul><ul><li>acepromazine, triflupromazine, chlorpromazine, and prochlorperazine. </li></ul><ul><li>Anticholinergic : methscopolamine., glycopyrrolate, propantheline and isopropamide. </li></ul><ul><li>Antihistaminics : diphenhydramine, dimenhydrinate, promethazine, buclizine, cyclizine, and meclizine. </li></ul><ul><li>Metoclopramide </li></ul><ul><li>Serotonin (5-HT) antagonists : Ondansetron and dolasetron </li></ul><ul><li>Domperidone </li></ul><ul><li>Butorphanol </li></ul>
  6. 6. Metoclopramide <ul><li>Emesis induced by chemotherapy, nausea and vomiting associated with delayed gastric emptying, reflux gastritis, and viral enteritis. </li></ul><ul><li>Concurrent use of phenothiazine and butyrophenone tranquilizers to be avoided </li></ul><ul><li>GI obstruction must be excluded prior to initiating metoclopramide therapy. </li></ul><ul><li>Readily crosses the blood-brain barrier </li></ul><ul><li>Extrapyramidal signs- involuntary muscle spasms, restlessness and aggression </li></ul>
  7. 7. Ondansetron and dolasetron <ul><li>Cytotoxic drugs and radiation -release of serotonin. </li></ul><ul><li>specific inhibitors of 5-HT 3 (Serotonin) receptors in the CTZ. </li></ul><ul><li>most effective antiemetics in radiation and chemotherapy induced , not effective for emesis caused by motion sickness. </li></ul>
  8. 8. Antiulcer drugs <ul><li>Acetylcholine M1 Receptor Antagonists </li></ul><ul><li>Antacids </li></ul><ul><li>Histamine (H2)-receptor Antagonists </li></ul><ul><li>Proton-pump inhibitors </li></ul><ul><li>Cytoprotective drugs </li></ul><ul><li>Prostaglandin E1 Analogues </li></ul>
  9. 9. Antacids <ul><li>Aluminum hydroxide, magnesium oxide or </li></ul><ul><li>hydroxide, and calcium carbonate </li></ul><ul><li>Interfere with the GI absorption of concurrently administered drugs. </li></ul><ul><li>Not to be given within 2 hours of other oral medications. </li></ul><ul><li>In ruminants, magnesium hydroxide -as a laxative in the treatment of rumen overload syndrome </li></ul><ul><li>Adverse Effects: constipation –Al, Ca , </li></ul><ul><li>loose stools with Mg </li></ul><ul><li>hypophosphatemia -Al , </li></ul><ul><li>hypermagnesemia –Mg </li></ul><ul><li>hypercalcemia , hypophosphatemia </li></ul><ul><li>gastric acid rebound phenomenon -Ca </li></ul>
  10. 10. Histamine (H2)-receptor Antagonists <ul><li>Famotidine >Nizatidine >Ranitidine >Cimetidine </li></ul><ul><li>Food delays the absorption of cimetidine, </li></ul><ul><li>minimal effect on ranitidine </li></ul><ul><li>enhances absorption of famotidine </li></ul><ul><li>Cimetidine- hepatic microsomal enzyme </li></ul><ul><li>inhibitor, reduces the metabolism of other drugs </li></ul>
  11. 11. Indications <ul><li>Gastric ulcers in canines, foals, and pigs. </li></ul><ul><li>Abomasal ulcers in cattle and calves </li></ul><ul><li>common in high-producing cows within the first 6 wk after parturition. </li></ul><ul><li>The most likely cause is prolonged inappetence, which results in sustained periods of low abomasal pH </li></ul><ul><li>Abomasal ulcers may also arise in association with lymphosarcoma, abomasal disorders (displacement or volvulus), or increased intraluminal pressure causing ischemia of abomasal mucosa </li></ul><ul><li>Abomasal ulcers common in milk-fed calves consumed milk or milk replacer for 4-12 wks </li></ul>
  12. 12. Proton-pump inhibitors (H+,K+ATPase Inhibitors) <ul><li>Omeprazole, Pantoprazole, ( caps, injectables ) </li></ul><ul><li>Lansoprazole, Rabeprazole, Esomeprazole ( caps) </li></ul><ul><li>24 hours single oral dose </li></ul><ul><li>More effective than H2 blockers </li></ul><ul><li>Microsomal enzyme inhibitor </li></ul><ul><li>Omeprazole - mucosal cell hyperplasia, hypertrophy and development of carcinoids. </li></ul><ul><li>Lansoprazole – better than omeprazole. </li></ul>
  13. 13. <ul><li>Cytoprotective drugs </li></ul><ul><li>Sucralfate- Combination therapy (sucralfate + histamine H2 antagonist, or sucralfate + H+, K+ - ATPase inhibitor) </li></ul><ul><li>Prostaglandin E1 Analogues </li></ul><ul><li>Promote gastric mucosal defense mechanisms </li></ul><ul><li>inhibiting parietal cell acid secretion </li></ul><ul><li>stimulating mucosal blood flow </li></ul><ul><li>bicarbonate secretion </li></ul><ul><li>mucus secretionand epithelial cell renewal </li></ul><ul><li>Misoprostol </li></ul><ul><li>GI bleeding and ulceration from NSAID therapy but is less efficacious than H2-blockers for treatment of ulcers not associated with NSAIDs </li></ul><ul><li>Side effects - diarrhea and flatulence CI: pregnancy </li></ul>
  14. 14. Prokinetics <ul><li>Metoclopramide </li></ul><ul><li>stimulates and coordinates esophageal, gastric, </li></ul><ul><li>pyloric, and duodenal motor activity. </li></ul><ul><li>It increases lower esophageal sphincter ( LES) tone </li></ul><ul><li>stimulates gastric contractions </li></ul><ul><li>relaxes the pylorus and duodenum </li></ul><ul><li>Indications </li></ul><ul><li>Gastric Emptying Disorders -Delayed gastric emptying </li></ul><ul><li>Small bowel motility disorders- is less effective in the distal small intestine and colon </li></ul><ul><li>Bloat and ruminal impaction </li></ul><ul><li>Disorders of ruminoreticular motility </li></ul>
  15. 15. <ul><li>Cisapride </li></ul><ul><li>without antidopaminergic effects (antiemetic action) </li></ul><ul><li>no extrapyramidal effects ( do not cross BBB) </li></ul><ul><li>More potent and broader prokinetic activity </li></ul><ul><li>increases the motility of the colon, as well as that of the esophagus, stomach, and small intestine </li></ul><ul><li>Indications </li></ul><ul><li>Gastric stasis,, gastroesophageal reflux, postoperative ileus and intestinal pseudo-obstruction in dogs and cats </li></ul><ul><li>In dogs with idiopathic megaesophagus that continue to regurgitate frequently despite a carefully managed, elevated feeding program </li></ul><ul><li>Rational agent in the treatment of idiopathic constipation </li></ul><ul><li>Cis-platinum chemotherapy Induced Emesis-Cisapride antagonizes 5-HT3 receptors but with less potency than 5-HT3 antagonists </li></ul>
  16. 16. <ul><li>Domperidone </li></ul><ul><li>regulates the motility of gastric and small intestinal smooth muscle </li></ul><ul><li>very little physiologic effect in the colon </li></ul><ul><li>superior to metoclopramide in stimulating antral contractions </li></ul><ul><li>Macrolide antibiotics </li></ul><ul><li>Erythromycin and Clarithromycin at Much lower than </li></ul><ul><li>the anti-microbial dosage </li></ul><ul><li>Histamine H2-receptor antagonists </li></ul><ul><li>Ranitidine and nizatidine . </li></ul><ul><li>Acetylcholinesterase Inhibitors </li></ul><ul><li>Neostigmine </li></ul><ul><li>indicated in paralytic ileus </li></ul><ul><li>increased secretion into the GI tract, hence contraindicated in small-intestinal disease. </li></ul><ul><li>In horses, it may decrease small-intestinal propulsive contractions and delay gastric emptying </li></ul>
  17. 17. Drugs used in the treatment of diarrhea <ul><li>Mucosal Protectants and Adsorbents </li></ul><ul><li>a. Kaolin-pectin -reduce bioavailability </li></ul><ul><li>b. Activated charcoal - common nonspecific treatment </li></ul><ul><li>c. Bismuth subsalicylate- Salicylate toxicosis in cats </li></ul><ul><li>Anticholinergic drugs </li></ul><ul><li>Hyoscine, Aminopentamide, isopropamide, </li></ul><ul><li>propantheline and dicyclomine </li></ul><ul><li>Opiates </li></ul><ul><li>antisecretory & antimotility effects, </li></ul><ul><li>not to be used in infection </li></ul><ul><li>Diphenoxylate and Loperamide </li></ul><ul><li>Overdose : abnormal pupillary response to light,circling, </li></ul><ul><li>constantvocalization, head pressing, mydriasis </li></ul><ul><li>Paralytic ileus, toxic megacolon, pancreatitis, </li></ul><ul><li>and CNS effects in cats. </li></ul>
  18. 18. <ul><li>Antimicrobials </li></ul><ul><li>Erythromycin, clindamycin, tylosin, tetracycline, chloramphenicol., metronidazole, amoxicillin, ampicillin, fluoroquinolones, cephalosporin plus an aminoglycoside (gentamicin, amikacin) </li></ul><ul><li>NSAIDs </li></ul><ul><li>antiprostaglandin activity </li></ul><ul><li>inhibit fluid and electrolyte hypersecretion </li></ul><ul><li>adverse GI, hepatic, and renal effects </li></ul>
  19. 19. Cathartics and laxatives <ul><li>Increase the motility of the intestine or increase the bulk of feces. </li></ul><ul><li>Clinical Indicatons </li></ul><ul><li>increase passage of gut contents associated with intestinal impaction, </li></ul><ul><li>to cleanse the bowel before radiography or endoscopy, </li></ul><ul><li>to eliminate toxins from the GI tract, </li></ul><ul><li>to soften feces after intestinal or anal surgery. </li></ul>
  20. 20. <ul><li>Stimulant Cathartics - Emodin </li></ul><ul><li>Castor oil </li></ul><ul><li>Raw linseed oil </li></ul><ul><li>Phenolphthalein and bisacodyl </li></ul><ul><li>Osmotic (Saline) Cathartics: Magnesium salts </li></ul><ul><li>Sodium salts </li></ul><ul><li>Sugar alcohols -mannitol and sorbitol, Lactulose </li></ul><ul><li>Bulk Laxatives -methylcellulose, psyllium, prunes, wheat bran, and canned pumpkin. </li></ul><ul><li>Lubricant Laxatives -Mineral oil( Liquid paraffin ) </li></ul><ul><li>. Fecal Softeners (Surfactants)- Docusate sodium </li></ul><ul><li>docusate calcium </li></ul><ul><li>docusate potassium </li></ul>
  21. 21. <ul><li>Ruminotorics </li></ul><ul><li>Fresh ruminal fluid is considered to be the best available ruminotoric </li></ul><ul><li>Magnesium hydroxide </li></ul><ul><li>Dioctyl sodium sulfosuccinate ( 90-120 mL in 1-2 L of water) </li></ul><ul><li>with ruminal massage helpful in promoting the dissolution </li></ul><ul><li>and passage of impacted fibrous ruminal contents. </li></ul><ul><li>markedly depress rumen protozoa; thus, ruminal fluid </li></ul><ul><li>transfaunation needed </li></ul>
  22. 22. <ul><li>Antifoaming agents </li></ul><ul><li>Poloxalene 25-50 g oral , or prevention as a top dressing to feed (1 g/45 kg body wt/day) or in a molasses block (1.5 g/45 kg body wt/day) </li></ul><ul><li>Polymerized methyl silicone (3.3% emulsion [cattle: 30-60 mL; sheep: 7-15 mL]) </li></ul><ul><li>Docusate sodium in emulsified soybean oil (6-12 fl oz containing 240 mg/mL) </li></ul><ul><li>Vegetable oils alone, such as peanut oil, sunflower oil, or soybean oil (cattle: 60 mL; sheep: 10-15 mL) </li></ul><ul><li>Ionophores (such as monensin) in the ration </li></ul>
  23. 23. <ul><li>Ruminoreticular antacids </li></ul><ul><li>Magnesium hydroxide (cattle: 100-300 g; sheep: 10-30 g) </li></ul><ul><li>Magnesium carbonate (cattle: 10-80 g; sheep: 1-8 g). </li></ul><ul><li>Mixed in10 L of warm water to ensure adequate dispersion through the ruminoreticular contents. </li></ul><ul><li>Activated charcoal (2 g/kg) to protect the ruminoreticular mucosa from further injury by inactivating toxins </li></ul>
  24. 24. <ul><li>Ruminoreticular acidifying agents </li></ul><ul><li>ruminal stasis or simple indigestion </li></ul><ul><li>acute ammonia poisoning. </li></ul><ul><li>Administration of weak acids in cold water </li></ul><ul><li>returns the pH of ruminoreticular content </li></ul><ul><li>toward physiologic levels </li></ul><ul><li>promotes the uptake of volatile fatty acids. </li></ul><ul><li>Acetic acid (4-5%) or vinegar (cattle: 4-8 L; sheep: 250-500 mL) </li></ul>
  25. 25. <ul><li>Ruminoreticular Motility Modulators </li></ul><ul><li>Anticholinergics </li></ul><ul><li>Adrenergics </li></ul><ul><li>Opiate analgesics </li></ul><ul><li>CNS depressants, </li></ul><ul><li>Several toxic compounds (eg, cyanide) result in ruminoreticular paresis. </li></ul><ul><li>Parasympathomimetic agents </li></ul><ul><li>Neostigmine (cattle: 0.02 mg/kg, SC; sheep: 0.01-0.02 mg/kg, SC) </li></ul><ul><li>generally produces the fewest side effects </li></ul><ul><li>tends to increase frequency, rather than strength, of ruminoreticular contractions which is particularly true in ruminal atony. </li></ul><ul><li>stimulatory effect is not always reliable, and some inhibition of motility can be seen </li></ul>

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