Pharmacology of Gastric Acid Lowering Drugs
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Questions and Answers

Which type of receptors do Histamine Type 2 Receptor Antagonists target?

  • Serotonin receptors
  • Motilin receptors
  • Histamine Type 2 receptors (correct)
  • Dopamine receptors

    • Which class of acid-lowering drugs requires activation?

  • Proton Pump Inhibitors (correct)
  • Antacids
  • Histamine Type 2 Receptor Antagonists
  • Potassium-Competitive Acid Blockers

    • What is the advantage of Potassium-Competitive Acid Blockers over Proton Pump Inhibitors?

  • Increased efficacy
  • Longer duration of action
  • Faster onset of action (correct)
  • Faster absorption

    • Which drug demonstrates anti-microbial activity, stimulates bicarbonate secretion, and forms a protective barrier along the surface of gastric epithelial cells?

    <p>Sucralfate</p> Signup and view all the answers

    Which class of acid-lowering drugs primarily undergoes renal elimination?

    <p>Histamine Type 2 Receptor Antagonists</p> Signup and view all the answers

    What is the name of the novel Potassium-Competitive Acid Blocker?

    <p>Vonoprazan</p> Signup and view all the answers

    Which type of agents stimulate gastrointestinal motility and are used in the treatment of GERD?

    <p>Prokinetic agents</p> Signup and view all the answers

    What is the primary mechanism of action of Proton Pump Inhibitors?

    <p>Blocking the H+/K+ ATPase enzyme</p> Signup and view all the answers

    Which type of agents are used to eradicate H. pylori infection?

    <p>Antibiotics</p> Signup and view all the answers

    What type of cells in the stomach are responsible for producing acid?

    <p>Parietal cells</p> Signup and view all the answers

    Which of the following reduces gastric acid production?

    <p>Excess acid</p> Signup and view all the answers

    What is the primary effect of H2 receptor antagonists?

    <p>Decrease in gastric acid secretion</p> Signup and view all the answers

    What is the most common indication for H2 receptor antagonists?

    <p>Gastroesophageal reflux disease (GERD)</p> Signup and view all the answers

    Which of the following is NOT a factor that regulates gastric acid production?

    <p>Epinephrine</p> Signup and view all the answers

    What is the mechanism of action of H2 receptor antagonists?

    <p>Blockade of histamine receptors</p> Signup and view all the answers

    What is the effect of histamine on gastric acid production?

    <p>Increase in gastric acid production</p> Signup and view all the answers

    What is the primary site of action for H2 receptor antagonists?

    <p>Parietal cells</p> Signup and view all the answers

    What is the duration of action of H2 receptor antagonists?

    <p>24 hours</p> Signup and view all the answers

    What is the primary indication for H2 receptor antagonists in terms of timing?

    <p>Before bedtime</p> Signup and view all the answers

    What is the mechanism of action of potassium-competitive active blockers?

    <p>Inhibit the ability of H+/K+ ATPase to bind to potassium, effectively inhibiting the pump</p> Signup and view all the answers

    What is the advantage of vonoprazan over PPIs?

    <p>It is more effective in killing H. pylori and has faster healing rates from bleeding</p> Signup and view all the answers

    What is the mechanism of action of antacids?

    <p>They react with gastric HCl to form a salt and water</p> Signup and view all the answers

    What is the primary mechanism of action of misoprostol?

    <p>It stimulates the production of mucus and bicarbonate secretion</p> Signup and view all the answers

    What is the mechanism of action of dopamine receptor antagonists in the gut?

    <p>They antagonize the action of dopamine in the gut, increasing LES tone and gastric emptying rate</p> Signup and view all the answers

    What is the primary mechanism of action of erythromycin?

    <p>It is a macrolide antibiotic that acts as a ligand for the motilin receptor</p> Signup and view all the answers

    What is the primary difference between PPIs and H2R antagonists?

    <p>PPIs inhibit the H+/K+ ATPase, while H2R antagonists inhibit histamine receptors</p> Signup and view all the answers

    What is the primary advantage of mucosal protective agents?

    <p>They increase the protective mechanisms of the gastric lining</p> Signup and view all the answers

    What is the primary mechanism of action of bismuth subsalicylate?

    <p>It has antimicrobial activity, stimulates bicarbonate secretion, and forms a protective barrier</p> Signup and view all the answers

    What is the primary mechanism of action of prokinetic agents?

    <p>They stimulate gastrointestinal motility and increase LES tone</p> Signup and view all the answers

    Which of the following H2 receptor antagonists has the greatest affinity for the H2 receptor?

    <p>Famotidine</p> Signup and view all the answers

    What is the primary mechanism of action of proton pump inhibitors?

    <p>Irreversible inactivation of the H/K ATPase</p> Signup and view all the answers

    Which of the following H2 receptor antagonists is contraindicated in renal dysfunction?

    <p>Nizatidine</p> Signup and view all the answers

    What is the primary reason for administering proton pump inhibitors 1 hour before a meal?

    <p>To coincide with the peak activity of proton pumps</p> Signup and view all the answers

    Which of the following is a potential interaction of omeprazole with another drug?

    <p>Warfarin</p> Signup and view all the answers

    What is the primary mechanism of metabolic activation of proton pump inhibitors?

    <p>Protonation of the pro-drug</p> Signup and view all the answers

    Which of the following is a characteristic of H2 receptor antagonists?

    <p>Little effect on cytochrome P450s</p> Signup and view all the answers

    What is the primary reason for the long duration of action of proton pump inhibitors?

    <p>Irreversible binding of the pump</p> Signup and view all the answers

    Which of the following is a side effect of H2 receptor antagonists?

    <p>Diarrhea</p> Signup and view all the answers

    What is the primary mechanism of action of ranitidine?

    <p>Blockade of H2 receptors</p> Signup and view all the answers

    Study Notes

    Pharmacology of Gastric Acid Lowering Drugs

    Overview of Gastrointestinal Disorders

    • Most common gastrointestinal disorders: peptic ulcer disease (gastric or duodenal in origin), gastroesophageal reflux disease (GERD), drug-induced injury, hypersecretory states (Zollinger-Ellison disease), and stress-related mucosal injury

    Physiology of Acid Production

    • Gastric acid is produced by parietal cells in the stomach fundus
    • Factors that regulate gastric acid production: Acetylcholine (+), Histamine (+), Gastrin (+), GRP (+), Excess acid (-) (via Somatostatin), Gastric inhibitory peptide (GIP) (-), Prostaglandin E2 (-), and EGF (-)

    Mechanism of Gastric Acid Lowering Drugs

    • Histamine Type 2 Receptor Antagonists (H2RAs):
      • Reduce volume of gastric secretion and concentration/acidity
      • Effective in treating basal acid secretion (at night)
      • Examples: Ranitidine (Zantac), Famotidine (Pepcid), Nizatidine
      • Adverse Effects: Minor side effects (diarrhea, headache, drowsiness, fatigue, constipation), Cimetidine inhibits binding of dihydrotestosterone to androgen receptors, crosses placenta, and is secreted in breast milk

    Proton Pump Inhibitors (PPIs)

    • Weak bases that concentrate in acidic environments (1000-fold more concentrated in stomach than elsewhere in the body)
    • Pro-drugs that require activation; the active drug interacts with H/K ATPase, irreversibly inactivating the enzyme
    • Examples: Omeprazole, Esomeprazole, Lansoprazole, Dexlansoprazole, Pantoprazole, Rabeprazole
    • Indicated for GERD and peptic ulcers, and in combination treatment of H. pylori infection
    • Pharmacokinetics: rapid first-pass hepatic metabolism, negligible renal clearance, highly plasma protein bound, and polymorphisms in CYP2C19 may affect efficacy and toxicity

    Adverse Effects of PPIs

    • Generally well tolerated, but may cause nausea, abdominal pain, flatulence, diarrhea, and interact with clopidogrel

    Potassium-Competitive Active Blockers (PCABs)

    • Inhibit ability of H/K ATPase to bind to potassium, effectively inhibiting the pump
    • Example: Vonoprazan (approved in Japan, pending approval in North and South America)
    • Advantages over PPIs: no need for protonation for activity, more consistent lowering of gastric pH, and less frequent bacterial resistance

    Antacids

    • Weak bases that react with gastric HCl to form a salt and water
    • Examples: Sodium Bicarbonate, Calcium Carbonate, Magnesium/Aluminum Hydroxides
    • Adverse Effects: Metabolic alkalosis, gastric distension, belching, and binding of other drugs (ACE inhibitors, quinolone antibiotics, ASA, NSAIDS, levothyroxine, glyburide, and misoprostol)

    Mucosal Protective Agents

    • Prostaglandins (Misoprostol): stimulate mucus and bicarbonate secretion, increase mucosal blood flow, and have anti-inflammatory properties
    • Bismuth Subsalicylate: part of quadruple therapy for H. pylori infections, inhibits pepsin activity, and increases mucous production

    Prokinetic Agents

    • Dopamine Receptor Antagonists (e.g., Domperidone): increase esophageal peristalsis, increase LES tone, and increase gastric emptying rate
    • 5-HT Agonists (e.g., Prucalopride): stimulate peristalsis, increase LES tone, and increase gastric emptying rate
    • Erythromycin: ligand for the motilin receptor, increases LES tone, and increases gastric emptying rate

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    Description

    This quiz covers the pharmacology of drugs used to treat peptic ulcers and GERD, including proton pump inhibitors, histamine type 2 receptor antagonists, and antacids. It also explores the therapy of H. Pylori infection and prokinetic drugs for treating GERD.

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