Questions and Answers
When should Proton Pump Inhibitors (PPIs) be taken for maximum effect?
What is the potential risk associated with long-term use of Proton Pump Inhibitors?
What should be done if an H2-receptor antagonist is needed alongside a PPI?
Which of the following medications is known to inhibit the metabolism of warfarin when taken with PPIs?
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Which condition can result from the long-term suppression of gastric acid due to Proton Pump Inhibitors?
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What is a common adverse effect associated with Misoprostol?
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What is a contraindication for the use of Misoprostol?
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In terms of therapeutic effectiveness, how do prostaglandin analogues compare to PPIs for acute treatment of peptic ulcers?
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What is a primary therapeutic use of aluminum- and magnesium-containing antacids?
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What is a potential adverse effect of magnesium hydroxide when used as an antacid?
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Which of the following is true regarding the action of antacids on pepsin?
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What side effect is associated with the use of aluminum-containing antacids?
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Which condition would make sodium bicarbonate an unsuitable long-term antacid option?
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Which mechanism describes how sucralfate provides mucosal protection?
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What is a significant concern when using antacids in patients with renal impairment?
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Which of the following statements about muscarinic receptor stimulation is correct?
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What is a common therapeutic use for H2 antagonists in high-risk ICU patients?
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Which of the following is a key pharmacokinetic property of cimetidine?
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What is a notable adverse effect of cimetidine that is not seen with ranitidine?
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How effective are low doses of H2 antagonists in treating heartburn in patients with GERD?
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Why might ketoconazole not be efficiently absorbed when taken with H2 antagonists?
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What is the primary excretion pathway for cimetidine?
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Which statement accurately reflects the difference in potency between ranitidine and cimetidine?
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Which of the following substances is least impacted by cimetidine's effects on drug metabolism?
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Study Notes
Acute Stress Ulcers
- Management with drugs is essential for high-risk ICU patients with physical trauma.
- H2 antagonists are key therapeutic agents.
Gastroesophageal Reflux Disease (GERD)
- Low doses of H2 antagonists treat heartburn effectively in about 50% of patients.
- Antacids act quickly to neutralize stomach acid but provide only temporary relief.
H2 Antagonists - Pharmacokinetics
- Cimetidine is administered orally, widely distributed, crosses breast milk and placenta.
- Metabolized slowly in the liver (30%); 70% excreted unaltered in urine.
- Short half-life; dosage adjustments needed for patients with hepatic or renal failure.
- It inhibits cytochrome P450, affecting drug metabolism (warfarin, diazepam, phenytoin).
H2 Antagonists - Adverse Effects
- Common side effects: headache, dizziness, diarrhea, muscular pain.
- CNS effects like confusion and hallucinations more likely in the elderly or after IV use.
- Cimetidine can cause endocrine effects: gynecomastia, galactorrhea, reduced sperm count.
- Medications like ketoconazole may have reduced absorption when taken with H2 antagonists.
Ranitidine
- Longer acting and 5-10 times more potent than cimetidine.
- Minimal side effects; no antiandrogenic or prolactin effects.
- Does not impact liver mixed-function oxygenase system, preserving other drug concentrations.
Proton Pump Inhibitors (PPI) - Therapeutic Uses
- Must be taken 30 minutes before meals for maximum effectiveness.
- H2 antagonists should follow the PPI if needed, especially in GERD patients.
Proton Pump Inhibitors (PPI) - Pharmacokinetics
- Effective orally and available for IV injection.
- Metabolites excreted in urine and feces.
Proton Pump Inhibitors (PPI) - Adverse Effects
- Long-term use increases fracture risk in the hip, wrist, and spine.
- Omeprazole can inhibit metabolism of warfarin, phenytoin, and others through CYP450.
- Prolonged use suppresses gastric acid, resulting in decreased vitamin B12 and calcium absorption.
- Associated with diarrhea and Clostridium difficile colitis.
Prostaglandin Analogues
- Prostaglandin E2 inhibits HCl secretion and promotes mucus and bicarbonate secretion.
- Misoprostol, a stable analog of prostaglandin E1, prevents NSAID-induced gastric ulcers.
- Less effective than H2 antagonists and PPIs for acute peptic ulcer treatment.
Prostaglandin Analogues - Adverse Effects
- Misoprostol can induce uterine contractions; contraindicated in pregnancy.
- Common adverse effects include dose-related diarrhea and nausea.
Antimuscarinic Agents
- Increase gastrointestinal motility and secretory activity via muscarinic receptor stimulation.
- Dicyclomine is a cholinergic antagonist used for peptic ulcer disease management.
- Side effects include cardiac arrhythmias, dry mouth, constipation, urinary retention.
Antacids - Mechanism of Action
- Antacids are weak bases that react with gastric acid to form water and salt, reducing acidity.
- Inactivate pepsin at a pH greater than 4.
Antacids - Common Types
- Aluminum and magnesium salts, like aluminum hydroxide and magnesium hydroxide.
- Sodium bicarbonate can produce transient metabolic alkalosis; not recommended for long-term use.
Antacids - Therapeutic Uses
- Aluminum- and magnesium-containing antacids alleviate symptoms of peptic ulcer disease and GERD.
- May assist in healing duodenal ulcers.
Antacids - Adverse Effects
- Aluminum hydroxide may cause constipation; magnesium hydroxide can induce diarrhea.
- Aluminum antacids can lead to hypophosphatemia due to phosphate binding.
- Sodium bicarbonate can cause belching, flatulence, and potential alkalosis.
Mucosal Protective Agents
- Known as cytoprotective compounds, they help prevent mucosal injury and promote healing.
- Sucralfate forms complex gels with epithelial cells, creating a protective barrier against HCl and pepsin.
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Description
This quiz covers the therapeutic uses and pharmacokinetics of H2 antagonists in managing acute stress ulcers and gastroesophageal reflux disease (GERD). Learn about their effectiveness and how they compare to antacids in various patient scenarios.