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Peptic Ulcer Drugs
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1
Question
What condition arises when aggressive factors overwhelm the defensive factors of the GI mucosa?
Page 2
Answer
Mucosal erosions or ulceration
2
Question
What are the aggressive factors in peptic ulcer disease listed on page 3?
Page 3
Answer
Hydrochloric acid (HCl), pepsin, H. pylori, drugs such as NSAIDs and glucocorticoids (GCs)
3
Question
List the defensive factors protecting the GI mucosa as described on page 3.
Page 3
Answer
1. Mucus secretion, 2. Bicarbonate secretion, 3. Prostaglandins (Pg) for regeneration of mucosa after injury, 4. Blood flow for regeneration of mucosa after injury
4
Question
What are the two main causes of peptic ulcer disease according to the source?
Page 3
Answer
Infection with gram-negative Helicobacter pylori and use of NSAIDs
5
Question
Which receptors on parietal cells are stimulated by gastrin, acetylcholine, and histamine to secrete acid?
Page 4
Answer
Gastrin receptors, M3 receptors, H2 receptors
6
Question
By what mechanism do parietal cells secrete HCl into the gastric lumen?
Page 4
Answer
HCl is secreted across the parietal cell canalicular membrane by the H+/K+-ATPase proton pump
7
Question
What second messenger increases upon stimulation of H2 receptors on parietal cells?
Page 4
Answer
cAMP
8
Question
What second messenger increases upon stimulation of M-receptors and gastrin receptors on parietal cells?
Page 4
Answer
Ca2+
9
Question
Name the three broad categories of drugs used in peptic ulcer disease from page 5.
Page 5
Answer
1. Drugs reducing secretion of gastric acid (antisecretory and antacids), 2. Drugs protecting gastric and duodenal mucosa (sucralfate, Pg, bismuth), 3. Drugs eradicating H. pylori (amoxicillin, macrolides, tetracyclines, metronidazole)
10
Question
What are the subtypes of antisecretory drugs listed under gastric acid reducers?
Page 6
Answer
Proton pump inhibitors, H2-receptor antagonists, antimuscarinic drugs
11
Question
How do H2-receptor antagonists exert their pharmacodynamic effect?
Page 7
Answer
Competitive antagonists of histamine for H2 receptors on parietal cells, blocking histamine binding and decreasing HCl secretion
12
Question
Which types of acid secretion do H2-receptor antagonists primarily suppress?
Page 7
Answer
Basal and meal-stimulated acid secretion, especially nocturnal secretion which is histamine-dependent
13
Question
What are the four main indications for H2-receptor antagonists?
Page 7
Answer
1. Peptic ulcer, 2. Gastroesophageal reflux disease (GERD), 3. Bleeding from upper gastrointestinal erosions or ulcers, 4. Zöllinger-Ellison syndrome
14
Question
What additional effects do H2-receptor antagonists have besides reducing HCl?
Page 7
Answer
Decrease production of pepsin and reduce intracellular cAMP
15
Question
Name the four H2-receptor antagonists listed with their trade names.
Page 9
Answer
1. Cimetidine, 2. Ranitidine (Ranitidin®, Zantac®), 3. Famotidine (Quamatel®, Famotidin®), 4. Nizatidine (Axid®)
16
Question
What is the dose regimen for ranitidine in treating peptic ulcer?
Page 10
Answer
4-8 weeks: 2 x 0.15 g or 0.3 g at bedtime
17
Question
What is the prophylactic dose for ranitidine in ulcer prevention?
Page 10
Answer
0.15 g at bedtime
18
Question
Compare the bioavailability of the four H2-receptor antagonists from the table.
Page 11
Answer
Cimetidine 60-70%, Ranitidine 50%, Famotidine 40-50%, Nizatidine 90%
19
Question
What are the half-lives (t½) of the H2-receptor antagonists?
Page 11
Answer
Cimetidine 2-2.5 h, Ranitidine 2-3 h, Famotidine 3-3.5 h, Nizatidine 1-2 h
20
Question
Which H2-receptor antagonist has the strongest effect on cytochrome P450?
Page 11
Answer
Cimetidine (effect rated as 1, others lower)
21
Question
List the common adverse drug reactions (ADRs) of H2-receptor antagonists.
Page 12
Answer
GIT: diarrhea (rarely anorexia, nausea, vomiting); CNS: headache, vertigo, somnolence; rashes; arthralgias; temporary increase of liver transaminases; risk of arrhythmias with IV administration
22
Question
Name the proton pump inhibitors (PPIs) listed with examples.
Page 13
Answer
Omeprazole (Sopral®, Probitor®), lansoprazole (Lanzul®, Lansoprol®), rabeprazole (Pariet®), pantoprazole (Controloc®, Panrazol®), esomeprazole (Emanera®, Nexium®)
23
Question
How do proton pump inhibitors (PPIs) work as prodrugs?
Page 15
Answer
Basic drugs that accumulate in the acid environment of parietal cell canaliculi, activated to form a stable covalent bond with H+/K+-ATPase, inhibiting the enzyme
24
Question
What types of gastric acid secretion do PPIs reduce?
Page 15
Answer
Both basal and stimulated gastric acid secretion
25
Question
What are the indications for proton pump inhibitors?
Page 16
Answer
Peptic ulcer, gastroesophageal reflux disease (GERD) with heartburn, Zöllinger-Ellison syndrome
26
Question
What are common ADRs of proton pump inhibitors?
Page 16
Answer
GIT: nausea, vomiting, diarrhea, liver dysfunction; CNS: headache, dizziness, somnolence, mental confusion; skin: rashes
27
Question
Which PPIs inhibit cytochrome P450 and affect drugs like warfarin and diazepam?
Page 16
Answer
Omeprazole and lansoprazole
28
Question
Why should PPIs be avoided with clopidogrel?
Page 16
Answer
PPIs may inhibit clopidogrel activation since clopidogrel is a prodrug activated by cytochrome P450
29
Question
What is the dosing regimen for omeprazole in peptic ulcer treatment?
Page 17
Answer
20 mg once daily for 4 weeks
30
Question
Compare oral bioavailability of PPIs from the pharmacokinetics table.
Page 18
Answer
Omeprazole 45%, lansoprazole 85%, pantoprazole 77%, rabeprazole 52%, esomeprazole 64-90%