H2 Antagonists and Stress Ulcers

Questions and Answers

When should Proton Pump Inhibitors (PPIs) be taken for maximum effect?

30 minutes before breakfast or the largest meal (correct)

At breakfast time

After dinner

At bedtime

What is the potential risk associated with long-term use of Proton Pump Inhibitors?

Increased risk of fractures (correct)

Increased risk of gastrointestinal bleeding

Increased risk of heart disease

Increased risk of liver failure

What should be done if an H2-receptor antagonist is needed alongside a PPI?

Take the H2-receptor antagonist before the PPI

Take the H2-receptor antagonist after the PPI (correct)

Take both medications at the same time

Skip the H2-receptor antagonist

Which of the following medications is known to inhibit the metabolism of warfarin when taken with PPIs?

Omeprazole Signup and view all the answers

Which condition can result from the long-term suppression of gastric acid due to Proton Pump Inhibitors?

Low vitamin B12 absorption Signup and view all the answers

What is a common adverse effect associated with Misoprostol?

Diarrhea Signup and view all the answers

What is a contraindication for the use of Misoprostol?

Pregnancy Signup and view all the answers

In terms of therapeutic effectiveness, how do prostaglandin analogues compare to PPIs for acute treatment of peptic ulcers?

Less effective than H2 antagonists and PPIs Signup and view all the answers

What is a primary therapeutic use of aluminum- and magnesium-containing antacids?

Symptomatic relief of peptic ulcer disease Signup and view all the answers

What is a potential adverse effect of magnesium hydroxide when used as an antacid?

Diarrhea Signup and view all the answers

Which of the following is true regarding the action of antacids on pepsin?

They reduce pepsin activity Signup and view all the answers

What side effect is associated with the use of aluminum-containing antacids?

Constipation Signup and view all the answers

Which condition would make sodium bicarbonate an unsuitable long-term antacid option?

Transient metabolic alkalosis Signup and view all the answers

Which mechanism describes how sucralfate provides mucosal protection?

Creating a physical barrier with complex gels Signup and view all the answers

What is a significant concern when using antacids in patients with renal impairment?

Accumulation of magnesium and calcium Signup and view all the answers

Which of the following statements about muscarinic receptor stimulation is correct?

Increases secretory activity in the gastrointestinal tract Signup and view all the answers

What is a common therapeutic use for H2 antagonists in high-risk ICU patients?

Prevention of acute stress ulcers Signup and view all the answers

Which of the following is a key pharmacokinetic property of cimetidine?

Inhibits cytochrome P450 Signup and view all the answers

What is a notable adverse effect of cimetidine that is not seen with ranitidine?

Gynecomastia Signup and view all the answers

How effective are low doses of H2 antagonists in treating heartburn in patients with GERD?

About 50% Signup and view all the answers

Why might ketoconazole not be efficiently absorbed when taken with H2 antagonists?

Ketoconazole requires an acidic medium for gastric absorption Signup and view all the answers

What is the primary excretion pathway for cimetidine?

Urine Signup and view all the answers

Which statement accurately reflects the difference in potency between ranitidine and cimetidine?

Ranitidine is 5-10 fold more potent than cimetidine. Signup and view all the answers

Which of the following substances is least impacted by cimetidine's effects on drug metabolism?

Propranolol Signup and view all the answers

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.