Pharmacology -- Antacids, motility and anti-motiliy agents Flashcards
3 treatments for ulcers
- Proton pump inhibitors
- H2 receptor blockers
- Antacids
5 treatable GIT conditions
- Reflux esophagitis
- Peptic ulcers
- Delayed gastric emptying
- Inadequate propulsion of chyme
- Infections and inflammations
How are peptic ulcers formed?
Imbalance favoring the acid pepsin aggression vs. mucosal defense
Describe how helicobacter pylori infection contributes to the formation of peptic ulcers
- Gastrin is a hormone that promotes acid secretion in the stomach
- Ordinarily, increase HCl inhibits the production of gastrin
- H. pylori blocks the inhibition of gastrin and instead allows gastrin to keep increasing stomach pH
5 drug targets in ulcer therapy
- Neutralizing acids with antacids
- H2 receptor blockers (cimetidine, ranitidine)
- M1 M3 blockers (propantheline)
- Adenylyl cyclase inhibitors
- H+/K+ ATPase pump blockers
2 H2 (histamine) receptor blockers
- Cimetidine
- Ranitidine
3 disadvantages of cimetidine
- Short duration of action
- Interaction with p450 enzymes
- Anti-androgenic effects
Alternative to cimetidine
Ranitidine (also an H2 receptor blocker)
3 advantages to using ranitidine as an alternative to cimetidine
- Longer duration of action
- No p450 interactions
- Weaker anti-adrogenic effects
What is emoprazole
An irreversible inactivtor of the H+/K+ pump
Why is it that omeprazole only blocks the H+/K+ pump in the stomach and not anywhere else in the body that needs it?
- Target dependent
- Can only be activated by low pH
- i.e. it is a prodrug activated by low pH
Why is it that many NSAIDs are accompanied by omeprazole?
NSAIDs are known to cause bleeding and ulcers, so omeprazole is used as an adjunct to prevent damage to the stomach due to its long duration of action
Side effect of omeprazole
Gastric mucosal hyperplasia
Possible mechanism for the side effect of omeprazole
Excessive gastrin secretion
Mechanisms of action of antacids
- Neutralization of intragastric HCl
- Increase in intragastric pH
leads to
- Reduction of pepsin activity
Systemic antacid
Sodium bicarbonate
Adverse effect of systemic antacids
Increase in blood pH
3 nonsystemic antacids
- Calcium
- Magnesion
- Aluminum
Problem with nonsystemic antacids
Poorly absorbed
Therapeutic effects of antacids
Effective management of peptic ulcers
Disadvatanges of antacids
- Frequent dosing required
- Disagreeable taste
2 properties of sodium and potassium antacids
- Rapid onset
- Short duration of action