Gastrointestinal Tract Pharmacology Quiz

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Questions and Answers

What are the major classes of drugs used to treat peptic ulcer disease that inhibit gastric acid secretion?

Proton pump inhibitors, H2-receptor antagonists, antimuscarinic agents, and prostaglandin analogs.

List two types of agents used to treat constipation.

Laxatives and purgatives.

How does Helicobacter pylori contribute to the development of peptic ulcers?

It causes hypergastrinaemia, leading to increased acid production.

What is the relationship between NSAID use and peptic ulcer disease?

NSAIDs can damage the stomach lining, increasing the risk of peptic ulcer formation. Signup and view all the answers

Why is it important to continuously administer drugs for peptic ulcers?

Peptic ulcers will recur if drugs are discontinued, as they often require ongoing treatment. Signup and view all the answers

Identify one type of pharmaceutical agent classified as a purgative.

Castor oil. Signup and view all the answers

What mechanism do proton pump inhibitors employ to reduce gastric acid secretion?

They inhibit the proton pump in gastric parietal cells. Signup and view all the answers

Name one antimuscarinic agent used in the treatment of peptic ulcers.

Pirenzepine. Signup and view all the answers

What is the mechanism of action of Proton Pump Inhibitors (PPIs) such as Omeprazole?

PPIs like Omeprazole inhibit the H+ pump by binding covalently to the SH group of the pump, irreversibly inactivating it. Signup and view all the answers

Explain the role of H2-receptor antagonists in managing peptic ulcers.

H2-receptor antagonists competitively block H2 receptors on parietal cells, suppressing all phases of gastric acid secretion. Signup and view all the answers

What are potential side effects associated with H2-receptor antagonists?

Side effects include reversible gynecomastia, elevated serum prolactin levels, and alterations in estrogen levels in men. Signup and view all the answers

Describe how sucralfate protects against ulcers.

Sucralfate forms a sticky gel that adheres to the ulcer base, creating a physical barrier against acid and pepsin. Signup and view all the answers

What contraindications should be considered when prescribing Misoprostol?

Misoprostol is contraindicated in pregnancy due to its effects on uterine contractions. Signup and view all the answers

List the systemic and non-systemic antacids mentioned in the content.

Systemic antacids include sodium bicarbonate and sodium citrate; non-systemic antacids include magnesium hydroxide, aluminum hydroxide, and calcium carbonate. Signup and view all the answers

What conditions are effectively treated with Proton Pump Inhibitors?

PPIs are effective for conditions like reflux, duodenal ulcers, gastric ulcers, and Zollinger-Ellison syndrome. Signup and view all the answers

Describe the role of Bismuth-containing preparations in peptic ulcer treatment.

Bismuth-containing preparations, such as colloidal bismuth subcitrate, have ulcer protective properties and can inhibit H.pylori. Signup and view all the answers

What role does Moa play in ulcer treatment?

Moa reacts with protein at the ulcer's base, protecting it from peptic digestion while stimulating the secretion of PGE2, mucus, and bicarbonate. Signup and view all the answers

How do systemic antacids differ from non-systemic antacids?

Systemic antacids like sodium bicarbonate are absorbed into the bloodstream, while non-systemic antacids like magnesium hydroxide are not absorbed and act locally in the gastrointestinal tract. Signup and view all the answers

Describe the mechanism by which anti-H. pylori agents work.

Anti-H. pylori agents utilize multiple antibiotics to eradicate H. pylori infection, prevent resistance, and promote rapid ulcer healing. Signup and view all the answers

What is the significance of the quadruple therapy regimen for H. pylori?

Quadruple therapy includes multiple medications to effectively eradicate H. pylori and provide symptom relief over a 14-day period. Signup and view all the answers

List two types of antiemetics and their indications.

Antihistamines like Diphenhydramine and 5-HT3 inhibitors like Ondansetron are often used to manage nausea and vomiting, especially during chemotherapy. Signup and view all the answers

Explain the mechanism of action for bulk-forming laxatives.

Bulk-forming laxatives work by increasing water retention and stool bulk, which distends the bowel and stimulates peristalsis. Signup and view all the answers

What common food sources can contribute to the effects of bulk-forming laxatives?

Common food sources include indigestible parts of fruits and vegetables, such as hydrophilic colloids, which enhance the laxative effect. Signup and view all the answers

What is the typical duration of treatment for H. pylori eradication therapy?

The typical duration for H. pylori eradication therapy is 1 to 2 weeks. Signup and view all the answers

Study Notes

Gastrointestinal Tract (GIT) Pharmacology

Gastrointestinal (GI) disorders can range from minor daily discomforts to major health issues.
Dietary adjustments can often improve symptoms caused by poor eating habits.
Pharmacological interventions are necessary when dietary measures fail.
Major GIT diseases include Peptic ulcer disease (PUD), diarrhoea and constipation.
Diarrhoea causes fluid and electrolyte imbalances. Treatment involves oral or intravenous fluid and electrolyte replacement therapy.
Constipation is typically treated with Laxatives or Purgatives.
Laxatives include Al, Mg and sodium salts, while Purgatives include mineral oils like Liquid paraffin, castor oil and stimulant purgatives like Bisacodyl.

Peptic Ulcer Disease (PUD)

Peptic ulcer refers to any ulcer in an area where the mucosa is bathed with HCL and pepsin of gastric juice (stomach and upper duodenum).
Damage to the mucosa and deeper tissue exposed to acid and pepsin leads to peptic ulcer.
Drugs effective in peptic ulcer either reduce gastric acid secretion or increase mucosal resistance to acid-pepsin attack.
Peptic ulcers that heal will always reoccur without continuous drug administration.

Causes of Peptic Ulcer

Chronic infection of the stomach with Helicobacteria pylori is a major cause of peptic ulcer formation.
H.pylori is found in approximately 95% of duodenal ulcers and 70% of stomach ulcers.
H.pylori infection causes hypergastrinaemia, which in turn increases acid production.

Drugs for Peptic Ulcers

Drugs that inhibit gastric acid secretion:
- Proton pump inhibitors (PPIs): omeprazole, esomeprazole, lansoprazole, pantoprazole, rabeprazole.
- H2-receptor antagonists: cimetidine, ranitidine, famotidine, roxatidine, nizatidine.
- Antimuscarinic agents (anticholinergics): Block muscarinic (M1 cholinergic receptors). Include Pirenzepine, Telenzepine.
- Prostaglandin analogs: misoprostol, enprostil.
Ulcer protective:
- Sucralfate.
- Bismuth subcitrate (CBS).
Drugs that neutralize gastric acid (antacids):
- Systemic antacids: sodium bicarbonate and sodium citrate.
- Non-systemic antacids: magnesium hydroxide, magnesium trisilicate, aluminum hydroxide, and calcium carbonate.
Anti- H.pylori drugs:
- Amoxicillin, tetracycline, clarithromycin, metronidazole, tinidazole, bismuth subsalicylate, H2-antagonists and PPIs.

Proton Pump Inhibitors (PPIs)

Proton pump, K+-ATPase, a membrane-bound enzyme, plays a crucial role in the final step of gastric acid secretion (basal and stimulated).
Omeprazole is the prototype drug. PPIs are prodrugs activated to sulfonamide at acidic pH.
Activated form binds covalently with SH group of H+ pump and irreversibly inactivates it.
PPIs are administered orally 30 minutes before meals.
Half-life is short (1.5 hours), but acid secretion suppression lasts up to 24 hours.

Indications for PPIs

Single daily administration can inhibit acid secretion by 100%.
Effective in reflux, duodenal and gastric ulcer, Multiple endocrine neoplasia (MEN) and Zollinger-Ellison syndrome.

Side Effects of PPIs

Generally well tolerated, but can cause diarrhoea.

H2-Receptor Antagonists

Mechanism of action: Competitively block H2 receptors on parietal cells; suppress all phases of acid secretion.
Most effective in suppressing nocturnal acid secretion and less potent than PPIs.

Side Effects of H2-Receptor Antagonists

Reversible gynaecomastia, elevated serum prolactin levels and altered oestrogen level in men.
Inhibition of cytochrome P450 metabolism.

Prostaglandin Analogues

Misoprostol is effective orally for prevention and treatment of NSAID-induced duodenal and gastric ulcers.
Misoprostol is a Prostaglandin E1 analogue that stimulates production of mucus and other protective factors like bicarbonate.

Common Side Effects of Misoprostol

Diarrhoea and abdominal cramps.
Contraindicated in pregnancy.

Ulcer Protective

Sucralfate: Complex aluminum hydroxide and sulphated sucrose. Forms a physical barrier against acid-pepsin. Polymerizes to form a sticky gel that adheres to the ulcer base and protects it.
Warning: Sucralfate should not be taken simultaneously with PPI or H2 blockers because the drug needs an acidic pH for its action.
Bismuth containing preparations: Bismuth salicylates and colloidal Bismuth subcitrate.
Mechanism of action: Similar to sucralfate. React with protein in the base of the ulcer and protect it from peptic digestion. Stimulates secretion of PGE2, mucus and bicarbonate.
98% ulcer healing reported when combined with antimicrobial agents, due to increased effects against H.pylori.

Drugs that Neutralize Gastric Acid (Antacids)

Antacids are bases that raise gastric pH by neutralizing gastric acids.
They provide effective treatment for many dyspepsia and symptomatic relief for many peptic ulcers and oesophageal reflux.

Types of Antacids

Systemic: Sodium bicarbonate and Sodium citrate.
Non-systemic: Magnesium hydroxide, magnesium trisilicate, aluminum hydroxide gel and calcium carbonate.

Anti-H.pylori Agents

H.pylori is a gram-negative, rod-shaped bacteria associated with gastritis, duodenal ulcer, gastric ulcer and gastric carcinoma.
Causes mucosal inflammation.
Ammonia produced by urease activity damages cells.

Combination Therapy for H.pylori

Use of multiple antibiotics for synergism.
Prevents or delays development of resistant organisms.
Prevents relapse.
Promotes rapid ulcer healing.
Eradicates H.pylori infection.

Treatment Duration for H.pylori

Treatment for 1 or 2 weeks required.

Triple Therapy for H.pylori (14 days)

Lansoprazole 30 mg BD + clarithromycin 500 mg BD + Amoxicillin 1 g BD.

Quadruple Therapy for H.pylori (14 days)

Lansoprazole 30 mg BD + Bismuth subsalicylate 525 mg QID + Tetracycline 500 mg QID + Metronidazole 500 TDS.

After H.pylori Treatment

PPIs should be continued for six more weeks after completing the eradication regimen.

Anti-Emetics

Include drugs like:
- Antihistamines- H1 blockers, such as Diphenhydramine.
- Phenothiazines- Promethazine, prochloperazine.
- 5-HT3 inhibitors- ondansetron.

Indications for Anti-Emetics

Any condition that is inducing emesis, such as chemotherapy, and GI infection.

Laxatives

Agents used to soften stool and relieve indigestion.
Classified based on their mechanism of action.
Bulk-forming:
- Nonabsorbable agents that increase water retention and stool bulk, which distends the bowel and increases peristalsis.
- Normally insoluble during the digestive process.
- Examples: Hydrophilic colloids (from indigestible parts of fruits and vegetables), Agar, Methycellulose, Bran, Lactulose, sorbitol and saline cathartics (Magnesium citrate and Magnesium hydroxide).

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Description

Test your knowledge on gastrointestinal disorders, dietary adjustments, and pharmacological interventions. This quiz covers essential topics including Peptic Ulcer Disease (PUD), diarrhoea, and constipation treatments. Prepare to explore different laxatives and purgatives used for managing GIT conditions.