BVSc Pharmacology - Unit 4: Drugs Acting on the Digestive System

Short Answer Questions (2-3 marks)

1. Define stomachics. Give two examples used in veterinary practice.
2. What is the mechanism of action of proton pump inhibitors (PPIs)?
3. Name the H2-receptor antagonists used in animals and state their therapeutic uses.
4. Differentiate between antacids and antiulcer drugs with one example each.
5. What is sucralfate? How does it protect the gastric mucosa?
6. Define carminatives. Give three examples and state their mode of action.
7. What is the difference between a laxative and a purgative?
8. Name the osmotic purgatives and explain their mechanism of action.
9. What are stimulant cathartics? Give two examples and mention their site of action.
10. Define emetics. Classify them with examples.
11. What is the mechanism of action of apomorphine as an emetic?
12. Name two antiemetics used in veterinary medicine and state their mechanism of action.
13. What are prokinetic drugs? Give two examples used in ruminants and monogastric animals.
14. What is metoclopramide? State its pharmacological actions on the digestive system.
15. What is activated charcoal? When and how is it used in veterinary practice?

Long Answer Questions (5-10 marks)

1. Classify drugs acting on the digestive system. Describe the pharmacology of antacids - types, mechanism of action, therapeutic uses, and adverse effects in domestic animals.
2. Write a detailed account of purgatives/laxatives: classification, mechanism of action, therapeutic uses, contraindications, and species differences in response.
3. Describe the pharmacology of antiemetics used in veterinary medicine. Discuss their classification, mechanism of action, and clinical uses in dogs and cats.
4. Write notes on prokinetic agents used in veterinary practice. Describe the mechanism of action of metoclopramide and domperidone and their uses in GI motility disorders.
5. Describe the drugs used in peptic ulcer disease in animals - include antacids, H2 blockers, PPIs, and cytoprotective agents with their mechanisms.
6. Classify emetics. Compare centrally acting and locally acting emetics with respect to mechanism of action, species sensitivity, and clinical uses.
7. Write an account on antidiarrheal drugs - classify them, give the mechanism of action of each class, and discuss their rational use in veterinary patients.

Objective / MCQ Type Questions

1. Which of the following is a centrally acting emetic?
   • (a) Copper sulphate
   • (b) Apomorphine ✓
   • (c) Mustard
   • (d) Sodium chloride
2. The mechanism of action of bulk-forming laxatives is:
   • (a) Stimulate enteric nerves
   • (b) Absorb water and increase stool bulk ✓
   • (c) Lubricate the intestinal wall
   • (d) Increase chloride secretion
3. Metoclopramide acts as a prokinetic by:
   • (a) Blocking H2 receptors
   • (b) Blocking dopamine D2 receptors and stimulating 5-HT4 receptors ✓
   • (c) Stimulating muscarinic receptors
   • (d) Inhibiting serotonin reuptake
4. Which species is most sensitive to emetics?
   • (a) Dogs ✓
   • (b) Horses
   • (c) Cattle
   • (d) Rabbits
5. Sucralfate works by:
   • (a) Inhibiting the H+/K+-ATPase pump
   • (b) Forming a protective barrier over ulcer craters ✓
   • (c) Neutralizing gastric acid directly
   • (d) Blocking H2 histamine receptors
6. Castor oil acts as a purgative after being converted to:
   • (a) Ricinoleic acid ✓
   • (b) Linoleic acid
   • (c) Oleic acid
   • (d) Arachidonic acid
7. Which of the following is NOT an antiulcer drug?
   • (a) Omeprazole
   • (b) Ranitidine
   • (c) Atropine ✓ (anticholinergic, rarely used now)
   • (d) Sucralfate
8. Osmotic purgatives include all EXCEPT:
   • (a) Magnesium sulphate
   • (b) Sodium sulphate
   • (c) Bisacodyl ✓
   • (d) Lactulose
9. Domperidone differs from metoclopramide in that it:
   • (a) Does not cross the blood-brain barrier ✓
   • (b) Acts on 5-HT3 receptors
   • (c) Causes more CNS side effects
   • (d) Is used as an antiulcer drug
10. Emesis is physiologically NOT possible in:
    • (a) Dogs
    • (b) Cats
    • (c) Horses ✓
    • (d) Pigs

Very Short / One-liners

1. Name the drug of choice for emesis induction in dogs. (Apomorphine)
2. What class of drug is omeprazole? (Proton pump inhibitor)
3. Give one example of a saline/osmotic purgative. (Magnesium sulphate / Epsom salt)
4. What is the role of misoprostol in GI pharmacology? (Prostaglandin E1 analogue - protects gastric mucosa, used to prevent NSAID-induced ulcers)
5. Name the antidiarrheal drug that reduces GI motility by acting on opioid receptors. (Loperamide)
6. What is melanosis coli? (Brown pigmentation of colon caused by chronic use of anthraquinone laxatives like senna and aloe)
7. Which antacid can cause constipation? (Aluminium hydroxide)
8. Which antacid can cause diarrhea? (Magnesium hydroxide)
9. Name one bulk laxative used in animals. (Methylcellulose / Psyllium husk)
10. Kaolin and pectin are used as (Antidiarrheal - adsorbents)

Sources: Goodman & Gilman's Pharmacological Basis of Therapeutics; Katzung's Basic & Clinical Pharmacology 16e; BVSc Unit 4 syllabus (confirmed topics: stomachics, antacids, antiulcers, prokinetics, carminatives, laxatives, purgatives, antidiarrheals, emetics, antiemetics).