pharma Flashcards
What factors regulate gastric acid secretion?
Acetylcholine, histamine, gastrin
Acetylcholine acts through muscarinic receptors, histamine through H2 receptors, and gastrin through CCK receptor2.
What stimulates the release of acetylcholine for gastric acid secretion?
Sight, smell, taste, anticipation of food, presence of food, gastric distension
These stimuli are part of the cephalic and gastric phases of digestion.
What is the role of somatostatin (SST) in gastric acid secretion?
Inhibits gastric acid secretion
SST is released in response to low gastric pH and suppresses gastrin release.
What are the gastric defenses against acid?
- Lower esophageal sphincter
- Mucosal blood flow
- Mucus secretion
- Bicarbonate secretion
- Prostaglandins E2 and I2
These mechanisms protect the stomach lining from acid damage.
What are the goals of therapy for acid peptic disease and GERD?
- Reduce gastric acid production
- Neutralize gastric H+
- Protect stomach walls
These goals aim to alleviate symptoms and promote healing.
What are the classes of anti-acid drugs?
- Antacids
- Inhibitors of gastric acid production
- Cytoprotective agents
Inhibitors include proton pump inhibitors (PPIs), H2 receptor antagonists, and muscarinic antagonists.
What are the main actions of antacids?
- Partially neutralize gastric acid
- Reduce pepsin activity
- Stimulate prostaglandin production
- Reduce ulcer pain
Antacids can promote healing of ulcers.
What are common examples of antacids?
- Magnesium hydroxide
- Aluminum hydroxide
- Calcium carbonate
- Sodium bicarbonate
These agents contain various salts that neutralize gastric acid.
What is a potential adverse effect of sodium bicarbonate?
Metabolic alkalosis
Sodium bicarbonate can cause systemic absorption leading to alkalosis, especially in patients with certain conditions.
What is the mechanism of action of proton pump inhibitors (PPIs)?
Covalently bind to H+/K+ ATPase pump
This inhibits gastric acid secretion for up to 36 hours.
What is the prototype proton pump inhibitor?
Omeprazole
Other examples include esomeprazole, lansoprazole, rabeprazole, and pantoprazole.
What are common adverse effects of omeprazole?
- Headache
- Dizziness
- Abdominal pain
- Diarrhea
These effects occur in at least 1% of patients.
What are H2 receptor antagonists used for?
- Duodenal ulcers
- Gastric ulcers
- Reflux esophagitis
They suppress gastric acid secretion effectively.
What is the prototype H2 receptor antagonist?
Cimetidine
Other examples include ranitidine, famotidine, and nizatidine.
What is the main action of sucralfate?
Forms a protective gel at ulcer sites
This gel adheres to epithelial cells and prevents damage from acid.
What are the therapeutic uses of sucralfate?
- Peptic ulceration
- Treatment of epithelial wounds
- Chemotherapy-induced mucositis
Sucralfate promotes healing and protects the mucosa.
What is a common side effect of sucralfate?
Constipation
Other effects are very low, but it can adsorb and reduce the bioavailability of many drugs.
True or False: Long-term use of PPIs is associated with an increased risk of certain infections.
True
This is likely due to decreased stomach acid production.
What is dyspepsia?
Dyspepsia refers to indigestion or discomfort in the upper abdomen.
What role does sucralfate play in epithelial wound healing?
Sucralfate increases the bio-availability of growth factors, especially fibroblast growth factor (FGF), promoting epithelial wound healing.
How does sucralfate help in the treatment of chemotherapy-induced mucositis?
Sucralfate accelerates the activation of growth factors.
What is the use of sucralfate in radiation proctitis?
Sucralfate is used as a paste enema.
What benefit does sucralfate provide in the prevention of ulceration of diversion colitis?
Sucralfate preserves the mucus layer covering the epithelium, reducing inflammation.
What is the advantage of sucralfate over H-2 blockers or antacids for stress ulcer prophylaxis?
Sucralfate is better for stress ulcer prophylaxis because H-2 blockers or antacids increase the pH of gastric contents, raising the risk of nosocomial pneumonia.
What is Behcet Disease and how does sucralfate help?
In combination with topical corticosteroids, sucralfate reduces pain and promotes healing of oral ulcers.
What is the prototype of prostaglandin analogs?
Misoprostol is the prototype of prostaglandin analogs.
What is the mechanism of action of misoprostol?
Misoprostol stimulates prostaglandin E1 receptors on parietal cells to reduce gastric acid secretion and increases mucus and bicarbonate secretion.
What does the term ‘cytoprotection’ refer to?
Cytoprotection means protection against gastric mucosal injury by mechanisms other than inhibition or neutralization of gastric acid.
What are the pharmacokinetics of misoprostol?
Misoprostol is extensively absorbed, with vaginal and sublingual routes showing greater efficacy due to bypassing the liver first-pass effect.
What are the adverse effects associated with misoprostol?
Adverse effects include diarrhea, abdominal pain, dyspepsia, flatulence, nausea, vomiting, and headache.
What are the therapeutic uses of misoprostol?
Therapeutic uses include prevention of NSAID-induced gastric ulcers, labor induction, medical abortions, completing miscarriages, and preventing post-partum bleeding.
What are bismuth compounds and their action?
Bismuth compounds, like bismuth subsalicylate, have weak antacid properties and bactericidal action against Helicobacter pylori.
What are the adverse effects of prolonged use of bismuth compounds?
Prolonged use can cause encephalopathy, osteodystrophy, darkening of the oral cavity, and dark stools.
What is the role of rebamipide?
Rebamipide exerts a cytoprotective effect by increasing prostaglandin generation in gastric mucosa and scavenging reactive oxygen species.
What does ecabet sodium do?
Ecabet sodium increases the formation of PGE2 and PGI2 and inhibits H. pylori enzymes, preventing bacterial adhesion.
What is Helicobacter pylori and its associated risks?
Helicobacter pylori is a gram-negative rod associated with gastritis and increased risks of gastric and duodenal ulcers, gastric adenocarcinoma, and gastric B-cell lymphoma.
What is the rapid urease test for Helicobacter pylori?
The rapid urease test (CLO test) diagnoses H. pylori by detecting urease enzyme activity, indicated by a color change in the medium.
